common-main: call sanitize_stdfds()
This is setup that should be done in every program for
safety, but we never got around to adding it everywhere (so
builtins benefited from the call in git.c, but any external
commands did not). Putting it in the common main() gives us
this safety everywhere.
Note that the case in daemon.c is a little funny. We wait
until we know whether we want to daemonize, and then either:
- call daemonize(), which will close stdio and reopen it to
/dev/null under the hood
- sanitize_stdfds(), to fix up any odd cases
But that is way too late; the point of sanitizing is to give
us reliable descriptors on 0/1/2, and we will already have
executed code, possibly called die(), etc. The sanitizing
should be the very first thing that happens.
With this patch, git-daemon will sanitize first, and can
remove the call in the non-daemonize case. It does mean that
daemonize() may just end up closing the descriptors we
opened, but that's not a big deal (it's not wrong to do so,
nor is it really less optimal than the case where our parent
process redirected us from /dev/null ahead of time).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-01 09:06:02 +03:00
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#include "cache.h"
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common-main: call git_extract_argv0_path()
Every program which links against libgit.a must call this
function, or risk hitting an assert() in system_path() that
checks whether we have configured argv0_path (though only
when RUNTIME_PREFIX is defined, so essentially only on
Windows).
Looking at the diff, you can see that putting it into the
common main() saves us having to do it individually in each
of the external commands. But what you can't see are the
cases where we _should_ have been doing so, but weren't
(e.g., git-credential-store, and all of the t/helper test
programs).
This has been an accident-waiting-to-happen for a long time,
but wasn't triggered until recently because it involves one
of those programs actually calling system_path(). That
happened with git-credential-store in v2.8.0 with ae5f677
(lazily load core.sharedrepository, 2016-03-11). The
program:
- takes a lock file, which...
- opens a tempfile, which...
- calls adjust_shared_perm to fix permissions, which...
- lazy-loads the config (as of ae5f677), which...
- calls system_path() to find the location of
/etc/gitconfig
On systems with RUNTIME_PREFIX, this means credential-store
reliably hits that assert() and cannot be used.
We never noticed in the test suite, because we set
GIT_CONFIG_NOSYSTEM there, which skips the system_path()
lookup entirely. But if we were to tweak git_config() to
find /etc/gitconfig even when we aren't going to open it,
then the test suite shows multiple failures (for
credential-store, and for some other test helpers). I didn't
include that tweak here because it's way too specific to
this particular call to be worth carrying around what is
essentially dead code.
The implementation is fairly straightforward, with one
exception: there is exactly one caller (git.c) that actually
cares about the result of the function, and not the
side-effect of setting up argv0_path. We can accommodate
that by simply replacing the value of argv[0] in the array
we hand down to cmd_main().
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-01 09:04:04 +03:00
|
|
|
#include "exec_cmd.h"
|
add an extra level of indirection to main()
There are certain startup tasks that we expect every git
process to do. In some cases this is just to improve the
quality of the program (e.g., setting up gettext()). In
others it is a requirement for using certain functions in
libgit.a (e.g., system_path() expects that you have called
git_extract_argv0_path()).
Most commands are builtins and are covered by the git.c
version of main(). However, there are still a few external
commands that use their own main(). Each of these has to
remember to include the correct startup sequence, and we are
not always consistent.
Rather than just fix the inconsistencies, let's make this
harder to get wrong by providing a common main() that can
run this standard startup.
We basically have two options to do this:
- the compat/mingw.h file already does something like this by
adding a #define that replaces the definition of main with a
wrapper that calls mingw_startup().
The upside is that the code in each program doesn't need
to be changed at all; it's rewritten on the fly by the
preprocessor.
The downside is that it may make debugging of the startup
sequence a bit more confusing, as the preprocessor is
quietly inserting new code.
- the builtin functions are all of the form cmd_foo(),
and git.c's main() calls them.
This is much more explicit, which may make things more
obvious to somebody reading the code. It's also more
flexible (because of course we have to figure out _which_
cmd_foo() to call).
The downside is that each of the builtins must define
cmd_foo(), instead of just main().
This patch chooses the latter option, preferring the more
explicit approach, even though it is more invasive. We
introduce a new file common-main.c, with the "real" main. It
expects to call cmd_main() from whatever other objects it is
linked against.
We link common-main.o against anything that links against
libgit.a, since we know that such programs will need to do
this setup. Note that common-main.o can't actually go inside
libgit.a, as the linker would not pick up its main()
function automatically (it has no callers).
The rest of the patch is just adjusting all of the various
external programs (mostly in t/helper) to use cmd_main().
I've provided a global declaration for cmd_main(), which
means that all of the programs also need to match its
signature. In particular, many functions need to switch to
"const char **" instead of "char **" for argv. This effect
ripples out to a few other variables and functions, as well.
This makes the patch even more invasive, but the end result
is much better. We should be treating argv strings as const
anyway, and now all programs conform to the same signature
(which also matches the way builtins are defined).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-01 08:58:58 +03:00
|
|
|
|
|
|
|
|
int main(int argc, char **av)
|
|
|
|
|
{
|
|
|
|
|
/*
|
|
|
|
|
* This const trickery is explained in
|
|
|
|
|
* 84d32bf7678259c08406571cd6ce4b7a6724dcba
|
|
|
|
|
*/
|
|
|
|
|
const char **argv = (const char **)av;
|
|
|
|
|
|
common-main: call sanitize_stdfds()
This is setup that should be done in every program for
safety, but we never got around to adding it everywhere (so
builtins benefited from the call in git.c, but any external
commands did not). Putting it in the common main() gives us
this safety everywhere.
Note that the case in daemon.c is a little funny. We wait
until we know whether we want to daemonize, and then either:
- call daemonize(), which will close stdio and reopen it to
/dev/null under the hood
- sanitize_stdfds(), to fix up any odd cases
But that is way too late; the point of sanitizing is to give
us reliable descriptors on 0/1/2, and we will already have
executed code, possibly called die(), etc. The sanitizing
should be the very first thing that happens.
With this patch, git-daemon will sanitize first, and can
remove the call in the non-daemonize case. It does mean that
daemonize() may just end up closing the descriptors we
opened, but that's not a big deal (it's not wrong to do so,
nor is it really less optimal than the case where our parent
process redirected us from /dev/null ahead of time).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-01 09:06:02 +03:00
|
|
|
/*
|
|
|
|
|
* Always open file descriptors 0/1/2 to avoid clobbering files
|
|
|
|
|
* in die(). It also avoids messing up when the pipes are dup'ed
|
|
|
|
|
* onto stdin/stdout/stderr in the child processes we spawn.
|
|
|
|
|
*/
|
|
|
|
|
sanitize_stdfds();
|
|
|
|
|
|
common-main: call git_extract_argv0_path()
Every program which links against libgit.a must call this
function, or risk hitting an assert() in system_path() that
checks whether we have configured argv0_path (though only
when RUNTIME_PREFIX is defined, so essentially only on
Windows).
Looking at the diff, you can see that putting it into the
common main() saves us having to do it individually in each
of the external commands. But what you can't see are the
cases where we _should_ have been doing so, but weren't
(e.g., git-credential-store, and all of the t/helper test
programs).
This has been an accident-waiting-to-happen for a long time,
but wasn't triggered until recently because it involves one
of those programs actually calling system_path(). That
happened with git-credential-store in v2.8.0 with ae5f677
(lazily load core.sharedrepository, 2016-03-11). The
program:
- takes a lock file, which...
- opens a tempfile, which...
- calls adjust_shared_perm to fix permissions, which...
- lazy-loads the config (as of ae5f677), which...
- calls system_path() to find the location of
/etc/gitconfig
On systems with RUNTIME_PREFIX, this means credential-store
reliably hits that assert() and cannot be used.
We never noticed in the test suite, because we set
GIT_CONFIG_NOSYSTEM there, which skips the system_path()
lookup entirely. But if we were to tweak git_config() to
find /etc/gitconfig even when we aren't going to open it,
then the test suite shows multiple failures (for
credential-store, and for some other test helpers). I didn't
include that tweak here because it's way too specific to
this particular call to be worth carrying around what is
essentially dead code.
The implementation is fairly straightforward, with one
exception: there is exactly one caller (git.c) that actually
cares about the result of the function, and not the
side-effect of setting up argv0_path. We can accommodate
that by simply replacing the value of argv[0] in the array
we hand down to cmd_main().
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-01 09:04:04 +03:00
|
|
|
argv[0] = git_extract_argv0_path(argv[0]);
|
|
|
|
|
|
add an extra level of indirection to main()
There are certain startup tasks that we expect every git
process to do. In some cases this is just to improve the
quality of the program (e.g., setting up gettext()). In
others it is a requirement for using certain functions in
libgit.a (e.g., system_path() expects that you have called
git_extract_argv0_path()).
Most commands are builtins and are covered by the git.c
version of main(). However, there are still a few external
commands that use their own main(). Each of these has to
remember to include the correct startup sequence, and we are
not always consistent.
Rather than just fix the inconsistencies, let's make this
harder to get wrong by providing a common main() that can
run this standard startup.
We basically have two options to do this:
- the compat/mingw.h file already does something like this by
adding a #define that replaces the definition of main with a
wrapper that calls mingw_startup().
The upside is that the code in each program doesn't need
to be changed at all; it's rewritten on the fly by the
preprocessor.
The downside is that it may make debugging of the startup
sequence a bit more confusing, as the preprocessor is
quietly inserting new code.
- the builtin functions are all of the form cmd_foo(),
and git.c's main() calls them.
This is much more explicit, which may make things more
obvious to somebody reading the code. It's also more
flexible (because of course we have to figure out _which_
cmd_foo() to call).
The downside is that each of the builtins must define
cmd_foo(), instead of just main().
This patch chooses the latter option, preferring the more
explicit approach, even though it is more invasive. We
introduce a new file common-main.c, with the "real" main. It
expects to call cmd_main() from whatever other objects it is
linked against.
We link common-main.o against anything that links against
libgit.a, since we know that such programs will need to do
this setup. Note that common-main.o can't actually go inside
libgit.a, as the linker would not pick up its main()
function automatically (it has no callers).
The rest of the patch is just adjusting all of the various
external programs (mostly in t/helper) to use cmd_main().
I've provided a global declaration for cmd_main(), which
means that all of the programs also need to match its
signature. In particular, many functions need to switch to
"const char **" instead of "char **" for argv. This effect
ripples out to a few other variables and functions, as well.
This makes the patch even more invasive, but the end result
is much better. We should be treating argv strings as const
anyway, and now all programs conform to the same signature
(which also matches the way builtins are defined).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-07-01 08:58:58 +03:00
|
|
|
return cmd_main(argc, argv);
|
|
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|
|
}
|