+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;
+}
+