Changes to wal.c so that SQLite can read even if the WAL file is opened read-only, provided the wal-index (shm file) is opened read/write.

FossilOrigin-Name: 932d19da73c9673cdd4cc01289b17761c23d23cb

1 files changed, 6 insertions, 1 deletions

diff --git a/src/wal.c b/src/wal.c
index 261bed196..54274640e 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -415,6 +415,7 @@ struct Wal {
   u8 exclusiveMode;          /* Non-zero if connection is in exclusive mode */
   u8 writeLock;              /* True if in a write transaction */
   u8 ckptLock;               /* True if holding a checkpoint lock */
+  u8 readOnly;               /* True if the WAL file is open read-only */
   WalIndexHdr hdr;           /* Wal-index header for current transaction */
   const char *zWalName;      /* Name of WAL file */
   u32 nCkpt;                 /* Checkpoint sequence counter in the wal-header */
@@ -1227,7 +1228,7 @@ int sqlite3WalOpen(
   flags = (SQLITE_OPEN_READWRITE|SQLITE_OPEN_CREATE|SQLITE_OPEN_WAL);
   rc = sqlite3OsOpen(pVfs, zWalName, pRet->pWalFd, flags, &flags);
   if( rc==SQLITE_OK && flags&SQLITE_OPEN_READONLY ){
-    rc = SQLITE_CANTOPEN;
+    pRet->readOnly = 1;
   }
 
   if( rc!=SQLITE_OK ){
@@ -2180,6 +2181,10 @@ int sqlite3WalBeginWriteTransaction(Wal *pWal){
   ** transaction. */
   assert( pWal->readLock>=0 );
 
+  if( pWal->readOnly ){
+    return SQLITE_READONLY;
+  }
+
   /* Only one writer allowed at a time.  Get the write lock.  Return
   ** SQLITE_BUSY if unable.
   */