Fix jsonForceRCStr() to also add the NULL terminator.

FossilOrigin-Name: 134b01f37f8f741d7f7b7eda81384695d1cbe4c39751d87f08832d5c9afdcef2

manifest

@@ -1,5 +1,5 @@
-C Merge\sthe\slatest\strunk\sfixes\sinto\sthe\sjson-opt\sbranch.
-D 2023-07-26T01:15:34.571
+C Fix\sjsonForceRCStr()\sto\salso\sadd\sthe\sNULL\sterminator.
+D 2023-07-26T11:00:47.983
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -598,7 +598,7 @@ F src/hash.h 3340ab6e1d13e725571d7cee6d3e3135f0779a7d8e76a9ce0a85971fa3953c51
 F src/hwtime.h f9c2dfb84dce7acf95ce6d289e46f5f9d3d1afd328e53da8f8e9008e3b3caae6
 F src/in-operator.md 10cd8f4bcd225a32518407c2fb2484089112fd71
 F src/insert.c 3f0a94082d978bbdd33c38fefea15346c6c6bffb70bc645a71dc0f1f87dd3276
-F src/json.c 790ca70b1f8884610fe5401ac6f260d955d47d9c14c9f3d2aa6541fd881faf07
+F src/json.c b3f20f01dc6e11071b0b5a8fda73a16c23fd7e65356ec715c0082e904f3fb284
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 176d6b2cb18a6ad73b133db17f6fc351c4d9a2d510deebdb76c22bde9cfd1465
 F src/main.c 512b1d45bc556edf4471a845afb7ba79e64bd5b832ab222dc195c469534cd002
@@ -2044,8 +2044,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P a4c1af616e672a0d4d04f2652e645617758231598fb7161b956883512303ae87 54b3c43fdfdaca6b129a5f0ee93c34eb001663775d33c087066650f5e164d1c1
-R 31a2d8c82324ae8c8feb0c4037e19a24
+P ef4e1664d159b98854d9aa580b0bb942f1726f32a190e2ea659c171131ddce9a
+R d6f55ea1e7a815bfa0f96bc129102acf
 U drh
-Z df17bf2cf88062fccaa06a3f8068b84c
+Z d5c0e742c545064eb8b7fe7e17a2bad7
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-ef4e1664d159b98854d9aa580b0bb942f1726f32a190e2ea659c171131ddce9a
+134b01f37f8f741d7f7b7eda81384695d1cbe4c39751d87f08832d5c9afdcef2

src/json.c

@@ -248,16 +248,6 @@ static int jsonGrow(JsonString *p, u32 N){
   return SQLITE_OK;
 }
 
-/* Try to force the string to be an RCStr string, rather than a
-** static string.  Return true on success.  The only reason this
-** might fail is due to an OOM fault.
-*/
-static int jsonForceRCStr(JsonString *p){
-  if( p->bStatic==0 ) return 1;
-  jsonGrow(p, p->nAlloc+1);
-  return p->bStatic==0;
-}
-
 /* Append N bytes from zIn onto the end of the JsonString string.
 */
 static SQLITE_NOINLINE void jsonAppendExpand(
@@ -315,6 +305,22 @@ static void jsonAppendChar(JsonString *p, char c){
   }
 }
 
+/* Try to force the string to be a zero-terminated RCStr string.
+**
+** Return true on success.  Return false if an OOM prevents this
+** from happening.
+*/
+static int jsonForceRCStr(JsonString *p){
+  jsonAppendChar(p, 0);
+  if( p->bErr ) return 0;
+  p->nUsed--;
+  if( p->bStatic==0 ) return 1;
+  p->nAlloc = 0;
+  jsonGrow(p, p->nUsed);
+  return p->bStatic==0;
+}
+
+
 /* Append a comma separator to the output buffer, if the previous
 ** character is not '[' or '{'.
 */
@@ -798,8 +804,6 @@ static void jsonReturnJson(
     jsonInit(&s, pCtx);
     jsonRenderNode(pParse, pNode, &s);
     if( bGenerateAlt && pParse->zAlt==0 && jsonForceRCStr(&s) ){
-      jsonAppendChar(&s, 0);
-      s.nUsed--;
       pParse->zAlt = sqlite3RCStrRef(s.zBuf);
       pParse->nAlt = s.nUsed;
     }