[PATCH 10/18] flag parameters: pipe

From: Ulrich Drepper
Date: Sun May 04 2008 - 23:48:15 EST

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;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

arch/cris/kernel/sys_cris.c | 2 +-
arch/ia64/ia32/sys_ia32.c | 2 +-
arch/ia64/kernel/sys_ia64.c | 2 +-
arch/m32r/kernel/sys_m32r.c | 2 +-
arch/mips/kernel/syscall.c | 2 +-
arch/parisc/hpux/sys_hpux.c | 2 +-
arch/sh/kernel/sys_sh32.c | 2 +-
arch/sparc/kernel/sys_sparc.c | 2 +-
arch/sparc64/kernel/sys_sparc.c | 2 +-
arch/x86/ia32/ia32entry.S | 1 +
arch/x86/ia32/sys_ia32.c | 2 +-
arch/x86/kernel/syscall_table_32.S | 1 +
arch/xtensa/kernel/syscall.c | 2 +-
fs/pipe.c | 23 ++++++++++++++++++-----
include/asm-x86/unistd_32.h | 1 +
include/asm-x86/unistd_64.h | 2 ++
include/linux/fs.h | 1 +
17 files changed, 35 insertions(+), 16 deletions(-)


Signed-off-by: Ulrich Drepper <drepper@xxxxxxxxxx>

diff --git a/arch/cris/kernel/sys_cris.c b/arch/cris/kernel/sys_cris.c
index 8b99841..e32ef68 100644
--- a/arch/cris/kernel/sys_cris.c
+++ b/arch/cris/kernel/sys_cris.c
@@ -37,7 +37,7 @@ asmlinkage int sys_pipe(unsigned long __user * fildes)
int error;

lock_kernel();
- error = do_pipe(fd);
+ error = do_pipe_flags(fd, 0);
unlock_kernel();
if (!error) {
if (copy_to_user(fildes, fd, 2*sizeof(int)))
diff --git a/arch/ia64/ia32/sys_ia32.c b/arch/ia64/ia32/sys_ia32.c
index 7e028ce..465116a 100644
--- a/arch/ia64/ia32/sys_ia32.c
+++ b/arch/ia64/ia32/sys_ia32.c
@@ -1139,7 +1139,7 @@ sys32_pipe (int __user *fd)
int retval;
int fds[2];

- retval = do_pipe(fds);
+ retval = do_pipe_flags(fds, 0);
if (retval)
goto out;
if (copy_to_user(fd, fds, sizeof(fds)))
diff --git a/arch/ia64/kernel/sys_ia64.c b/arch/ia64/kernel/sys_ia64.c
index 1eda194..bcbb6d8 100644
--- a/arch/ia64/kernel/sys_ia64.c
+++ b/arch/ia64/kernel/sys_ia64.c
@@ -160,7 +160,7 @@ sys_pipe (void)
int fd[2];
int retval;

- retval = do_pipe(fd);
+ retval = do_pipe_flags(fd, 0);
if (retval)
goto out;
retval = fd[0];
diff --git a/arch/m32r/kernel/sys_m32r.c b/arch/m32r/kernel/sys_m32r.c
index 6d7a80f..fc90b8b 100644
--- a/arch/m32r/kernel/sys_m32r.c
+++ b/arch/m32r/kernel/sys_m32r.c
@@ -88,7 +88,7 @@ sys_pipe(unsigned long r0, unsigned long r1, unsigned long r2,
int fd[2];
int error;

- error = do_pipe(fd);
+ error = do_pipe_flags(fd, 0);
if (!error) {
if (copy_to_user((void __user *)r0, fd, 2*sizeof(int)))
error = -EFAULT;
diff --git a/arch/mips/kernel/syscall.c b/arch/mips/kernel/syscall.c
index af1bdc8..20d5391 100644
--- a/arch/mips/kernel/syscall.c
+++ b/arch/mips/kernel/syscall.c
@@ -45,7 +45,7 @@ asmlinkage int sys_pipe(nabi_no_regargs volatile struct pt_regs regs)
int fd[2];
int error, res;

- error = do_pipe(fd);
+ error = do_pipe_flags(fd, 0);
if (error) {
res = error;
goto out;
diff --git a/arch/parisc/hpux/sys_hpux.c b/arch/parisc/hpux/sys_hpux.c
index 0c5b9da..be255eb 100644
--- a/arch/parisc/hpux/sys_hpux.c
+++ b/arch/parisc/hpux/sys_hpux.c
@@ -448,7 +448,7 @@ int hpux_pipe(int *kstack_fildes)
int error;

lock_kernel();
- error = do_pipe(kstack_fildes);
+ error = do_pipe_flags(kstack_fildes, 0);
unlock_kernel();
return error;
}
diff --git a/arch/sh/kernel/sys_sh32.c b/arch/sh/kernel/sys_sh32.c
index 125e493..f0aa5c3 100644
--- a/arch/sh/kernel/sys_sh32.c
+++ b/arch/sh/kernel/sys_sh32.c
@@ -29,7 +29,7 @@ asmlinkage int sys_pipe(unsigned long r4, unsigned long r5,
int fd[2];
int error;

- error = do_pipe(fd);
+ error = do_pipe_flags(fd, 0);
if (!error) {
regs->regs[1] = fd[1];
return fd[0];
diff --git a/arch/sparc/kernel/sys_sparc.c b/arch/sparc/kernel/sys_sparc.c
index f188b5d..681fdf2 100644
--- a/arch/sparc/kernel/sys_sparc.c
+++ b/arch/sparc/kernel/sys_sparc.c
@@ -97,7 +97,7 @@ asmlinkage int sparc_pipe(struct pt_regs *regs)
int fd[2];
int error;

- error = do_pipe(fd);
+ error = do_pipe_flags(fd, 0);
if (error)
goto out;
regs->u_regs[UREG_I1] = fd[1];
diff --git a/arch/sparc64/kernel/sys_sparc.c b/arch/sparc64/kernel/sys_sparc.c
index 8d4761f..936178d 100644
--- a/arch/sparc64/kernel/sys_sparc.c
+++ b/arch/sparc64/kernel/sys_sparc.c
@@ -418,7 +418,7 @@ asmlinkage long sparc_pipe(struct pt_regs *regs)
int fd[2];
int error;

- error = do_pipe(fd);
+ error = do_pipe_flags(fd, 0);
if (error)
goto out;
regs->u_regs[UREG_I1] = fd[1];
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index b5e329d..37e4992 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -735,4 +735,5 @@ ia32_sys_call_table:
.quad sys_eventfd2
.quad sys_epoll_create2
.quad sys_dup3 /* 330 */
+ .quad sys_pipe2
ia32_syscall_end:
diff --git a/arch/x86/ia32/sys_ia32.c b/arch/x86/ia32/sys_ia32.c
index f00afdf..d3c6408 100644
--- a/arch/x86/ia32/sys_ia32.c
+++ b/arch/x86/ia32/sys_ia32.c
@@ -238,7 +238,7 @@ asmlinkage long sys32_pipe(int __user *fd)
int retval;
int fds[2];

- retval = do_pipe(fds);
+ retval = do_pipe_flags(fds, 0);
if (retval)
goto out;
if (copy_to_user(fd, fds, sizeof(fds)))
diff --git a/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
index adff556..f59aba5 100644
--- a/arch/x86/kernel/syscall_table_32.S
+++ b/arch/x86/kernel/syscall_table_32.S
@@ -330,3 +330,4 @@ ENTRY(sys_call_table)
.long sys_eventfd2
.long sys_epoll_create2
.long sys_dup3 /* 330 */
+ .long sys_pipe2
diff --git a/arch/xtensa/kernel/syscall.c b/arch/xtensa/kernel/syscall.c
index f3e16ef..ac15ecb 100644
--- a/arch/xtensa/kernel/syscall.c
+++ b/arch/xtensa/kernel/syscall.c
@@ -49,7 +49,7 @@ asmlinkage long xtensa_pipe(int __user *userfds)
int fd[2];
int error;

- error = do_pipe(fd);
+ error = do_pipe_flags(fd, 0);
if (!error) {
if (copy_to_user(userfds, fd, 2 * sizeof(int)))
error = -EFAULT;
diff --git a/fs/pipe.c b/fs/pipe.c
index 3499f9f..796c0a0 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1027,26 +1027,29 @@ 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);
fr = create_read_pipe(fw);
error = PTR_ERR(fr);
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;
@@ -1075,16 +1078,21 @@ 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)))
error = -EFAULT;
@@ -1092,6 +1100,11 @@ 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
diff --git a/include/asm-x86/unistd_32.h b/include/asm-x86/unistd_32.h
index 8317d94..b3daf50 100644
--- a/include/asm-x86/unistd_32.h
+++ b/include/asm-x86/unistd_32.h
@@ -336,6 +336,7 @@
#define __NR_eventfd2 328
#define __NR_epoll_create2 329
#define __NR_dup3 330
+#define __NR_pipe2 331

#ifdef __KERNEL__

diff --git a/include/asm-x86/unistd_64.h b/include/asm-x86/unistd_64.h
index fe26e36..5ef6778 100644
--- a/include/asm-x86/unistd_64.h
+++ b/include/asm-x86/unistd_64.h
@@ -649,6 +649,8 @@ __SYSCALL(__NR_fallocate, sys_fallocate)
__SYSCALL(__NR_epoll_create2, sys_epoll_create2)
#define __NR_dup3 292
__SYSCALL(__NR_dup3, sys_dup3)
+#define __NR_pipe2 293
+__SYSCALL(__NR_pipe2, sys_pipe2)


#ifndef __NO_STUBS
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a1ba005..3694eeb 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1775,6 +1775,7 @@ static inline void allow_write_access(struct file *file)
atomic_inc(&file->f_path.dentry->d_inode->i_writecount);
}
extern int do_pipe(int *);
+extern int do_pipe_flags(int *, int);
extern struct file *create_read_pipe(struct file *f);
extern struct file *create_write_pipe(void);
extern void free_write_pipe(struct file *);
--
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