Strengthen the defense against OOM in the instr() SQL function.

FossilOrigin-Name: a0971e713682a73d8c7c20511db256c20d2f6388

manifest

@@ -1,5 +1,5 @@
-C Add\sa\stest\sto\sensure\sthat\sthe\sapp-defined\spcache\sxFetch()\smethod\sis\snever\npassed\sa\skey\sof\szero.
-D 2016-12-30T14:25:42.274
+C Strengthen\sthe\sdefense\sagainst\sOOM\sin\sthe\sinstr()\sSQL\sfunction.
+D 2016-12-30T15:16:20.650
 F Makefile.in 41bd4cad981487345c4a84081074bcdb876e4b2e
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc b8ca53350ae545e3562403d5da2a69cec79308da
@@ -344,7 +344,7 @@ F src/delete.c c8bc10d145c9666a34ae906250326fdaa8d58fa5
 F src/expr.c a90e37bc542abe33890cafccacbf8a7db9cb5401
 F src/fault.c 460f3e55994363812d9d60844b2a6de88826e007
 F src/fkey.c 2e9aabe1aee76273aff8a84ee92c464e095400ae
-F src/func.c e0190fd64810a66889bd52c8950f6b5ab3e67356
+F src/func.c 00cd42119843ab0730fac5ae35fc09f344b08259
 F src/global.c dcdb89f30b7aa531c5660030af106bc5bc48ef2e
 F src/hash.c 63d0ee752a3b92d4695b2b1f5259c4621b2cfebd
 F src/hash.h ab34c5c54a9e9de2e790b24349ba5aab3dbb4fd4
@@ -1540,7 +1540,7 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 56ff72ab44288296efc99a608f7edc4346366a50
-R e9376a0e6f39c186396a7f16973b7c00
+P 0bdbe49c6d392c4c86a6c01219c9d91d150dea7d
+R 08bfc0b07daab66cd8d9a28810d0ff87
 U drh
-Z a28c5cf75c694c3d54fc5cc0da0c3d0d
+Z 6b0be7f43941c0b0506a1dbb2af0a32d

manifest.uuid

@@ -1 +1 @@
-0bdbe49c6d392c4c86a6c01219c9d91d150dea7d
+a0971e713682a73d8c7c20511db256c20d2f6388

src/func.c

@@ -204,13 +204,14 @@ static void instrFunc(
     if( typeHaystack==SQLITE_BLOB && typeNeedle==SQLITE_BLOB ){
       zHaystack = sqlite3_value_blob(argv[0]);
       zNeedle = sqlite3_value_blob(argv[1]);
+      assert( zNeedle!=0 );
+      assert( zHaystack!=0 || nHaystack==0 );
       isText = 0;
     }else{
       zHaystack = sqlite3_value_text(argv[0]);
       zNeedle = sqlite3_value_text(argv[1]);
       isText = 1;
-      if( zNeedle==0 ) return;
-      assert( zHaystack );
+      if( zHaystack==0 || zNeedle==0 ) return;
     }
     while( nNeedle<=nHaystack && memcmp(zHaystack, zNeedle, nNeedle)!=0 ){
       N++;