glibc/libio/iopopen.c
Adhemerval Zanella 478f70780f Remove __waitpid_nocancel
It enables and disables cancellation with pthread_setcancelstate
before calling the waitpid.  It simplifies the waitpid implementation
for architectures that do not provide either __NR_waitpid or
__NR_wait4.

Checked on x86_64-linux-gnu.
2019-12-19 16:11:09 -03:00

324 lines
9.4 KiB
C

/* Copyright (C) 1993-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Written by Per Bothner <bothner@cygnus.com>.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>.
As a special exception, if you link the code in this file with
files compiled with a GNU compiler to produce an executable,
that does not cause the resulting executable to be covered by
the GNU Lesser General Public License. This exception does not
however invalidate any other reasons why the executable file
might be covered by the GNU Lesser General Public License.
This exception applies to code released by its copyright holders
in files containing the exception. */
#include "libioP.h"
#include <fcntl.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <shlib-compat.h>
#include <not-cancel.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <spawn.h>
#include <paths.h>
struct _IO_proc_file
{
struct _IO_FILE_plus file;
/* Following fields must match those in class procbuf (procbuf.h) */
pid_t pid;
struct _IO_proc_file *next;
};
typedef struct _IO_proc_file _IO_proc_file;
static const struct _IO_jump_t _IO_proc_jumps;
static struct _IO_proc_file *proc_file_chain;
#ifdef _IO_MTSAFE_IO
static _IO_lock_t proc_file_chain_lock = _IO_lock_initializer;
static void
unlock (void *not_used)
{
_IO_lock_unlock (proc_file_chain_lock);
}
#endif
/* POSIX states popen shall ensure that any streams from previous popen()
calls that remain open in the parent process should be closed in the new
child process.
To avoid a race-condition between checking which file descriptors need to
be close (by transversing the proc_file_chain list) and the insertion of a
new one after a successful posix_spawn this function should be called
with proc_file_chain_lock acquired. */
static bool
spawn_process (posix_spawn_file_actions_t *fa, FILE *fp, const char *command,
int do_cloexec, int pipe_fds[2], int parent_end, int child_end,
int child_pipe_fd)
{
for (struct _IO_proc_file *p = proc_file_chain; p; p = p->next)
{
int fd = _IO_fileno ((FILE *) p);
/* If any stream from previous popen() calls has fileno
child_pipe_fd, it has been already closed by the adddup2 action
above. */
if (fd != child_pipe_fd
&& __posix_spawn_file_actions_addclose (fa, fd) != 0)
return false;
}
if (__posix_spawn (&((_IO_proc_file *) fp)->pid, _PATH_BSHELL, fa, 0,
(char *const[]){ (char*) "sh", (char*) "-c",
(char *) command, NULL }, __environ) != 0)
return false;
__close_nocancel (pipe_fds[child_end]);
if (!do_cloexec)
/* Undo the effects of the pipe2 call which set the
close-on-exec flag. */
__fcntl (pipe_fds[parent_end], F_SETFD, 0);
_IO_fileno (fp) = pipe_fds[parent_end];
((_IO_proc_file *) fp)->next = proc_file_chain;
proc_file_chain = (_IO_proc_file *) fp;
return true;
}
FILE *
_IO_new_proc_open (FILE *fp, const char *command, const char *mode)
{
int read_or_write;
/* These are indexes for pipe_fds. */
int parent_end, child_end;
int pipe_fds[2];
int child_pipe_fd;
bool spawn_ok;
int do_read = 0;
int do_write = 0;
int do_cloexec = 0;
while (*mode != '\0')
switch (*mode++)
{
case 'r':
do_read = 1;
break;
case 'w':
do_write = 1;
break;
case 'e':
do_cloexec = 1;
break;
default:
errout:
__set_errno (EINVAL);
return NULL;
}
if ((do_read ^ do_write) == 0)
goto errout;
if (_IO_file_is_open (fp))
return NULL;
/* 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)
{
parent_end = 0;
child_end = 1;
read_or_write = _IO_NO_WRITES;
child_pipe_fd = 1;
}
else
{
parent_end = 1;
child_end = 0;
read_or_write = _IO_NO_READS;
child_pipe_fd = 0;
}
posix_spawn_file_actions_t fa;
/* posix_spawn_file_actions_init does not fail. */
__posix_spawn_file_actions_init (&fa);
/* The descriptor is already the one the child will use. In this case
it must be moved to another one otherwise, there is no safe way to
remove the close-on-exec flag in the child without creating a FD leak
race in the parent. */
if (pipe_fds[child_end] == child_pipe_fd)
{
int tmp = __fcntl (child_pipe_fd, F_DUPFD_CLOEXEC, 0);
if (tmp < 0)
goto spawn_failure;
__close_nocancel (pipe_fds[child_end]);
pipe_fds[child_end] = tmp;
}
if (__posix_spawn_file_actions_adddup2 (&fa, pipe_fds[child_end],
child_pipe_fd) != 0)
goto spawn_failure;
#ifdef _IO_MTSAFE_IO
_IO_cleanup_region_start_noarg (unlock);
_IO_lock_lock (proc_file_chain_lock);
#endif
spawn_ok = spawn_process (&fa, fp, command, do_cloexec, pipe_fds,
parent_end, child_end, child_pipe_fd);
#ifdef _IO_MTSAFE_IO
_IO_lock_unlock (proc_file_chain_lock);
_IO_cleanup_region_end (0);
#endif
__posix_spawn_file_actions_destroy (&fa);
if (!spawn_ok)
{
spawn_failure:
__close_nocancel (pipe_fds[child_end]);
__close_nocancel (pipe_fds[parent_end]);
__set_errno (ENOMEM);
return NULL;
}
_IO_mask_flags (fp, read_or_write, _IO_NO_READS|_IO_NO_WRITES);
return fp;
}
FILE *
_IO_new_popen (const char *command, const char *mode)
{
struct locked_FILE
{
struct _IO_proc_file fpx;
#ifdef _IO_MTSAFE_IO
_IO_lock_t lock;
#endif
} *new_f;
FILE *fp;
new_f = (struct locked_FILE *) malloc (sizeof (struct locked_FILE));
if (new_f == NULL)
return NULL;
#ifdef _IO_MTSAFE_IO
new_f->fpx.file.file._lock = &new_f->lock;
#endif
fp = &new_f->fpx.file.file;
_IO_init_internal (fp, 0);
_IO_JUMPS (&new_f->fpx.file) = &_IO_proc_jumps;
_IO_new_file_init_internal (&new_f->fpx.file);
if (_IO_new_proc_open (fp, command, mode) != NULL)
return (FILE *) &new_f->fpx.file;
_IO_un_link (&new_f->fpx.file);
free (new_f);
return NULL;
}
int
_IO_new_proc_close (FILE *fp)
{
/* This is not name-space clean. FIXME! */
int wstatus;
_IO_proc_file **ptr = &proc_file_chain;
pid_t wait_pid;
int status = -1;
/* Unlink from proc_file_chain. */
#ifdef _IO_MTSAFE_IO
_IO_cleanup_region_start_noarg (unlock);
_IO_lock_lock (proc_file_chain_lock);
#endif
for ( ; *ptr != NULL; ptr = &(*ptr)->next)
{
if (*ptr == (_IO_proc_file *) fp)
{
*ptr = (*ptr)->next;
status = 0;
break;
}
}
#ifdef _IO_MTSAFE_IO
_IO_lock_unlock (proc_file_chain_lock);
_IO_cleanup_region_end (0);
#endif
if (status < 0 || __close_nocancel (_IO_fileno(fp)) < 0)
return -1;
/* POSIX.2 Rationale: "Some historical implementations either block
or ignore the signals SIGINT, SIGQUIT, and SIGHUP while waiting
for the child process to terminate. Since this behavior is not
described in POSIX.2, such implementations are not conforming." */
do
{
int state;
__libc_ptf_call (__pthread_setcancelstate,
(PTHREAD_CANCEL_DISABLE, &state), 0);
wait_pid = __waitpid (((_IO_proc_file *) fp)->pid, &wstatus, 0);
__libc_ptf_call (__pthread_setcancelstate, (state, NULL), 0);
}
while (wait_pid == -1 && errno == EINTR);
if (wait_pid == -1)
return -1;
return wstatus;
}
static const struct _IO_jump_t _IO_proc_jumps libio_vtable = {
JUMP_INIT_DUMMY,
JUMP_INIT(finish, _IO_new_file_finish),
JUMP_INIT(overflow, _IO_new_file_overflow),
JUMP_INIT(underflow, _IO_new_file_underflow),
JUMP_INIT(uflow, _IO_default_uflow),
JUMP_INIT(pbackfail, _IO_default_pbackfail),
JUMP_INIT(xsputn, _IO_new_file_xsputn),
JUMP_INIT(xsgetn, _IO_default_xsgetn),
JUMP_INIT(seekoff, _IO_new_file_seekoff),
JUMP_INIT(seekpos, _IO_default_seekpos),
JUMP_INIT(setbuf, _IO_new_file_setbuf),
JUMP_INIT(sync, _IO_new_file_sync),
JUMP_INIT(doallocate, _IO_file_doallocate),
JUMP_INIT(read, _IO_file_read),
JUMP_INIT(write, _IO_new_file_write),
JUMP_INIT(seek, _IO_file_seek),
JUMP_INIT(close, _IO_new_proc_close),
JUMP_INIT(stat, _IO_file_stat),
JUMP_INIT(showmanyc, _IO_default_showmanyc),
JUMP_INIT(imbue, _IO_default_imbue)
};
strong_alias (_IO_new_popen, __new_popen)
versioned_symbol (libc, _IO_new_popen, _IO_popen, GLIBC_2_1);
versioned_symbol (libc, __new_popen, popen, GLIBC_2_1);
versioned_symbol (libc, _IO_new_proc_open, _IO_proc_open, GLIBC_2_1);
versioned_symbol (libc, _IO_new_proc_close, _IO_proc_close, GLIBC_2_1);