git-commit-vandalism/common-main.c
Jeff King 5732f2b1ef common-main: delay trace2 initialization
We initialize the trace2 system in the common main() function so that
all programs (even ones that aren't builtins) will enable tracing. But
trace2 startup is relatively heavy-weight, as we have to actually read
on-disk config to decide whether to trace. This can cause unexpected
interactions with other common-main initialization. For instance, we'll
end up in the config code before calling initialize_the_repository(),
and the usual invariant that the_repository is never NULL will not hold.

Let's push the trace2 initialization further down in common-main, to
just before we execute cmd_main(). The other parts of the initialization
are much more self-contained and less likely to call library code that
depends on those kinds of invariants.

Originally the trace2 code tried to start as early as possible to get
accurate timings. But the timer initialization was split out from the
config reading in a089724958 (trace2: refactor setting process starting
time, 2019-04-15), so there shouldn't be any impact from this patch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-08-06 13:09:01 -07:00

58 lines
1.3 KiB
C

#include "cache.h"
#include "exec-cmd.h"
#include "attr.h"
/*
* Many parts of Git have subprograms communicate via pipe, expect the
* upstream of a pipe to die with SIGPIPE when the downstream of a
* pipe does not need to read all that is written. Some third-party
* programs that ignore or block SIGPIPE for their own reason forget
* to restore SIGPIPE handling to the default before spawning Git and
* break this carefully orchestrated machinery.
*
* Restore the way SIGPIPE is handled to default, which is what we
* expect.
*/
static void restore_sigpipe_to_default(void)
{
sigset_t unblock;
sigemptyset(&unblock);
sigaddset(&unblock, SIGPIPE);
sigprocmask(SIG_UNBLOCK, &unblock, NULL);
signal(SIGPIPE, SIG_DFL);
}
int main(int argc, const char **argv)
{
int result;
trace2_initialize_clock();
/*
* 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();
restore_sigpipe_to_default();
git_resolve_executable_dir(argv[0]);
git_setup_gettext();
initialize_the_repository();
attr_start();
trace2_initialize();
trace2_cmd_start(argv);
trace2_collect_process_info(TRACE2_PROCESS_INFO_STARTUP);
result = cmd_main(argc, argv);
trace2_cmd_exit(result);
return result;
}