git/Documentation/git-cat-file.txt

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git-cat-file(1)
===============
NAME
----
doc/cat-file: make synopsis and description less confusing The DESCRIPTION's "first form" is actually the 1st, 2nd, 3rd and 5th form in SYNOPSIS, the "second form" is the 4th one. Interestingly, this state of affairs was introduced in 97fe7250753b (cat-file docs: fix SYNOPSIS and "-h" output, 2021-12-28) with the claim of "Now the two will match again." ("the two" being DESCRIPTION and SYNOPSIS)... The description also suffers from other correctness and clarity issues, e.g., the "first form" paragraph discusses -p, -s and -t, but leaves out -e, which is included in the corresponding SYNOPSIS section; the second paragraph mentions <format>, which doesn't occur in SYNOPSIS at all, and of the three batch options, really only describes the behavior of --batch-check. Also the mention of "drivers" seems an implementation detail not adding much clarity in a short summary (and isn't expanded upon in the rest of the man page, either). Rather than trying to maintain one-to-one (or N-to-M) correspondence between the DESCRIPTION and SYNOPSIS forms, creating duplication and providing opportunities for error, shorten the former into a concise summary describing the two general modes of operation: batch and non-batch, leaving details to the subsequent manual sections. While here, fix a grammar error in the description of -e and make the following further minor improvements: NAME: shorten ("content or type and size" isn't the whole story; say "details" and leave the actual details to later sections) SYNOPSIS and --help: move the (--textconv | --filters) form before --batch, closer to the other non-batch forms Signed-off-by: Štěpán Němec <stepnem@smrk.net> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-09 17:56:04 +00:00
git-cat-file - Provide contents or details of repository objects
SYNOPSIS
--------
[verse]
'git cat-file' <type> <object>
'git cat-file' (-e | -p) <object>
'git cat-file' (-t | -s) [--allow-unknown-type] <object>
doc/cat-file: make synopsis and description less confusing The DESCRIPTION's "first form" is actually the 1st, 2nd, 3rd and 5th form in SYNOPSIS, the "second form" is the 4th one. Interestingly, this state of affairs was introduced in 97fe7250753b (cat-file docs: fix SYNOPSIS and "-h" output, 2021-12-28) with the claim of "Now the two will match again." ("the two" being DESCRIPTION and SYNOPSIS)... The description also suffers from other correctness and clarity issues, e.g., the "first form" paragraph discusses -p, -s and -t, but leaves out -e, which is included in the corresponding SYNOPSIS section; the second paragraph mentions <format>, which doesn't occur in SYNOPSIS at all, and of the three batch options, really only describes the behavior of --batch-check. Also the mention of "drivers" seems an implementation detail not adding much clarity in a short summary (and isn't expanded upon in the rest of the man page, either). Rather than trying to maintain one-to-one (or N-to-M) correspondence between the DESCRIPTION and SYNOPSIS forms, creating duplication and providing opportunities for error, shorten the former into a concise summary describing the two general modes of operation: batch and non-batch, leaving details to the subsequent manual sections. While here, fix a grammar error in the description of -e and make the following further minor improvements: NAME: shorten ("content or type and size" isn't the whole story; say "details" and leave the actual details to later sections) SYNOPSIS and --help: move the (--textconv | --filters) form before --batch, closer to the other non-batch forms Signed-off-by: Štěpán Němec <stepnem@smrk.net> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-09 17:56:04 +00:00
'git cat-file' (--textconv | --filters)
[<rev>:<path|tree-ish> | --path=<path|tree-ish> <rev>]
'git cat-file' (--batch | --batch-check | --batch-command) [--batch-all-objects]
[--buffer] [--follow-symlinks] [--unordered]
cat-file: add option '-Z' that delimits input and output with NUL In db9d67f2e9 (builtin/cat-file.c: support NUL-delimited input with `-z`, 2022-07-22), we have introduced a new mode to read the input via NUL-delimited records instead of newline-delimited records. This allows the user to query for revisions that have newlines in their path component. While unusual, such queries are perfectly valid and thus it is clear that we should be able to support them properly. Unfortunately, the commit only changed the input to be NUL-delimited, but didn't change the output at the same time. While this is fine for queries that are processed successfully, it is less so for queries that aren't. In the case of missing commits for example the result can become entirely unparsable: ``` $ printf "7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10\n1234567890\n\n\commit000" | git cat-file --batch -z 7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10 1234567890 commit missing ``` This is of course a crafted query that is intentionally gaming the deficiency, but more benign queries that contain newlines would have similar problems. Ideally, we should have also changed the output to be NUL-delimited when `-z` is specified to avoid this problem. As the input is NUL-delimited, it is clear that the output in this case cannot ever contain NUL characters by itself. Furthermore, Git does not allow NUL characters in revisions anyway, further stressing the point that using NUL-delimited output is safe. The only exception is of course the object data itself, but as git-cat-file(1) prints the size of the object data clients should read until that specified size has been consumed. But even though `-z` has only been introduced a few releases ago in Git v2.38.0, changing the output format retroactively to also NUL-delimit output would be a backwards incompatible change. And while one could make the argument that the output is inherently broken already, we need to assume that there are existing users out there that use it just fine given that revisions containing newlines are quite exotic. Instead, introduce a new option `-Z` that switches to NUL-delimited input and output. While this new option could arguably only switch the output format to be NUL-delimited, the consequence would be that users have to always specify both `-z` and `-Z` when the input may contain newlines. On the other hand, if the user knows that there never will be newlines in the input, they don't have to use either of those options. There is thus no usecase that would warrant treating input and output format separately, which is why we instead opt to "do the right thing" and have `-Z` mean to NUL-terminate both formats. The old `-z` option is marked as deprecated with a hint that its output may become unparsable. It is thus hidden both from the synopsis as well as the command's help output. Co-authored-by: Toon Claes <toon@iotcl.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-06 05:19:45 +00:00
[--textconv | --filters] [-Z]
DESCRIPTION
-----------
doc/cat-file: make synopsis and description less confusing The DESCRIPTION's "first form" is actually the 1st, 2nd, 3rd and 5th form in SYNOPSIS, the "second form" is the 4th one. Interestingly, this state of affairs was introduced in 97fe7250753b (cat-file docs: fix SYNOPSIS and "-h" output, 2021-12-28) with the claim of "Now the two will match again." ("the two" being DESCRIPTION and SYNOPSIS)... The description also suffers from other correctness and clarity issues, e.g., the "first form" paragraph discusses -p, -s and -t, but leaves out -e, which is included in the corresponding SYNOPSIS section; the second paragraph mentions <format>, which doesn't occur in SYNOPSIS at all, and of the three batch options, really only describes the behavior of --batch-check. Also the mention of "drivers" seems an implementation detail not adding much clarity in a short summary (and isn't expanded upon in the rest of the man page, either). Rather than trying to maintain one-to-one (or N-to-M) correspondence between the DESCRIPTION and SYNOPSIS forms, creating duplication and providing opportunities for error, shorten the former into a concise summary describing the two general modes of operation: batch and non-batch, leaving details to the subsequent manual sections. While here, fix a grammar error in the description of -e and make the following further minor improvements: NAME: shorten ("content or type and size" isn't the whole story; say "details" and leave the actual details to later sections) SYNOPSIS and --help: move the (--textconv | --filters) form before --batch, closer to the other non-batch forms Signed-off-by: Štěpán Němec <stepnem@smrk.net> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-09 17:56:04 +00:00
Output the contents or other properties such as size, type or delta
information of one or more objects.
This command can operate in two modes, depending on whether an option
from the `--batch` family is specified.
In non-batch mode, the command provides information on an object
named on the command line.
doc/cat-file: make synopsis and description less confusing The DESCRIPTION's "first form" is actually the 1st, 2nd, 3rd and 5th form in SYNOPSIS, the "second form" is the 4th one. Interestingly, this state of affairs was introduced in 97fe7250753b (cat-file docs: fix SYNOPSIS and "-h" output, 2021-12-28) with the claim of "Now the two will match again." ("the two" being DESCRIPTION and SYNOPSIS)... The description also suffers from other correctness and clarity issues, e.g., the "first form" paragraph discusses -p, -s and -t, but leaves out -e, which is included in the corresponding SYNOPSIS section; the second paragraph mentions <format>, which doesn't occur in SYNOPSIS at all, and of the three batch options, really only describes the behavior of --batch-check. Also the mention of "drivers" seems an implementation detail not adding much clarity in a short summary (and isn't expanded upon in the rest of the man page, either). Rather than trying to maintain one-to-one (or N-to-M) correspondence between the DESCRIPTION and SYNOPSIS forms, creating duplication and providing opportunities for error, shorten the former into a concise summary describing the two general modes of operation: batch and non-batch, leaving details to the subsequent manual sections. While here, fix a grammar error in the description of -e and make the following further minor improvements: NAME: shorten ("content or type and size" isn't the whole story; say "details" and leave the actual details to later sections) SYNOPSIS and --help: move the (--textconv | --filters) form before --batch, closer to the other non-batch forms Signed-off-by: Štěpán Němec <stepnem@smrk.net> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-09 17:56:04 +00:00
In batch mode, arguments are read from standard input.
OPTIONS
-------
<object>::
The name of the object to show.
For a more complete list of ways to spell object names, see
the "SPECIFYING REVISIONS" section in linkgit:gitrevisions[7].
-t::
Instead of the content, show the object type identified by
`<object>`.
-s::
Instead of the content, show the object size identified by
`<object>`. If used with `--use-mailmap` option, will show
the size of updated object after replacing idents using the
mailmap mechanism.
-e::
Exit with zero status if `<object>` exists and is a valid
doc/cat-file: make synopsis and description less confusing The DESCRIPTION's "first form" is actually the 1st, 2nd, 3rd and 5th form in SYNOPSIS, the "second form" is the 4th one. Interestingly, this state of affairs was introduced in 97fe7250753b (cat-file docs: fix SYNOPSIS and "-h" output, 2021-12-28) with the claim of "Now the two will match again." ("the two" being DESCRIPTION and SYNOPSIS)... The description also suffers from other correctness and clarity issues, e.g., the "first form" paragraph discusses -p, -s and -t, but leaves out -e, which is included in the corresponding SYNOPSIS section; the second paragraph mentions <format>, which doesn't occur in SYNOPSIS at all, and of the three batch options, really only describes the behavior of --batch-check. Also the mention of "drivers" seems an implementation detail not adding much clarity in a short summary (and isn't expanded upon in the rest of the man page, either). Rather than trying to maintain one-to-one (or N-to-M) correspondence between the DESCRIPTION and SYNOPSIS forms, creating duplication and providing opportunities for error, shorten the former into a concise summary describing the two general modes of operation: batch and non-batch, leaving details to the subsequent manual sections. While here, fix a grammar error in the description of -e and make the following further minor improvements: NAME: shorten ("content or type and size" isn't the whole story; say "details" and leave the actual details to later sections) SYNOPSIS and --help: move the (--textconv | --filters) form before --batch, closer to the other non-batch forms Signed-off-by: Štěpán Němec <stepnem@smrk.net> Acked-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-10-09 17:56:04 +00:00
object. If `<object>` is of an invalid format, exit with non-zero
status and emit an error on stderr.
-p::
Pretty-print the contents of `<object>` based on its type.
<type>::
Typically this matches the real type of `<object>` but asking
for a type that can trivially be dereferenced from the given
`<object>` is also permitted. An example is to ask for a
"tree" with `<object>` being a commit object that contains it,
or to ask for a "blob" with `<object>` being a tag object that
points at it.
--[no-]mailmap::
--[no-]use-mailmap::
Use mailmap file to map author, committer and tagger names
and email addresses to canonical real names and email addresses.
See linkgit:git-shortlog[1].
--textconv::
Show the content as transformed by a textconv filter. In this case,
`<object>` has to be of the form `<tree-ish>:<path>`, or `:<path>` in
order to apply the filter to the content recorded in the index at
`<path>`.
--filters::
Show the content as converted by the filters configured in
the current working tree for the given `<path>` (i.e. smudge filters,
end-of-line conversion, etc). In this case, `<object>` has to be of
the form `<tree-ish>:<path>`, or `:<path>`.
--path=<path>::
For use with `--textconv` or `--filters`, to allow specifying an object
name and a path separately, e.g. when it is difficult to figure out
the revision from which the blob came.
--batch::
--batch=<format>::
Print object information and contents for each object provided
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
on stdin. May not be combined with any other options or arguments
except `--textconv`, `--filters`, or `--use-mailmap`.
+
--
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
* When used with `--textconv` or `--filters`, the input lines
must specify the path, separated by whitespace. See the section
`BATCH OUTPUT` below for details.
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
* When used with `--use-mailmap`, for commit and tag objects, the
contents part of the output shows the identities replaced using the
mailmap mechanism, while the information part of the output shows
the size of the object as if it actually recorded the replacement
identities.
--
--batch-check::
--batch-check=<format>::
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
Print object information for each object provided on stdin. May not be
combined with any other options or arguments except `--textconv`, `--filters`
or `--use-mailmap`.
+
--
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
* When used with `--textconv` or `--filters`, the input lines must
specify the path, separated by whitespace. See the section
`BATCH OUTPUT` below for details.
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
* When used with `--use-mailmap`, for commit and tag objects, the
printed object information shows the size of the object as if the
identities recorded in it were replaced by the mailmap mechanism.
--
cat-file: add --batch-command mode Add a new flag --batch-command that accepts commands and arguments from stdin, similar to git-update-ref --stdin. At GitLab, we use a pair of long running cat-file processes when accessing object content. One for iterating over object metadata with --batch-check, and the other to grab object contents with --batch. However, if we had --batch-command, we wouldn't need to keep both processes around, and instead just have one --batch-command process where we can flip between getting object info, and getting object contents. Since we have a pair of cat-file processes per repository, this means we can get rid of roughly half of long lived git cat-file processes. Given there are many repositories being accessed at any given time, this can lead to huge savings. git cat-file --batch-command will enter an interactive command mode whereby the user can enter in commands and their arguments that get queued in memory: <command1> [arg1] [arg2] LF <command2> [arg1] [arg2] LF When --buffer mode is used, commands will be queued in memory until a flush command is issued that execute them: flush LF The reason for a flush command is that when a consumer process (A) talks to a git cat-file process (B) and interactively writes to and reads from it in --buffer mode, (A) needs to be able to control when the buffer is flushed to stdout. Currently, from (A)'s perspective, the only way is to either 1. kill (B)'s process 2. send an invalid object to stdin. 1. is not ideal from a performance perspective as it will require spawning a new cat-file process each time, and 2. is hacky and not a good long term solution. With this mechanism of queueing up commands and letting (A) issue a flush command, process (A) can control when the buffer is flushed and can guarantee it will receive all of the output when in --buffer mode. --batch-command also will not allow (B) to flush to stdout until a flush is received. This patch adds the basic structure for adding command which can be extended in the future to add more commands. It also adds the following two commands (on top of the flush command): contents <object> LF info <object> LF The contents command takes an <object> argument and prints out the object contents. The info command takes an <object> argument and prints out the object metadata. These can be used in the following way with --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF flush LF info <object> LF flush LF When used without --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF info <object> LF Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: John Cai <johncai86@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-18 18:23:14 +00:00
--batch-command::
--batch-command=<format>::
Enter a command mode that reads commands and arguments from stdin. May
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
only be combined with `--buffer`, `--textconv`, `--use-mailmap` or
`--filters`.
+
--
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
* When used with `--textconv` or `--filters`, the input lines must
specify the path, separated by whitespace. See the section
`BATCH OUTPUT` below for details.
cat-file: add mailmap support to --batch-check option Even though the cat-file command with `--batch-check` option does not complain when `--use-mailmap` option is given, the latter option is ignored. Compute the size of the object after replacing the idents and report it instead. In order to make `--batch-check` option honour the mailmap mechanism we have to read the contents of the commit/tag object. There were two ways to do it: 1. Make two calls to `oid_object_info_extended()`. If `--use-mailmap` option is given, the first call will get us the type of the object and second call will only be made if the object type is either a commit or tag to get the contents of the object. 2. Make one call to `oid_object_info_extended()` to get the type of the object. Then, if the object type is either of commit or tag, make a call to `repo_read_object_file()` to read the contents of the object. I benchmarked the following command with both the above approaches and compared against the current implementation where `--use-mailmap` option is ignored: `git cat-file --use-mailmap --batch-all-objects --batch-check --buffer --unordered` The results can be summarized as follows: Time (mean ± σ) default 827.7 ms ± 104.8 ms first approach 6.197 s ± 0.093 s second approach 1.975 s ± 0.217 s Since, the second approach is faster than the first one, I implemented it in this patch. The command git cat-file can now use the mailmap mechanism to replace idents with canonical versions for commit and tag objects. There are several options like `--batch`, `--batch-check` and `--batch-command` that can be combined with `--use-mailmap`. But the documentation for `--batch`, `--batch-check` and `--batch-command` doesn't say so. This patch fixes that documentation. Mentored-by: Christian Couder <christian.couder@gmail.com> Mentored-by: John Cai <johncai86@gmail.com> Helped-by: Taylor Blau <me@ttaylorr.com> Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Siddharth Asthana <siddharthasthana31@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-20 06:01:13 +00:00
* When used with `--use-mailmap`, for commit and tag objects, the
`contents` command shows the identities replaced using the
mailmap mechanism, while the `info` command shows the size
of the object as if it actually recorded the replacement
identities.
--
cat-file: add --batch-command mode Add a new flag --batch-command that accepts commands and arguments from stdin, similar to git-update-ref --stdin. At GitLab, we use a pair of long running cat-file processes when accessing object content. One for iterating over object metadata with --batch-check, and the other to grab object contents with --batch. However, if we had --batch-command, we wouldn't need to keep both processes around, and instead just have one --batch-command process where we can flip between getting object info, and getting object contents. Since we have a pair of cat-file processes per repository, this means we can get rid of roughly half of long lived git cat-file processes. Given there are many repositories being accessed at any given time, this can lead to huge savings. git cat-file --batch-command will enter an interactive command mode whereby the user can enter in commands and their arguments that get queued in memory: <command1> [arg1] [arg2] LF <command2> [arg1] [arg2] LF When --buffer mode is used, commands will be queued in memory until a flush command is issued that execute them: flush LF The reason for a flush command is that when a consumer process (A) talks to a git cat-file process (B) and interactively writes to and reads from it in --buffer mode, (A) needs to be able to control when the buffer is flushed to stdout. Currently, from (A)'s perspective, the only way is to either 1. kill (B)'s process 2. send an invalid object to stdin. 1. is not ideal from a performance perspective as it will require spawning a new cat-file process each time, and 2. is hacky and not a good long term solution. With this mechanism of queueing up commands and letting (A) issue a flush command, process (A) can control when the buffer is flushed and can guarantee it will receive all of the output when in --buffer mode. --batch-command also will not allow (B) to flush to stdout until a flush is received. This patch adds the basic structure for adding command which can be extended in the future to add more commands. It also adds the following two commands (on top of the flush command): contents <object> LF info <object> LF The contents command takes an <object> argument and prints out the object contents. The info command takes an <object> argument and prints out the object metadata. These can be used in the following way with --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF flush LF info <object> LF flush LF When used without --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF info <object> LF Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: John Cai <johncai86@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-18 18:23:14 +00:00
+
`--batch-command` recognizes the following commands:
+
--
contents <object>::
Print object contents for object reference `<object>`. This corresponds to
the output of `--batch`.
info <object>::
Print object info for object reference `<object>`. This corresponds to the
output of `--batch-check`.
flush::
Used with `--buffer` to execute all preceding commands that were issued
since the beginning or since the last flush was issued. When `--buffer`
is used, no output will come until a `flush` is issued. When `--buffer`
is not used, commands are flushed each time without issuing `flush`.
--
+
2015-06-22 10:45:59 +00:00
--batch-all-objects::
Instead of reading a list of objects on stdin, perform the
requested batch operation on all objects in the repository and
any alternate object stores (not just reachable objects).
Requires `--batch` or `--batch-check` be specified. By default,
the objects are visited in order sorted by their hashes; see
cat-file: disable refs/replace with --batch-all-objects When we're enumerating all objects in the object database, it doesn't make sense to respect refs/replace. The point of this option is to enumerate all of the objects in the database at a low level. By definition we'd already show the replacement object's contents (under its real oid), and showing those contents under another oid is almost certainly working against what the user is trying to do. Note that you could make the same argument for something like: git show-index <foo.idx | awk '{print $2}' | git cat-file --batch but there we can't know in cat-file exactly what the user intended, because we don't know the source of the input. They could be trying to do low-level debugging, or they could be doing something more high-level (e.g., imagine a porcelain built around cat-file for its object accesses). So in those cases, we'll have to rely on the user specifying "git --no-replace-objects" to tell us what to do. One _could_ make an argument that "cat-file --batch" is sufficiently low-level plumbing that it should not respect replace-objects at all (and the caller should do any replacement if they want it). But we have been doing so for some time. The history is a little tangled: - looking back as far as v1.6.6, we would not respect replace refs for --batch-check, but would for --batch (because the former used sha1_object_info(), and the replace mechanism only affected actual object reads) - this discrepancy was made even weirder by 98e2092b50 (cat-file: teach --batch to stream blob objects, 2013-07-10), where we always output the header using the --batch-check code, and then printed the object separately. This could lead to "cat-file --batch" dying (when it notices the size or type changed for a non-blob object) or even producing bogus output (in streaming mode, we didn't notice that we wrote the wrong number of bytes). - that persisted until 1f7117ef7a (sha1_file: perform object replacement in sha1_object_info_extended(), 2013-12-11), which then respected replace refs for both forms. So it has worked reliably this way for over 7 years, and we should make sure it continues to do so. That could also be an argument that --batch-all-objects should not change behavior (which this patch is doing), but I really consider the current behavior to be an unintended bug. It's a side effect of how the code is implemented (feeding the oids back into oid_object_info() rather than looking at what we found while reading the loose and packed object storage). The implementation is straight-forward: we just disable the global read_replace_refs flag when we're in --batch-all-objects mode. It would perhaps be a little cleaner to change the flag we pass to oid_object_info_extended(), but that's not enough. We also read objects via read_object_file() and stream_blob_to_fd(). The former could switch to its _extended() form, but the streaming code has no mechanism for disabling replace refs. Setting the global flag works, and as a bonus, it's impossible to have any "oops, we're sometimes replacing the object and sometimes not" bugs in the output (like the ones caused by 98e2092b50 above). The tests here cover the regular-input and --batch-all-objects cases, for both --batch-check and --batch. There is a test in t6050 that covers the regular-input case with --batch already, but this new one goes much further in actually verifying the output (plus covering --batch-check explicitly). This is perhaps a little overkill and the tests would be simpler just covering --batch-check, but I wanted to make sure we're checking that --batch output is consistent between the header and the content. The global-flag technique used here makes that easy to get right, but this is future-proofing us against regressions. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-05 20:36:07 +00:00
also `--unordered` below. Objects are presented as-is, without
respecting the "replace" mechanism of linkgit:git-replace[1].
2015-06-22 10:45:59 +00:00
--buffer::
Normally batch output is flushed after each object is output, so
that a process can interactively read and write from
`cat-file`. With this option, the output uses normal stdio
buffering; this is much more efficient when invoking
cat-file: add --batch-command mode Add a new flag --batch-command that accepts commands and arguments from stdin, similar to git-update-ref --stdin. At GitLab, we use a pair of long running cat-file processes when accessing object content. One for iterating over object metadata with --batch-check, and the other to grab object contents with --batch. However, if we had --batch-command, we wouldn't need to keep both processes around, and instead just have one --batch-command process where we can flip between getting object info, and getting object contents. Since we have a pair of cat-file processes per repository, this means we can get rid of roughly half of long lived git cat-file processes. Given there are many repositories being accessed at any given time, this can lead to huge savings. git cat-file --batch-command will enter an interactive command mode whereby the user can enter in commands and their arguments that get queued in memory: <command1> [arg1] [arg2] LF <command2> [arg1] [arg2] LF When --buffer mode is used, commands will be queued in memory until a flush command is issued that execute them: flush LF The reason for a flush command is that when a consumer process (A) talks to a git cat-file process (B) and interactively writes to and reads from it in --buffer mode, (A) needs to be able to control when the buffer is flushed to stdout. Currently, from (A)'s perspective, the only way is to either 1. kill (B)'s process 2. send an invalid object to stdin. 1. is not ideal from a performance perspective as it will require spawning a new cat-file process each time, and 2. is hacky and not a good long term solution. With this mechanism of queueing up commands and letting (A) issue a flush command, process (A) can control when the buffer is flushed and can guarantee it will receive all of the output when in --buffer mode. --batch-command also will not allow (B) to flush to stdout until a flush is received. This patch adds the basic structure for adding command which can be extended in the future to add more commands. It also adds the following two commands (on top of the flush command): contents <object> LF info <object> LF The contents command takes an <object> argument and prints out the object contents. The info command takes an <object> argument and prints out the object metadata. These can be used in the following way with --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF flush LF info <object> LF flush LF When used without --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF info <object> LF Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: John Cai <johncai86@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-18 18:23:14 +00:00
`--batch-check` or `--batch-command` on a large number of objects.
cat-file: support "unordered" output for --batch-all-objects If you're going to access the contents of every object in a packfile, it's generally much more efficient to do so in pack order, rather than in hash order. That increases the locality of access within the packfile, which in turn is friendlier to the delta base cache, since the packfile puts related deltas next to each other. By contrast, hash order is effectively random, since the sha1 has no discernible relationship to the content. This patch introduces an "--unordered" option to cat-file which iterates over packs in pack-order under the hood. You can see the results when dumping all of the file content: $ time ./git cat-file --batch-all-objects --buffer --batch | wc -c 6883195596 real 0m44.491s user 0m42.902s sys 0m5.230s $ time ./git cat-file --unordered \ --batch-all-objects --buffer --batch | wc -c 6883195596 real 0m6.075s user 0m4.774s sys 0m3.548s Same output, different order, way faster. The same speed-up applies even if you end up accessing the object content in a different process, like: git cat-file --batch-all-objects --buffer --batch-check | grep blob | git cat-file --batch='%(objectname) %(rest)' | wc -c Adding "--unordered" to the first command drops the runtime in git.git from 24s to 3.5s. Side note: there are actually further speedups available for doing it all in-process now. Since we are outputting the object content during the actual pack iteration, we know where to find the object and could skip the extra lookup done by oid_object_info(). This patch stops short of that optimization since the underlying API isn't ready for us to make those sorts of direct requests. So if --unordered is so much better, why not make it the default? Two reasons: 1. We've promised in the documentation that --batch-all-objects outputs in hash order. Since cat-file is plumbing, people may be relying on that default, and we can't change it. 2. It's actually _slower_ for some cases. We have to compute the pack revindex to walk in pack order. And our de-duplication step uses an oidset, rather than a sort-and-dedup, which can end up being more expensive. If we're just accessing the type and size of each object, for example, like: git cat-file --batch-all-objects --buffer --batch-check my best-of-five warm cache timings go from 900ms to 1100ms using --unordered. Though it's possible in a cold-cache or under memory pressure that we could do better, since we'd have better locality within the packfile. And one final question: why is it "--unordered" and not "--pack-order"? The answer is again two-fold: 1. "pack order" isn't a well-defined thing across the whole set of objects. We're hitting loose objects, as well as objects in multiple packs, and the only ordering we're promising is _within_ a single pack. The rest is apparently random. 2. The point here is optimization. So we don't want to promise any particular ordering, but only to say that we will choose an ordering which is likely to be efficient for accessing the object content. That leaves the door open for further changes in the future without having to add another compatibility option. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-10 23:24:57 +00:00
--unordered::
When `--batch-all-objects` is in use, visit objects in an
order which may be more efficient for accessing the object
contents than hash order. The exact details of the order are
unspecified, but if you do not require a specific order, this
should generally result in faster output, especially with
`--batch`. Note that `cat-file` will still show each object
only once, even if it is stored multiple times in the
repository.
--allow-unknown-type::
Allow `-s` or `-t` to query broken/corrupt objects of unknown type.
--follow-symlinks::
With `--batch` or `--batch-check`, follow symlinks inside the
repository when requesting objects with extended SHA-1
expressions of the form tree-ish:path-in-tree. Instead of
providing output about the link itself, provide output about
the linked-to object. If a symlink points outside the
tree-ish (e.g. a link to `/foo` or a root-level link to `../foo`),
the portion of the link which is outside the tree will be
printed.
+
This option does not (currently) work correctly when an object in the
index is specified (e.g. `:link` instead of `HEAD:link`) rather than
one in the tree.
+
This option cannot (currently) be used unless `--batch` or
`--batch-check` is used.
+
For example, consider a git repository containing:
+
--
f: a file containing "hello\n"
link: a symlink to f
dir/link: a symlink to ../f
plink: a symlink to ../f
alink: a symlink to /etc/passwd
--
+
For a regular file `f`, `echo HEAD:f | git cat-file --batch` would print
+
--
ce013625030ba8dba906f756967f9e9ca394464a blob 6
--
+
And `echo HEAD:link | git cat-file --batch --follow-symlinks` would
print the same thing, as would `HEAD:dir/link`, as they both point at
`HEAD:f`.
+
Without `--follow-symlinks`, these would print data about the symlink
itself. In the case of `HEAD:link`, you would see
+
--
4d1ae35ba2c8ec712fa2a379db44ad639ca277bd blob 1
--
+
Both `plink` and `alink` point outside the tree, so they would
respectively print:
+
--
symlink 4
../f
symlink 11
/etc/passwd
--
cat-file: add option '-Z' that delimits input and output with NUL In db9d67f2e9 (builtin/cat-file.c: support NUL-delimited input with `-z`, 2022-07-22), we have introduced a new mode to read the input via NUL-delimited records instead of newline-delimited records. This allows the user to query for revisions that have newlines in their path component. While unusual, such queries are perfectly valid and thus it is clear that we should be able to support them properly. Unfortunately, the commit only changed the input to be NUL-delimited, but didn't change the output at the same time. While this is fine for queries that are processed successfully, it is less so for queries that aren't. In the case of missing commits for example the result can become entirely unparsable: ``` $ printf "7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10\n1234567890\n\n\commit000" | git cat-file --batch -z 7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10 1234567890 commit missing ``` This is of course a crafted query that is intentionally gaming the deficiency, but more benign queries that contain newlines would have similar problems. Ideally, we should have also changed the output to be NUL-delimited when `-z` is specified to avoid this problem. As the input is NUL-delimited, it is clear that the output in this case cannot ever contain NUL characters by itself. Furthermore, Git does not allow NUL characters in revisions anyway, further stressing the point that using NUL-delimited output is safe. The only exception is of course the object data itself, but as git-cat-file(1) prints the size of the object data clients should read until that specified size has been consumed. But even though `-z` has only been introduced a few releases ago in Git v2.38.0, changing the output format retroactively to also NUL-delimit output would be a backwards incompatible change. And while one could make the argument that the output is inherently broken already, we need to assume that there are existing users out there that use it just fine given that revisions containing newlines are quite exotic. Instead, introduce a new option `-Z` that switches to NUL-delimited input and output. While this new option could arguably only switch the output format to be NUL-delimited, the consequence would be that users have to always specify both `-z` and `-Z` when the input may contain newlines. On the other hand, if the user knows that there never will be newlines in the input, they don't have to use either of those options. There is thus no usecase that would warrant treating input and output format separately, which is why we instead opt to "do the right thing" and have `-Z` mean to NUL-terminate both formats. The old `-z` option is marked as deprecated with a hint that its output may become unparsable. It is thus hidden both from the synopsis as well as the command's help output. Co-authored-by: Toon Claes <toon@iotcl.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-06 05:19:45 +00:00
-Z::
Only meaningful with `--batch`, `--batch-check`, or
`--batch-command`; input and output is NUL-delimited instead of
newline-delimited.
builtin/cat-file.c: support NUL-delimited input with `-z` When callers are using `cat-file` via one of the stdin-driven `--batch` modes, all input is newline-delimited. This presents a problem when callers wish to ask about, e.g. tree-entries that have a newline character present in their filename. To support this niche scenario, introduce a new `-z` mode to the `--batch`, `--batch-check`, and `--batch-command` suite of options that instructs `cat-file` to treat its input as NUL-delimited, allowing the individual commands themselves to have newlines present. The refactoring here is slightly unfortunate, since we turn loops like: while (strbuf_getline(&buf, stdin) != EOF) into: while (1) { int ret; if (opt->nul_terminated) ret = strbuf_getline_nul(&input, stdin); else ret = strbuf_getline(&input, stdin); if (ret == EOF) break; } It's tempting to think that we could use `strbuf_getwholeline()` and specify either `\n` or `\0` as the terminating character. But for input on platforms that include a CR character preceeding the LF, this wouldn't quite be the same, since `strbuf_getline(...)` will trim any trailing CR, while `strbuf_getwholeline(&buf, stdin, '\n')` will not. In the future, we could clean this up further by introducing a variant of `strbuf_getwholeline()` that addresses the aforementioned gap, but that approach felt too heavy-handed for this pair of uses. Some tests are added in t1006 to ensure that `cat-file` produces the same output in `--batch`, `--batch-check`, and `--batch-command` modes with and without the new `-z` option. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-07-22 23:29:05 +00:00
-z::
Only meaningful with `--batch`, `--batch-check`, or
`--batch-command`; input is NUL-delimited instead of
cat-file: add option '-Z' that delimits input and output with NUL In db9d67f2e9 (builtin/cat-file.c: support NUL-delimited input with `-z`, 2022-07-22), we have introduced a new mode to read the input via NUL-delimited records instead of newline-delimited records. This allows the user to query for revisions that have newlines in their path component. While unusual, such queries are perfectly valid and thus it is clear that we should be able to support them properly. Unfortunately, the commit only changed the input to be NUL-delimited, but didn't change the output at the same time. While this is fine for queries that are processed successfully, it is less so for queries that aren't. In the case of missing commits for example the result can become entirely unparsable: ``` $ printf "7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10\n1234567890\n\n\commit000" | git cat-file --batch -z 7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10 1234567890 commit missing ``` This is of course a crafted query that is intentionally gaming the deficiency, but more benign queries that contain newlines would have similar problems. Ideally, we should have also changed the output to be NUL-delimited when `-z` is specified to avoid this problem. As the input is NUL-delimited, it is clear that the output in this case cannot ever contain NUL characters by itself. Furthermore, Git does not allow NUL characters in revisions anyway, further stressing the point that using NUL-delimited output is safe. The only exception is of course the object data itself, but as git-cat-file(1) prints the size of the object data clients should read until that specified size has been consumed. But even though `-z` has only been introduced a few releases ago in Git v2.38.0, changing the output format retroactively to also NUL-delimit output would be a backwards incompatible change. And while one could make the argument that the output is inherently broken already, we need to assume that there are existing users out there that use it just fine given that revisions containing newlines are quite exotic. Instead, introduce a new option `-Z` that switches to NUL-delimited input and output. While this new option could arguably only switch the output format to be NUL-delimited, the consequence would be that users have to always specify both `-z` and `-Z` when the input may contain newlines. On the other hand, if the user knows that there never will be newlines in the input, they don't have to use either of those options. There is thus no usecase that would warrant treating input and output format separately, which is why we instead opt to "do the right thing" and have `-Z` mean to NUL-terminate both formats. The old `-z` option is marked as deprecated with a hint that its output may become unparsable. It is thus hidden both from the synopsis as well as the command's help output. Co-authored-by: Toon Claes <toon@iotcl.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-06 05:19:45 +00:00
newline-delimited. This option is deprecated in favor of
`-Z` as the output can otherwise be ambiguous.
builtin/cat-file.c: support NUL-delimited input with `-z` When callers are using `cat-file` via one of the stdin-driven `--batch` modes, all input is newline-delimited. This presents a problem when callers wish to ask about, e.g. tree-entries that have a newline character present in their filename. To support this niche scenario, introduce a new `-z` mode to the `--batch`, `--batch-check`, and `--batch-command` suite of options that instructs `cat-file` to treat its input as NUL-delimited, allowing the individual commands themselves to have newlines present. The refactoring here is slightly unfortunate, since we turn loops like: while (strbuf_getline(&buf, stdin) != EOF) into: while (1) { int ret; if (opt->nul_terminated) ret = strbuf_getline_nul(&input, stdin); else ret = strbuf_getline(&input, stdin); if (ret == EOF) break; } It's tempting to think that we could use `strbuf_getwholeline()` and specify either `\n` or `\0` as the terminating character. But for input on platforms that include a CR character preceeding the LF, this wouldn't quite be the same, since `strbuf_getline(...)` will trim any trailing CR, while `strbuf_getwholeline(&buf, stdin, '\n')` will not. In the future, we could clean this up further by introducing a variant of `strbuf_getwholeline()` that addresses the aforementioned gap, but that approach felt too heavy-handed for this pair of uses. Some tests are added in t1006 to ensure that `cat-file` produces the same output in `--batch`, `--batch-check`, and `--batch-command` modes with and without the new `-z` option. Signed-off-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-07-22 23:29:05 +00:00
OUTPUT
------
If `-t` is specified, one of the `<type>`.
If `-s` is specified, the size of the `<object>` in bytes.
If `-e` is specified, no output, unless the `<object>` is malformed.
If `-p` is specified, the contents of `<object>` are pretty-printed.
If `<type>` is specified, the raw (though uncompressed) contents of the `<object>`
will be returned.
BATCH OUTPUT
------------
If `--batch` or `--batch-check` is given, `cat-file` will read objects
cat-file: only split on whitespace when %(rest) is used Commit c334b87b (cat-file: split --batch input lines on whitespace, 2013-07-11) taught `cat-file --batch-check` to split input lines on the first whitespace, and stash everything after the first token into the %(rest) output format element. It claimed: Object names cannot contain spaces, so any input with spaces would have resulted in a "missing" line. But that is not correct. Refs, object sha1s, and various peeling suffixes cannot contain spaces, but some object names can. In particular: 1. Tree paths like "[<tree>]:path with whitespace" 2. Reflog specifications like "@{2 days ago}" 3. Commit searches like "rev^{/grep me}" or ":/grep me" To remain backwards compatible, we cannot split on whitespace by default, hence we will ship 1.8.4 with the commit reverted. Resurrect its attempt but in a weaker form; only do the splitting when "%(rest)" is used in the output format. Since that element did not exist at all before c334b87, old scripts cannot be affected. The existence of object names with spaces does mean that you cannot reliably do: echo ":path with space and other data" | git cat-file --batch-check="%(objectname) %(rest)" as it would split the path and feed only ":path" to get_sha1. But that command is nonsensical. If you wanted to see "and other data" in "%(rest)", git cannot possibly know where the filename ends and the "rest" begins. It might be more robust to have something like "-z" to separate the input elements. But this patch is still a reasonable step before having that. It makes the easy cases easy; people who do not care about %(rest) do not have to consider it, and the %(rest) code handles the spaces and newlines of "rev-list --objects" correctly. Hard cases remain hard but possible (if you might get whitespace in your input, you do not get to use %(rest) and must split and join the output yourself using more flexible tools). And most importantly, it does not preclude us from having different splitting rules later if a "-z" (or similar) option is added. So we can make the hard cases easier later, if we choose to. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-08-02 11:59:07 +00:00
from stdin, one per line, and print information about them. By default,
the whole line is considered as an object, as if it were fed to
linkgit:git-rev-parse[1].
cat-file: add --batch-command mode Add a new flag --batch-command that accepts commands and arguments from stdin, similar to git-update-ref --stdin. At GitLab, we use a pair of long running cat-file processes when accessing object content. One for iterating over object metadata with --batch-check, and the other to grab object contents with --batch. However, if we had --batch-command, we wouldn't need to keep both processes around, and instead just have one --batch-command process where we can flip between getting object info, and getting object contents. Since we have a pair of cat-file processes per repository, this means we can get rid of roughly half of long lived git cat-file processes. Given there are many repositories being accessed at any given time, this can lead to huge savings. git cat-file --batch-command will enter an interactive command mode whereby the user can enter in commands and their arguments that get queued in memory: <command1> [arg1] [arg2] LF <command2> [arg1] [arg2] LF When --buffer mode is used, commands will be queued in memory until a flush command is issued that execute them: flush LF The reason for a flush command is that when a consumer process (A) talks to a git cat-file process (B) and interactively writes to and reads from it in --buffer mode, (A) needs to be able to control when the buffer is flushed to stdout. Currently, from (A)'s perspective, the only way is to either 1. kill (B)'s process 2. send an invalid object to stdin. 1. is not ideal from a performance perspective as it will require spawning a new cat-file process each time, and 2. is hacky and not a good long term solution. With this mechanism of queueing up commands and letting (A) issue a flush command, process (A) can control when the buffer is flushed and can guarantee it will receive all of the output when in --buffer mode. --batch-command also will not allow (B) to flush to stdout until a flush is received. This patch adds the basic structure for adding command which can be extended in the future to add more commands. It also adds the following two commands (on top of the flush command): contents <object> LF info <object> LF The contents command takes an <object> argument and prints out the object contents. The info command takes an <object> argument and prints out the object metadata. These can be used in the following way with --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF flush LF info <object> LF flush LF When used without --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF info <object> LF Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: John Cai <johncai86@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-18 18:23:14 +00:00
When `--batch-command` is given, `cat-file` will read commands from stdin,
one per line, and print information based on the command given. With
`--batch-command`, the `info` command followed by an object will print
information about the object the same way `--batch-check` would, and the
`contents` command followed by an object prints contents in the same way
`--batch` would.
You can specify the information shown for each object by using a custom
`<format>`. The `<format>` is copied literally to stdout for each
object, with placeholders of the form `%(atom)` expanded, followed by a
newline. The available atoms are:
`objectname`::
The full hex representation of the object name.
`objecttype`::
The type of the object (the same as `cat-file -t` reports).
`objectsize`::
The size, in bytes, of the object (the same as `cat-file -s`
reports).
`objectsize:disk`::
The size, in bytes, that the object takes up on disk. See the
note about on-disk sizes in the `CAVEATS` section below.
`deltabase`::
If the object is stored as a delta on-disk, this expands to the
full hex representation of the delta base object name.
Otherwise, expands to the null OID (all zeroes). See `CAVEATS`
below.
cat-file: only split on whitespace when %(rest) is used Commit c334b87b (cat-file: split --batch input lines on whitespace, 2013-07-11) taught `cat-file --batch-check` to split input lines on the first whitespace, and stash everything after the first token into the %(rest) output format element. It claimed: Object names cannot contain spaces, so any input with spaces would have resulted in a "missing" line. But that is not correct. Refs, object sha1s, and various peeling suffixes cannot contain spaces, but some object names can. In particular: 1. Tree paths like "[<tree>]:path with whitespace" 2. Reflog specifications like "@{2 days ago}" 3. Commit searches like "rev^{/grep me}" or ":/grep me" To remain backwards compatible, we cannot split on whitespace by default, hence we will ship 1.8.4 with the commit reverted. Resurrect its attempt but in a weaker form; only do the splitting when "%(rest)" is used in the output format. Since that element did not exist at all before c334b87, old scripts cannot be affected. The existence of object names with spaces does mean that you cannot reliably do: echo ":path with space and other data" | git cat-file --batch-check="%(objectname) %(rest)" as it would split the path and feed only ":path" to get_sha1. But that command is nonsensical. If you wanted to see "and other data" in "%(rest)", git cannot possibly know where the filename ends and the "rest" begins. It might be more robust to have something like "-z" to separate the input elements. But this patch is still a reasonable step before having that. It makes the easy cases easy; people who do not care about %(rest) do not have to consider it, and the %(rest) code handles the spaces and newlines of "rev-list --objects" correctly. Hard cases remain hard but possible (if you might get whitespace in your input, you do not get to use %(rest) and must split and join the output yourself using more flexible tools). And most importantly, it does not preclude us from having different splitting rules later if a "-z" (or similar) option is added. So we can make the hard cases easier later, if we choose to. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-08-02 11:59:07 +00:00
`rest`::
If this atom is used in the output string, input lines are split
at the first whitespace boundary. All characters before that
whitespace are considered to be the object name; characters
after that first run of whitespace (i.e., the "rest" of the
line) are output in place of the `%(rest)` atom.
If no format is specified, the default format is `%(objectname)
%(objecttype) %(objectsize)`.
cat-file: add --batch-command mode Add a new flag --batch-command that accepts commands and arguments from stdin, similar to git-update-ref --stdin. At GitLab, we use a pair of long running cat-file processes when accessing object content. One for iterating over object metadata with --batch-check, and the other to grab object contents with --batch. However, if we had --batch-command, we wouldn't need to keep both processes around, and instead just have one --batch-command process where we can flip between getting object info, and getting object contents. Since we have a pair of cat-file processes per repository, this means we can get rid of roughly half of long lived git cat-file processes. Given there are many repositories being accessed at any given time, this can lead to huge savings. git cat-file --batch-command will enter an interactive command mode whereby the user can enter in commands and their arguments that get queued in memory: <command1> [arg1] [arg2] LF <command2> [arg1] [arg2] LF When --buffer mode is used, commands will be queued in memory until a flush command is issued that execute them: flush LF The reason for a flush command is that when a consumer process (A) talks to a git cat-file process (B) and interactively writes to and reads from it in --buffer mode, (A) needs to be able to control when the buffer is flushed to stdout. Currently, from (A)'s perspective, the only way is to either 1. kill (B)'s process 2. send an invalid object to stdin. 1. is not ideal from a performance perspective as it will require spawning a new cat-file process each time, and 2. is hacky and not a good long term solution. With this mechanism of queueing up commands and letting (A) issue a flush command, process (A) can control when the buffer is flushed and can guarantee it will receive all of the output when in --buffer mode. --batch-command also will not allow (B) to flush to stdout until a flush is received. This patch adds the basic structure for adding command which can be extended in the future to add more commands. It also adds the following two commands (on top of the flush command): contents <object> LF info <object> LF The contents command takes an <object> argument and prints out the object contents. The info command takes an <object> argument and prints out the object metadata. These can be used in the following way with --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF flush LF info <object> LF flush LF When used without --buffer: info <object> LF contents <object> LF contents <object> LF info <object> LF info <object> LF Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: John Cai <johncai86@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-02-18 18:23:14 +00:00
If `--batch` is specified, or if `--batch-command` is used with the `contents`
command, the object information is followed by the object contents (consisting
of `%(objectsize)` bytes), followed by a newline.
For example, `--batch` without a custom format would produce:
------------
<oid> SP <type> SP <size> LF
<contents> LF
------------
Whereas `--batch-check='%(objectname) %(objecttype)'` would produce:
------------
<oid> SP <type> LF
------------
If a name is specified on stdin that cannot be resolved to an object in
the repository, then `cat-file` will ignore any custom format and print:
------------
<object> SP missing LF
------------
If a name is specified that might refer to more than one object (an ambiguous short sha), then `cat-file` will ignore any custom format and print:
------------
<object> SP ambiguous LF
------------
If `--follow-symlinks` is used, and a symlink in the repository points
outside the repository, then `cat-file` will ignore any custom format
and print:
------------
symlink SP <size> LF
<symlink> LF
------------
The symlink will either be absolute (beginning with a `/`), or relative
to the tree root. For instance, if dir/link points to `../../foo`, then
`<symlink>` will be `../foo`. `<size>` is the size of the symlink in bytes.
If `--follow-symlinks` is used, the following error messages will be
displayed:
------------
<object> SP missing LF
------------
is printed when the initial symlink requested does not exist.
------------
dangling SP <size> LF
<object> LF
------------
is printed when the initial symlink exists, but something that
it (transitive-of) points to does not.
------------
loop SP <size> LF
<object> LF
------------
is printed for symlink loops (or any symlinks that
require more than 40 link resolutions to resolve).
------------
notdir SP <size> LF
<object> LF
------------
is printed when, during symlink resolution, a file is used as a
directory name.
cat-file: add option '-Z' that delimits input and output with NUL In db9d67f2e9 (builtin/cat-file.c: support NUL-delimited input with `-z`, 2022-07-22), we have introduced a new mode to read the input via NUL-delimited records instead of newline-delimited records. This allows the user to query for revisions that have newlines in their path component. While unusual, such queries are perfectly valid and thus it is clear that we should be able to support them properly. Unfortunately, the commit only changed the input to be NUL-delimited, but didn't change the output at the same time. While this is fine for queries that are processed successfully, it is less so for queries that aren't. In the case of missing commits for example the result can become entirely unparsable: ``` $ printf "7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10\n1234567890\n\n\commit000" | git cat-file --batch -z 7ce4f05bae8120d9fa258e854a8669f6ea9cb7b1 blob 10 1234567890 commit missing ``` This is of course a crafted query that is intentionally gaming the deficiency, but more benign queries that contain newlines would have similar problems. Ideally, we should have also changed the output to be NUL-delimited when `-z` is specified to avoid this problem. As the input is NUL-delimited, it is clear that the output in this case cannot ever contain NUL characters by itself. Furthermore, Git does not allow NUL characters in revisions anyway, further stressing the point that using NUL-delimited output is safe. The only exception is of course the object data itself, but as git-cat-file(1) prints the size of the object data clients should read until that specified size has been consumed. But even though `-z` has only been introduced a few releases ago in Git v2.38.0, changing the output format retroactively to also NUL-delimit output would be a backwards incompatible change. And while one could make the argument that the output is inherently broken already, we need to assume that there are existing users out there that use it just fine given that revisions containing newlines are quite exotic. Instead, introduce a new option `-Z` that switches to NUL-delimited input and output. While this new option could arguably only switch the output format to be NUL-delimited, the consequence would be that users have to always specify both `-z` and `-Z` when the input may contain newlines. On the other hand, if the user knows that there never will be newlines in the input, they don't have to use either of those options. There is thus no usecase that would warrant treating input and output format separately, which is why we instead opt to "do the right thing" and have `-Z` mean to NUL-terminate both formats. The old `-z` option is marked as deprecated with a hint that its output may become unparsable. It is thus hidden both from the synopsis as well as the command's help output. Co-authored-by: Toon Claes <toon@iotcl.com> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-06-06 05:19:45 +00:00
Alternatively, when `-Z` is passed, the line feeds in any of the above examples
are replaced with NUL terminators. This ensures that output will be parsable if
the output itself would contain a linefeed and is thus recommended for
scripting purposes.
CAVEATS
-------
Note that the sizes of objects on disk are reported accurately, but care
should be taken in drawing conclusions about which refs or objects are
responsible for disk usage. The size of a packed non-delta object may be
much larger than the size of objects which delta against it, but the
choice of which object is the base and which is the delta is arbitrary
and is subject to change during a repack.
Note also that multiple copies of an object may be present in the object
database; in this case, it is undefined which copy's size or delta base
will be reported.
GIT
---
Part of the linkgit:git[1] suite