Enhance PRAGMA integrity_check so that it can detect when there are extra

bytes at the end of an index record, which might cause OP_IdxRowid to
malfunction.  dbsqlfuzz c1aa3986534d5feab8d21f28b3c1712df2ef358ba.  Test case
in TH3.

FossilOrigin-Name: f418bdd627e84e7d494f730d7124d8f4846ebcde031f5b2498685c9aceebb3c8

manifest

@@ -1,5 +1,5 @@
-C When\sit\sis\sknown\swhen\spreparing\sa\sstatement\sthat\sX\scannot\sbe\sNULL,\stransform\sthe\sexpression\s(X\sIS\sNULL)\sto\sinteger\svalue\s1\sinstead\sof\s'true'.\sThis\sis\sbecause\sunder\ssome\scircumstances,\s"Y\sIS\sTRUE"\smay\snot\sbe\sequivalent\sto\s"Y\sIS\s1".
-D 2023-03-03T16:25:18.921
+C Enhance\sPRAGMA\sintegrity_check\sso\sthat\sit\scan\sdetect\swhen\sthere\sare\sextra\nbytes\sat\sthe\send\sof\san\sindex\srecord,\swhich\smight\scause\sOP_IdxRowid\sto\nmalfunction.\s\sdbsqlfuzz\sc1aa3986534d5feab8d21f28b3c1712df2ef358ba.\s\sTest\scase\nin\sTH3.
+D 2023-03-03T18:35:00.504
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -616,7 +616,7 @@ F src/parse.y 960d2da92a23f8ba2ca22748a51bd75ee2c575564f2cbc59f119640e7f5b4c5d
 F src/pcache.c f4268f7f73c6a3db12ce22fd25bc68dc42315d19599414ab1207d7cf32f79197
 F src/pcache.h 4f87acd914cef5016fae3030343540d75f5b85a1877eed1a2a19b9f284248586
 F src/pcache1.c dee95e3cd2b61e6512dc814c5ab76d5eb36f0bfc9441dbb4260fccc0d12bbddc
-F src/pragma.c 82d5090a35eac75876d3b41f48d06b2370553c9576bf2942233c462e03eb94c9
+F src/pragma.c e698baae96396cac8ff55afef1c0b84632a4b825548bf98f0c4fd1e0a90ed4bc
 F src/pragma.h e690a356c18e98414d2e870ea791c1be1545a714ba623719deb63f7f226d8bb7
 F src/prepare.c ce87a08cfddd45a147150db34190b1986f2d4a0e0828858cb6bd908c78fb02e3
 F src/printf.c fb31597cf93200eba9167573094ee312b0d51b2c1998613284ceb2c8c212b492
@@ -2048,8 +2048,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P e95439119ac200cb47d0e277622f41ee7986b364487cd252b485ce5fa030d70f
-R 832f5112357909076c536cf7b9bea8b8
-U dan
-Z 3d9689df10ad73a0297a8e055e1db782
+P cc4bb05b3653e9502b95ea6fe0bfb77feebc11285b66e1dde4c7b945928efbf1
+R e3264926b184a1150ff1e42cc58b6e34
+U drh
+Z 4bf4a9f38f38c1a43669629bffba2cbf
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-cc4bb05b3653e9502b95ea6fe0bfb77feebc11285b66e1dde4c7b945928efbf1
+f418bdd627e84e7d494f730d7124d8f4846ebcde031f5b2498685c9aceebb3c8

src/pragma.c

@@ -1987,6 +1987,23 @@ void sqlite3Pragma(
             jmp4 = integrityCheckResultRow(v);
             sqlite3VdbeJumpHere(v, jmp2);
 
+            /* The OP_IdxRowid opcode is an optimized version of OP_Column
+            ** that extracts the rowid off the end of the index record.
+            ** But it only works correctly if index record does not have
+            ** any extra bytes at the end.  Verify that this is the case. */
+            if( HasRowid(pTab) ){
+              int jmp7;
+              sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur+j, 3);
+              jmp7 = sqlite3VdbeAddOp3(v, OP_Eq, 3, 0, r1+pIdx->nColumn-1);
+              VdbeCoverage(v);
+              sqlite3VdbeLoadString(v, 3,
+                 "rowid not at end-of-record for row ");
+              sqlite3VdbeAddOp3(v, OP_Concat, 7, 3, 3);
+              sqlite3VdbeLoadString(v, 4, " of index ");
+              sqlite3VdbeGoto(v, jmp5-1);
+              sqlite3VdbeJumpHere(v, jmp7);
+            }
+
             /* Any indexed columns with non-BINARY collations must still hold
             ** the exact same text value as the table. */
             label6 = 0;