Cygwin: flock: Fix overlap handling in lf_setlock() and lf_clearlock()

Currently, create_lock_obj() can create multiple locks with the same
lock range that have different version number. However, lf_setlock()
and lf_clearlock() cannot handle this case appropriately. With this
patch, make lf_setlock() and lf_clearlock() find overlap again even
when ovcase = 1 (lock and overlap have the same lock range).

Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html
Fixes: 2e560a092c1c ("* flock.cc (LOCK_OBJ_NAME_LEN): Change to accommodate extra lf_ver field.")
Reported-by: Sebastian Feld <sebastian.n.feld@gmail.com>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>

diff --git a/winsup/cygwin/flock.cc b/winsup/cygwin/flock.cc
index 794e66bd7e1d036c12768e4001e2c5ca6ba5d048..b41cba5c70366b923f3286df3435045c2dcffa23 100644 (file)
--- a/winsup/cygwin/flock.cc
+++ b/winsup/cygwin/flock.cc
@@ -1410,12 +1410,16 @@ lf_setlock (lockf_t *lock, inode_t *node, lockf_t **clean, HANDLE fhdl)
           */
          if (lock_cnt > MAX_LOCKF_CNT - room_for_clearlock)
            return ENOLCK;
+         /* Do not create a lock here. It should be done after all
+            overlaps have been removed. */
          lf_wakelock (overlap, fhdl);
-         overlap->lf_type = lock->lf_type;
-         overlap->create_lock_obj ();
-         lock->lf_next = *clean;
-         *clean = lock;
-         break;
+         *prev = overlap->lf_next;
+         overlap->lf_next = *clean;
+         *clean = overlap;
+         /* We may have multiple versions (lf_ver) having same lock range.
+            Therefore, we need to find overlap repeatedly. (originally,
+            just 'break' here. */
+         continue;
 
        case 2: /* overlap contains lock */
          /*
@@ -1563,10 +1567,16 @@ lf_clearlock (lockf_t *unlock, lockf_t **clean, HANDLE fhdl)
       switch (ovcase)
        {
        case 1: /* overlap == lock */
+       case 3: /* lock contains overlap */
          *prev = overlap->lf_next;
+         lf = overlap->lf_next;
          overlap->lf_next = *clean;
          *clean = overlap;
-         break;
+         first_loop = false;
+         /* We may have multiple versions (lf_ver) having same lock range.
+            Therefore, we need to find overlap repeatedly. (originally,
+            just 'break' here. */
+         continue;
 
        case 2: /* overlap contains lock: split it */
          if (overlap->lf_start == unlock->lf_start)
@@ -1582,13 +1592,8 @@ lf_clearlock (lockf_t *unlock, lockf_t **clean, HANDLE fhdl)
            overlap->lf_next->create_lock_obj ();
          break;
 
-       case 3: /* lock contains overlap */
-         *prev = overlap->lf_next;
-         lf = overlap->lf_next;
-         overlap->lf_next = *clean;
-         *clean = overlap;
-         first_loop = false;
-         continue;
+       /* case 3: */ /* lock contains overlap */
+         /* Merged into case 1 */
 
        case 4: /* overlap starts before lock */
            overlap->lf_end = unlock->lf_start - 1;

diff --git a/winsup/cygwin/release/3.5.5 b/winsup/cygwin/release/3.5.5
index 13982632b019ac9aca9b16adc85d35a1472136bc..b70b91ed816b0699fe6c7453f529e1d7ca1892b1 100644 (file)
--- a/winsup/cygwin/release/3.5.5
+++ b/winsup/cygwin/release/3.5.5
@@ -39,3 +39,6 @@ Fixes:
 
 - Fix access violation in lf_clearlock() called from flock().
   Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html
+
+- Fix NtCreateEvent() error in create_lock_ob() called from flock().
+  Addresses: https://cygwin.com/pipermail/cygwin/2024-November/256750.html