From: Takashi Yano <takashi.yano@nifty.ne.jp>
Date: Fri, 15 Nov 2024 12:58:22 +0000 (+0900)
Subject: Cygwin: flock: Fix overlap handling in lf_setlock() and lf_clearlock()
X-Git-Url: https://sourceware.org/git/?a=commitdiff_plain;h=8dee07a1f12682307be07e12a7fd8d5c8ecc1e2b;p=newlib-cygwin.git

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 794e66bd7..b41cba5c7 100644
--- 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 13982632b..b70b91ed8 100644
--- 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