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44 commits

Author SHA1 Message Date
Junio C Hamano
7c3d15fe31 Merge branch 'jk/snprintf-truncation'
Avoid unchecked snprintf() to make future code auditing easier.

* jk/snprintf-truncation:
  fmt_with_err: add a comment that truncation is OK
  shorten_unambiguous_ref: use xsnprintf
  fsmonitor: use internal argv_array of struct child_process
  log_write_email_headers: use strbufs
  http: use strbufs instead of fixed buffers
2018-05-30 21:51:28 +09:00
Jeff King
ac4896f007 fmt_with_err: add a comment that truncation is OK
Functions like die_errno() use fmt_with_err() to combine the
caller-provided format with the strerror() string. We use a
fixed stack buffer because we're already handling an error
and don't have any way to report another one. Our buffer
should generally be big enough to fit this, but if it's not,
truncation is our best option. Let's add a comment to that
effect, so that anybody auditing the code for truncation
bugs knows that this is fine.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-21 09:59:14 +09:00
Johannes Schindelin
a86303cb5d test-tool: help verifying BUG() code paths
When we call BUG(), we signal via SIGABRT that something bad happened,
dumping cores if so configured. In some setups these coredumps are
redirected to some central place such as /proc/sys/kernel/core_pattern,
which is a good thing.

However, when we try to verify in our test suite that bugs are caught in
certain code paths, we do *not* want to clutter such a central place
with unnecessary coredumps.

So let's special-case the test helpers (which we use to verify such code
paths) so that the BUG() calls will *not* call abort() but exit with a
special-purpose exit code instead.

Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-05-06 19:06:13 +09:00
Jeff King
0e5bba53af add UNLEAK annotation for reducing leak false positives
It's a common pattern in git commands to allocate some
memory that should last for the lifetime of the program and
then not bother to free it, relying on the OS to throw it
away.

This keeps the code simple, and it's fast (we don't waste
time traversing structures or calling free at the end of the
program). But it also triggers warnings from memory-leak
checkers like valgrind or LSAN. They know that the memory
was still allocated at program exit, but they don't know
_when_ the leaked memory stopped being useful. If it was
early in the program, then it's probably a real and
important leak. But if it was used right up until program
exit, it's not an interesting leak and we'd like to suppress
it so that we can see the real leaks.

This patch introduces an UNLEAK() macro that lets us do so.
To understand its design, let's first look at some of the
alternatives.

Unfortunately the suppression systems offered by
leak-checking tools don't quite do what we want. A
leak-checker basically knows two things:

  1. Which blocks were allocated via malloc, and the
     callstack during the allocation.

  2. Which blocks were left un-freed at the end of the
     program (and which are unreachable, but more on that
     later).

Their suppressions work by mentioning the function or
callstack of a particular allocation, and marking it as OK
to leak.  So imagine you have code like this:

  int cmd_foo(...)
  {
	/* this allocates some memory */
	char *p = some_function();
	printf("%s", p);
	return 0;
  }

You can say "ignore allocations from some_function(),
they're not leaks". But that's not right. That function may
be called elsewhere, too, and we would potentially want to
know about those leaks.

So you can say "ignore the callstack when main calls
some_function".  That works, but your annotations are
brittle. In this case it's only two functions, but you can
imagine that the actual allocation is much deeper. If any of
the intermediate code changes, you have to update the
suppression.

What we _really_ want to say is that "the value assigned to
p at the end of the function is not a real leak". But
leak-checkers can't understand that; they don't know about
"p" in the first place.

However, we can do something a little bit tricky if we make
some assumptions about how leak-checkers work. They
generally don't just report all un-freed blocks. That would
report even globals which are still accessible when the
leak-check is run.  Instead they take some set of memory
(like BSS) as a root and mark it as "reachable". Then they
scan the reachable blocks for anything that looks like a
pointer to a malloc'd block, and consider that block
reachable. And then they scan those blocks, and so on,
transitively marking anything reachable from a global as
"not leaked" (or at least leaked in a different category).

So we can mark the value of "p" as reachable by putting it
into a variable with program lifetime. One way to do that is
to just mark "p" as static. But that actually affects the
run-time behavior if the function is called twice (you
aren't likely to call main() twice, but some of our cmd_*()
functions are called from other commands).

Instead, we can trick the leak-checker by putting the value
into _any_ reachable bytes. This patch keeps a global
linked-list of bytes copied from "unleaked" variables. That
list is reachable even at program exit, which confers
recursive reachability on whatever values we unleak.

In other words, you can do:

  int cmd_foo(...)
  {
	char *p = some_function();
	printf("%s", p);
	UNLEAK(p);
	return 0;
  }

to annotate "p" and suppress the leak report.

But wait, couldn't we just say "free(p)"? In this toy
example, yes. But UNLEAK()'s byte-copying strategy has
several advantages over actually freeing the memory:

  1. It's recursive across structures. In many cases our "p"
     is not just a pointer, but a complex struct whose
     fields may have been allocated by a sub-function. And
     in some cases (e.g., dir_struct) we don't even have a
     function which knows how to free all of the struct
     members.

     By marking the struct itself as reachable, that confers
     reachability on any pointers it contains (including those
     found in embedded structs, or reachable by walking
     heap blocks recursively.

  2. It works on cases where we're not sure if the value is
     allocated or not. For example:

       char *p = argc > 1 ? argv[1] : some_function();

     It's safe to use UNLEAK(p) here, because it's not
     freeing any memory. In the case that we're pointing to
     argv here, the reachability checker will just ignore
     our bytes.

  3. Likewise, it works even if the variable has _already_
     been freed. We're just copying the pointer bytes. If
     the block has been freed, the leak-checker will skip
     over those bytes as uninteresting.

  4. Because it's not actually freeing memory, you can
     UNLEAK() before we are finished accessing the variable.
     This is helpful in cases like this:

       char *p = some_function();
       return another_function(p);

     Writing this with free() requires:

       int ret;
       char *p = some_function();
       ret = another_function(p);
       free(p);
       return ret;

     But with unleak we can just write:

       char *p = some_function();
       UNLEAK(p);
       return another_function(p);

This patch adds the UNLEAK() macro and enables it
automatically when Git is compiled with SANITIZE=leak.  In
normal builds it's a noop, so we pay no runtime cost.

It also adds some UNLEAK() annotations to show off how the
feature works. On top of other recent leak fixes, these are
enough to get t0000 and t0001 to pass when compiled with
LSAN.

Note the case in commit.c which actually converts a
strbuf_release() into an UNLEAK. This code was already
non-leaky, but the free didn't do anything useful, since
we're exiting. Converting it to an annotation means that
non-leak-checking builds pay no runtime cost. The cost is
minimal enough that it's probably not worth going on a
crusade to convert these kinds of frees to UNLEAKS. I did it
here for consistency with the "sb" leak (though it would
have been equally correct to go the other way, and turn them
both into strbuf_release() calls).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-08 15:43:17 +09:00
Ævar Arnfjörð Bjarmason
2d3c02f5db die(): stop hiding errors due to overzealous recursion guard
Change the recursion limit for the default die routine from a *very*
low 1 to 1024. This ensures that infinite recursions are broken, but
doesn't lose the meaningful error messages under threaded execution
where threads concurrently start to die.

The intent of the existing code, as explained in commit
cd163d4b4e ("usage.c: detect recursion in die routines and bail out
immediately", 2012-11-14), is to break infinite recursion in cases
where the die routine itself calls die(), and would thus infinitely
recurse.

However, doing that very aggressively by immediately printing out
"recursion detected in die handler" if we've already called die() once
means that threaded invocations of git can end up only printing out
the "recursion detected" error, while hiding the meaningful error.

An example of this is running a threaded grep which dies on execution
against pretty much any repo, git.git will do:

    git grep -P --threads=8 '(*LIMIT_MATCH=1)-?-?-?---$'

With the current version of git this will print some combination of
multiple PCRE failures that caused the abort and multiple "recursion
detected", some invocations will print out multiple "recursion
detected" errors with no PCRE error at all!

Before this change, running the above grep command 1000 times against
git.git[1] and taking the top 20 results will on my system yield the
following distribution of actual errors ("E") and recursion
errors ("R"):

    322 E R
    306 E
    116 E R R
     65 R R
     54 R E
     49 E E
     44 R
     15 E R R R
      9 R R R
      7 R E R
      5 R R E
      3 E R R R R
      2 E E R
      1 R R R R
      1 R R R E
      1 R E R R

The exact results are obviously random and system-dependent, but this
shows the race condition in this code. Some small part of the time
we're about to print out the actual error ("E") but another thread's
recursion error beats us to it, and sometimes we print out nothing but
the recursion error.

With this change we get, now with "W" to mean the new warning being
emitted indicating that we've called die() many times:

    502 E
    160 E W E
    120 E E
     53 E W
     35 E W E E
     34 W E E
     29 W E E E
     16 E E W
     16 E E E
     11 W E E E E
      7 E E W E
      4 W E
      3 W W E E
      2 E W E E E
      1 W W E
      1 W E W E
      1 E W W E E E
      1 E W W E E
      1 E W W E
      1 E W E E W

Which still sucks a bit, due to a still present race-condition in this
code we're sometimes going to print out several errors still, or
several warnings, or two duplicate errors without the warning.

But we will never have a case where we completely hide the actual
error as we do now.

Now, git-grep could make use of the pluggable error facility added in
commit c19a490e37 ("usage: allow pluggable die-recursion checks",
2013-04-16). There's other threaded code that calls set_die_routine()
or set_die_is_recursing_routine().

But this is about fixing the general die() behavior with threading
when we don't have such a custom routine yet. Right now the common
case is not an infinite recursion in the handler, but us losing error
messages by default because we're overly paranoid about our recursion
check.

So let's just set the recursion limit to a number higher than the
number of threads we're ever likely to spawn. Now we won't lose
errors, and if we have a recursing die handler we'll still die within
microseconds.

There are race conditions in this code itself, in particular the
"dying" variable is not thread mutexed, so we e.g. won't be dying at
exactly 1024, or for that matter even be able to accurately test
"dying == 2", see the cases where we print out more than one "W"
above.

But that doesn't really matter, for the recursion guard we just need
to die "soon", not at exactly 1024 calls, and for printing the correct
error and only one warning most of the time in the face of threaded
death this is good enough and a net improvement on the current code.

1. for i in {1..1000}; do git grep -P --threads=8 '(*LIMIT_MATCH=1)-?-?-?---$' 2>&1|perl -pe 's/^fatal: r.*/R/; s/^fatal: p.*/E/; s/^warning.*/W/' | tr '\n' ' '; echo; done | sort | uniq -c | sort -nr | head -n 20

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-21 14:09:13 -07:00
Junio C Hamano
e350625b68 Merge branch 'bw/forking-and-threading' into maint
The "run-command" API implementation has been made more robust
against dead-locking in a threaded environment.

* bw/forking-and-threading:
  usage.c: drop set_error_handle()
  run-command: restrict PATH search to executable files
  run-command: expose is_executable function
  run-command: block signals between fork and execve
  run-command: add note about forking and threading
  run-command: handle dup2 and close errors in child
  run-command: eliminate calls to error handling functions in child
  run-command: don't die in child when duping /dev/null
  run-command: prepare child environment before forking
  string-list: add string_list_remove function
  run-command: use the async-signal-safe execv instead of execvp
  run-command: prepare command before forking
  t0061: run_command executes scripts without a #! line
  t5550: use write_script to generate post-update hook
2017-06-13 13:27:00 -07:00
Ramsay Jones
3d7dd2d3b6 usage: add NORETURN to BUG() function definitions
Commit d8193743e0 ("usage.c: add BUG() function", 12-05-2017) added the
BUG() functions and macros as a replacement for calls to die("BUG: ..").
The use of NORETURN on the declarations (in git-compat-util.h) and the
lack of NORETURN on the function definitions, however, leads sparse to
complain thus:

      SP usage.c
  usage.c:220:6: error: symbol 'BUG_fl' redeclared with different type
  (originally declared at git-compat-util.h:1074) - different modifiers

In order to suppress the sparse error, add the NORETURN to the function
definitions.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-22 11:00:53 +09:00
Jeff King
e3f43ce765 usage.c: drop set_error_handle()
The set_error_handle() function was introduced by 3b331e926
(vreportf: report to arbitrary filehandles, 2015-08-11) so
that run-command could send post-fork, pre-exec errors to
the parent's original stderr.

That use went away in 79319b194 (run-command: eliminate
calls to error handling functions in child, 2017-04-19),
which pushes all of the error reporting to the parent.
This leaves no callers of set_error_handle(). As we're not
likely to add any new ones, let's drop it.

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Brandon Williams <bmwill@google.com>
Reviewed-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-15 13:00:25 +09:00
Jeff King
d8193743e0 usage.c: add BUG() function
There's a convention in Git's code base to write assertions
as:

  if (...some_bad_thing...)
	die("BUG: the terrible thing happened");

with the idea that users should never see a "BUG:" message
(but if they, it at least gives a clue what happened).  We
use die() here because it's convenient, but there are a few
draw-backs:

  1. Without parsing the messages, it's hard for callers to
     distinguish BUG assertions from regular errors.

     For instance, it would be nice if the test suite could
     check that we don't hit any assertions, but
     test_must_fail will pass BUG deaths as OK.

  2. It would be useful to add more debugging features to
     BUG assertions, like file/line numbers or dumping core.

  3. The die() handler can be replaced, and might not
     actually exit the whole program (e.g., it may just
     pthread_exit()). This is convenient for normal errors,
     but for an assertion failure (which is supposed to
     never happen), we're probably better off taking down
     the whole process as quickly and cleanly as possible.

We could address these by checking in die() whether the
error message starts with "BUG", and behaving appropriately.
But there's little advantage at that point to sharing the
die() code, and only downsides (e.g., we can't change the
BUG() interface independently). Moreover, converting all of
the existing BUG calls reveals that the test suite does
indeed trigger a few of them.

Instead, this patch introduces a new BUG() function, which
prints an error before dying via SIGABRT. This gives us test
suite checking and core dumps.  The function is actually a
macro (when supported) so that we can show the file/line
number.

We can convert die("BUG") invocations to BUG() in further
patches, dealing with any test fallouts individually.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-05-15 11:29:51 +09:00
Junio C Hamano
daf75f2e6b Merge branch 'jk/vreport-sanitize'
An error message with an ASCII control character like '\r' in it
can alter the message to hide its early part, which is problematic
when a remote side gives such an error message that the local side
will relay with a "remote: " prefix.

* jk/vreport-sanitize:
  vreport: sanitize ASCII control chars
  Revert "vreportf: avoid intermediate buffer"
2017-01-31 13:14:56 -08:00
Jeff King
f290089879 vreport: sanitize ASCII control chars
Our error() and die() calls may report messages with
arbitrary data (e.g., filenames or even data from a remote
server). Let's make it harder to cause confusion with
mischievous filenames. E.g., try:

  git rev-parse "$(printf "\rfatal: this argument is too sneaky")" --

or

  git rev-parse "$(printf "\x1b[5mblinky\x1b[0m")" --

Let's block all ASCII control characters, with the exception
of TAB and LF. We use both in our own messages (and we are
necessarily sanitizing the complete output of snprintf here,
as we do not have access to the individual varargs). And TAB
and LF are unlikely to cause confusion (you could put
"\nfatal: sneaky\n" in your filename, but it would at least
not _cover up_ the message leading to it, unlike "\r").

We'll replace the characters with a "?", which is similar to
how "ls" behaves. It might be nice to do something less
lossy, like converting them to "\x" hex codes. But replacing
with a single character makes it easy to do in-place and
without worrying about length limitations. This feature
should kick in rarely enough that the "?" marks are almost
never seen.

We'll leave high-bit characters as-is, as they are likely to
be UTF-8 (though there may be some Unicode mischief you
could cause, which may require further patches).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-11 13:54:08 -08:00
Jeff King
b5a9e435c6 Revert "vreportf: avoid intermediate buffer"
This reverts commit f4c3edc0b1.

The purpose of that commit was to let us write errors of
arbitrary length to stderr by skipping the intermediate
buffer and sending our varargs straight to fprintf. That
works, but it comes with a downside: we do not get access to
the varargs before they are sent to stderr.

On balance, it's not a good tradeoff. Error messages larger
than our 4K buffer are quite uncommon, and we've lost the
ability to make any modifications to the output (e.g., to
remove non-printable characters).

The only way to have both would be one of:

  1. Write into a dynamic buffer. But this is a bad idea for
     a low-level function that may be called when malloc()
     has failed.

  2. Do our own printf-format varargs parsing. This is too
     complex to be worth the trouble.

Let's just revert that change and go back to a fixed buffer.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-11 13:52:00 -08:00
Junio C Hamano
81358dc238 Merge branch 'cc/apply-am'
"git am" has been taught to make an internal call to "git apply"'s
innards without spawning the latter as a separate process.

* cc/apply-am: (41 commits)
  builtin/am: use apply API in run_apply()
  apply: learn to use a different index file
  apply: pass apply state to build_fake_ancestor()
  apply: refactor `git apply` option parsing
  apply: change error_routine when silent
  usage: add get_error_routine() and get_warn_routine()
  usage: add set_warn_routine()
  apply: don't print on stdout in verbosity_silent mode
  apply: make it possible to silently apply
  apply: use error_errno() where possible
  apply: make some parsing functions static again
  apply: move libified code from builtin/apply.c to apply.{c,h}
  apply: rename and move opt constants to apply.h
  builtin/apply: rename option parsing functions
  builtin/apply: make create_one_file() return -1 on error
  builtin/apply: make try_create_file() return -1 on error
  builtin/apply: make write_out_results() return -1 on error
  builtin/apply: make write_out_one_result() return -1 on error
  builtin/apply: make create_file() return -1 on error
  builtin/apply: make add_index_file() return -1 on error
  ...
2016-09-19 13:47:18 -07:00
Christian Couder
725149beab usage: add get_error_routine() and get_warn_routine()
Let's make it possible to get the current error_routine and warn_routine,
so that we can store them before using set_error_routine() or
set_warn_routine() to use new ones.

This way we will be able put back the original routines, when we are done
with using new ones.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-09-07 12:29:53 -07:00
Christian Couder
b83f108b08 usage: add set_warn_routine()
There are already set_die_routine() and set_error_routine(),
so let's add set_warn_routine() as this will be needed in a
following commit.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-09-07 12:29:53 -07:00
Jeff King
4df5e91867 error_errno: use constant return similar to error()
Commit e208f9c (make error()'s constant return value more
visible, 2012-12-15) introduced some macro trickery to make
the constant return from error() more visible to callers,
which in turn can help gcc produce better warnings (and
possibly even better code).

Later, fd1d672 (usage.c: add warning_errno() and
error_errno(), 2016-05-08) introduced another variant, and
subsequent commits converted some uses of error() to
error_errno(), losing the magic from e208f9c for those
sites.

As a result, compiling vcs-svn/svndiff.c with "gcc -O3"
produces -Wmaybe-uninitialized false positives (at least
with gcc 6.2.0). Let's give error_errno() the same
treatment, which silences these warnings.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-31 11:11:54 -07:00
Nguyễn Thái Ngọc Duy
fd1d672300 usage.c: add warning_errno() and error_errno()
Similar to die_errno(), these functions will append strerror()
automatically.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-09 12:29:08 -07:00
Nguyễn Thái Ngọc Duy
58e4e5118a usage.c: move format processing out of die_errno()
fmt_with_err() will be shared with the coming error_errno() and
warning_errno().

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-05-09 12:29:08 -07:00
Jeff King
f4c3edc0b1 vreportf: avoid intermediate buffer
When we call "die(fmt, args...)", we end up in vreportf with
two pieces of information:

  1. The prefix "fatal: "

  2. The original fmt and va_list of args.

We format item (2) into a temporary buffer, and then fprintf
the prefix and the temporary buffer, along with a newline.
This has the unfortunate side effect of truncating any error
messages that are longer than 4096 bytes.

Instead, let's use separate calls for the prefix and
newline, letting us hand the item (2) directly to vfprintf.
This is essentially undoing d048a96 (print
warning/error/fatal messages in one shot, 2007-11-09), which
tried to have the whole output end up in a single `write`
call.

But we can address this instead by explicitly requesting
line-buffering for the output handle, and by making sure
that the buffer is empty before we start (so that outputting
the prefix does not cause a flush due to hitting the buffer
limit).

We may still break the output into two writes if the content
is larger than our buffer, but there's not much we can do
there; depending on the stdio implementation, that might
have happened even with a single fprintf call.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-11 14:29:36 -07:00
Jeff King
3b331e9267 vreportf: report to arbitrary filehandles
The vreportf function always goes to stderr, but run-command
wants child errors to go to the parent's original stderr. To
solve this, commit a5487dd duplicates the stderr fd and
installs die and error handlers to direct the output
appropriately (which later turned into the vwritef
function). This has two downsides, though:

  - we make multiple calls to write(), which contradicts the
    "write at once" logic from d048a96 (print
    warning/error/fatal messages in one shot, 2007-11-09).

  - the custom handlers basically duplicate the normal
    handlers.  They're only a few lines of code, but we
    should not have to repeat the magic "exit(128)", for
    example.

We can solve the first by using fdopen() on the duplicated
descriptor. We can't pass this to vreportf, but we could
introduce a new vreportf_to to handle it.

However, to fix the second problem, we instead introduce a
new "set_error_handle" function, which lets the normal
vreportf calls output to a handle besides stderr. Thus we
can get rid of our custom handlers entirely, and just ask
the regular handlers to output to our new descriptor.

And as vwritef has no more callers, it can just go away.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-11 14:24:50 -07:00
Junio C Hamano
9526aa461f Merge branch 'jk/a-thread-only-dies-once'
A regression fix for the logic to detect die() handler triggering
itself recursively.

* jk/a-thread-only-dies-once:
  run-command: use thread-aware die_is_recursing routine
  usage: allow pluggable die-recursion checks
2013-04-19 13:45:05 -07:00
Jeff King
c19a490e37 usage: allow pluggable die-recursion checks
When any git code calls die or die_errno, we use a counter
to detect recursion into the die functions from any of the
helper functions. However, such a simple counter is not good
enough for threaded programs, which may call die from a
sub-thread, killing only the sub-thread (but incrementing
the counter for everyone).

Rather than try to deal with threads ourselves here, let's
just allow callers to plug in their own recursion-detection
function. This is similar to how we handle the die routine
(the caller plugs in a die routine which may kill only the
sub-thread).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-04-16 15:02:46 -07:00
Jeff King
e208f9cc75 make error()'s constant return value more visible
When git is compiled with "gcc -Wuninitialized -O3", some
inlined calls provide an additional opportunity for the
compiler to do static analysis on variable initialization.
For example, with two functions like this:

  int get_foo(int *foo)
  {
	if (something_that_might_fail() < 0)
		return error("unable to get foo");
	*foo = 0;
	return 0;
  }

  void some_fun(void)
  {
	  int foo;
	  if (get_foo(&foo) < 0)
		  return -1;
	  printf("foo is %d\n", foo);
  }

If get_foo() is not inlined, then when compiling some_fun,
gcc sees only that a pointer to the local variable is
passed, and must assume that it is an out parameter that
is initialized after get_foo returns.

However, when get_foo() is inlined, the compiler may look at
all of the code together and see that some code paths in
get_foo() do not initialize the variable. As a result, it
prints a warning. But what the compiler can't see is that
error() always returns -1, and therefore we know that either
we return early from some_fun, or foo ends up initialized,
and the code is safe.  The warning is a false positive.

If we can make the compiler aware that error() will always
return -1, it can do a better job of analysis. The simplest
method would be to inline the error() function. However,
this doesn't work, because gcc will not inline a variadc
function. We can work around this by defining a macro. This
relies on two gcc extensions:

  1. Variadic macros (these are present in C99, but we do
     not rely on that).

  2. Gcc treats the "##" paste operator specially between a
     comma and __VA_ARGS__, which lets our variadic macro
     work even if no format parameters are passed to
     error().

Since we are using these extra features, we hide the macro
behind an #ifdef. This is OK, though, because our goal was
just to help gcc.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-12-15 10:45:58 -08:00
Brandon Casey
cd163d4b4e usage.c: detect recursion in die routines and bail out immediately
It is theoretically possible for a die handler to get into a state of
infinite recursion.  For example, if a die handler called another function
which itself called die().  Let's at least detect this situation, inform the
user, and call exit.

Signed-off-by: Brandon Casey <bcasey@nvidia.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-11-15 18:04:54 -08:00
Clemens Buchacher
3bc4181fde error_routine: use parent's stderr if exec fails
The new process's error output may be redirected elsewhere, but if
the exec fails, output should still go to the parent's stderr. This
has already been done for the die_routine. Do the same for
error_routine.

Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-07-31 18:27:07 -07:00
Stephen Boyd
c2e86addb8 Fix sparse warnings
Fix warnings from 'make check'.

 - These files don't include 'builtin.h' causing sparse to complain that
   cmd_* isn't declared:

   builtin/clone.c:364, builtin/fetch-pack.c:797,
   builtin/fmt-merge-msg.c:34, builtin/hash-object.c:78,
   builtin/merge-index.c:69, builtin/merge-recursive.c:22
   builtin/merge-tree.c:341, builtin/mktag.c:156, builtin/notes.c:426
   builtin/notes.c:822, builtin/pack-redundant.c:596,
   builtin/pack-refs.c:10, builtin/patch-id.c:60, builtin/patch-id.c:149,
   builtin/remote.c:1512, builtin/remote-ext.c:240,
   builtin/remote-fd.c:53, builtin/reset.c:236, builtin/send-pack.c:384,
   builtin/unpack-file.c:25, builtin/var.c:75

 - These files have symbols which should be marked static since they're
   only file scope:

   submodule.c:12, diff.c:631, replace_object.c:92, submodule.c:13,
   submodule.c:14, trace.c:78, transport.c:195, transport-helper.c:79,
   unpack-trees.c:19, url.c:3, url.c:18, url.c:104, url.c:117, url.c:123,
   url.c:129, url.c:136, thread-utils.c:21, thread-utils.c:48

 - These files redeclare symbols to be different types:

   builtin/index-pack.c:210, parse-options.c:564, parse-options.c:571,
   usage.c:49, usage.c:58, usage.c:63, usage.c:72

 - These files use a literal integer 0 when they really should use a NULL
   pointer:

   daemon.c:663, fast-import.c:2942, imap-send.c:1072, notes-merge.c:362

While we're in the area, clean up some unused #includes in builtin files
(mostly exec_cmd.h).

Signed-off-by: Stephen Boyd <bebarino@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-03-22 10:16:54 -07:00
Johannes Sixt
ebaa79f462 Make report() from usage.c public as vreportf() and use it.
There exist already a number of static functions named 'report', therefore,
the function name was changed.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2010-03-07 00:37:35 -08:00
Björn Gustavsson
625a860cb7 Fix truncated usage messages
The usage messages for some commands (such as 'git diff-tree')
are truncated because they don't fit in a fixed buffer of
1024 bytes.

It would be tempting to eliminate the buffer and the problem once
and for all by doing the output in three steps, but doing so could
(according to commit d048a96e) increase the likelyhood of messing
up the display.

So we just increase the size of the buffer.

Signed-off-by: Björn Gustavsson <bgustavsson@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-11-22 16:14:48 -08:00
Jonathan Nieder
64b1cb74f8 Introduce usagef() that takes a printf-style format
Some new callers would want to use printf-like formatting, when issuing
their usage messages.  An option is to change usage() itself also be like
printf(), which would make it similar to die() and warn().

But usage() is typically fixed, as opposed to die() and warn() that gives
diagnostics depending on the situation.  Indeed, the majority of strings
given by existing callsites to usage() are fixed strings.  If we were to
make usage() take printf-style format, they all need to be changed to have
"%s" as their first argument.

So instead, introduce usagef() so that limited number of callers can use
it.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-11-10 12:00:21 -08:00
Erik Faye-Lund
18660bc96e add NORETURN_PTR for function pointers
Some compilers (including at least MSVC and ARM RVDS) supports
NORETURN on function declarations, but not on function pointers.

This patch makes it possible to define NORETURN for these compilers,
by splitting the NORETURN macro into two - one for function
declarations and one for function pointers.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
2009-10-01 04:12:21 -04:00
Erik Faye-Lund
a4f3131c07 increase portability of NORETURN declarations
Some compilers (including at least MSVC) support NORETURN
on function declarations, but only before the function-name.

This patch makes it possible to define NORETURN to something
meaningful for those compilers.

Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
2009-10-01 04:12:21 -04:00
Junio C Hamano
f8b5a8e13c die_errno(): double % in strerror() output just in case
[tr: handle border case where % is placed at end of buffer]

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-06-27 11:14:53 -07:00
Thomas Rast
b875036e5a Introduce die_errno() that appends strerror(errno) to die()
There are many calls to die() that do, or should, report
strerror(errno) to indicate how the syscall they guard failed.
Introduce a small helper function for this case.

Note:

- POSIX says vsnprintf can modify errno in some unlikely cases, so we
  have to use errno early.

- We take some care to pass the original format to die_routine(), in
  case someone wants to call die_errno() with custom format
  characters.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-06-27 11:14:53 -07:00
Shawn O. Pearce
389d176771 Increase the size of the die/warning buffer to avoid truncation
Long messages like those from lockfile.c when a lock can't be
obtained truncate with only 256 bytes in the message buffer.
Bump it to 1024 to give more space for these longer cases.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2009-03-24 16:58:20 -07:00
Nanako Shiraishi
07ad5a157d usage.c: remove unused functions
This removes three functions that are not used anywhere.

Signed-off-by: Nanako Shiraishi <nanako3@lavabit.com>
Acked-by: Lars Hjemli <hjemli@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
2008-09-29 07:30:16 -07:00
Nicolas Pitre
d048a96ee9 print warning/error/fatal messages in one shot
Not doing so is likely to create a messed up display when sent over the
sideband protocol.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2007-11-09 22:25:36 -08:00
Theodore Ts'o
46efd2d93c Rename warn() to warning() to fix symbol conflicts on BSD and Mac OS
This fixes a problem reported by Randal Schwartz:

>I finally tracked down all the (albeit inconsequential) errors I was getting
>on both OpenBSD and OSX.  It's the warn() function in usage.c.  There's
>warn(3) in BSD-style distros.  It'd take a "great rename" to change it, but if
>someone with better C skills than I have could do that, my linker and I would
>appreciate it.

It was annoying to me, too, when I was doing some mergetool testing on
Mac OS X, so here's a fix.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: "Randal L. Schwartz" <merlyn@stonehenge.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-03-31 01:11:11 -07:00
Shawn O. Pearce
fa39b6b5b1 Introduce a global level warn() function.
Like the existing error() function the new warn() function can be
used to describe a situation that probably should not be occuring,
but which the user (and Git) can continue to work around without
running into too many problems.

An example situation is a bad commit SHA1 found in a reflog.
Attempting to read this record out of the reflog isn't really an
error as we have skipped over it in the past.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-12-21 22:59:34 -08:00
Junio C Hamano
ce88ac5b12 usage: minimum type fix.
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-06-24 00:12:52 -07:00
Petr Baudis
39a3f5ea7c Customizable error handlers
This patch makes the usage(), die() and error() handlers customizable.
Nothing in the git code itself uses that but many other libgit users
(like Git.pm) will.

This is implemented using the mutator functions primarily because you
cannot directly modifying global variables of libgit from a program that
dlopen()ed it, apparently. But having functions for that is a better API
anyway.

Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-06-24 00:12:52 -07:00
Junio C Hamano
4050c0df8e Clean up compatibility definitions.
This attempts to clean up the way various compatibility
functions are defined and used.

 - A new header file, git-compat-util.h, is introduced.  This
   looks at various NO_XXX and does necessary function name
   replacements, equivalent of -Dstrcasestr=gitstrcasestr in the
   Makefile.

 - Those function name replacements are removed from the Makefile.

 - Common features such as usage(), die(), xmalloc() are moved
   from cache.h to git-compat-util.h; cache.h includes
   git-compat-util.h itself.

Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-12-05 15:50:29 -08:00
Linus Torvalds
5d1a5c02e8 [PATCH] Better error reporting for "git status"
Instead of "git status" ignoring (and hiding) potential errors from the
"git-update-index" call, make it exit if it fails, and show the error.

In order to do this, use the "-q" flag (to ignore not-up-to-date files)
and add a new "--unmerged" flag that allows unmerged entries in the index
without any errors.

This also avoids marking the index "changed" if an entry isn't actually
modified, and makes sure that we exit with an understandable error message
if the index is corrupt or unreadable. "read_cache()" no longer returns an
error for the caller to check.

Finally, make die() and usage() exit with recognizable error codes, if we
ever want to check the failure reason in scripts.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2005-10-01 23:55:47 -07:00
Linus Torvalds
6b0c312106 Include file cleanups..
Add <limits.h> to the include files handled by "cache.h", and remove
extraneous #include directives from various .c files. The rule is that
"cache.h" gets all the basic stuff, so that we'll have as few system
dependencies as possible.
2005-05-22 11:54:17 -07:00
Linus Torvalds
0fcfd160b0 Split up read-cache.c into more logical clumps.
Do the usage and error reporting in "usage.c", and the sha1 file
accesses in "sha1_file.c".

Small, nice, easily separated parts. Good.
2005-04-18 13:04:43 -07:00