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Add support for LINUX_O_DIRECT, LINUX_O_DIRECT and LINUX_O_NOFOLLOW flags

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to open() [1].
Improve locking for accessing session control structures [2].
Try to document (most likely harmless) races in the code [3].

Based on submission by:	Intron (intron at intron ac) [1]
Reviewed by:		jhb [2]
Discussed with:		netchild, rwatson, jhb [3]
This commit is contained in:
Konstantin Belousov 2007-01-18 09:32:08 +00:00
parent bc68fcf37c
commit 4349c6ba29
1 changed files with 48 additions and 19 deletions
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67
sys/compat/linux/linux_file.c
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@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/stat.h>
#include <sys/sx.h>
#include <sys/syscallsubr.h>
#include <sys/sysproto.h>
#include <sys/tty.h>
@ -88,6 +89,8 @@ int
linux_open(struct thread *td, struct linux_open_args *args)
{
struct proc *p = td->td_proc;
struct file *fp;
int fd;
char *path;
int bsd_flags, error;
@ -126,28 +129,54 @@ linux_open(struct thread *td, struct linux_open_args *args)
bsd_flags |= O_EXCL;
if (args->flags & LINUX_O_NOCTTY)
bsd_flags |= O_NOCTTY;
if (args->flags & LINUX_O_DIRECT)
bsd_flags |= O_DIRECT;
if (args->flags & LINUX_O_NOFOLLOW)
bsd_flags |= O_NOFOLLOW;
/* XXX LINUX_O_NOATIME: unable to be easily implemented. */
error = kern_open(td, path, UIO_SYSSPACE, bsd_flags, args->mode);
PROC_LOCK(p);
if (!error && !(bsd_flags & O_NOCTTY) &&
SESS_LEADER(p) && !(p->p_flag & P_CONTROLT)) {
struct file *fp;
PROC_UNLOCK(p);
error = fget(td, td->td_retval[0], &fp);
if (!error) {
if (fp->f_type == DTYPE_VNODE)
fo_ioctl(fp, TIOCSCTTY, (caddr_t) 0, td->td_ucred,
td);
fdrop(fp, td);
}
} else {
PROC_UNLOCK(p);
#ifdef DEBUG
if (ldebug(open))
printf(LMSG("open returns error %d"), error);
#endif
if (!error) {
fd = td->td_retval[0];
/*
* XXX In between kern_open() and fget(), another process
* having the same filedesc could use that fd without
* checking below.
*/
error = fget(td, fd, &fp);
if (!error) {
sx_slock(&proctree_lock);
PROC_LOCK(p);
if (!(bsd_flags & O_NOCTTY) &&
SESS_LEADER(p) && !(p->p_flag & P_CONTROLT)) {
PROC_UNLOCK(p);
sx_unlock(&proctree_lock);
if (fp->f_type == DTYPE_VNODE)
(void) fo_ioctl(fp, TIOCSCTTY, (caddr_t) 0,
td->td_ucred, td);
} else {
PROC_UNLOCK(p);
sx_sunlock(&proctree_lock);
}
if (args->flags & LINUX_O_DIRECTORY) {
if (fp->f_type != DTYPE_VNODE ||
fp->f_vnode->v_type != VDIR) {
error = ENOTDIR;
}
}
fdrop(fp, td);
/*
* XXX as above, fdrop()/kern_close() pair is racy.
*/
if (error)
kern_close(td, fd);
}
}
#ifdef DEBUG
if (ldebug(open))
printf(LMSG("open returns error %d"), error);
#endif
LFREEPATH(path);
return error;
}