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authorUlrich Drepper <drepper@redhat.com>2008-07-23 21:29:30 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-07-24 10:47:28 -0700
commited8cae8ba01348bfd83333f4648dd807b04d7f08 (patch)
treec71a1c8e771c1c55728bb7c40612fbdcefbc858a /fs/pipe.c
parent336dd1f70ff62d7dd8655228caed4c5bfc818c56 (diff)
downloadlwn-ed8cae8ba01348bfd83333f4648dd807b04d7f08.tar.gz
lwn-ed8cae8ba01348bfd83333f4648dd807b04d7f08.zip
flag parameters: pipe
This patch introduces the new syscall pipe2 which is like pipe but it also takes an additional parameter which takes a flag value. This patch implements the handling of O_CLOEXEC for the flag. I did not add support for the new syscall for the architectures which have a special sys_pipe implementation. I think the maintainers of those archs have the chance to go with the unified implementation but that's up to them. The implementation introduces do_pipe_flags. I did that instead of changing all callers of do_pipe because some of the callers are written in assembler. I would probably screw up changing the assembly code. To avoid breaking code do_pipe is now a small wrapper around do_pipe_flags. Once all callers are changed over to do_pipe_flags the old do_pipe function can be removed. The following test must be adjusted for architectures other than x86 and x86-64 and in case the syscall numbers changed. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #include <fcntl.h> #include <stdio.h> #include <unistd.h> #include <sys/syscall.h> #ifndef __NR_pipe2 # ifdef __x86_64__ # define __NR_pipe2 293 # elif defined __i386__ # define __NR_pipe2 331 # else # error "need __NR_pipe2" # endif #endif int main (void) { int fd[2]; if (syscall (__NR_pipe2, fd, 0) != 0) { puts ("pipe2(0) failed"); return 1; } for (int i = 0; i < 2; ++i) { int coe = fcntl (fd[i], F_GETFD); if (coe == -1) { puts ("fcntl failed"); return 1; } if (coe & FD_CLOEXEC) { printf ("pipe2(0) set close-on-exit for fd[%d]\n", i); return 1; } } close (fd[0]); close (fd[1]); if (syscall (__NR_pipe2, fd, O_CLOEXEC) != 0) { puts ("pipe2(O_CLOEXEC) failed"); return 1; } for (int i = 0; i < 2; ++i) { int coe = fcntl (fd[i], F_GETFD); if (coe == -1) { puts ("fcntl failed"); return 1; } if ((coe & FD_CLOEXEC) == 0) { printf ("pipe2(O_CLOEXEC) does not set close-on-exit for fd[%d]\n", i); return 1; } } close (fd[0]); close (fd[1]); puts ("OK"); return 0; } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Signed-off-by: Ulrich Drepper <drepper@redhat.com> Acked-by: Davide Libenzi <davidel@xmailserver.org> Cc: Michael Kerrisk <mtk.manpages@googlemail.com> Cc: <linux-arch@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/pipe.c')
-rw-r--r--fs/pipe.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/fs/pipe.c b/fs/pipe.c
index 700f4e0d9572..68e82061070c 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1027,12 +1027,15 @@ struct file *create_read_pipe(struct file *wrf)
return f;
}
-int do_pipe(int *fd)
+int do_pipe_flags(int *fd, int flags)
{
struct file *fw, *fr;
int error;
int fdw, fdr;
+ if (flags & ~O_CLOEXEC)
+ return -EINVAL;
+
fw = create_write_pipe();
if (IS_ERR(fw))
return PTR_ERR(fw);
@@ -1041,12 +1044,12 @@ int do_pipe(int *fd)
if (IS_ERR(fr))
goto err_write_pipe;
- error = get_unused_fd();
+ error = get_unused_fd_flags(flags);
if (error < 0)
goto err_read_pipe;
fdr = error;
- error = get_unused_fd();
+ error = get_unused_fd_flags(flags);
if (error < 0)
goto err_fdr;
fdw = error;
@@ -1074,16 +1077,21 @@ int do_pipe(int *fd)
return error;
}
+int do_pipe(int *fd)
+{
+ return do_pipe_flags(fd, 0);
+}
+
/*
* sys_pipe() is the normal C calling standard for creating
* a pipe. It's not the way Unix traditionally does this, though.
*/
-asmlinkage long __weak sys_pipe(int __user *fildes)
+asmlinkage long __weak sys_pipe2(int __user *fildes, int flags)
{
int fd[2];
int error;
- error = do_pipe(fd);
+ error = do_pipe_flags(fd, flags);
if (!error) {
if (copy_to_user(fildes, fd, sizeof(fd))) {
sys_close(fd[0]);
@@ -1094,6 +1102,11 @@ asmlinkage long __weak sys_pipe(int __user *fildes)
return error;
}
+asmlinkage long __weak sys_pipe(int __user *fildes)
+{
+ return sys_pipe2(fildes, 0);
+}
+
/*
* pipefs should _never_ be mounted by userland - too much of security hassle,
* no real gain from having the whole whorehouse mounted. So we don't need