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![Jeff King](/assets/img/avatar_default.png)
A common use of "cat-file --batch-check" is to feed a list of objects from "rev-list --objects" or a similar command. In this instance, all of our input objects are 40-byte sha1 ids. However, cat-file has always allowed arbitrary revision specifiers, and feeds the result to get_sha1(). Fortunately, get_sha1() recognizes a 40-byte sha1 before doing any hard work trying to look up refs, meaning this scenario should end up spending very little time converting the input into an object sha1. However, since798c35f
(get_sha1: warn about full or short object names that look like refs, 2013-05-29), when we encounter this case, we spend the extra effort to do a refname lookup anyway, just to print a warning. This is further exacerbated byca91993
(get_packed_ref_cache: reload packed-refs file when it changes, 2013-06-20), which makes individual ref lookup more expensive by requiring a stat() of the packed-refs file for each missing ref. With no patches, this is the time it takes to run: $ git rev-list --objects --all >objects $ time git cat-file --batch-check='%(objectname)' <objects on the linux.git repository: real 1m13.494s user 0m25.924s sys 0m47.532s If we revertca91993
, the packed-refs up-to-date check, it gets a little better: real 0m54.697s user 0m21.692s sys 0m32.916s but we are still spending quite a bit of time on ref lookup (and we would not want to revert that patch, anyway, which has correctness issues). If we revert798c35f
, disabling the warning entirely, we get a much more reasonable time: real 0m7.452s user 0m6.836s sys 0m0.608s This patch does the moral equivalent of this final case (and gets similar speedups). We introduce a global flag that callers of get_sha1() can use to avoid paying the price for the warning. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
386 lines
9.4 KiB
C
386 lines
9.4 KiB
C
/*
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* GIT - The information manager from hell
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*
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* Copyright (C) Linus Torvalds, 2005
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*/
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#include "cache.h"
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#include "exec_cmd.h"
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#include "tag.h"
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#include "tree.h"
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#include "builtin.h"
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#include "parse-options.h"
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#include "diff.h"
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#include "userdiff.h"
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#include "streaming.h"
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static int cat_one_file(int opt, const char *exp_type, const char *obj_name)
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{
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unsigned char sha1[20];
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enum object_type type;
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char *buf;
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unsigned long size;
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struct object_context obj_context;
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if (get_sha1_with_context(obj_name, 0, sha1, &obj_context))
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die("Not a valid object name %s", obj_name);
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buf = NULL;
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switch (opt) {
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case 't':
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type = sha1_object_info(sha1, NULL);
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if (type > 0) {
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printf("%s\n", typename(type));
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return 0;
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}
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break;
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case 's':
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type = sha1_object_info(sha1, &size);
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if (type > 0) {
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printf("%lu\n", size);
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return 0;
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}
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break;
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case 'e':
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return !has_sha1_file(sha1);
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case 'p':
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type = sha1_object_info(sha1, NULL);
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if (type < 0)
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die("Not a valid object name %s", obj_name);
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/* custom pretty-print here */
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if (type == OBJ_TREE) {
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const char *ls_args[3] = { NULL };
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ls_args[0] = "ls-tree";
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ls_args[1] = obj_name;
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return cmd_ls_tree(2, ls_args, NULL);
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}
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if (type == OBJ_BLOB)
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return stream_blob_to_fd(1, sha1, NULL, 0);
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buf = read_sha1_file(sha1, &type, &size);
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if (!buf)
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die("Cannot read object %s", obj_name);
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/* otherwise just spit out the data */
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break;
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case 'c':
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if (!obj_context.path[0])
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die("git cat-file --textconv %s: <object> must be <sha1:path>",
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obj_name);
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if (!textconv_object(obj_context.path, obj_context.mode, sha1, 1, &buf, &size))
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die("git cat-file --textconv: unable to run textconv on %s",
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obj_name);
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break;
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case 0:
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if (type_from_string(exp_type) == OBJ_BLOB) {
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unsigned char blob_sha1[20];
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if (sha1_object_info(sha1, NULL) == OBJ_TAG) {
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enum object_type type;
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unsigned long size;
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char *buffer = read_sha1_file(sha1, &type, &size);
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if (memcmp(buffer, "object ", 7) ||
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get_sha1_hex(buffer + 7, blob_sha1))
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die("%s not a valid tag", sha1_to_hex(sha1));
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free(buffer);
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} else
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hashcpy(blob_sha1, sha1);
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if (sha1_object_info(blob_sha1, NULL) == OBJ_BLOB)
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return stream_blob_to_fd(1, blob_sha1, NULL, 0);
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/*
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* we attempted to dereference a tag to a blob
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* and failed; there may be new dereference
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* mechanisms this code is not aware of.
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* fall-back to the usual case.
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*/
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}
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buf = read_object_with_reference(sha1, exp_type, &size, NULL);
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break;
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default:
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die("git cat-file: unknown option: %s", exp_type);
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}
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if (!buf)
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die("git cat-file %s: bad file", obj_name);
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write_or_die(1, buf, size);
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return 0;
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}
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struct expand_data {
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unsigned char sha1[20];
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enum object_type type;
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unsigned long size;
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unsigned long disk_size;
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const char *rest;
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/*
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* If mark_query is true, we do not expand anything, but rather
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* just mark the object_info with items we wish to query.
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*/
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int mark_query;
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/*
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* After a mark_query run, this object_info is set up to be
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* passed to sha1_object_info_extended. It will point to the data
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* elements above, so you can retrieve the response from there.
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*/
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struct object_info info;
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};
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static int is_atom(const char *atom, const char *s, int slen)
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{
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int alen = strlen(atom);
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return alen == slen && !memcmp(atom, s, alen);
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}
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static void expand_atom(struct strbuf *sb, const char *atom, int len,
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void *vdata)
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{
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struct expand_data *data = vdata;
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if (is_atom("objectname", atom, len)) {
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if (!data->mark_query)
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strbuf_addstr(sb, sha1_to_hex(data->sha1));
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} else if (is_atom("objecttype", atom, len)) {
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if (!data->mark_query)
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strbuf_addstr(sb, typename(data->type));
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} else if (is_atom("objectsize", atom, len)) {
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if (data->mark_query)
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data->info.sizep = &data->size;
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else
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strbuf_addf(sb, "%lu", data->size);
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} else if (is_atom("objectsize:disk", atom, len)) {
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if (data->mark_query)
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data->info.disk_sizep = &data->disk_size;
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else
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strbuf_addf(sb, "%lu", data->disk_size);
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} else if (is_atom("rest", atom, len)) {
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if (!data->mark_query && data->rest)
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strbuf_addstr(sb, data->rest);
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} else
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die("unknown format element: %.*s", len, atom);
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}
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static size_t expand_format(struct strbuf *sb, const char *start, void *data)
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{
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const char *end;
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if (*start != '(')
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return 0;
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end = strchr(start + 1, ')');
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if (!end)
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die("format element '%s' does not end in ')'", start);
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expand_atom(sb, start + 1, end - start - 1, data);
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return end - start + 1;
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}
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static void print_object_or_die(int fd, const unsigned char *sha1,
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enum object_type type, unsigned long size)
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{
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if (type == OBJ_BLOB) {
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if (stream_blob_to_fd(fd, sha1, NULL, 0) < 0)
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die("unable to stream %s to stdout", sha1_to_hex(sha1));
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}
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else {
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enum object_type rtype;
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unsigned long rsize;
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void *contents;
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contents = read_sha1_file(sha1, &rtype, &rsize);
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if (!contents)
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die("object %s disappeared", sha1_to_hex(sha1));
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if (rtype != type)
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die("object %s changed type!?", sha1_to_hex(sha1));
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if (rsize != size)
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die("object %s change size!?", sha1_to_hex(sha1));
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write_or_die(fd, contents, size);
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free(contents);
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}
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}
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struct batch_options {
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int enabled;
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int print_contents;
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const char *format;
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};
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static int batch_one_object(const char *obj_name, struct batch_options *opt,
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struct expand_data *data)
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{
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struct strbuf buf = STRBUF_INIT;
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if (!obj_name)
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return 1;
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if (get_sha1(obj_name, data->sha1)) {
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printf("%s missing\n", obj_name);
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fflush(stdout);
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return 0;
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}
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data->type = sha1_object_info_extended(data->sha1, &data->info);
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if (data->type <= 0) {
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printf("%s missing\n", obj_name);
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fflush(stdout);
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return 0;
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}
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strbuf_expand(&buf, opt->format, expand_format, data);
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strbuf_addch(&buf, '\n');
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write_or_die(1, buf.buf, buf.len);
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strbuf_release(&buf);
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if (opt->print_contents) {
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print_object_or_die(1, data->sha1, data->type, data->size);
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write_or_die(1, "\n", 1);
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}
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return 0;
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}
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static int batch_objects(struct batch_options *opt)
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{
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struct strbuf buf = STRBUF_INIT;
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struct expand_data data;
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if (!opt->format)
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opt->format = "%(objectname) %(objecttype) %(objectsize)";
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/*
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* Expand once with our special mark_query flag, which will prime the
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* object_info to be handed to sha1_object_info_extended for each
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* object.
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*/
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memset(&data, 0, sizeof(data));
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data.mark_query = 1;
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strbuf_expand(&buf, opt->format, expand_format, &data);
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data.mark_query = 0;
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/*
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* We are going to call get_sha1 on a potentially very large number of
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* objects. In most large cases, these will be actual object sha1s. The
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* cost to double-check that each one is not also a ref (just so we can
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* warn) ends up dwarfing the actual cost of the object lookups
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* themselves. We can work around it by just turning off the warning.
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*/
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warn_on_object_refname_ambiguity = 0;
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while (strbuf_getline(&buf, stdin, '\n') != EOF) {
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char *p;
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int error;
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/*
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* Split at first whitespace, tying off the beginning of the
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* string and saving the remainder (or NULL) in data.rest.
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*/
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p = strpbrk(buf.buf, " \t");
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if (p) {
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while (*p && strchr(" \t", *p))
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*p++ = '\0';
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}
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data.rest = p;
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error = batch_one_object(buf.buf, opt, &data);
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if (error)
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return error;
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}
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return 0;
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}
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static const char * const cat_file_usage[] = {
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N_("git cat-file (-t|-s|-e|-p|<type>|--textconv) <object>"),
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N_("git cat-file (--batch|--batch-check) < <list_of_objects>"),
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NULL
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};
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static int git_cat_file_config(const char *var, const char *value, void *cb)
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{
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if (userdiff_config(var, value) < 0)
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return -1;
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return git_default_config(var, value, cb);
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}
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static int batch_option_callback(const struct option *opt,
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const char *arg,
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int unset)
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{
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struct batch_options *bo = opt->value;
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if (unset) {
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memset(bo, 0, sizeof(*bo));
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return 0;
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}
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bo->enabled = 1;
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bo->print_contents = !strcmp(opt->long_name, "batch");
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bo->format = arg;
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return 0;
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}
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int cmd_cat_file(int argc, const char **argv, const char *prefix)
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{
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int opt = 0;
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const char *exp_type = NULL, *obj_name = NULL;
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struct batch_options batch = {0};
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const struct option options[] = {
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OPT_GROUP(N_("<type> can be one of: blob, tree, commit, tag")),
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OPT_SET_INT('t', NULL, &opt, N_("show object type"), 't'),
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OPT_SET_INT('s', NULL, &opt, N_("show object size"), 's'),
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OPT_SET_INT('e', NULL, &opt,
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N_("exit with zero when there's no error"), 'e'),
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OPT_SET_INT('p', NULL, &opt, N_("pretty-print object's content"), 'p'),
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OPT_SET_INT(0, "textconv", &opt,
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N_("for blob objects, run textconv on object's content"), 'c'),
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{ OPTION_CALLBACK, 0, "batch", &batch, "format",
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N_("show info and content of objects fed from the standard input"),
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PARSE_OPT_OPTARG, batch_option_callback },
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{ OPTION_CALLBACK, 0, "batch-check", &batch, "format",
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N_("show info about objects fed from the standard input"),
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PARSE_OPT_OPTARG, batch_option_callback },
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OPT_END()
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};
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git_config(git_cat_file_config, NULL);
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if (argc != 3 && argc != 2)
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usage_with_options(cat_file_usage, options);
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argc = parse_options(argc, argv, prefix, options, cat_file_usage, 0);
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if (opt) {
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if (argc == 1)
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obj_name = argv[0];
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else
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usage_with_options(cat_file_usage, options);
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}
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if (!opt && !batch.enabled) {
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if (argc == 2) {
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exp_type = argv[0];
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obj_name = argv[1];
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} else
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usage_with_options(cat_file_usage, options);
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}
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if (batch.enabled && (opt || argc)) {
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usage_with_options(cat_file_usage, options);
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}
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if (batch.enabled)
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return batch_objects(&batch);
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return cat_one_file(opt, exp_type, obj_name);
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}
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