Fix a couple uninitialized variables in the xShmLock method of the unix VFS.

Improved debugging logic for xShmLock.

FossilOrigin-Name: 69567c5fca9e30b7660e6f56350be929c3890d7e

manifest

@@ -1,5 +1,8 @@
-C When\sclosing\sa\sWAL\sconnection,\sattempt\san\sexclusive\slock\son\sthe\sdatabase\sfile.\sIf\sthe\slock\sis\sobtained,\scheckpoint\sthe\sdatabase\sand\sdelete\sthe\swal\sand\swal-index\sfiles.
-D 2010-04-30T15:49:28
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA1
+
+C Fix\sa\scouple\suninitialized\svariables\sin\sthe\sxShmLock\smethod\sof\sthe\sunix\sVFS.\nImproved\sdebugging\slogic\sfor\sxShmLock.
+D 2010-04-30T15:54:47
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in d83a0ffef3dcbfb08b410a6c6dd6c009ec9167fb
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -150,7 +153,7 @@ F src/os.c 8bc63cf91e9802e2b807198e54e50227fa889306
 F src/os.h 534b082c3cb349ad05fa6fa0b06087e022af282c
 F src/os_common.h 0d6ee583b6ee3185eb9d951f890c6dd03021a08d
 F src/os_os2.c 8ad77a418630d7dee91d1bb04f79c2096301d3a0
-F src/os_unix.c b2322d8fb389b4bc7834b1596bd8afac776a2f20
+F src/os_unix.c 7d10d3a8b4f3e0c7bde874ca7e488ea95b7cae35
 F src/os_win.c a8fc01d8483be472e495793c01064fd87e56a5c1
 F src/pager.c 434f9751fc2dfc11ade004282deda5f8560bcba2
 F src/pager.h 934b598583a9d936bb13c37d62a2fe68ac48781c
@@ -808,7 +811,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 837d82a92977cbfa0963411daf8160d286a7ed32
-R 3059f2f53adc88a1128c0bd66d3f0bb8
-U dan
-Z 901b5f2ba561b4eab874813e39c862c1
+P c05e7dca172719f33e245c08d0c0e8ab47e5a537
+R 948b3a20fa291178488b4491978dd814
+U drh
+Z 0b83af1d29a8669f0e45a2c764ca0612
+-----BEGIN PGP SIGNATURE-----
+Version: GnuPG v1.4.6 (GNU/Linux)
+
+iD8DBQFL2v1KoxKgR168RlERAtTvAJ9anChtmXUlkLMCUv41sdV2i+tOhgCfd+Pd
+kBX8Xzf3zeWR2SKzYU3eb8s=
+=dWTT
+-----END PGP SIGNATURE-----

manifest.uuid

@@ -1 +1 @@
-c05e7dca172719f33e245c08d0c0e8ab47e5a537
+69567c5fca9e30b7660e6f56350be929c3890d7e

src/os_unix.c

@@ -4716,6 +4716,7 @@ static int unixShmSystemLock(
   f.l_whence = SEEK_SET;
   if( (lockMask & UNIX_SHM_MUTEX)!=0 && lockType!=F_UNLCK ){
     lockOp = F_SETLKW;
+    OSTRACE(("SHM-LOCK requesting blocking lock\n"));
   }else{
     lockOp = F_SETLK;
   }
@@ -4768,7 +4769,7 @@ static int unixShmSystemLock(
       OSTRACE(("write-lock failed"));
     }
   }
-  OSTRACE((" - change requested %s - afterwards %s,%s\n",
+  OSTRACE((" - change requested %s - afterwards %s:%s\n",
            unixShmLockString(lockMask),
            unixShmLockString(pFile->sharedMask),
            unixShmLockString(pFile->exclMask)));
@@ -4794,6 +4795,7 @@ static int unixShmUnlock(
   assert( sqlite3_mutex_held(pFile->mutex) );
 
   /* Compute locks held by sibling connections */
+  allMask = 0;
   for(pX=pFile->pFirst; pX; pX=pX->pNext){
     if( pX==p ) continue;
     assert( (pX->exclMask & (p->exclMask|p->sharedMask))==0 );
@@ -4834,6 +4836,7 @@ static int unixShmSharedLock(
   ** If any sibling already holds an exclusive lock, go ahead and return
   ** SQLITE_BUSY.
   */
+  allShared = 0;
   for(pX=pFile->pFirst; pX; pX=pX->pNext){
     if( pX==p ) continue;
     if( (pX->exclMask & readMask)!=0 ) return SQLITE_BUSY;
@@ -5004,12 +5007,13 @@ static int unixShmOpen(
     if( unixShmSystemLock(pFile, F_WRLCK, UNIX_SHM_DMS)==SQLITE_OK ){
       if( ftruncate(pFile->h, 0) ){
         rc = SQLITE_IOERR;
-        goto shm_open_err;
       }
     }
+    if( rc==SQLITE_OK ){
       rc = unixShmSystemLock(pFile, F_RDLCK, UNIX_SHM_DMS);
-    if( rc ) goto shm_open_err;
+    }
     unixShmSystemLock(pFile, F_UNLCK, UNIX_SHM_MUTEX);
+    if( rc ) goto shm_open_err;
   }
 
   /* Make the new connection a child of the unixShmFile */
@@ -5201,10 +5205,14 @@ static int unixShmLock(
    || desiredLock==p->lockState
    || (desiredLock==SQLITE_SHM_READ && p->lockState==SQLITE_SHM_READ_FULL)
   ){
+    OSTRACE(("SHM-LOCK shmid-%d, pid-%d request %d and got %d\n",
+             p->id, getpid(), desiredLock, p->lockState));
     if( pGotLock ) *pGotLock = p->lockState;
     return SQLITE_OK;
   }
 
+  OSTRACE(("SHM-LOCK shmid-%d, pid-%d request %d->%d\n",
+            p->id, getpid(), p->lockState, desiredLock));
   sqlite3_mutex_enter(pFile->mutex);
   switch( desiredLock ){
     case SQLITE_SHM_UNLOCK: {
@@ -5293,6 +5301,7 @@ static int unixShmLock(
     }
   }
   sqlite3_mutex_leave(pFile->mutex);
+  OSTRACE(("SHM-LOCK shmid-%d, pid-%d got %d\n", p->id,getpid(),p->lockState));
   if( pGotLock ) *pGotLock = p->lockState;
   return rc;
 }