Add NEVER() and ALWAYS() macros for the JSON5-control-character change.

Also fix an incorrect comparison used to determine if a buffer needed to
be resized.

FossilOrigin-Name: e3c0c0e686f3b7710f79587cf465b5aac52d8f2f2986a3de885a656f652cbfd3

manifest

@@ -1,5 +1,5 @@
-C Fix\sfailure\sto\sdetect\sunterminated\sstring\sliterals\sin\sjson_valid()\sin\sthe\nprevious\scheck-in.
-D 2024-01-31T14:44:59.052
+C Add\sNEVER()\sand\sALWAYS()\smacros\sfor\sthe\sJSON5-control-character\schange.\nAlso\sfix\san\sincorrect\scomparison\sused\sto\sdetermine\sif\sa\sbuffer\sneeded\sto\nbe\sresized.
+D 2024-01-31T15:20:13.599
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -698,7 +698,7 @@ 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 24f2517b5dc7e678ee3006eaa0c0e6b13ff90e71849f8c4064134eb28a97f618
+F src/json.c e4e5f70b602c1dc9592b798166697bedeb84c61ffe857c9302ded54d5024603d
 F src/legacy.c d7874bc885906868cd51e6c2156698f2754f02d9eee1bae2d687323c3ca8e5aa
 F src/loadext.c 7432c944ff197046d67a1207790a1b13eec4548c85a9457eb0896bb3641dfb36
 F src/main.c 438b95162acfa17b7d218f586f5bde11d6ae82bcf030c9611fc537556870ad6b
@@ -2161,8 +2161,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 34709c7cc910539e23a830ad8b589a97a88be25e924a59670c1017fb51447dad
-R b63eb752943f01d1de6f4800dabd8585
+P 5d725644621cf640fb743d59ccf89dac777540410e67501eb00b83638c8c857f
+R 877424d5c7313c59d7195755bacacb98
 U drh
-Z f52460ed1f18979ad0fa2f0cc99e3abc
+Z b4bc4db54d1dcd1788bd56fd303b8ecb
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-5d725644621cf640fb743d59ccf89dac777540410e67501eb00b83638c8c857f
+e3c0c0e686f3b7710f79587cf465b5aac52d8f2f2986a3de885a656f652cbfd3

src/json.c

@@ -1425,7 +1425,7 @@ static u32 jsonbValidityCheck(
           }else if( z[j]<=0x1f ){
             /* Control characters in JSON5 string literals are ok */
             if( x==JSONB_TEXTJ ) return j+1;
-          }else if( z[j]!='\\' || j+1>=k ){
+          }else if( NEVER(z[j]!='\\') || j+1>=k ){
             return j+1;
           }else if( strchr("\"\\/bfnrt",z[j+1])!=0 ){
             j++;
@@ -2223,7 +2223,7 @@ static u32 jsonTranslateBlobToText(
           continue;
         }
         if( zIn[0]<=0x1f ){
-          if( pOut->nUsed+7<pOut->nAlloc && jsonStringGrow(pOut,7) ) break;
+          if( pOut->nUsed+7>pOut->nAlloc && jsonStringGrow(pOut,7) ) break;
           jsonAppendControlChar(pOut, zIn[0]);
           zIn++;
           sz2--;
@@ -4419,7 +4419,7 @@ static void jsonErrorFunc(
         /* Convert byte-offset s.iErr into a character offset */
         u32 k;
         assert( s.zJson!=0 );  /* Because s.oom is false */
-        for(k=0; k<s.iErr && s.zJson[k]; k++){
+        for(k=0; k<s.iErr && ALWAYS(s.zJson[k]); k++){
           if( (s.zJson[k] & 0xc0)!=0x80 ) iErrPos++;
         }
         iErrPos++;