From 9f4aad446b5ed8b0006c323f4df2db1e5743bf90 Mon Sep 17 00:00:00 2001
From: mistachkin <mistachkin@noemail.net>
Date: Thu, 9 Nov 2017 18:53:51 +0000
Subject: [PATCH] Further corrections to read-only SHM file handling on Win32.

FossilOrigin-Name: 43c311701bdf1202918cd46fa6133a11458e0ef8ddb09e46290a231083f395ce
---
 manifest      | 12 ++++++------
 manifest.uuid |  2 +-
 src/os_win.c  | 18 +++++++++++-------
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/manifest b/manifest
index eb409a8a6a..0ecda71659 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Corrections\sto\sWin32\slock\sdetection\sfor\sSHM\sfiles.
-D 2017-11-09T18:21:51.933
+C Further\scorrections\sto\sread-only\sSHM\sfile\shandling\son\sWin32.
+D 2017-11-09T18:53:51.070
 F Makefile.in 5bae3f2f3d42f2ad52b141562d74872c97ac0fca6c54953c91bb150a0e6427a8
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 3a5cb477ec3ce5274663b693164e349db63348667cd45bad78cc13d580b691e2
@@ -448,7 +448,7 @@ F src/os.h 48388821692e87da174ea198bf96b1b2d9d83be5dfc908f673ee21fafbe0d432
 F src/os_common.h b2f4707a603e36811d9b1a13278bffd757857b85
 F src/os_setup.h 0dbaea40a7d36bf311613d31342e0b99e2536586
 F src/os_unix.c e87cef0bb894b94d96ee3af210be669549d111c580817d14818101b992640767
-F src/os_win.c eac2f14343eaf9ff8c02d7025ce459f64dc1334c1f6739be5b6595aabed32ca2
+F src/os_win.c f55a1ae65702e1762dcc175c1b3b32818bcb4d5faee83d2159adafbac94770c4
 F src/os_win.h 7b073010f1451abe501be30d12f6bc599824944a
 F src/pager.c 07cf850241667874fcce9d7d924c814305e499b26c804322e2261247b5921903
 F src/pager.h 581698f2177e8bd4008fe4760898ce20b6133d1df22139b9101b5155f900df7a
@@ -1669,7 +1669,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 0b26a5a26d700e20eea5ebbd620af0af6f2d61c652cfca5b8563267588cb2be6
-R e599061360fdeb01478e7f6faea2d0b3
+P 3a91be975daee65c3e1199855613066015d5df8ad44ababdef31d1c698b5e746
+R b94c408b8a8461b2b6bed04445c4e88e
 U mistachkin
-Z 310f1e71824409858101a715db0b42e2
+Z 2f572d772e98ad83ecab51d538357fde
diff --git a/manifest.uuid b/manifest.uuid
index 238938df65..3ece53ff59 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-3a91be975daee65c3e1199855613066015d5df8ad44ababdef31d1c698b5e746
\ No newline at end of file
+43c311701bdf1202918cd46fa6133a11458e0ef8ddb09e46290a231083f395ce
\ No newline at end of file
diff --git a/src/os_win.c b/src/os_win.c
index 34069351df..6b0bb3dbd0 100644
--- a/src/os_win.c
+++ b/src/os_win.c
@@ -2105,8 +2105,9 @@ static int winIoerrRetryDelay = SQLITE_WIN32_IOERR_RETRY_DELAY;
 ** to file locking.
 */
 #if !defined(winIsLockingError)
-#define winIsLockingError(a) (((a)==ERROR_ACCESS_DENIED)        || \
+#define winIsLockingError(a) (((a)==NO_ERROR)                   || \
                               ((a)==ERROR_LOCK_VIOLATION)       || \
+                              ((a)==ERROR_HANDLE_EOF)           || \
                               ((a)==ERROR_IO_PENDING))
 #endif
 
@@ -3847,6 +3848,7 @@ static void winShmPurge(sqlite3_vfs *pVfs, int deleteFlag){
 */
 static int winGetShmDmsLockType(
   winFile *pFile, /* File handle object */
+  int bReadOnly,  /* Non-zero if the SHM was opened read-only */
   int *pLockType  /* WINSHM_UNLCK, WINSHM_RDLCK, or WINSHM_WRLCK */
 ){
 #if !SQLITE_OS_WINCE && !defined(SQLITE_WIN32_NO_OVERLAPPED)
@@ -3867,24 +3869,25 @@ static int winGetShmDmsLockType(
   overlapped.OffsetHigh = (LONG)((offset>>32) & 0x7fffffff);
   pOverlapped = &overlapped;
 #endif
-  if( !osWriteFile(pFile->h, &notUsed1, 1, &notUsed2, pOverlapped) ){
-    DWORD lastErrno = osGetLastError();
+  if( bReadOnly ||
+      !osWriteFile(pFile->h, &notUsed1, 1, &notUsed2, pOverlapped) ){
+    DWORD lastErrno = bReadOnly ? NO_ERROR : osGetLastError();
     if( !osReadFile(pFile->h, &notUsed1, 1, &notUsed2, pOverlapped) ){
       lastErrno = osGetLastError();
       if( winIsLockingError(lastErrno) ){
-        *pLockType = WINSHM_WRLCK;
+        if( pLockType ) *pLockType = WINSHM_WRLCK;
       }else{
         return SQLITE_IOERR_READ;
       }
     }else{
       if( winIsLockingError(lastErrno) ){
-        *pLockType = WINSHM_RDLCK;
+        if( pLockType ) *pLockType = WINSHM_RDLCK;
       }else{
         return SQLITE_IOERR_WRITE;
       }
     }
   }else{
-    *pLockType = WINSHM_UNLCK;
+    if( pLockType ) *pLockType = WINSHM_UNLCK;
   }
   return SQLITE_OK;
 }
@@ -3920,7 +3923,8 @@ static int winLockSharedMemory(winShmNode *pShmNode){
   ** process might open and use the *-shm file without truncating it.
   ** And if the *-shm file has been corrupted by a power failure or
   ** system crash, the database itself may also become corrupt.  */
-  if( winGetShmDmsLockType(&pShmNode->hFile, &lockType)!=SQLITE_OK ){
+  if( winGetShmDmsLockType(&pShmNode->hFile, pShmNode->isReadonly,
+                           &lockType)!=SQLITE_OK ){
     rc = SQLITE_IOERR_LOCK;
   }else if( lockType==WINSHM_UNLCK ){
     if( pShmNode->isReadonly ){