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Assume that pipe2 is always available

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The Debian patches for Hurd (which are already required to build
glibc before this commit) contain an implementation of pipe2.
This commit is contained in:
Florian Weimer
2017-04-18 14:09:01 +02:00
parent 025b33ae84
commit 46d8874d5b
6 changed files with 32 additions and 96 deletions
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80
libio/iopopen.c
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@ -140,29 +140,17 @@ _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode)
if (_IO_file_is_open (fp))
return NULL;
#ifdef O_CLOEXEC
# ifndef __ASSUME_PIPE2
if (__have_pipe2 >= 0)
# endif
{
int r = __pipe2 (pipe_fds, O_CLOEXEC);
# ifndef __ASSUME_PIPE2
if (__have_pipe2 == 0)
__have_pipe2 = r != -1 || errno != ENOSYS ? 1 : -1;
if (__have_pipe2 > 0)
# endif
if (r < 0)
return NULL;
}
#endif
#ifndef __ASSUME_PIPE2
# ifdef O_CLOEXEC
if (__have_pipe2 < 0)
# endif
if (__pipe (pipe_fds) < 0)
return NULL;
#endif
/* Atomically set the O_CLOEXEC flag for the pipe end used by the
child process (to avoid leaking the file descriptor in case of a
concurrent fork). This is later reverted in the child process.
When popen returns, the parent pipe end can be O_CLOEXEC or not,
depending on the 'e' open mode, but there is only one flag which
controls both descriptors. The parent end is adjusted below,
after creating the child process. (In the child process, the
parent end should be closed on execve, so O_CLOEXEC remains set
there.) */
if (__pipe2 (pipe_fds, O_CLOEXEC) < 0)
return NULL;
if (do_read)
{
@ -183,27 +171,13 @@ _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode)
int child_std_end = do_read ? 1 : 0;
struct _IO_proc_file *p;
#ifndef __ASSUME_PIPE2
/* If we have pipe2 the descriptor is marked for close-on-exec. */
_IO_close (parent_end);
#endif
if (child_end != child_std_end)
{
_IO_dup2 (child_end, child_std_end);
#ifndef __ASSUME_PIPE2
_IO_close (child_end);
#endif
}
_IO_dup2 (child_end, child_std_end);
#ifdef O_CLOEXEC
else
{
/* The descriptor is already the one we will use. But it must
not be marked close-on-exec. Undo the effects. */
# ifndef __ASSUME_PIPE2
if (__have_pipe2 > 0)
# endif
__fcntl (child_end, F_SETFD, 0);
}
/* The descriptor is already the one we will use. But it must
not be marked close-on-exec. Undo the effects. */
__fcntl (child_end, F_SETFD, 0);
#endif
/* POSIX.2: "popen() shall ensure that any streams from previous
popen() calls that remain open in the parent process are closed
@ -229,26 +203,10 @@ _IO_new_proc_open (_IO_FILE *fp, const char *command, const char *mode)
return NULL;
}
if (do_cloexec)
{
#ifndef __ASSUME_PIPE2
# ifdef O_CLOEXEC
if (__have_pipe2 < 0)
# endif
__fcntl (parent_end, F_SETFD, FD_CLOEXEC);
#endif
}
else
{
#ifdef O_CLOEXEC
/* Undo the effects of the pipe2 call which set the
close-on-exec flag. */
# ifndef __ASSUME_PIPE2
if (__have_pipe2 > 0)
# endif
__fcntl (parent_end, F_SETFD, 0);
#endif
}
if (!do_cloexec)
/* Undo the effects of the pipe2 call which set the
close-on-exec flag. */
__fcntl (parent_end, F_SETFD, 0);
_IO_fileno (fp) = parent_end;