Re: [PATCH] When exec'ing sub-commands, fall back on execvp (thePATH)

["Scott R Parish" <srp@srparish.net>]

Yeah, that seems to work fine. The theoretical drawback to this approach
is that it could possibly effect the order in which the paths are tried.
For instance, if a user did "export GIT_EXEC_PATH=", then the
builtin_exec_path wouldn't be tried before the PATH. (i doubt that it
would be a problem, but thought i should note it)

sRp


----- Original Message -----
Subject: Re: [PATCH] When exec'ing sub-commands, fall back on execvp
(thePATH)
Date: Sat, October 20, 2007 0:30
From: "Johannes Schindelin" <Johannes.Schindelin@gmx.de>

> Hi,
>
> On Fri, 19 Oct 2007, Scott Parish wrote:
>
> > diff --git a/exec_cmd.c b/exec_cmd.c
> > index 9b74ed2..674c9f3 100644
> > --- a/exec_cmd.c
> > +++ b/exec_cmd.c
> > @@ -34,15 +34,15 @@ int execv_git_cmd(const char **argv)
> >  {
> >          char git_command[PATH_MAX + 1];
> >          int i;
> > +        int rc;
> >          const char *paths[] = { current_exec_path,
> >                                  getenv(EXEC_PATH_ENVIRONMENT),
> >                                  builtin_exec_path };
> > +        const char *tmp;
> > +        size_t len;
> >
> >          for (i = 0; i < ARRAY_SIZE(paths); ++i) {
> > -                size_t len;
> > -                int rc;
> >                  const char *exec_dir = paths[i];
> > -                const char *tmp;
> >
> >                  if (!exec_dir || !*exec_dir) continue;
> >
> > @@ -106,8 +106,26 @@ int execv_git_cmd(const char **argv)
> >
> >                  argv[0] = tmp;
> >          }
> > -        return -1;
> >
> > +        rc = snprintf(git_command, sizeof(git_command), "git-%s",
argv[0]);
> > +        if (rc < 0 || rc >= sizeof(git_command) - len) {
> > +                fprintf(stderr, "git: command name given is too
long.\n");
> > +                return -1;
> > +        }
> > +
> > +        tmp = argv[0];
> > +        argv[0] = git_command;
> > +
> > +        trace_argv_printf(argv, -1, "trace: exec:");
> > +
> > +        /* execve() can only ever return if it fails */
> > +        execvp(git_command, (char **)argv);
> > +
> > +        trace_printf("trace: exec failed: %s\n", strerror(errno));
> > +
> > +        argv[0] = tmp;
> > +
> > +        return -1;
> >  }
>
> I am not sure that this is elegant enough: Something like this (completely
> untested) might be better:
>
> diff --git a/exec_cmd.c b/exec_cmd.c
> index 9b74ed2..c928f37 100644
> --- a/exec_cmd.c
> +++ b/exec_cmd.c
> @@ -36,7 +36,8 @@ int execv_git_cmd(const char **argv)
>          int i;
>          const char *paths[] = { current_exec_path,
>                                  getenv(EXEC_PATH_ENVIRONMENT),
> -                                builtin_exec_path };
> +                                builtin_exec_path,
> +                                "" };
>
>          for (i = 0; i < ARRAY_SIZE(paths); ++i) {
>                  size_t len;
> @@ -44,9 +45,12 @@ int execv_git_cmd(const char **argv)
>                  const char *exec_dir = paths[i];
>                  const char *tmp;
>
> -                if (!exec_dir || !*exec_dir) continue;
> +                if (!exec_dir) continue;
>
> -                if (*exec_dir != '/') {
> +                if (!*exec_dir)
> +                        /* try PATH */
> +                        *git_command = '\0';
> +                else if (*exec_dir != '/') {
>                          if (!getcwd(git_command, sizeof(git_command))) {
>                                  fprintf(stderr, "git: cannot determine "
>                                          "current directory: %s\n",
> @@ -81,7 +85,7 @@ int execv_git_cmd(const char **argv)
>
>                  len = strlen(git_command);
>                  rc = snprintf(git_command + len, sizeof(git_command) -
len,
> -                              "/git-%s", argv[0]);
> +                              "%sgit-%s", *exec_dir ? "/" : "", argv[0]);
>                  if (rc < 0 || rc >= sizeof(git_command) - len) {
>                          fprintf(stderr,
>                                  "git: command name given is too long.\n");
>
> Ciao,
> Dscho
>
> -
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