From: dan <dan@noemail.net>
Date: Fri, 28 Aug 2020 20:01:06 +0000 (+0000)
Subject: Fix handling of an xShmLock(SHARED, UNLOCK) call when the caller does not hold any... 
X-Git-Tag: version-3.34.0~120^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=refs%2Fheads%2Funixshmlock-opt;p=thirdparty%2Fsqlite.git

Fix handling of an xShmLock(SHARED, UNLOCK) call when the caller does not hold any lock on the specified slot, but another connection in the same process holds an EXCLUSIVE.

FossilOrigin-Name: 3eb365027b885e1f61965efd53a3643b6ff441ae01e79038a091314516a50dd4
---

diff --git a/manifest b/manifest
index fd5ff92eb8..5d3cdf5b16 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Modify\sthe\sunixShmLock()\sfunction\sto\savoid\siterating\sthrough\sthe\s(possibly\slarge)\sset\sof\sconnections\sto\sthe\ssame\sdatabase\sfile.
-D 2020-08-28T19:27:15.533
+C Fix\shandling\sof\san\sxShmLock(SHARED,\sUNLOCK)\scall\swhen\sthe\scaller\sdoes\snot\shold\sany\slock\son\sthe\sspecified\sslot,\sbut\sanother\sconnection\sin\sthe\ssame\sprocess\sholds\san\sEXCLUSIVE.
+D 2020-08-28T20:01:06.517
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -519,7 +519,7 @@ F src/os.c 80e4cf3e5da06be03ca641661e331ce60eeeeabf0d7354dbb1c0e166d0eedbbe
 F src/os.h 48388821692e87da174ea198bf96b1b2d9d83be5dfc908f673ee21fafbe0d432
 F src/os_common.h b2f4707a603e36811d9b1a13278bffd757857b85
 F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
-F src/os_unix.c 0120726d5ceb10f0a932dbcca3cd2c4c0f110c7f8eab3a788b34cc7accdad6cc
+F src/os_unix.c d707ed2867a2fb32101469327acf3274165d9935e9ab9e27bdab0c1a7d661be7
 F src/os_win.c a2149ff0a85c1c3f9cc102a46c673ce87e992396ba3411bfb53db66813b32f1d
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c 3700a1c55427a3d4168ad1f1b8a8b0cb9ace1d107e4506e30a8f1e66d8a1195e
@@ -1879,10 +1879,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 1a04920998368e56276fd0b100be8343609c6ff8a731cf8e26a0490f9c6dabdf
-R 2ca214335aa99f522db85aff8974dca1
-T *branch * unixshmlock-opt
-T *sym-unixshmlock-opt *
-T -sym-trunk *
+P e0faddf0dfc3a40b6b94408296dd781dd0264ecc9f2129ce4405438433fb00e0
+R e6bcf42bbee53ae5585d2ea1ed2212fa
 U dan
-Z 2322c300ab82408a3c9b557087654b84
+Z 13cfa1981b90fb57cb3c9a6bb39ef17d
diff --git a/manifest.uuid b/manifest.uuid
index 93095b8459..a7a42b45e0 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-e0faddf0dfc3a40b6b94408296dd781dd0264ecc9f2129ce4405438433fb00e0
\ No newline at end of file
+3eb365027b885e1f61965efd53a3643b6ff441ae01e79038a091314516a50dd4
\ No newline at end of file
diff --git a/src/os_unix.c b/src/os_unix.c
index 0eb2d5b000..5419a042a6 100644
--- a/src/os_unix.c
+++ b/src/os_unix.c
@@ -4888,30 +4888,32 @@ static int unixShmLock(
   sqlite3_mutex_enter(pShmNode->pShmMutex);
   assert( assertLockingArrayOk(pShmNode) );
   if( flags & SQLITE_SHM_UNLOCK ){
-    int ii;
-    int bUnlock = 1;
+    if( (p->exclMask|p->sharedMask) & mask ){
+      int ii;
+      int bUnlock = 1;
 
-    for(ii=ofst; ii<ofst+n; ii++){
-      if( aLock[ii]>((p->sharedMask & (1<<ii)) ? 1 : 0) ){
-        bUnlock = 0;
+      for(ii=ofst; ii<ofst+n; ii++){
+        if( aLock[ii]>((p->sharedMask & (1<<ii)) ? 1 : 0) ){
+          bUnlock = 0;
+        }
       }
-    }
 
-    if( bUnlock ){
-      rc = unixShmSystemLock(pDbFd, F_UNLCK, ofst+UNIX_SHM_BASE, n);
-      if( rc==SQLITE_OK ){
-        memset(&aLock[ofst], 0, sizeof(int)*n);
+      if( bUnlock ){
+        rc = unixShmSystemLock(pDbFd, F_UNLCK, ofst+UNIX_SHM_BASE, n);
+        if( rc==SQLITE_OK ){
+          memset(&aLock[ofst], 0, sizeof(int)*n);
+        }
+      }else if( p->sharedMask & (1<<ofst) ){
+        assert( n==1 && aLock[ofst]>1 );
+        aLock[ofst]--;
       }
-    }else if( p->sharedMask & (1<<ofst) ){
-      assert( n==1 && aLock[ofst]>1 );
-      aLock[ofst]--;
-    }
 
-    /* Undo the local locks */
-    if( rc==SQLITE_OK ){
-      p->exclMask &= ~mask;
-      p->sharedMask &= ~mask;
-    } 
+      /* Undo the local locks */
+      if( rc==SQLITE_OK ){
+        p->exclMask &= ~mask;
+        p->sharedMask &= ~mask;
+      } 
+    }
   }else if( flags & SQLITE_SHM_SHARED ){
     assert( n==1 );
     assert( (p->exclMask & (1<<ofst))==0 );