From 22d2b35b200f76085c16a2e14ca30b58510fcbe7 Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Tue, 16 Oct 2007 23:30:26 -0700 Subject: [PATCH] F_DUPFD_CLOEXEC implementation One more small change to extend the availability of creation of file descriptors with FD_CLOEXEC set. Adding a new command to fcntl() requires no new system call and the overall impact on code size if minimal. If this patch gets accepted we will also add this change to the next revision of the POSIX spec. To test the patch, use the following little program. Adjust the value of F_DUPFD_CLOEXEC appropriately. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ #include #include #include #include #include #ifndef F_DUPFD_CLOEXEC # define F_DUPFD_CLOEXEC 12 #endif int main (int argc, char *argv[]) { if (argc > 1) { if (fcntl (3, F_GETFD) == 0) { puts ("descriptor not closed"); exit (1); } if (errno != EBADF) { puts ("error not EBADF"); exit (1); } exit (0); } int fd = fcntl (STDOUT_FILENO, F_DUPFD_CLOEXEC, 0); if (fd == -1 && errno == EINVAL) { puts ("F_DUPFD_CLOEXEC not supported"); return 0; } if (fd != 3) { puts ("program called with descriptors other than 0,1,2"); return 1; } execl ("/proc/self/exe", "/proc/self/exe", "1", NULL); puts ("execl failed"); return 1; } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Signed-off-by: Ulrich Drepper Cc: Al Viro Cc: Christoph Hellwig Cc: Cc: Kyle McMartin Cc: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/fcntl.c | 12 ++++++++---- include/linux/fcntl.h | 15 ++++++++++----- 2 files changed, 18 insertions(+), 9 deletions(-) diff --git a/fs/fcntl.c b/fs/fcntl.c index 78b2ff04405..c9db73fc5e3 100644 --- a/fs/fcntl.c +++ b/fs/fcntl.c @@ -110,7 +110,7 @@ out: return error; } -static int dupfd(struct file *file, unsigned int start) +static int dupfd(struct file *file, unsigned int start, int cloexec) { struct files_struct * files = current->files; struct fdtable *fdt; @@ -122,7 +122,10 @@ static int dupfd(struct file *file, unsigned int start) /* locate_fd() may have expanded fdtable, load the ptr */ fdt = files_fdtable(files); FD_SET(fd, fdt->open_fds); - FD_CLR(fd, fdt->close_on_exec); + if (cloexec) + FD_SET(fd, fdt->close_on_exec); + else + FD_CLR(fd, fdt->close_on_exec); spin_unlock(&files->file_lock); fd_install(fd, file); } else { @@ -195,7 +198,7 @@ asmlinkage long sys_dup(unsigned int fildes) struct file * file = fget(fildes); if (file) - ret = dupfd(file, 0); + ret = dupfd(file, 0, 0); return ret; } @@ -319,8 +322,9 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg, switch (cmd) { case F_DUPFD: + case F_DUPFD_CLOEXEC: get_file(filp); - err = dupfd(filp, arg); + err = dupfd(filp, arg, cmd == F_DUPFD_CLOEXEC); break; case F_GETFD: err = get_close_on_exec(fd) ? FD_CLOEXEC : 0; diff --git a/include/linux/fcntl.h b/include/linux/fcntl.h index 40b93265d4b..86037400a6e 100644 --- a/include/linux/fcntl.h +++ b/include/linux/fcntl.h @@ -3,12 +3,17 @@ #include -/* Cancel a blocking posix lock; internal use only until we expose an - * asynchronous lock api to userspace: */ -#define F_CANCELLK (F_LINUX_SPECIFIC_BASE+5) +#define F_SETLEASE (F_LINUX_SPECIFIC_BASE + 0) +#define F_GETLEASE (F_LINUX_SPECIFIC_BASE + 1) -#define F_SETLEASE (F_LINUX_SPECIFIC_BASE+0) -#define F_GETLEASE (F_LINUX_SPECIFIC_BASE+1) +/* + * Cancel a blocking posix lock; internal use only until we expose an + * asynchronous lock api to userspace: + */ +#define F_CANCELLK (F_LINUX_SPECIFIC_BASE + 5) + +/* Create a file descriptor with FD_CLOEXEC set. */ +#define F_DUPFD_CLOEXEC (F_LINUX_SPECIFIC_BASE + 6) /* * Request nofications on a directory. -- 2.41.1