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git/exec_cmd.c
Jeff King c1bb33c99c git_extract_argv0_path: do nothing without RUNTIME_PREFIX
When the RUNTIME_PREFIX compile-time knob isn't set, we
never look at the argv0_path we extract. We can push its
declaration inside the #ifdef to make it more clear that the
extract code is effectively a noop.

This also un-confuses leak-checking of the argv0_path
variable when RUNTIME_PREFIX isn't set. The compiler is free
to drop this static variable that we set but never look at
(and "gcc -O2" does so).  But the compiler still must call
strbuf_detach(), since it doesn't know whether that function
has side effects; it just throws away the result rather than
putting it into the global.

Leak-checkers which work by scanning the data segment for
pointers to heap blocks would normally consider the block
as reachable at program end. But if the compiler removes the
variable entirely, there's nothing to find.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-07 09:41:14 +09:00

165 lines
3.2 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;
#ifdef RUNTIME_PREFIX
static const char *argv0_path;
static const char *system_prefix(void)
{
static const char *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);
}
return prefix;
}
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);
}
#else
static const char *system_prefix(void)
{
return PREFIX;
}
void git_extract_argv0_path(const char *argv0)
{
}
#endif /* RUNTIME_PREFIX */
char *system_path(const char *path)
{
struct strbuf d = STRBUF_INIT;
if (is_absolute_path(path))
return xstrdup(path);
strbuf_addf(&d, "%s/%s", system_prefix(), path);
return strbuf_detach(&d, NULL);
}
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)
{
static char *cached_exec_path;
if (argv_exec_path)
return argv_exec_path;
if (!cached_exec_path) {
const char *env = getenv(EXEC_PATH_ENVIRONMENT);
if (env && *env)
cached_exec_path = xstrdup(env);
else
cached_exec_path = system_path(GIT_EXEC_PATH);
}
return cached_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);
}