remove no-longer-needed special case handling in popen

popen was special-casing the possibility (only possible when the
parent closed stdin and/or stdout) that the child's end of the pipe
was already on the final desired fd number, in which case there was no
way to get rid of its close-on-exec flag in the child. commit
6fc6ca1a323bc0b6b9e9cdc8fa72221ae18fe206 made this unnecessary by
implementing the POSIX-future requirement that dup2 file actions with
equal source and destination fd values remove the close-on-exec flag.

diff --git a/src/stdio/popen.c b/src/stdio/popen.c
index 92cb57e..b53a557 100644 (file)
--- a/src/stdio/popen.c
+++ b/src/stdio/popen.c
@@ -33,21 +33,6 @@ FILE *popen(const char *cmd, const char *mode)
        }
        FLOCK(f);
 
-       /* If the child's end of the pipe happens to already be on the final
-        * fd number to which it will be assigned (either 0 or 1), it must
-        * be moved to a different fd. Otherwise, there is no safe way to
-        * remove the close-on-exec flag in the child without also creating
-        * a file descriptor leak race condition in the parent. */
-       if (p[1-op] == 1-op) {
-               int tmp = fcntl(1-op, F_DUPFD_CLOEXEC, 0);
-               if (tmp < 0) {
-                       e = errno;
-                       goto fail;
-               }
-               __syscall(SYS_close, p[1-op]);
-               p[1-op] = tmp;
-       }
-
        e = ENOMEM;
        if (!posix_spawn_file_actions_init(&fa)) {
                if (!posix_spawn_file_actions_adddup2(&fa, p[1-op], 1-op)) {
@@ -64,7 +49,6 @@ FILE *popen(const char *cmd, const char *mode)
                }
                posix_spawn_file_actions_destroy(&fa);
        }
-fail:
        fclose(f);
        __syscall(SYS_close, p[1-op]);