[PATCH 09/18] flag parameters: dup2
From: Ulrich Drepper <hidden>
Date: 2008-05-05 03:49:16
Also in:
lkml
Subsystem:
abi/api, file locking (flock() and fcntl()/lockf()), filesystems (vfs and infrastructure), the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Jeff Layton, Chuck Lever, Alexander Viro, Christian Brauner, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
This patch adds the new dup3 syscall. It extends the old dup2
syscall by one parameter which is meant to hold a flag value. Support
for the O_CLOEXEC flag is added in this patch.
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 <time.h>
#include <unistd.h>
#include <sys/syscall.h>
#ifndef __NR_dup3
# ifdef __x86_64__
# define __NR_dup3 292
# elif defined __i386__
# define __NR_dup3 330
# else
# error "need __NR_dup3"
# endif
#endif
int
main (void)
{
int fd = syscall (__NR_dup3, 1, 4, 0);
if (fd == -1)
{
puts ("dup3(0) failed");
return 1;
}
int coe = fcntl (fd, F_GETFD);
if (coe == -1)
{
puts ("fcntl failed");
return 1;
}
if (coe & FD_CLOEXEC)
{
puts ("dup3(0) set close-on-exec flag");
return 1;
}
close (fd);
fd = syscall (__NR_dup3, 1, 4, O_CLOEXEC);
if (fd == -1)
{
puts ("dup3(O_CLOEXEC) failed");
return 1;
}
coe = fcntl (fd, F_GETFD);
if (coe == -1)
{
puts ("fcntl failed");
return 1;
}
if ((coe & FD_CLOEXEC) == 0)
{
puts ("dup3(O_CLOEXEC) set close-on-exec flag");
return 1;
}
close (fd);
puts ("OK");
return 0;
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/x86/ia32/ia32entry.S | 1 +
arch/x86/kernel/syscall_table_32.S | 1 +
fs/fcntl.c | 15 +++++++++++++--
include/asm-x86/unistd_32.h | 1 +
include/asm-x86/unistd_64.h | 2 ++
include/linux/syscalls.h | 1 +
6 files changed, 19 insertions(+), 2 deletions(-)
Signed-off-by: Ulrich Drepper <redacted>
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@@ -734,4 +734,5 @@ ia32_sys_call_table: .quad compat_sys_signalfd4 .quad sys_eventfd2 .quad sys_epoll_create2 + .quad sys_dup3 /* 330 */ ia32_syscall_end:
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@@ -329,3 +329,4 @@ ENTRY(sys_call_table) .long sys_signalfd4 .long sys_eventfd2 .long sys_epoll_create2 + .long sys_dup3 /* 330 */
diff --git a/fs/fcntl.c b/fs/fcntl.c
index bfd7765..49a2284 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c@@ -126,13 +126,16 @@ 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;
@@ -164,7 +167,10 @@ 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)
@@ -182,6 +188,11 @@ 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;
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@@ -335,6 +335,7 @@ #define __NR_signalfd4 327 #define __NR_eventfd2 328 #define __NR_epoll_create2 329 +#define __NR_dup3 330 #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@@ -647,6 +647,8 @@ __SYSCALL(__NR_fallocate, sys_fallocate) __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 --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 0522f36..aeb2df8 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h@@ -305,6 +305,7 @@ asmlinkage long sys_fcntl64(unsigned int fd, #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);