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remove no-longer-needed special case handling in popen

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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
6fc6ca1a32 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.
This commit is contained in:
Rich Felker 2021-03-15 10:26:21 -04:00
parent 8ef9d46f4d
commit 122002f0dd
1 changed files with 0 additions and 16 deletions
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16
src/stdio/popen.c
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@ -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]);