Prevent memory leaks when re-processing values of string type.

* src/grecs.hin (GRECS_CONST): New flag.
* src/tree.c (grecs_string_convert): For string types, free the
old value prior to assigning the new one, unless the GRECS_CONST
flag is set.  In any case, clear the GRECS_CONST flag after
assigning new value.

2 files changed, 18 insertions, 9 deletions

diff --git a/src/grecs.hin b/src/grecs.hin
index 48e2937..812834f 100644
--- a/src/grecs.hin
+++ b/src/grecs.hin
@@ -97,12 +97,16 @@ enum grecs_data_type {
 	grecs_type_null
 };
 
-#define GRECS_DFLT 0x00
-#define GRECS_AGGR 0x01
-#define GRECS_MULT 0x02
-#define GRECS_INAC 0x04
-#define GRECS_LIST 0x08
-#define GRECS_HIDDEN 0x10
+#define GRECS_DFLT   0x00   /* Default keyword flags */
+#define GRECS_AGGR   0x01   /* Multiple entries aggregate */
+#define GRECS_MULT   0x02   /* Statement can appear multiple times */
+#define GRECS_INAC   0x04   /* Inactive keyword */
+#define GRECS_LIST   0x08   /* Value is a list of declared type */
+#define GRECS_HIDDEN 0x10   /* Hidden keyword: don't display in help output */
+#define GRECS_CONST  0x20   /* For string types: initial value is constant,
+			       don't try to free it before assigning new value.
+			       This flag is cleared after the first assignment.
+			    */
 
 enum grecs_callback_command {
 	grecs_callback_section_begin,
diff --git a/src/tree.c b/src/tree.c
index 4f3189c..eea90a5 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -546,7 +546,7 @@ string_to_sockaddr(struct grecs_sockaddr *sp, const char *string,
 
 int
 grecs_string_convert(void *target, enum grecs_data_type type,
-		      const char *string, grecs_locus_t const *locus)
+		     const char *string, grecs_locus_t const *locus)
 {
   switch (type) {
   case grecs_type_void:
@@ -556,7 +556,7 @@ grecs_string_convert(void *target, enum grecs_data_type type,
 	  break;
 	  
   case grecs_type_string:
-	  *(const char**)target = grecs_strdup(string);
+	  *(char**)target = grecs_strdup(string);
 	  break;
 	    
   case grecs_type_short:
@@ -824,10 +824,15 @@ grecs_process_ident(struct grecs_keyword *kwp, grecs_value_t *value,
 			grecs_list_append(list, ptr);
 		}
 		*(struct grecs_list**)target = list;
-	} else
+	} else {
+		if (kwp->type == grecs_type_string
+		    && !(kwp->flags & GRECS_CONST))
+			free(*(char**)target);
 		grecs_string_convert(target, kwp->type,
 				     value->v.string,
 				     &value->locus);
+	}
+	kwp->flags &= ~GRECS_CONST;
 }