Fix crashes that could occur if SQL NULL values were passed to the built-in

FTS5 snippet function. Edit: breaks amalgamation builds.

FossilOrigin-Name: 6a790b67a0a5c698526db16ea262b13ecdd1b6ca74e80bdccfcad88ddbdc933a

ext/fts5/fts5_aux.c

@@ -358,6 +358,16 @@ static int fts5SnippetScore(
   return rc;
 }
 
+/*
+** Return the value in pVal interpreted as utf-8 text. Except, if pVal 
+** contains a NULL value, return a pointer to a static string zero
+** bytes in length instead of a NULL pointer.
+*/
+static const char *fts5ValueToText(sqlite3_value *pVal){
+  const char *zRet = (const char*)sqlite3_value_text(pVal);
+  return zRet ? zRet : "";
+}
+
 /*
 ** Implementation of snippet() function.
 */
@@ -393,9 +403,9 @@ static void fts5SnippetFunction(
   nCol = pApi->xColumnCount(pFts);
   memset(&ctx, 0, sizeof(HighlightContext));
   iCol = sqlite3_value_int(apVal[0]);
-  ctx.zOpen = (const char*)sqlite3_value_text(apVal[1]);
-  ctx.zClose = (const char*)sqlite3_value_text(apVal[2]);
-  zEllips = (const char*)sqlite3_value_text(apVal[3]);
+  ctx.zOpen = fts5ValueToText(apVal[1]);
+  ctx.zClose = fts5ValueToText(apVal[2]);
+  zEllips = fts5ValueToText(apVal[3]);
   nToken = sqlite3_value_int(apVal[4]);
 
   iBestCol = (iCol>=0 ? iCol : 0);

ext/fts5/test/fts5af.test

@@ -175,6 +175,16 @@ do_execsql_test 5.1 {
   SELECT snippet(p1, 0, '[', ']', '...', 6) FROM p1('x');
 } {{[x] a a a a a...}}
 
+do_execsql_test 5.2 {
+  SELECT snippet(p1, 0, '[', ']', NULL, 6) FROM p1('x');
+} {{[x] a a a a a}}
+do_execsql_test 5.3 {
+  SELECT snippet(p1, 0, NULL, ']', '...', 6) FROM p1('x');
+} {{x] a a a a a...}}
+do_execsql_test 5.4 {
+  SELECT snippet(p1, 0, '[', NULL, '...', 6) FROM p1('x');
+} {{[x a a a a a...}}
+
 } ;# foreach_detail_mode 
 
 finish_test

manifest

@@ -1,5 +1,5 @@
-C Add\soptions\sto\sspeedtest1.c\sand\sspeed-check.sh\sfor\stesting\sperformance\sof\nfloating-point\scomputatations.
-D 2017-12-26T14:30:44.117
+C Fix\scrashes\sthat\scould\soccur\sif\sSQL\sNULL\svalues\swere\spassed\sto\sthe\sbuilt-in\nFTS5\ssnippet\sfunction.\sEdit:\sbreaks\samalgamation\sbuilds.
+D 2017-12-26T14:32:25.807
 F Makefile.in ceb40bfcb30ebba8e1202b34c56ff7e13e112f9809e2381d99be32c2726058f5
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 6480671f7c129e61208d69492b3c71ce4310d49fceac83cfb17f1c081e242b69
@@ -106,7 +106,7 @@ F ext/fts3/unicode/parseunicode.tcl da577d1384810fb4e2b209bf3313074353193e95
 F ext/fts5/extract_api_docs.tcl a36e54ec777172ddd3f9a88daf593b00848368e0
 F ext/fts5/fts5.h 62f3e33ceeb9a428db139f9c012186b371da1cc7
 F ext/fts5/fts5Int.h eda28e3a0a5d87c412e8355fe35da875b04cb389908c8eb0d867ad662adbc491
-F ext/fts5/fts5_aux.c 67acf8d51723cf28ffc3828210ba662df4b8d267
+F ext/fts5/fts5_aux.c ca666a3bbe07c5a3bbe9fffaea19c935a1efaf337333e28bad7bdd1971ffd093
 F ext/fts5/fts5_buffer.c 1dd1ec0446b3acfc2d7d407eb894762a461613e2695273f48e449bfd13e973ff
 F ext/fts5/fts5_config.c 5af9c360e99669d29f06492c370892394aba0857
 F ext/fts5/fts5_expr.c 01048018d21524e2c302b063ff5c3cdcf546e03297215e577205d85b47499deb
@@ -129,7 +129,7 @@ F ext/fts5/test/fts5ab.test 9205c839332c908aaad2b01ab8670ece8b161e8f2ec8a9fabf18
 F ext/fts5/test/fts5ac.test a7aa7e1fefc6e1918aa4d3111d5c44a09177168e962c5fd2cca9620de8a7ed6d
 F ext/fts5/test/fts5ad.test e8cf959dfcd57c8e46d6f5f25665686f3b6627130a9a981371dafdf6482790de
 F ext/fts5/test/fts5ae.test 1142d16d9cc193894dc13cc8f9c7a8a21411ac61b5567a878514df6f9f0d7bb7
-F ext/fts5/test/fts5af.test aa635947bda31ac87fbe99483eef4d9a8571f58ad89c75dfb63312a35688eceb
+F ext/fts5/test/fts5af.test 724247405b13f8f06cc6ce464dc4f152dc5dd4e86b12c2099685d8f19747bf7b
 F ext/fts5/test/fts5ag.test 7816f25a0707578f08145ab539fc0ca025f8951e788b28a6a18a06b2099469dd
 F ext/fts5/test/fts5ah.test 27b5a33bfd0363ca8a4dc659e6e2a5df3dea1c3c5b04bc51ca6aeb1277bd9b21
 F ext/fts5/test/fts5ai.test d837c42249c0d8ad1a2912270e22cf2f303790a611f85c0be3a58e42a3696e3d
@@ -1687,8 +1687,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 90d6e4f10d3055a776d24854c442a2a68e726af8fc382cdb6241a834082e4c4c
-Q +b3c6105181d22c8a53f5bf662e3d182bba962ee8afd1ad972ebd10094b20fc17
-R c2447707ab323a591ab8e05be0f0cae9
+P ebfea8728fec955b1d74b1d0a3de498fd1a32e8b39572a8fdab606ed87b169b4
+Q +553a3ad32498ddda920216cd44a376a439a58fbb326d2d3800528867db1ffa9d
+R 742f62796704fae3ae9dc15618c72290
 U dan
-Z 1002781326ca68c114cfc46396055176
+Z ecb93df9cf8c6f4bd1c8f7a6ca97d753

manifest.uuid

@@ -1 +1 @@
-ebfea8728fec955b1d74b1d0a3de498fd1a32e8b39572a8fdab606ed87b169b4
+6a790b67a0a5c698526db16ea262b13ecdd1b6ca74e80bdccfcad88ddbdc933a