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authorUlrich Drepper <drepper@redhat.com>2007-10-16 23:30:26 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-17 08:43:01 -0700
commit22d2b35b200f76085c16a2e14ca30b58510fcbe7 (patch)
tree669ce98845b73c0a2e12b37beaa24aed8481e1d2
parent18796aa00243a594a2bd6733f1360aa38c3cd8f4 (diff)
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 <errno.h> #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #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 <drepper@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: <linux-arch@vger.kernel.org> Cc: Kyle McMartin <kyle@mcmartin.ca> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--fs/fcntl.c12
-rw-r--r--include/linux/fcntl.h15
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 <asm/fcntl.h>
-/* 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.