hashtbl, strtbl: add hash_free_all(), split strtbl_find()

Add hash_free_all() to factor common code of iterating over all
members of a hash to free them with a single nasm_free().

Split strtbl_find() into strtbl_find() and strtbl_add().  It is very
unlikely that the same call site will want to have both of these
functionalities, and in the end the code for the two functions are
surprisingly different.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

include/hashtbl.h

@@ -81,5 +81,6 @@ void *hash_iterate(const struct hash_table *head,
 		   struct hash_tbl_node **iterator,
 		   const char **key);
 void hash_free(struct hash_table *head);
+void hash_free_all(struct hash_table *head, bool free_keys);
 
 #endif /* NASM_HASHTBL_H */

nasmlib/hashtbl.c

@@ -222,7 +222,9 @@ void *hash_iterate(const struct hash_table *head,
 
 /*
  * Free the hash itself.  Doesn't free the data elements; use
- * hash_iterate() to do that first, if needed.
+ * hash_iterate() to do that first, if needed.  This function is normally
+ * used when the hash data entries are either freed separately, or
+ * compound objects which can't be freed in a single operation.
  */
 void hash_free(struct hash_table *head)
 {
@@ -230,3 +232,25 @@ void hash_free(struct hash_table *head)
     head->table = NULL;
     nasm_free(p);
 }
+
+/*
+ * Frees the hash *and* all data elements.  This is applicable only in
+ * the case where the data element is a single allocation.  If the
+ * second argument is false, the key string is part of the data
+ * allocation or belongs to an allocation which will be freed
+ * separately, if it is true the keys are also freed.
+ */
+void hash_free_all(struct hash_table *head, bool free_keys)
+{
+    struct hash_tbl_node *iter = NULL;
+    const char *keyp;
+    void *d;
+
+    while ((d = hash_iterate(head, &iter, &keyp))) {
+        nasm_free(d);
+        if (free_keys)
+            nasm_free((void *)keyp);
+    }
+
+    hash_free(head);
+}

nasmlib/srcfile.c

@@ -55,13 +55,7 @@ void src_init(void)
 
 void src_free(void)
 {
-    struct hash_tbl_node *iter = NULL;
-    void *dp;
-
-    while ((dp = hash_iterate(&filename_hash, &iter, NULL)) != NULL)
-        nasm_free(dp);
-
-    hash_free(&filename_hash);
+    hash_free_all(&filename_hash, false);
 }
 
 /*

output/strtbl.c

@@ -57,30 +57,24 @@ void strtbl_init(struct nasm_strtbl *tbl)
 {
     tbl->size = 0;
     hash_init(&tbl->hash, HASH_LARGE);
-    strtbl_find(tbl, "", true); /* Index 0 is always an empty string */
+    strtbl_add(tbl, "");       /* Index 0 is always an empty string */
 }
 
 void strtbl_free(struct nasm_strtbl *tbl)
 {
-    struct hash_tbl_node *iter = NULL;
-    struct strtbl_entry *se;
-
-    while ((se = hash_iterate(&tbl->hash, &iter, NULL)))
-        nasm_free(se);
-
-    hash_free(&tbl->hash);
+    hash_free_all(&tbl->hash, false);
 }
 
-size_t strtbl_find(struct nasm_strtbl *tbl, const char *str, bool add)
+size_t strtbl_add(struct nasm_strtbl *tbl, const char *str)
 {
-    struct hash_insert hi;
-    void **dp;
+    void **sep;
     struct strtbl_entry *se;
+    struct hash_insert hi;
 
-    dp = hash_find(&tbl->hash, str, &hi);
-    if (dp) {
-        se = *dp;
-    } else if (add) {
+    sep = hash_find(&tbl->hash, str, &hi);
+    if (sep) {
+        se = *sep;
+    } else {
         size_t bytes = strlen(str) + 1;
 
         se = nasm_malloc(sizeof(struct strtbl_entry)-1+bytes);
@@ -90,13 +84,25 @@ size_t strtbl_find(struct nasm_strtbl *tbl, const char *str, bool add)
         memcpy(se->str, str, bytes);
 
         hash_add(&hi, se->str, se);
-    } else {
-        return STRTBL_NONE;
     }
 
     return se->index;
 }
 
+size_t strtbl_find(struct nasm_strtbl *tbl, const char *str)
+{
+    void **sep;
+    struct strtbl_entry *se;
+
+    sep = hash_find(&tbl->hash, str, NULL);
+    if (sep) {
+        se = *sep;
+        return se->index;
+    } else {
+        return STRTBL_NONE;
+    }
+}
+
 /* This create a linearized buffer containing the actual string table */
 void *strtbl_generate(const struct nasm_strtbl *tbl)
 {

output/strtbl.h

@@ -46,7 +46,8 @@ struct nasm_strtbl {
 
 void strtbl_init(struct nasm_strtbl *tbl);
 void strtbl_free(struct nasm_strtbl *tbl);
-size_t strtbl_find(struct nasm_strtbl *tbl, const char *str, bool add);
+size_t strtbl_find(struct nasm_strtbl *tbl, const char *str);
+size_t strtbl_add(struct nasm_strtbl *tbl, const char *str);
 static inline size_t strtbl_size(const struct nasm_strtbl *tbl)
 {
     return tbl->size;