take purely descriptor-related stuff from fcntl.c to file.c

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/fcntl.c

@@ -26,127 +26,6 @@
 #include <asm/siginfo.h>
 #include <asm/uaccess.h>
 
-void set_close_on_exec(unsigned int fd, int flag)
-{
-	struct files_struct *files = current->files;
-	struct fdtable *fdt;
-	spin_lock(&files->file_lock);
-	fdt = files_fdtable(files);
-	if (flag)
-		__set_close_on_exec(fd, fdt);
-	else
-		__clear_close_on_exec(fd, fdt);
-	spin_unlock(&files->file_lock);
-}
-
-static bool get_close_on_exec(unsigned int fd)
-{
-	struct files_struct *files = current->files;
-	struct fdtable *fdt;
-	bool res;
-	rcu_read_lock();
-	fdt = files_fdtable(files);
-	res = close_on_exec(fd, fdt);
-	rcu_read_unlock();
-	return res;
-}
-
-SYSCALL_DEFINE3(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;
-
-	if (unlikely(oldfd == newfd))
-		return -EINVAL;
-
-	if (newfd >= rlimit(RLIMIT_NOFILE))
-		return -EMFILE;
-
-	spin_lock(&files->file_lock);
-	err = expand_files(files, newfd);
-	file = fcheck(oldfd);
-	if (unlikely(!file))
-		goto Ebadf;
-	if (unlikely(err < 0)) {
-		if (err == -EMFILE)
-			goto Ebadf;
-		goto out_unlock;
-	}
-	/*
-	 * We need to detect attempts to do dup2() over allocated but still
-	 * not finished descriptor.  NB: OpenBSD avoids that at the price of
-	 * extra work in their equivalent of fget() - they insert struct
-	 * file immediately after grabbing descriptor, mark it larval if
-	 * more work (e.g. actual opening) is needed and make sure that
-	 * fget() treats larval files as absent.  Potentially interesting,
-	 * but while extra work in fget() is trivial, locking implications
-	 * and amount of surgery on open()-related paths in VFS are not.
-	 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
-	 * deadlocks in rather amusing ways, AFAICS.  All of that is out of
-	 * scope of POSIX or SUS, since neither considers shared descriptor
-	 * tables and this condition does not arise without those.
-	 */
-	err = -EBUSY;
-	fdt = files_fdtable(files);
-	tofree = fdt->fd[newfd];
-	if (!tofree && fd_is_open(newfd, fdt))
-		goto out_unlock;
-	get_file(file);
-	rcu_assign_pointer(fdt->fd[newfd], file);
-	__set_open_fd(newfd, fdt);
-	if (flags & O_CLOEXEC)
-		__set_close_on_exec(newfd, fdt);
-	else
-		__clear_close_on_exec(newfd, fdt);
-	spin_unlock(&files->file_lock);
-
-	if (tofree)
-		filp_close(tofree, files);
-
-	return newfd;
-
-Ebadf:
-	err = -EBADF;
-out_unlock:
-	spin_unlock(&files->file_lock);
-	return err;
-}
-
-SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
-{
-	if (unlikely(newfd == oldfd)) { /* corner case */
-		struct files_struct *files = current->files;
-		int retval = oldfd;
-
-		rcu_read_lock();
-		if (!fcheck_files(files, oldfd))
-			retval = -EBADF;
-		rcu_read_unlock();
-		return retval;
-	}
-	return sys_dup3(oldfd, newfd, 0);
-}
-
-SYSCALL_DEFINE1(dup, unsigned int, fildes)
-{
-	int ret = -EBADF;
-	struct file *file = fget_raw(fildes);
-
-	if (file) {
-		ret = get_unused_fd();
-		if (ret >= 0)
-			fd_install(ret, file);
-		else
-			fput(file);
-	}
-	return ret;
-}
-
 #define SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT | O_NOATIME)
 
 static int setfl(int fd, struct file * filp, unsigned long arg)
@@ -376,14 +255,10 @@ static long do_fcntl(int fd, unsigned int cmd, unsigned long arg,
 
 	switch (cmd) {
 	case F_DUPFD:
-	case F_DUPFD_CLOEXEC:
-		if (arg >= rlimit(RLIMIT_NOFILE))
+		err = f_dupfd(arg, filp, 0);
 		break;
-		err = alloc_fd(arg, cmd == F_DUPFD_CLOEXEC ? O_CLOEXEC : 0);
-		if (err >= 0) {
-			get_file(filp);
-			fd_install(err, filp);
-		}
+	case F_DUPFD_CLOEXEC:
+		err = f_dupfd(arg, filp, FD_CLOEXEC);
 		break;
 	case F_GETFD:
 		err = get_close_on_exec(fd) ? FD_CLOEXEC : 0;

fs/file.c

@@ -6,6 +6,7 @@
  *  Manage the dynamic fd arrays in the process files_struct.
  */
 
+#include <linux/syscalls.h>
 #include <linux/export.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
@@ -794,3 +795,134 @@ struct file *fget_raw_light(unsigned int fd, int *fput_needed)
 
 	return file;
 }
+
+void set_close_on_exec(unsigned int fd, int flag)
+{
+	struct files_struct *files = current->files;
+	struct fdtable *fdt;
+	spin_lock(&files->file_lock);
+	fdt = files_fdtable(files);
+	if (flag)
+		__set_close_on_exec(fd, fdt);
+	else
+		__clear_close_on_exec(fd, fdt);
+	spin_unlock(&files->file_lock);
+}
+
+bool get_close_on_exec(unsigned int fd)
+{
+	struct files_struct *files = current->files;
+	struct fdtable *fdt;
+	bool res;
+	rcu_read_lock();
+	fdt = files_fdtable(files);
+	res = close_on_exec(fd, fdt);
+	rcu_read_unlock();
+	return res;
+}
+
+SYSCALL_DEFINE3(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;
+
+	if (newfd >= rlimit(RLIMIT_NOFILE))
+		return -EMFILE;
+
+	spin_lock(&files->file_lock);
+	err = expand_files(files, newfd);
+	file = fcheck(oldfd);
+	if (unlikely(!file))
+		goto Ebadf;
+	if (unlikely(err < 0)) {
+		if (err == -EMFILE)
+			goto Ebadf;
+		goto out_unlock;
+	}
+	/*
+	 * We need to detect attempts to do dup2() over allocated but still
+	 * not finished descriptor.  NB: OpenBSD avoids that at the price of
+	 * extra work in their equivalent of fget() - they insert struct
+	 * file immediately after grabbing descriptor, mark it larval if
+	 * more work (e.g. actual opening) is needed and make sure that
+	 * fget() treats larval files as absent.  Potentially interesting,
+	 * but while extra work in fget() is trivial, locking implications
+	 * and amount of surgery on open()-related paths in VFS are not.
+	 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
+	 * deadlocks in rather amusing ways, AFAICS.  All of that is out of
+	 * scope of POSIX or SUS, since neither considers shared descriptor
+	 * tables and this condition does not arise without those.
+	 */
+	err = -EBUSY;
+	fdt = files_fdtable(files);
+	tofree = fdt->fd[newfd];
+	if (!tofree && fd_is_open(newfd, fdt))
+		goto out_unlock;
+	get_file(file);
+	rcu_assign_pointer(fdt->fd[newfd], file);
+	__set_open_fd(newfd, fdt);
+	if (flags & O_CLOEXEC)
+		__set_close_on_exec(newfd, fdt);
+	else
+		__clear_close_on_exec(newfd, fdt);
+	spin_unlock(&files->file_lock);
+
+	if (tofree)
+		filp_close(tofree, files);
+
+	return newfd;
+
+Ebadf:
+	err = -EBADF;
+out_unlock:
+	spin_unlock(&files->file_lock);
+	return err;
+}
+
+SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
+{
+	if (unlikely(newfd == oldfd)) { /* corner case */
+		struct files_struct *files = current->files;
+		int retval = oldfd;
+
+		rcu_read_lock();
+		if (!fcheck_files(files, oldfd))
+			retval = -EBADF;
+		rcu_read_unlock();
+		return retval;
+	}
+	return sys_dup3(oldfd, newfd, 0);
+}
+
+SYSCALL_DEFINE1(dup, unsigned int, fildes)
+{
+	int ret = -EBADF;
+	struct file *file = fget_raw(fildes);
+
+	if (file) {
+		ret = get_unused_fd();
+		if (ret >= 0)
+			fd_install(ret, file);
+		else
+			fput(file);
+	}
+	return ret;
+}
+
+int f_dupfd(unsigned int from, struct file *file, unsigned flags)
+{
+	int err;
+	if (from >= rlimit(RLIMIT_NOFILE))
+		return -EINVAL;
+	err = alloc_fd(from, flags);
+	if (err >= 0) {
+		get_file(file);
+		fd_install(err, file);
+	}
+	return err;
+}

include/linux/file.h

@@ -30,7 +30,9 @@ extern struct file *fget(unsigned int fd);
 extern struct file *fget_light(unsigned int fd, int *fput_needed);
 extern struct file *fget_raw(unsigned int fd);
 extern struct file *fget_raw_light(unsigned int fd, int *fput_needed);
+extern int f_dupfd(unsigned int from, struct file *file, unsigned flags);
 extern void set_close_on_exec(unsigned int fd, int flag);
+extern bool get_close_on_exec(unsigned int fd);
 extern void put_filp(struct file *);
 extern int alloc_fd(unsigned start, unsigned flags);
 extern int get_unused_fd_flags(unsigned flags);