Propagate null gstring through string_catn()

[exim.git] / src / src / lookups / mysql.c

diff --git a/src/src/lookups/mysql.c b/src/src/lookups/mysql.c
index 4e6ca8a72cd813b034b8684a5915ac41137d72fb..b36ce0950f209c0c68ecb22e7b67c555df714984 100644 (file)
--- a/src/src/lookups/mysql.c
+++ b/src/src/lookups/mysql.c
@@ -308,7 +308,7 @@ fields = mysql_fetch_fields(mysql_result);
 
 while ((mysql_row_data = mysql_fetch_row(mysql_result)))
   {
-  unsigned long *lengths = mysql_fetch_lengths(mysql_result);
+  unsigned long * lengths = mysql_fetch_lengths(mysql_result);
 
   if (result)
     result = string_catn(result, US"\n", 1);
@@ -319,7 +319,9 @@ while ((mysql_row_data = mysql_fetch_row(mysql_result)))
                        result);
 
   else if (mysql_row_data[0] != NULL)    /* NULL value yields nothing */
-      result = string_catn(result, US mysql_row_data[0], lengths[0]);
+      result = lengths[0] == 0 && !result
+       ? string_get(1)         /* for 0-len string result ensure non-null gstring */
+        : string_catn(result, US mysql_row_data[0], lengths[0]);
   }
 
 /* more results? -1 = no, >0 = error, 0 = yes (keep looping)
@@ -416,38 +418,33 @@ Returns:     the processed string or NULL for a bad option
 */
 
 static uschar *
-mysql_quote(uschar *s, uschar *opt)
+mysql_quote(uschar * s, uschar * opt)
 {
 register int c;
 int count = 0;
 uschar *t = s;
 uschar *quoted;
 
-if (opt != NULL) return NULL;     /* No options recognized */
+if (opt) return NULL;     /* No options recognized */
 
-while ((c = *t++) != 0)
+while ((c = *t++))
   if (Ustrchr("\n\t\r\b\'\"\\", c) != NULL) count++;
 
 if (count == 0) return s;
 t = quoted = store_get(Ustrlen(s) + count + 1, is_tainted(s));
 
-while ((c = *s++) != 0)
+while ((c = *s++))
   {
   if (Ustrchr("\n\t\r\b\'\"\\", c) != NULL)
     {
     *t++ = '\\';
     switch(c)
       {
-      case '\n': *t++ = 'n';
-      break;
-      case '\t': *t++ = 't';
-      break;
-      case '\r': *t++ = 'r';
-      break;
-      case '\b': *t++ = 'b';
-      break;
-      default:   *t++ = c;
-      break;
+      case '\n': *t++ = 'n'; break;
+      case '\t': *t++ = 't'; break;
+      case '\r': *t++ = 'r'; break;
+      case '\b': *t++ = 'b'; break;
+      default:   *t++ = c;   break;
       }
     }
   else *t++ = c;