On Windows, async procedures have always been run in threads, and the
implementation used Windows specific APIs. Rewrite the code to use pthreads.
A new configuration option is introduced so that the threaded implementation
can also be used on POSIX systems. Since this option is intended only as
playground on POSIX, but is mandatory on Windows, the option is not
documented.
One detail is that on POSIX it is necessary to set FD_CLOEXEC on the pipe
handles. On Windows, this is not needed because pipe handles are not
inherited to child processes, and the new calls to set_cloexec() are
effectively no-ops.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This patch adds the possibility to supply a set of non-0 file
descriptors for async process communication instead of the
default-created pipe.
Additionally, we now support bi-directional communiction with the
async procedure, by giving the async function both read and write
file descriptors.
To retain compatiblity and similar "API feel" with start_command,
we require start_async callers to set .out = -1 to get a readable
file descriptor. If either of .in or .out is 0, we supply no file
descriptor to the async process.
[sp: Note: Erik started this patch, and a huge bulk of it is
his work. All bugs were introduced later by Shawn.]
Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Like .out, .err may now be set to a file descriptor > 0, which
is a writable pipe/socket/file that the child's stderr will be
redirected into.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Many callsites run "sh -c $CMD" to run $CMD. We can make it
a little simpler for them by factoring out the munging of
argv.
For simple cases with no arguments, this doesn't help much, but:
1. For cases with arguments, we save the caller from
having to build the appropriate shell snippet.
2. We can later optimize to avoid the shell when
there are no metacharacters in the program.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The code which is conditional on MinGW32 is actually conditional on Windows.
Use the WIN32 symbol, which is defined by the MINGW32 and MSVC environments,
but not by Cygwin.
Define SNPRINTF_SIZE_CORR=1 for MSVC too, as its vsnprintf function does
not add NUL at the end of the buffer if the result fits the buffer size
exactly.
Signed-off-by: Frank Li <lznuaa@gmail.com>
Signed-off-by: Marius Storm-Olsen <mstormo@gmail.com>
Acked-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the case where a program was not found, it was still the task of the
caller to report an error to the user. Usually, this is an interesting case
but only few callers actually reported a specific error (though many call
sites report a generic error message regardless of the cause).
With this change the error is reported by run_command, but since there is
one call site in git.c that does not want that, an option is added to
struct child_process, which is used to turn the error off.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The motivation for this change is that system call failures are serious
errors that should be reported to the user, but only few callers took the
burden to decode the error codes that the functions returned into error
messages.
If at all, then only an unspecific error message was given. A prominent
example is this:
$ git upload-pack . | :
fatal: unable to run 'git-upload-pack'
In this example, git-upload-pack, the external command invoked through the
git wrapper, dies due to SIGPIPE, but the git wrapper does not bother to
report the real cause. In fact, this very error message is copied to the
syslog if git-daemon's client aborts the connection early.
With this change, system call failures are reported immediately after the
failure and only a generic failure code is returned to the caller. In the
above example the error is now to the point:
$ git upload-pack . | :
error: git-upload-pack died of signal
Note that there is no error report if the invoked program terminated with
a non-zero exit code, because it is reasonable to expect that the invoked
program has already reported an error. (But many run_command call sites
nevertheless write a generic error message.)
There was one special return code that was used to identify the case where
run_command failed because the requested program could not be exec'd. This
special case is now treated like a system call failure with errno set to
ENOENT. No error is reported in this case, because the call site in git.c
expects this as a normal result. Therefore, the callers that carefully
decoded the return value still check for this condition.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
As a general guideline, functions in git's code return zero to indicate
success and negative values to indicate failure. The run_command family of
functions followed this guideline. But there are actually two different
kinds of failure:
- failures of system calls;
- non-zero exit code of the program that was run.
Usually, a non-zero exit code of the program is a failure and means a
failure to the caller. Except that sometimes it does not. For example, the
exit code of merge programs (e.g. external merge drivers) conveys
information about how the merge failed, and not all exit calls are
actually failures.
Furthermore, the return value of run_command is sometimes used as exit
code by the caller.
This change arranges that the exit code of the program is returned as a
positive value, which can now be regarded as the "result" of the function.
System call failures continue to be reported as negative values.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some old versions of gcc don't seem to like us negating an
enum constant. Let's work around it by negating the other
half of the comparison instead.
Reported by Pierre Poissinger on gcc 2.9.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
run_command() returns a single integer specifying either an
error code or the exit status of the spawned program. The
only way to tell the difference is that the error codes are
outside of the allowed range of exit status values.
Rather than make each caller implement the test against a
magic limit, let's provide a macro.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
A function that runs a hook is used in several Git commands.
builtin-commit.c has the one that is most general for cases without
piping. The one in builtin-gc.c prints some useful warnings.
This patch moves a merged version of these variants into libgit and
lets the other builtins use this libified run_hook().
The run_hook() function used in receive-pack.c feeds the standard
input of the pre-receive or post-receive hooks. This function is
renamed to run_receive_hook() because the libified run_hook() cannot
handle this.
Mentored-by: Daniel Barkalow <barkalow@iabervon.org>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Stephan Beyer <s-beyer@gmx.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This function is not used anywhere.
Johannes Sixt <johannes.sixt@telecom.at>:
> Future callers can use run_command_v_opt_cd_env() instead.
Signed-off-by: Nanako Shiraishi <nanako3@lavabit.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This is a function provided by the caller which is called
_after_ the process is forked, but before the spawned
program is executed. On platforms (like mingw) where
subprocesses are forked and executed in a single call, the
preexec callback is simply ignored.
This will be used in the following patch to do some setup
for 'less' that must happen in the forked child.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In upload-pack we must explicitly close the output channel of rev-list.
(On Unix, the channel is closed automatically because process that runs
rev-list terminates.)
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Callers of start_command() can set the members .in and .out of struct
child_process to a value > 0 to specify that this descriptor is used as
the stdin or stdout of the child process.
Previously, if start_command() was successful, this descriptor was closed
upon return. Here we now make sure that the descriptor is also closed in
case of failures. All callers are updated not to close the file descriptor
themselves after start_command() was called.
Note that earlier run_gpg_verify() of git-verify-tag set .out = 1, which
worked because start_command() treated this as a special case, but now
this is incorrect because it closes the descriptor. The intent here is to
inherit stdout to the child, which is achieved by .out = 0.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
By setting .in, .out, or .err members of struct child_process to -1, the
callers of start_command() can request that a pipe is allocated that talks
to the child process and one end is returned by replacing -1 with the
file descriptor.
Previously, a flag was set (for .in and .out, but not .err) to signal
finish_command() to close the pipe end that start_command() had handed out,
so it was optional for callers to close the pipe, and many already do so.
Now we make it mandatory to close the pipe.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Some callers may wish to redirect stderr to /dev/null in some
contexts, such as if they are executing a command only to get
the exit status and don't want users to see whatever output it
may produce as a side-effect of computing that exit status.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This adds start_async() and finish_async(), which runs a function
asynchronously. Communication with the caller happens only via pipes.
For this reason, this implementation forks off a child process that runs
the function.
[sp: Style nit fixed by removing unnecessary block on if condition
inside of start_async()]
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This adds another stanza that allocates a pipe that is connected to the
child's stderr and that the caller can read from. In order to request this
pipe, the caller sets cmd->err to -1.
The implementation is not exactly modeled after the stdout case: For stdout
the caller can supply an existing file descriptor, but this facility is
nowhere needed in the stderr case. Additionally, the caller is required to
close cmd->err.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
To unset a variable, just specify its name, without "=". For example:
const char *env[] = {"GIT_DIR=.git", "PWD", NULL};
const char *argv[] = {"git-ls-files", "-s", NULL};
int err = run_command_v_opt_cd_env(argv, RUN_GIT_CMD, ".", env);
The PWD will be unset before executing git-ls-files.
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
There is no way to specify and override for the environment:
there'd be no user for it yet.
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
It can make code simplier (no need to preserve cwd) and safer
(no chance the cwd of the current process is accidentally forgotten).
Signed-off-by: Alex Riesen <raa.lkml@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Some run-command callers may wish to just discard any data that
is sent to stdout from the child. This is a lot like our existing
no_stdin support, we just open /dev/null and duplicate the descriptor
into position.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Some potential callers of the run_command family of functions need
to control not only the stdin redirection of the child, but also
the stdout redirection of the child. This can now be setup much
like the already existing stdin redirection.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Sometimes callers trying to use run_command to execute a child
process will want to setup a pipe or file descriptor to redirect
into the child's stdin.
This idea is completely stolen from builtin-bundle's fork_with_pipe,
written by Johannes Schindelin. All credit (and blame) should lie
with Dscho. ;-)
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
If the calling process wants to send data to stdin of a
child process it will need to arrange for a pipe and get
the child process running, feed data to it, then wait
for the child process to finish. So we split the run
function into two halves, allowing callers to first
start the child then later finish it.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
There are a number of places where we do some variation of
fork()+exec() but we also need to setup redirection in the process,
much like what run_command does for us already with its option flags.
It would be nice to reuse more of the run_command logic, especially
as that non-fork API helps us to port to odd platforms like Win32.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
We don't actually use these va_list based variants of run_command
anymore. I'm removing them before I make further improvements.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Currently the update hook invoked by receive-pack has its stdin
connected to the pushing client. The hook shouldn't attempt to
read from this stream, and doing so may consume data that was
meant for receive-pack. Instead we should give the update hook
/dev/null as its stdin, ensuring that it always receives EOF and
doesn't disrupt the protocol if it attempts to read any data.
The post-update hook is similar, as it gets invoked with /dev/null
on stdin to prevent the hook from reading data from the client.
Previously we had invoked it with stdout also connected to /dev/null,
throwing away anything on stdout, to prevent client protocol errors.
Instead we should redirect stdout to stderr, like we do with the
update hook.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
If an update hook outputs to stdout then that output will be sent
back over the wire to the push client as though it were part of
the git protocol. This tends to cause protocol errors on the
client end of the connection, as the hook output is not expected
in that context. Most hook developers work around this by making
sure their hook outputs everything to stderr.
But hooks shouldn't need to perform such special behavior. Instead
we can just dup stderr to stdout prior to invoking the update hook.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
The argc parameter is never used by the run_command_v family of
functions. Instead they require that the passed argv[] be NULL
terminated so they can rely on the operating system's execvp
function to correctly pass the arguments to the new process.
Making the caller pass the argc is just confusing, as the caller
could be mislead into believing that the argc might take precendece
over the argv, or that the argv does not need to be NULL terminated.
So goodbye argc. Don't come back.
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
Mark Wooding noticed there was a type mismatch warning in git.c; this
patch does things slightly differently (mostly tightening const) and
was what I was holding onto, waiting for the setup-revisions change
to be merged into the master branch.
Signed-off-by: Junio C Hamano <junkio@cox.net>
The git suite may not be in PATH (and thus programs such as
git-send-pack could not exec git-rev-list). Thus there is a need for
logic that will locate these programs. Modifying PATH is not
desirable as it result in behavior differing from the user's
intentions, as we may end up prepending "/usr/bin" to PATH.
- git C programs will use exec*_git_cmd() APIs to exec sub-commands.
- exec*_git_cmd() will execute a git program by searching for it in
the following directories:
1. --exec-path (as used by "git")
2. The GIT_EXEC_PATH environment variable.
3. $(gitexecdir) as set in Makefile (default value $(bindir)).
- git wrapper will modify PATH as before to enable shell scripts to
invoke "git-foo" commands.
Ideally, shell scripts should use the git wrapper to become independent
of PATH, and then modifying PATH will not be necessary.
[jc: with minor updates after a brief review.]
Signed-off-by: Michal Ostrowski <mostrows@watson.ibm.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
When calling post-update hook, don't leave stdin and stdout connected to
the pushing connection.
Signed-off-by: Daniel Barkalow <barkalow@iabervon.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
The earlier one conflated update and post-update hooks for no
good reason. Correct that ugly hack. Now post-update hooks
will take the list of successfully updated refs.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Just before updating a ref,
$GIT_DIR/hooks/update refname old-sha1 new-sha1
is called if executable. The hook can decline the ref to be
updated by exiting with a non-zero status, or allow it to be
updated by exiting with a zero status. The mechanism also
allows e.g sending of a mail with pushed commits on the remote
repository.
Documentation update with an example hook is included.
jc: The credits of the basic idea and initial implementation go
to Josef, but I ended up rewriting major parts of his patch, so
bugs are all mine. Also I changed the semantics for the hook
from his original version (which were post-update hook) so that
the hook can optionally decline to update the ref, and also can
be used to implement the overall cleanups. The latter was
primarily to implement a suggestion from Linus that calling
update-server-info should be made optional.
Signed-off-by: Junio C Hamano <junkio@cox.net>
Johannes Sixt