diff options
Diffstat (limited to 'source3/locking')
| -rw-r--r-- | source3/locking/locking.c | 71 |
1 files changed, 56 insertions, 15 deletions
diff --git a/source3/locking/locking.c b/source3/locking/locking.c index 6e321d0626..639bc7be0b 100644 --- a/source3/locking/locking.c +++ b/source3/locking/locking.c @@ -25,6 +25,10 @@ May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode locking to deal with multiple share modes per open file. + + September 1997. Jeremy Allison (jallison@whistle.com). Added oplock + support. + */ #include "includes.h" @@ -726,13 +730,60 @@ BOOL lock_share_entry(int cnum, uint32 dev, uint32 inode, share_lock_token *ptok { int old_umask; + BOOL gotlock = False; unbecome_user(); old_umask = umask(0); + + /* + * There was a race condition in the original slow share mode code. + * A smbd could open a share mode file, and before getting + * the lock, another smbd could delete the last entry for + * the share mode file and delete the file entry from the + * directory. Thus this smbd would be left with a locked + * share mode fd attached to a file that no longer had a + * directory entry. Thus another smbd would think that + * there were no outstanding opens on the file. To fix + * this we now check we can do a stat() call on the filename + * before allowing the lock to proceed, and back out completely + * and try the open again if we cannot. + * Jeremy Allison (jallison@whistle.com). + */ + + do + { + struct stat dummy_stat; + #ifdef SECURE_SHARE_MODES - fd = (share_lock_token)open(fname,O_RDWR|O_CREAT,0600); + fd = (share_lock_token)open(fname,O_RDWR|O_CREAT,0600); #else /* SECURE_SHARE_MODES */ - fd = (share_lock_token)open(fname,O_RDWR|O_CREAT,0666); + fd = (share_lock_token)open(fname,O_RDWR|O_CREAT,0666); #endif /* SECURE_SHARE_MODES */ + + /* At this point we have an open fd to the share mode file. + Lock the first byte exclusively to signify a lock. */ + if(fcntl_lock(fd, F_SETLKW, 0, 1, F_WRLCK) == False) + { + DEBUG(0,("ERROR lock_share_entry: fcntl_lock on file %s failed with %s\n", + fname, strerror(errno))); + close(fd); + return False; + } + + /* + * If we cannot stat the filename, the file was deleted between + * the open and the lock call. Back out and try again. + */ + + if(stat(fname, &dummy_stat)!=0) + { + DEBUG(2,("lock_share_entry: Re-issuing open on %s to fix race. Error was %s\n", + fname, strerror(errno))); + close(fd); + } + else + gotlock = True; + } while(!gotlock); + umask(old_umask); if(!become_user(cnum,Connections[cnum].vuid)) { @@ -750,18 +801,8 @@ BOOL lock_share_entry(int cnum, uint32 dev, uint32 inode, share_lock_token *ptok } } - /* At this point we have an open fd to the share mode file. - Lock the first byte exclusively to signify a lock. */ - if(fcntl_lock(fd, F_SETLKW, 0, 1, F_WRLCK) == False) - { - DEBUG(0,("ERROR lock_share_entry: fcntl_lock failed with %s\n", - strerror(errno))); - close(fd); - return False; - } - - *ptok = (share_lock_token)fd; - return True; + *ptok = (share_lock_token)fd; + return True; } /******************************************************************* @@ -781,7 +822,7 @@ BOOL unlock_share_entry(int cnum, uint32 dev, uint32 inode, share_lock_token tok ret = False; } - close((int)token); + close(fd); return ret; } |