[PATCH 2/5] run-command: prepare argv before forking

[Brandon Williams]

In order to avoid allocation between 'fork()' and 'exec()' the argv
array used in the exec call is prepared prior to forking the process.

Signed-off-by: Brandon Williams <bmw...@google.com>
---
 run-command.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

diff --git a/run-command.c b/run-command.c
index 682bc3ca5..2514b54bc 100644
--- a/run-command.c
+++ b/run-command.c
@@ -226,18 +226,6 @@ static const char **prepare_shell_cmd(struct argv_array 
*out, const char **argv)
 }
 
 #ifndef GIT_WINDOWS_NATIVE
-static int execv_shell_cmd(const char **argv)
-{
-       struct argv_array nargv = ARGV_ARRAY_INIT;
-       prepare_shell_cmd(&nargv, argv);
-       trace_argv_printf(nargv.argv, "trace: exec:");
-       sane_execvpe(nargv.argv[0], (char **)nargv.argv, NULL);
-       argv_array_clear(&nargv);
-       return -1;
-}
-#endif
-
-#ifndef GIT_WINDOWS_NATIVE
 static int child_notifier = -1;
 
 static void notify_parent(void)
@@ -377,9 +365,20 @@ int start_command(struct child_process *cmd)
 #ifndef GIT_WINDOWS_NATIVE
 {
        int notify_pipe[2];
+       struct argv_array argv = ARGV_ARRAY_INIT;
+
        if (pipe(notify_pipe))
                notify_pipe[0] = notify_pipe[1] = -1;
 
+       if (cmd->git_cmd) {
+               argv_array_push(&argv, "git");
+               argv_array_pushv(&argv, cmd->argv);
+       } else if (cmd->use_shell) {
+               prepare_shell_cmd(&argv, cmd->argv);
+       } else {
+               argv_array_pushv(&argv, cmd->argv);
+       }
+
        cmd->pid = fork();
        failed_errno = errno;
        if (!cmd->pid) {
@@ -442,12 +441,9 @@ int start_command(struct child_process *cmd)
                                        unsetenv(*cmd->env);
                        }
                }
-               if (cmd->git_cmd)
-                       execv_git_cmd(cmd->argv);
-               else if (cmd->use_shell)
-                       execv_shell_cmd(cmd->argv);
-               else
-                       sane_execvpe(cmd->argv[0], (char *const*) cmd->argv, 
NULL);
+
+               sane_execvpe(argv.argv[0], (char *const*) argv.argv, NULL);
+
                if (errno == ENOENT) {
                        if (!cmd->silent_exec_failure)
                                error("cannot run %s: %s", cmd->argv[0],
@@ -480,6 +476,8 @@ int start_command(struct child_process *cmd)
                cmd->pid = -1;
        }
        close(notify_pipe[0]);
+
+       argv_array_clear(&argv);
 }
 #else
 {
-- 
2.12.2.715.g7642488e1d-goog