1 files changed, 97 insertions, 22 deletions

diff --git a/src/interfaces/ecpg/preproc/util.c b/src/interfaces/ecpg/preproc/util.c
index cb1eca7f3cb..f177df32488 100644
--- a/src/interfaces/ecpg/preproc/util.c
+++ b/src/interfaces/ecpg/preproc/util.c
@@ -104,33 +104,117 @@ mm_strdup(const char *string)
 	return new;
 }
 
+
 /*
- * String concatenation
+ * "Local" memory management support
+ *
+ * These functions manage memory that is only needed for a short time
+ * (processing of one input statement) within the ecpg grammar.
+ * Data allocated with these is not meant to be freed separately;
+ * rather it's freed by calling reclaim_local_storage() at the end
+ * of each statement cycle.
  */
 
+typedef struct loc_chunk
+{
+	struct loc_chunk *next;		/* list link */
+	unsigned int chunk_used;	/* index of first unused byte in data[] */
+	unsigned int chunk_avail;	/* # bytes still available in data[] */
+	char		data[FLEXIBLE_ARRAY_MEMBER];	/* actual storage */
+} loc_chunk;
+
+#define LOC_CHUNK_OVERHEAD	MAXALIGN(offsetof(loc_chunk, data))
+#define LOC_CHUNK_MIN_SIZE	8192
+
+/* Head of list of loc_chunks */
+static loc_chunk *loc_chunks = NULL;
+
 /*
- * Concatenate 2 strings, inserting a space between them unless either is empty
+ * Allocate local space of the requested size.
  *
- * The input strings are freed.
+ * Exits on OOM.
+ */
+void *
+loc_alloc(size_t size)
+{
+	void	   *result;
+	loc_chunk  *cur_chunk = loc_chunks;
+
+	/* Ensure all allocations are adequately aligned */
+	size = MAXALIGN(size);
+
+	/* Need a new chunk? */
+	if (cur_chunk == NULL || size > cur_chunk->chunk_avail)
+	{
+		size_t		chunk_size = Max(size, LOC_CHUNK_MIN_SIZE);
+
+		cur_chunk = mm_alloc(chunk_size + LOC_CHUNK_OVERHEAD);
+		/* Depending on alignment rules, we could waste a bit here */
+		cur_chunk->chunk_used = LOC_CHUNK_OVERHEAD - offsetof(loc_chunk, data);
+		cur_chunk->chunk_avail = chunk_size;
+		/* New chunk becomes the head of the list */
+		cur_chunk->next = loc_chunks;
+		loc_chunks = cur_chunk;
+	}
+
+	result = cur_chunk->data + cur_chunk->chunk_used;
+	cur_chunk->chunk_used += size;
+	cur_chunk->chunk_avail -= size;
+	return result;
+}
+
+/*
+ * Copy given string into local storage
+ */
+char *
+loc_strdup(const char *string)
+{
+	char	   *result = loc_alloc(strlen(string) + 1);
+
+	strcpy(result, string);
+	return result;
+}
+
+/*
+ * Reclaim local storage when appropriate
+ */
+void
+reclaim_local_storage(void)
+{
+	loc_chunk  *cur_chunk,
+			   *next_chunk;
+
+	for (cur_chunk = loc_chunks; cur_chunk; cur_chunk = next_chunk)
+	{
+		next_chunk = cur_chunk->next;
+		free(cur_chunk);
+	}
+	loc_chunks = NULL;
+}
+
+
+/*
+ * String concatenation support routines.  These return "local" (transient)
+ * storage.
+ */
+
+/*
+ * Concatenate 2 strings, inserting a space between them unless either is empty
  */
 char *
-cat2_str(char *str1, char *str2)
+cat2_str(const char *str1, const char *str2)
 {
-	char	   *res_str = (char *) mm_alloc(strlen(str1) + strlen(str2) + 2);
+	char	   *res_str = (char *) loc_alloc(strlen(str1) + strlen(str2) + 2);
 
 	strcpy(res_str, str1);
 	if (strlen(str1) != 0 && strlen(str2) != 0)
 		strcat(res_str, " ");
 	strcat(res_str, str2);
-	free(str1);
-	free(str2);
 	return res_str;
 }
 
 /*
  * Concatenate N strings, inserting spaces between them unless they are empty
- *
- * The input strings are freed.
  */
 char *
 cat_str(int count,...)
@@ -154,36 +238,27 @@ cat_str(int count,...)
 
 /*
  * Concatenate 2 strings, with no space between
- *
- * The input strings are freed.
  */
 char *
-make2_str(char *str1, char *str2)
+make2_str(const char *str1, const char *str2)
 {
-	char	   *res_str = (char *) mm_alloc(strlen(str1) + strlen(str2) + 1);
+	char	   *res_str = (char *) loc_alloc(strlen(str1) + strlen(str2) + 1);
 
 	strcpy(res_str, str1);
 	strcat(res_str, str2);
-	free(str1);
-	free(str2);
 	return res_str;
 }
 
 /*
  * Concatenate 3 strings, with no space between
- *
- * The input strings are freed.
  */
 char *
-make3_str(char *str1, char *str2, char *str3)
+make3_str(const char *str1, const char *str2, const char *str3)
 {
-	char	   *res_str = (char *) mm_alloc(strlen(str1) + strlen(str2) + strlen(str3) + 1);
+	char	   *res_str = (char *) loc_alloc(strlen(str1) + strlen(str2) + strlen(str3) + 1);
 
 	strcpy(res_str, str1);
 	strcat(res_str, str2);
 	strcat(res_str, str3);
-	free(str1);
-	free(str2);
-	free(str3);
 	return res_str;
 }