some more compiler attributes

make sure all textcode/scan_* routines work if dest or destlen is NULL

textcode/scan_jsonescape.c

@@ -63,11 +63,11 @@ size_t scan_jsonescape(const char *src,char *dest,size_t *destlen) {
     ++written;
   }
 done:
-  *destlen=written;
+  if (destlen) *destlen=written;
   return i;
 abort:
   if (prev!=(unsigned int)-1) i-=6; // if we abort and there still was an open surrogate pair, cancel it
-  *destlen=written;
+  if (destlen) *destlen=written;
   return i;
 }
 

textcode/scan_quotedprintable.c

@@ -8,16 +8,16 @@ size_t scan_quotedprintable(const char *src,char *dest,size_t *destlen) {
     if (s[i]=='=') {
       int j=scan_fromhex(s[i+1]);
       if (j<0) break;
-      dest[written]=j<<4;
+      if (dest) dest[written]=j<<4;
       j=scan_fromhex(s[i+2]);
       if (j<0) break;
-      dest[written]|=j;
+      if (dest) dest[written]|=j;
       i+=2;
     } else {
-      dest[written]=s[i];
+      if (dest) dest[written]=s[i];
     }
     ++written;
   }
-  *destlen=written;
+  if (destlen) *destlen=written;
   return i;
 }

textcode/scan_urlencoded.c

@@ -12,17 +12,17 @@ static size_t inner_scan_urlencoded(const char *src,char *dest,size_t *destlen,i
       c=j<<4;
       j=scan_fromhex(s[i+2]);
       if (j<0) break;
-      dest[written]=c|j;
+      if (dest) dest[written]=c|j;
       i+=2;
-    } else if (s[i]=='+' && plus)
-      dest[written]=' ';
-    else if (s[i]<=' ' || s[i]=='?' || s[i]=='&')
+    } else if (s[i]=='+' && plus) {
+      if (dest) dest[written]=' ';
+    } else if (s[i]<=' ' || s[i]=='?' || s[i]=='&')
       break;	/* invalid input */
     else
-      dest[written]=s[i];
+      if (dest) dest[written]=s[i];
     ++written;
   }
-  *destlen=written;
+  if (destlen) *destlen=written;
   return i;
 }
 

textcode/scan_yenc.c

@@ -8,13 +8,13 @@ size_t scan_yenc(const char *src,char *dest,size_t *destlen) {
     if (s[i]=='=') {
       ++i;
       if (s[i]=='y') break;
-      dest[written]=s[i]-64-42;
+      if (dest) dest[written]=s[i]-64-42;
     } else if (s[i]=='\n' || s[i]=='\r' || s[i]=='\0')
       break;
     else
-      dest[written]=s[i]-42;
+      if (dest) dest[written]=s[i]-42;
     ++written;
   }
-  *destlen=written;
+  if (destlen) *destlen=written;
   return i;
 }