1
0
Fork 0
mirror of https://github.com/git/git.git synced 2024-10-30 22:07:53 +01:00
git/exec_cmd.c
Jeff King 6854a8f5c9 common-main: stop munging argv[0] path
Since 650c44925 (common-main: call git_extract_argv0_path(),
2016-07-01), the argv[0] that is seen in cmd_main() of
individual programs is always the basename of the
executable, as common-main strips off the full path. This
can produce confusing results for git-daemon, which wants to
re-exec itself.

For instance, if the program was originally run as
"/usr/lib/git/git-daemon", it will try just re-execing
"git-daemon", which will find the first instance in $PATH.
If git's exec-path has not been prepended to $PATH, we may
find the git-daemon from a different version (or no
git-daemon at all).

Normally this isn't a problem. Git commands are run as "git
daemon", the git wrapper puts the exec-path at the front of
$PATH, and argv[0] is already "daemon" anyway. But running
git-daemon via its full exec-path, while not really a
recommended method, did work prior to 650c44925. Let's make
it work again.

The real goal of 650c44925 was not to munge argv[0], but to
reliably set the argv0_path global. The only reason it
munges at all is that one caller, the git.c wrapper,
piggy-backed on that computation to find the command
basename.  Instead, let's leave argv[0] untouched in
common-main, and have git.c do its own basename computation.

While we're at it, let's drop the return value from
git_extract_argv0_path(). It was only ever used in this one
callsite, and its dual purposes is what led to this
confusion in the first place.

Note that by changing the interface, the compiler can
confirm for us that there are no other callers storing the
return value. But the compiler can't tell us whether any of
the cmd_main() functions (besides git.c) were relying on the
basename munging. However, we can observe that prior to
650c44925, no other cmd_main() functions did that munging,
and no new cmd_main() functions have been introduced since
then. So we can't be regressing any of those cases.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-11-29 11:01:48 -08:00

149 lines
2.9 KiB
C

#include "cache.h"
#include "exec_cmd.h"
#include "quote.h"
#include "argv-array.h"
#define MAX_ARGS 32
static const char *argv_exec_path;
static const char *argv0_path;
char *system_path(const char *path)
{
#ifdef RUNTIME_PREFIX
static const char *prefix;
#else
static const char *prefix = PREFIX;
#endif
struct strbuf d = STRBUF_INIT;
if (is_absolute_path(path))
return xstrdup(path);
#ifdef RUNTIME_PREFIX
assert(argv0_path);
assert(is_absolute_path(argv0_path));
if (!prefix &&
!(prefix = strip_path_suffix(argv0_path, GIT_EXEC_PATH)) &&
!(prefix = strip_path_suffix(argv0_path, BINDIR)) &&
!(prefix = strip_path_suffix(argv0_path, "git"))) {
prefix = PREFIX;
trace_printf("RUNTIME_PREFIX requested, "
"but prefix computation failed. "
"Using static fallback '%s'.\n", prefix);
}
#endif
strbuf_addf(&d, "%s/%s", prefix, path);
return strbuf_detach(&d, NULL);
}
void git_extract_argv0_path(const char *argv0)
{
const char *slash;
if (!argv0 || !*argv0)
return;
slash = find_last_dir_sep(argv0);
if (slash)
argv0_path = xstrndup(argv0, slash - argv0);
}
void git_set_argv_exec_path(const char *exec_path)
{
argv_exec_path = exec_path;
/*
* Propagate this setting to external programs.
*/
setenv(EXEC_PATH_ENVIRONMENT, exec_path, 1);
}
/* Returns the highest-priority, location to look for git programs. */
const char *git_exec_path(void)
{
const char *env;
if (argv_exec_path)
return argv_exec_path;
env = getenv(EXEC_PATH_ENVIRONMENT);
if (env && *env) {
return env;
}
return system_path(GIT_EXEC_PATH);
}
static void add_path(struct strbuf *out, const char *path)
{
if (path && *path) {
strbuf_add_absolute_path(out, path);
strbuf_addch(out, PATH_SEP);
}
}
void setup_path(void)
{
const char *old_path = getenv("PATH");
struct strbuf new_path = STRBUF_INIT;
add_path(&new_path, git_exec_path());
if (old_path)
strbuf_addstr(&new_path, old_path);
else
strbuf_addstr(&new_path, _PATH_DEFPATH);
setenv("PATH", new_path.buf, 1);
strbuf_release(&new_path);
}
const char **prepare_git_cmd(struct argv_array *out, const char **argv)
{
argv_array_push(out, "git");
argv_array_pushv(out, argv);
return out->argv;
}
int execv_git_cmd(const char **argv) {
struct argv_array nargv = ARGV_ARRAY_INIT;
prepare_git_cmd(&nargv, argv);
trace_argv_printf(nargv.argv, "trace: exec:");
/* execvp() can only ever return if it fails */
sane_execvp("git", (char **)nargv.argv);
trace_printf("trace: exec failed: %s\n", strerror(errno));
argv_array_clear(&nargv);
return -1;
}
int execl_git_cmd(const char *cmd,...)
{
int argc;
const char *argv[MAX_ARGS + 1];
const char *arg;
va_list param;
va_start(param, cmd);
argv[0] = cmd;
argc = 1;
while (argc < MAX_ARGS) {
arg = argv[argc++] = va_arg(param, char *);
if (!arg)
break;
}
va_end(param);
if (MAX_ARGS <= argc)
return error("too many args to run %s", cmd);
argv[argc] = NULL;
return execv_git_cmd(argv);
}