run-command: treat inaccessible directories as ENOENT

[thirdparty/git.git] / run-command.c

diff --git a/run-command.c b/run-command.c
index 1c5104388429e50722769358d5d89948c55bb3aa..805d41f93d66b9147b837fb51f365e85f8f44fda 100644 (file)
--- a/run-command.c
+++ b/run-command.c
@@ -18,6 +18,68 @@ static inline void dup_devnull(int to)
 }
 #endif
 
+static char *locate_in_PATH(const char *file)
+{
+       const char *p = getenv("PATH");
+       struct strbuf buf = STRBUF_INIT;
+
+       if (!p || !*p)
+               return NULL;
+
+       while (1) {
+               const char *end = strchrnul(p, ':');
+
+               strbuf_reset(&buf);
+
+               /* POSIX specifies an empty entry as the current directory. */
+               if (end != p) {
+                       strbuf_add(&buf, p, end - p);
+                       strbuf_addch(&buf, '/');
+               }
+               strbuf_addstr(&buf, file);
+
+               if (!access(buf.buf, F_OK))
+                       return strbuf_detach(&buf, NULL);
+
+               if (!*end)
+                       break;
+               p = end + 1;
+       }
+
+       strbuf_release(&buf);
+       return NULL;
+}
+
+static int exists_in_PATH(const char *file)
+{
+       char *r = locate_in_PATH(file);
+       free(r);
+       return r != NULL;
+}
+
+int sane_execvp(const char *file, char * const argv[])
+{
+       if (!execvp(file, argv))
+               return 0; /* cannot happen ;-) */
+
+       /*
+        * When a command can't be found because one of the directories
+        * listed in $PATH is unsearchable, execvp reports EACCES, but
+        * careful usability testing (read: analysis of occasional bug
+        * reports) reveals that "No such file or directory" is more
+        * intuitive.
+        *
+        * We avoid commands with "/", because execvp will not do $PATH
+        * lookups in that case.
+        *
+        * The reassignment of EACCES to errno looks like a no-op below,
+        * but we need to protect against exists_in_PATH overwriting errno.
+        */
+       if (errno == EACCES && !strchr(file, '/'))
+               errno = exists_in_PATH(file) ? EACCES : ENOENT;
+       return -1;
+}
+
 static const char **prepare_shell_cmd(const char **argv)
 {
        int argc, nargc = 0;
@@ -56,7 +118,7 @@ static int execv_shell_cmd(const char **argv)
 {
        const char **nargv = prepare_shell_cmd(argv);
        trace_argv_printf(nargv, "trace: exec:");
-       execvp(nargv[0], (char **)nargv);
+       sane_execvp(nargv[0], (char **)nargv);
        free(nargv);
        return -1;
 }
@@ -278,7 +340,7 @@ fail_pipe:
                } else if (cmd->use_shell) {
                        execv_shell_cmd(cmd->argv);
                } else {
-                       execvp(cmd->argv[0], (char *const*) cmd->argv);
+                       sane_execvp(cmd->argv[0], (char *const*) cmd->argv);
                }
                if (errno == ENOENT) {
                        if (!cmd->silent_exec_failure)