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Date: Sun, 27 Apr 2008 23:20:28 -0400
From: Ulrich Drepper <drepper@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org, torvalds@...ux-foundation.org
Subject: [PATCH] dup2 w/flags
This patch adds dup3 which is dup2 with an additional parameter. The
parameter takes the usual O_* flags, with only O_CLOEXEC handled so far
(it's possible to handle O_NONBLOCK in future, if this is wanted).
I've read some people mentioning that we simply should use a new fcntl()
extension similar to F_DUPFD_CLOEXEC. I think that's a terrible idea
and in any case not better than sys_indirect. A new syscall is the
cleanest solution and it's really only a little bit of effort.
b/arch/x86/ia32/ia32entry.S | 1 +
b/arch/x86/kernel/syscall_table_32.S | 1 +
b/include/asm-x86/unistd_32.h | 1 +
b/include/asm-x86/unistd_64.h | 2 ++
b/include/linux/syscalls.h | 1 +
b/fs/fcntl.c | 15 +++++++++++++--
6 files changed, 19 insertions(+), 2 deletions(-)
Signed-off-by: Ulrich Drepper <drepper@...hat.com>
diff -u b/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
--- b/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -736,2 +736,3 @@
.quad sys_epoll_create2
+ .quad sys_dup3 /* 330 */
ia32_syscall_end:
diff -u b/arch/x86/kernel/syscall_table_32.S b/arch/x86/kernel/syscall_table_32.S
--- b/arch/x86/kernel/syscall_table_32.S
+++ b/arch/x86/kernel/syscall_table_32.S
@@ -331,0 +332 @@
+ .long sys_dup3 /* 330 */
diff -u b/include/asm-x86/unistd_32.h b/include/asm-x86/unistd_32.h
--- b/include/asm-x86/unistd_32.h
+++ b/include/asm-x86/unistd_32.h
@@ -335,6 +335,7 @@
#define __NR_signalfd4 327
#define __NR_eventfd2 328
#define __NR_epoll_create2 329
+#define __NR_dup3 330
#ifdef __KERNEL__
diff -u b/include/asm-x86/unistd_64.h b/include/asm-x86/unistd_64.h
--- b/include/asm-x86/unistd_64.h
+++ b/include/asm-x86/unistd_64.h
@@ -647,6 +647,8 @@
__SYSCALL(__NR_eventfd2, sys_eventfd2)
#define __NR_epoll_create2 291
__SYSCALL(__NR_epoll_create2, sys_epoll_create2)
+#define __NR_dup3 292
+__SYSCALL(__NR_dup3, sys_dup3)
#ifndef __NO_STUBS
diff -u b/include/linux/syscalls.h b/include/linux/syscalls.h
--- b/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -303,6 +303,7 @@
#endif
asmlinkage long sys_dup(unsigned int fildes);
asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd);
+asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags);
asmlinkage long sys_ioperm(unsigned long from, unsigned long num, int on);
asmlinkage long sys_ioctl(unsigned int fd, unsigned int cmd,
unsigned long arg);
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -125,13 +125,16 @@ static int dupfd(struct file *file, unsigned int start, int cloexec)
return fd;
}
-asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
+asmlinkage long sys_dup3(unsigned int oldfd, unsigned int newfd, int flags)
{
int err = -EBADF;
struct file * file, *tofree;
struct files_struct * files = current->files;
struct fdtable *fdt;
+ if ((flags & ~O_CLOEXEC) != 0)
+ return -EINVAL;
+
spin_lock(&files->file_lock);
if (!(file = fcheck(oldfd)))
goto out_unlock;
@@ -163,7 +166,10 @@ asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
rcu_assign_pointer(fdt->fd[newfd], file);
FD_SET(newfd, fdt->open_fds);
- FD_CLR(newfd, fdt->close_on_exec);
+ if (flags & O_CLOEXEC)
+ FD_SET(newfd, fdt->close_on_exec);
+ else
+ FD_CLR(newfd, fdt->close_on_exec);
spin_unlock(&files->file_lock);
if (tofree)
@@ -181,6 +187,11 @@ out_fput:
goto out;
}
+asmlinkage long sys_dup2(unsigned int oldfd, unsigned int newfd)
+{
+ return sys_dup3(oldfd, newfd, 0);
+}
+
asmlinkage long sys_dup(unsigned int fildes)
{
int ret = -EBADF;
--
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