[newlib-cygwin/cygwin-3_5-branch] Cygwin: flock: Fix overlap handling in lf_setlock() and lf_clearlock()

[Takashi Yano]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=67b31bc4ae1fc60d0407210a52e39bcbea0dc6f5

commit 67b31bc4ae1fc60d0407210a52e39bcbea0dc6f5
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date:   Fri Nov 15 21:58:22 2024 +0900

    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>
    (cherry picked from commit 8dee07a1f12682307be07e12a7fd8d5c8ecc1e2b)

Diff:
---
 winsup/cygwin/flock.cc      | 31 ++++++++++++++++++-------------
 winsup/cygwin/release/3.5.5 |  3 +++
 2 files changed, 21 insertions(+), 13 deletions(-)

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