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139 Коммитов

Автор SHA1 Сообщение Дата
Junio C Hamano 2b72dbbcf3 Merge branch 'ti/glibc-stdio-mutex-from-signal-handler'
Allocation related functions and stdio are unsafe things to call
inside a signal handler, and indeed killing the pager can cause
glibc to deadlock waiting on allocation mutex as our signal handler
tries to free() some data structures in wait_for_pager().  Reduce
these unsafe calls.

* ti/glibc-stdio-mutex-from-signal-handler:
  pager: don't use unsafe functions in signal handlers
2015-10-07 13:38:16 -07:00
Junio C Hamano 88bad58d38 Merge branch 'jk/async-pkt-line'
The debugging infrastructure for pkt-line based communication has
been improved to mark the side-band communication specifically.

* jk/async-pkt-line:
  pkt-line: show packets in async processes as "sideband"
  run-command: provide in_async query function
2015-10-05 12:30:09 -07:00
Takashi Iwai 507d7804c0 pager: don't use unsafe functions in signal handlers
Since the commit a3da882120 (pager: do wait_for_pager on signal
death), we call wait_for_pager() in the pager's signal handler.  The
recent bug report revealed that this causes a deadlock in glibc at
aborting "git log" [*1*].  When this happens, git process is left
unterminated, and it can't be killed by SIGTERM but only by SIGKILL.

The problem is that wait_for_pager() function does more than waiting
for pager process's termination, but it does cleanups and printing
errors.  Unfortunately, the functions that may be used in a signal
handler are very limited [*2*].  Particularly, malloc(), free() and the
variants can't be used in a signal handler because they take a mutex
internally in glibc.  This was the cause of the deadlock above.  Other
than the direct calls of malloc/free, many functions calling
malloc/free can't be used.  strerror() is such one, either.

Also the usage of fflush() and printf() in a signal handler is bad,
although it seems working so far.  In a safer side, we should avoid
them, too.

This patch tries to reduce the calls of such functions in signal
handlers.  wait_for_signal() takes a flag and avoids the unsafe
calls.   Also, finish_command_in_signal() is introduced for the
same reason.  There the free() calls are removed, and only waits for
the children without whining at errors.

[*1*] https://bugzilla.opensuse.org/show_bug.cgi?id=942297
[*2*] http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04_03

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-04 14:57:51 -07:00
Jeff King 661a8cf408 run-command: provide in_async query function
It's not easy for arbitrary code to find out whether it is
running in an async process or not. A top-level function
which is fed to start_async() can know (you just pass down
an argument saying "you are async"). But that function may
call other global functions, and we would not want to have
to pass the information all the way through the call stack.

Nor can we simply set a global variable, as those may be
shared between async threads and the main thread (if the
platform supports pthreads). We need pthread tricks _or_ a
global variable, depending on how start_async is
implemented.

The callers don't have enough information to do this right,
so let's provide a simple query function that does.
Fortunately we can reuse the existing infrastructure to make
the pthread case simple (and even simplify die_async() by
using our new function).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-01 15:11:53 -07:00
Junio C Hamano 1302c9f514 Merge branch 'jk/long-error-messages'
The codepath to produce error messages had a hard-coded limit to
the size of the message, primarily to avoid memory allocation while
calling die().

* jk/long-error-messages:
  vreportf: avoid intermediate buffer
  vreportf: report to arbitrary filehandles
2015-08-25 14:57:06 -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
Jeff King 03f2c7731b find_hook: keep our own static buffer
The find_hook function returns the results of git_path,
which is a static buffer shared by other path-related calls.
Returning such a buffer is slightly dangerous, because it
can be overwritten by seemingly unrelated functions.

Let's at least keep our _own_ static buffer, so you can
only get in trouble by calling find_hook in quick
succession, which is less likely to happen and more obvious
to notice.

While we're at it, let's add some documentation of the
function's limitations.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-08-10 15:37:13 -07:00
Junio C Hamano 68a2e6a2c8 Merge branch 'nd/multiple-work-trees'
A replacement for contrib/workdir/git-new-workdir that does not
rely on symbolic links and make sharing of objects and refs safer
by making the borrowee and borrowers aware of each other.

* nd/multiple-work-trees: (41 commits)
  prune --worktrees: fix expire vs worktree existence condition
  t1501: fix test with split index
  t2026: fix broken &&-chain
  t2026 needs procondition SANITY
  git-checkout.txt: a note about multiple checkout support for submodules
  checkout: add --ignore-other-wortrees
  checkout: pass whole struct to parse_branchname_arg instead of individual flags
  git-common-dir: make "modules/" per-working-directory directory
  checkout: do not fail if target is an empty directory
  t2025: add a test to make sure grafts is working from a linked checkout
  checkout: don't require a work tree when checking out into a new one
  git_path(): keep "info/sparse-checkout" per work-tree
  count-objects: report unused files in $GIT_DIR/worktrees/...
  gc: support prune --worktrees
  gc: factor out gc.pruneexpire parsing code
  gc: style change -- no SP before closing parenthesis
  checkout: clean up half-prepared directories in --to mode
  checkout: reject if the branch is already checked out elsewhere
  prune: strategies for linked checkouts
  checkout: support checking out into a new working directory
  ...
2015-05-11 14:23:39 -07:00
Junio C Hamano ea1fd481b4 Merge branch 'jk/run-command-capture'
The run-command interface was easy to abuse and make a pipe for us
to read from the process, wait for the process to finish and then
attempt to read its output, which is a pattern that lead to a
deadlock.  Fix such uses by introducing a helper to do this
correctly (i.e. we need to read first and then wait the process to
finish) and also add code to prevent such abuse in the run-command
helper.

* jk/run-command-capture:
  run-command: forbid using run_command with piped output
  trailer: use capture_command
  submodule: use capture_command
  wt-status: use capture_command
  run-command: introduce capture_command helper
  wt_status: fix signedness mismatch in strbuf_read call
  wt-status: don't flush before running "submodule status"
2015-03-25 12:54:27 -07:00
Jeff King c29b3962af run-command: forbid using run_command with piped output
Because run_command both spawns and wait()s for the command
before returning control to the caller, any reads from the
pipes we open must necessarily happen after wait() returns.
This can lead to deadlock, as the child process may block
on writing to us while we are blocked waiting for it to
exit.

Worse, it only happens when the child fills the pipe
buffer, which means that the problem may come and go
depending on the platform and the size of the output
produced by the child.

Let's detect and flag this dangerous construct so that we
can catch potential bugs early in the test suite rather than
having them happen in the field.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-03-22 21:39:22 -07:00
Jeff King 911ec99b68 run-command: introduce capture_command helper
Something as simple as reading the stdout from a command
turns out to be rather hard to do right. Doing:

  cmd.out = -1;
  run_command(&cmd);
  strbuf_read(&buf, cmd.out, 0);

can result in deadlock if the child process produces a large
amount of output. What happens is:

  1. The parent spawns the child with its stdout connected
     to a pipe, of which the parent is the sole reader.

  2. The parent calls wait(), blocking until the child exits.

  3. The child writes to stdout. If it writes more data than
     the OS pipe buffer can hold, the write() call will
     block.

This is a deadlock; the parent is waiting for the child to
exit, and the child is waiting for the parent to call
read().

So we might try instead:

  start_command(&cmd);
  strbuf_read(&buf, cmd.out, 0);
  finish_command(&cmd);

But that is not quite right either. We are examining cmd.out
and running finish_command whether start_command succeeded
or not, which is wrong. Moreover, these snippets do not do
any error handling. If our read() fails, we must make sure
to still call finish_command (to reap the child process).
And both snippets failed to close the cmd.out descriptor,
which they must do (provided start_command succeeded).

Let's introduce a run-command helper that can make this a
bit simpler for callers to get right.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-03-22 21:38:31 -07:00
Kyle J. McKay 1b56cdf901 git-compat-util.h: move SHELL_PATH default into header
If SHELL_PATH is not defined we use "/bin/sh".  However,
run-command.c is not the only file that needs to use
the default value so move it into a common header.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-03-10 15:11:24 -07:00
Junio C Hamano 77a801d237 Merge branch 'jc/hook-cleanup'
Remove unused code.

* jc/hook-cleanup:
  run-command.c: retire unused run_hook_with_custom_index()
2014-12-22 12:27:10 -08:00
Nguyễn Thái Ngọc Duy dcf692625a path.c: make get_pathname() call sites return const char *
Before the previous commit, get_pathname returns an array of PATH_MAX
length. Even if git_path() and similar functions does not use the
whole array, git_path() caller can, in theory.

After the commit, get_pathname() may return a buffer that has just
enough room for the returned string and git_path() caller should never
write beyond that.

Make git_path(), mkpath() and git_path_submodule() return a const
buffer to make sure callers do not write in it at all.

This could have been part of the previous commit, but the "const"
conversion is too much distraction from the core changes in path.c.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-12-01 11:00:10 -08:00
Junio C Hamano 814dd8e078 run-command.c: retire unused run_hook_with_custom_index()
This was originally meant to be used to rewrite run_commit_hook()
that only special cases the GIT_INDEX_FILE environment, but the
run_hook_ve() refactoring done earlier made the implementation of
run_commit_hook() thin and clean enough.

Nobody uses this, so retire it as an unfinished clean-up made
unnecessary.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-12-01 08:39:43 -08:00
René Scharfe 6066a7eac4 run-command: use void to declare that functions take no parameters
Explicitly declare that git_atexit_dispatch() and git_atexit_clear()
take no parameters instead of leaving their parameter list empty and
thus unspecified.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-11-10 14:43:19 -08:00
Junio C Hamano e4da4fbe0e Merge branch 'eb/no-pthreads'
Allow us build with NO_PTHREADS=NoThanks compilation option.

* eb/no-pthreads:
  Handle atexit list internaly for unthreaded builds
  pack-objects: set number of threads before checking and warning
  index-pack: fix compilation with NO_PTHREADS
2014-10-24 14:59:10 -07:00
Etienne Buira 0f4b6db3ba Handle atexit list internaly for unthreaded builds
Wrap atexit()s calls on unthreaded builds to handle callback list
internally.

This is needed because on unthreaded builds, asyncs inherits parent's
atexit() list, that gets run as soon as the async exit()s (and again at
the end of async's parent process). That led to remove temporary files
too early.

Also remove a by-atexit-callback guard against this kind of issue in
clone.c, as this patch makes it redundant.

Fixes test 5537 (temporary shallow file vanished before unpack-objects
could open it)

BTW remove an unused variable in shallow.c.

Helped-by: Duy Nguyen <pclouds@gmail.com>
Helped-by: Andreas Schwab <schwab@linux-m68k.org>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Etienne Buira <etienne.buira@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-10-19 15:38:30 -07:00
René Scharfe 19a583dc39 run-command: add env_array, an optional argv_array for env
Similar to args, add a struct argv_array member to struct child_process
that simplifies specifying the environment for children.  It is freed
automatically by finish_command() or if start_command() encounters an
error.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-10-19 15:26:31 -07:00
René Scharfe 1f87293d78 run-command: inline prepare_run_command_v_opt()
Merge prepare_run_command_v_opt() and its only caller.  This removes a
pointer indirection and allows to initialize the struct child_process
using CHILD_PROCESS_INIT.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-08-20 09:56:12 -07:00
René Scharfe 41e9bad75e run-command: call run_command_v_opt_cd_env() instead of duplicating it
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-08-20 09:55:41 -07:00
René Scharfe 483bbd4e4c run-command: introduce child_process_init()
Add a helper function for initializing those struct child_process
variables for which the macro CHILD_PROCESS_INIT can't be used.

Suggested-by: Jeff King <peff@peff.net>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-08-20 09:54:58 -07:00
René Scharfe d318027932 run-command: introduce CHILD_PROCESS_INIT
Most struct child_process variables are cleared using memset first after
declaration.  Provide a macro, CHILD_PROCESS_INIT, that can be used to
initialize them statically instead.  That's shorter, doesn't require a
function call and is slightly more readable (especially given that we
already have STRBUF_INIT, ARGV_ARRAY_INIT etc.).

Helped-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-08-20 09:53:37 -07:00
Junio C Hamano 385e171a5b Merge branch 'sk/mingw-uni-fix-more'
Most of these are battle-tested in msysgit and are needed to
complete what has been merged to 'master' already.

* sk/mingw-uni-fix-more:
  Win32: enable color output in Windows cmd.exe
  Win32: patch Windows environment on startup
  Win32: keep the environment sorted
  Win32: use low-level memory allocation during initialization
  Win32: reduce environment array reallocations
  Win32: don't copy the environment twice when spawning child processes
  Win32: factor out environment block creation
  Win32: unify environment function names
  Win32: unify environment case-sensitivity
  Win32: fix environment memory leaks
  Win32: Unicode environment (incoming)
  Win32: Unicode environment (outgoing)
  Revert "Windows: teach getenv to do a case-sensitive search"
  tests: do not pass iso8859-1 encoded parameter
2014-07-30 14:21:09 -07:00
Karsten Blees 77734da241 Win32: don't copy the environment twice when spawning child processes
When spawning child processes via start_command(), the environment and all
environment entries are copied twice. First by make_augmented_environ /
copy_environ to merge with child_process.env. Then a second time by
make_environment_block to create a sorted environment block string as
required by CreateProcess.

Move the merge logic to make_environment_block so that we only need to copy
the environment once. This changes semantics of the env parameter: it now
expects a delta (such as child_process.env) rather than a full environment.
This is not a problem as the parameter is only used by start_command()
(all other callers previously passed char **environ, and now pass NULL).

The merge logic no longer xstrdup()s the environment strings, so do_putenv
must not free them. Add a parameter to distinguish this from normal putenv.

Remove the now unused make_augmented_environ / free_environ API.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Stepan Kasal <kasal@ucw.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-21 09:32:49 -07:00
René Scharfe d1d094564a run-command: use internal argv_array of struct child_process in run_hook_ve()
Use the existing argv_array member instead of providing our own.  This
way we don't have to initialize or clean it up explicitly.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-07-17 15:09:24 -07:00
Jeff King c460c0ecdc run-command: store an optional argv_array
All child_process structs need to point to an argv. For
flexibility, we do not mandate the use of a dynamic
argv_array. However, because the child_process does not own
the memory, this can make memory management with a
separate argv_array difficult.

For example, if a function calls start_command but not
finish_command, the argv memory must persist. The code needs
to arrange to clean up the argv_array separately after
finish_command runs. As a result, some of our code in this
situation just leaks the memory.

To help such cases, this patch adds a built-in argv_array to
the child_process, which gets cleaned up automatically (both
in finish_command and when start_command fails).  Callers
may use it if they choose, but can continue to use the raw
argv if they wish.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-05-15 09:49:09 -07:00
Benoit Pierre 15048f8a9a commit: fix patch hunk editing with "commit -p -m"
Don't change git environment: move the GIT_EDITOR=":" override to the
hook command subprocess, like it's already done for GIT_INDEX_FILE.

Signed-off-by: Benoit Pierre <benoit.pierre@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2014-03-18 11:25:12 -07:00
Felipe Contreras 5a50085c6b run-command: trivial style fixes
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-10-31 13:48:26 -07:00
Junio C Hamano 1d1934caf1 Merge branch 'tr/fd-gotcha-fixes'
Two places we did not check return value (expected to be a file
descriptor) correctly.

* tr/fd-gotcha-fixes:
  run-command: dup_devnull(): guard against syscalls failing
  git_mkstemps: correctly test return value of open()
2013-07-22 11:23:13 -07:00
Thomas Rast a77f106c78 run-command: dup_devnull(): guard against syscalls failing
dup_devnull() did not check the return values of open() and dup2().
Fix this omission.

Signed-off-by: Thomas Rast <trast@inf.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-07-12 10:30:09 -07:00
Jonathan Nieder 380395d094 mingw: rename WIN32 cpp macro to GIT_WINDOWS_NATIVE
Throughout git, it is assumed that the WIN32 preprocessor symbol is
defined on native Windows setups (mingw and msvc) and not on Cygwin.
On Cygwin, most of the time git can pretend this is just another Unix
machine, and Windows-specific magic is generally counterproductive.

Unfortunately Cygwin *does* define the WIN32 symbol in some headers.
Best to rely on a new git-specific symbol GIT_WINDOWS_NATIVE instead,
defined as follows:

	#if defined(WIN32) && !defined(__CYGWIN__)
	# define GIT_WINDOWS_NATIVE
	#endif

After this change, it should be possible to drop the
CYGWIN_V15_WIN32API setting without any negative effect.

[rj: %s/WINDOWS_NATIVE/GIT_WINDOWS_NATIVE/g ]

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-05-08 12:14:35 -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 1ece66bc9e run-command: use thread-aware die_is_recursing routine
If we die from an async thread, we do not actually exit the
program, but just kill the thread. This confuses the static
counter in usage.c's default die_is_recursing function; it
updates the counter once for the thread death, and then when
the main program calls die() itself, it erroneously thinks
we are recursing. The end result is that we print "recursion
detected in die handler" instead of the real error in such a
case (the easiest way to trigger this is having a remote
connection hang up while running a sideband demultiplexer).

This patch solves it by using a per-thread counter when the
async_die function is installed; we detect recursion in each
thread (including the main one), but they do not step on
each other's toes.

Other threaded code does not need to worry about this, as
they do not install specialized die handlers; they just let
a die() from a sub-thread take down the whole program.

Since we are overriding the default recursion-check
function, there is an interesting corner case that is not a
problem, but bears some explanation. Imagine the main thread
calls die(), and then in the die_routine starts an async
call. We will switch to using thread-local storage, which
starts at 0, for the main thread's counter, even though
the original counter was actually at 1. That's OK, though,
for two reasons:

  1. It would miss only the first level of recursion, and
     would still find recursive failures inside the async
     helper.

  2. We do not currently and are not likely to start doing
     anything as heavyweight as starting an async routine
     from within a die routine or helper function.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-04-16 15:02:48 -07:00
Jeff King 25043d8aea run-command: always set failed_errno in start_command
When we fail to fork, we set the failed_errno variable to
the value of errno so it is not clobbered by later syscalls.
However, we do so in a conditional, and it is hard to see
later under what conditions the variable has a valid value.

Instead of setting it only when fork fails, let's just
always set it after forking. This is more obvious for human
readers (as we are no longer setting it as a side effect of
a strerror call), and it is more obvious to gcc, which no
longer generates a spurious -Wuninitialized warning. It also
happens to match what the WIN32 half of the #ifdef does.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-03-21 14:06:48 -07:00
Junio C Hamano b5b56ea40c Merge branch 'sb/run-command-fd-error-reporting'
* sb/run-command-fd-error-reporting:
  run-command: be more informative about what failed
2013-02-07 14:41:42 -08:00
Stephen Boyd 939296c4a4 run-command: be more informative about what failed
While debugging an error with verify_signed_buffer() the error
messages from run-command weren't very useful:

 error: cannot create pipe for gpg: Too many open files
 error: could not run gpg.

because they didn't indicate *which* pipe couldn't be created.

Print which pipe failed to be created in the error message so we
can more easily debug similar problems in the future.

For example, the above error now prints:

 error: cannot create standard error pipe for gpg: Too many open files
 error: could not run gpg.

Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-02-01 14:11:50 -08:00
Aaron Schrab 5a7da2dca1 hooks: Add function to check if a hook exists
Create find_hook() function to determine if a given hook exists and is
executable.  If it is, the path to the script will be returned,
otherwise NULL is returned.

This encapsulates the tests that are used to check for the existence of
a hook in one place, making it easier to modify those checks if that is
found to be necessary.  This also makes it simple for places that can
use a hook to check if a hook exists before doing, possibly lengthy,
setup work which would be pointless if no such hook is present.

The returned value is left as a static value from get_pathname() rather
than a duplicate because it is anticipated that the return value will
either be used as a boolean, immediately added to an argv_array list
which would result in it being duplicated at that point, or used to
actually run the command without much intervening work.  Callers which
need to hold onto the returned value for a longer time are expected to
duplicate the return value themselves.

Signed-off-by: Aaron Schrab <aaron@schrab.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-01-14 09:25:40 -08:00
Jeff King 709ca730f8 run-command: encode signal death as a positive integer
When a sub-command dies due to a signal, we encode the
signal number into the numeric exit status as "signal -
128". This is easy to identify (versus a regular positive
error code), and when cast to an unsigned integer (e.g., by
feeding it to exit), matches what a POSIX shell would return
when reporting a signal death in $? or through its own exit
code.

So we have a negative value inside the code, but once it
passes across an exit() barrier, it looks positive (and any
code we receive from a sub-shell will have the positive
form). E.g., death by SIGPIPE (signal 13) will look like
-115 to us in inside git, but will end up as 141 when we
call exit() with it. And a program killed by SIGPIPE but run
via the shell will come to us with an exit code of 141.

Unfortunately, this means that when the "use_shell" option
is set, we need to be on the lookout for _both_ forms. We
might or might not have actually invoked the shell (because
we optimize out some useless shell calls). If we didn't invoke
the shell, we will will see the sub-process's signal death
directly, and run-command converts it into a negative value.
But if we did invoke the shell, we will see the shell's
128+signal exit status. To be thorough, we would need to
check both, or cast the value to an unsigned char (after
checking that it is not -1, which is a magic error value).

Fortunately, most callsites do not care at all whether the
exit was from a code or from a signal; they merely check for
a non-zero status, and sometimes propagate the error via
exit(). But for the callers that do care, we can make life
slightly easier by just using the consistent positive form.

This actually fixes two minor bugs:

  1. In launch_editor, we check whether the editor died from
     SIGINT or SIGQUIT. But we checked only the negative
     form, meaning that we would fail to notice a signal
     death exit code which was propagated through the shell.

  2. In handle_alias, we assume that a negative return value
     from run_command means that errno tells us something
     interesting (like a fork failure, or ENOENT).
     Otherwise, we simply propagate the exit code. Negative
     signal death codes confuse us, and we print a useless
     "unable to run alias 'foo': Success" message. By
     encoding signal deaths using the positive form, the
     existing code just propagates it as it would a normal
     non-zero exit code.

The downside is that callers of run_command can no longer
differentiate between a signal received directly by the
sub-process, and one propagated. However, no caller
currently cares, and since we already optimize out some
calls to the shell under the hood, that distinction is not
something that should be relied upon by callers.

Fix the same logic in t/test-terminal.perl for consistency [jc:
raised by Jonathan in the discussion].

Signed-off-by: Jeff King <peff@peff.net>
Acked-by: Johannes Sixt <j6t@kdbg.org>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-01-06 11:09:18 -08:00
Jeff King 0398fc3496 fix compilation with NO_PTHREADS
Commit 1327452 cleaned up an unused parameter from
wait_or_whine, but forgot to update a caller that is inside
"#ifdef NO_PTHREADS".

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2013-01-05 22:47:27 -08:00
Jeff King a2767c5c91 run-command: do not warn about child death from terminal
SIGINT and SIGQUIT are not generally interesting signals to
the user, since they are typically caused by them hitting "^C"
or otherwise telling their terminal to send the signal.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-12-02 02:06:43 -08:00
Jeff King 13274526c1 run-command: drop silent_exec_failure arg from wait_or_whine
We do not actually use this parameter; instead we complain
from the child itself (for fork/exec) or from start_command
(if we are using spawn on Windows).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-12-02 02:04:50 -08:00
Jeff King 55ff630075 Merge branch 'jk/no-more-pre-exec-callback'
Removes a workaround for buggy version of less older than version
406.

* jk/no-more-pre-exec-callback:
  pager: drop "wait for output to run less" hack
2012-10-25 06:41:15 -04:00
Junio C Hamano cc84144d48 Merge branch 'dg/run-command-child-cleanup' into maint
* dg/run-command-child-cleanup:
  run-command.c: fix broken list iteration in clear_child_for_cleanup
2012-09-20 15:55:12 -07:00
Junio C Hamano 5816cc7ca1 Merge branch 'dg/run-command-child-cleanup'
The code to wait for subprocess and remove it from our internal queue
wasn't quite right.

* dg/run-command-child-cleanup:
  run-command.c: fix broken list iteration in clear_child_for_cleanup
2012-09-14 21:39:37 -07:00
Junio C Hamano 91feb387f2 Merge branch 'jc/maint-sane-execvp-notdir' into maint-1.7.11
* jc/maint-sane-execvp-notdir:
  sane_execvp(): ignore non-directory on $PATH
2012-09-11 11:09:19 -07:00
David Gould bdee397d7c run-command.c: fix broken list iteration in clear_child_for_cleanup
Iterate through children_to_clean using 'next' fields but with an
extra level of indirection. This allows us to update the chain when
we remove a child and saves us managing several variables around
the loop mechanism.

Signed-off-by: David Gould <david@optimisefitness.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-09-11 10:30:31 -07:00
Junio C Hamano 12d858aeb4 Merge branch 'jc/maint-sane-execvp-notdir'
"git foo" errored out with "Not a directory" when the user had a non
directory on $PATH, and worse yet it masked an alias "foo" to run.

* jc/maint-sane-execvp-notdir:
  sane_execvp(): ignore non-directory on $PATH
2012-09-03 15:53:26 -07:00
Junio C Hamano a78550831a sane_execvp(): ignore non-directory on $PATH
When you have a non-directory on your PATH, a funny thing happens:

	$ PATH=$PATH:/bin/sh git foo
	fatal: cannot exec 'git-foo': Not a directory?

Worse yet, as real commands always take precedence over aliases,
this behaviour interacts rather badly with them:

	$ PATH=$PATH:/bin/sh git -c alias.foo=show git foo -s
	fatal: cannot exec 'git-foo': Not a directory?

This is because an ENOTDIR error from the underlying execvp(2) is
reported back to the caller of our sane_execvp() wrapper as-is.

Translating it to ENOENT, just like the case where we _might_ have
the command in an unreadable directory, fixes it.  Without an alias,
we would get

	git: 'foo' is not a git command. See 'git --help'.

and we use the 'foo' alias when it is available, of course.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-07-31 12:51:30 -07:00
Jeff King e8320f350f pager: drop "wait for output to run less" hack
Commit 35ce862 (pager: Work around window resizing bug in
'less', 2007-01-24) causes git's pager sub-process to wait
to receive input after forking but before exec-ing the
pager. To handle this, run-command had to grow a "pre-exec
callback" feature. Unfortunately, this feature does not work
at all on Windows (where we do not fork), and interacts
poorly with run-command's parent notification system. Its
use should be discouraged.

The bug in less was fixed in version 406, which was released
in June 2007. It is probably safe at this point to remove
our workaround. That lets us rip out the preexec_cb feature
entirely.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2012-06-05 09:38:00 -07:00