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* syscalls.cc (popen): Introduce Glibc 'e' flag to allow thread-safe 

opening of the pipe with O_CLOEXEC flag.  Simplify FD_CLOEXEC handling.
This commit is contained in:
Corinna Vinschen 2014-01-17 11:07:37 +00:00
parent 92a8ea56e5
commit 3507271d6b
2 changed files with 48 additions and 12 deletions
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5
winsup/cygwin/ChangeLog
View File

@ -1,3 +1,8 @@
2014-01-17 Corinna Vinschen <corinna@vinschen.de>
* syscalls.cc (popen): Introduce Glibc 'e' flag to allow thread-safe
opening of the pipe with O_CLOEXEC flag. Simplify FD_CLOEXEC handling.
2014-01-17 Corinna Vinschen <corinna@vinschen.de>
* include/sys/file.h (LOCK_SH): Drop definition in favor of new

55
winsup/cygwin/syscalls.cc
View File

@ -4236,11 +4236,36 @@ extern "C" FILE *
popen (const char *command, const char *in_type)
{
const char *type = in_type;
char rw = *type++;
char fdopen_flags[3] = "\0\0";
int pipe_flags = 0;
/* Sanity check in_type */
if (*type == 'b' || *type == 't')
type++;
#define rw fdopen_flags[0]
#define bintext fdopen_flags[1]
/* Sanity check. GLibc allows any order and any number of repetition,
as long as the string doesn't contradict itself. We do the same here. */
while (*type)
{
if (*type == 'r' || *type == 'w')
{
if (rw && rw != *type)
break;
rw = *type++;
}
else if (*type == 'b' || *type == 't')
{
if (bintext && bintext != *type)
break;
bintext = *type++;
}
else if (*type == 'e')
{
pipe_flags = O_CLOEXEC;
++type;
}
else
break;
}
if ((rw != 'r' && rw != 'w') || (*type != '\0'))
{
set_errno (EINVAL);
@ -4248,13 +4273,13 @@ popen (const char *command, const char *in_type)
}
int fds[2];
if (pipe (fds) < 0)
if (pipe2 (fds, pipe_flags) < 0)
return NULL;
int myix = rw == 'r' ? 0 : 1;
lock_process now;
FILE *fp = fdopen (fds[myix], in_type);
FILE *fp = fdopen (fds[myix], fdopen_flags);
if (fp)
{
/* If fds are in the range of stdin/stdout/stderr, move them
@ -4290,9 +4315,13 @@ popen (const char *command, const char *in_type)
NULL
};
/* Don't pass our end of the pipe to the child process */
int fd_state = fcntl64 (myfd, F_GETFD, 0);
fcntl64 (myfd, F_SETFD, fd_state | FD_CLOEXEC);
/* With 'e' flag given, we have to revert the close-on-exec on the child
end of the pipe. Otherwise don't pass our end of the pipe to the
child process. */
if (pipe_flags & O_CLOEXEC)
fcntl64 (__std[stdchild], F_SETFD, 0);
else
fcntl64 (myfd, F_SETFD, FD_CLOEXEC);
/* Also don't pass the file handle currently associated with stdin/stdout
to the child. This function may actually fail if the stdchild fd
@ -4318,10 +4347,8 @@ popen (const char *command, const char *in_type)
if (fds[myix] != orig_fds[myix])
cygheap->fdtab.move_fd (fds[myix], myfd = orig_fds[myix]);
fhandler_pipe *fh = (fhandler_pipe *) cygheap->fdtab[myfd];
/* Flag that this handle is associated with popen and then reset
the handle's original close-on-exec state. */
/* Flag that this handle is associated with popen. */
fh->set_popen_pid (pid);
fcntl64 (myfd, F_SETFD, fd_state);
return fp;
}
}
@ -4332,6 +4359,10 @@ popen (const char *command, const char *in_type)
close (fds[0]);
close (fds[1]);
set_errno (save_errno);
#undef rw
#undef bintext
return NULL;
}