MT#55283 update memory arena logic

Use a pointer to the arena plus a comparison test to determine whether
to ref or to dup the string, instead of a function pointer. The function
pointer alone wasn't enough as there can be multiple arenas.

Change-Id: Icd317e524fc2e5842f90d172ef7089d2cb0a5a28
(cherry picked from commit 4ea7873)

Author: rfuchs

daemon/media_player.c

@@ -1281,7 +1281,7 @@ static struct media_player_media_file *media_player_media_file_new(str blob) {
 	__auto_type fo = obj_alloc0(struct media_player_media_file,
 			media_player_media_file_free);
 	fo->blob = blob;
-	fo->blob.dup = call_ref; // string is allocated by reference on `fo`
+	fo->blob.arena = memory_arena; // string is allocated by reference on `fo`
 	RTPE_GAUGE_ADD(media_cache, blob.len);
 	fo->atime_us = fo->mtime_us = rtpe_now;
 	return fo;

include/arena.h

@@ -29,16 +29,12 @@ INLINE char *memory_arena_dup(const char *b, size_t len) {
 	ret[len] = '\0';
 	return ret;
 }
-INLINE char *memory_arena_ref(const char *b, size_t len) {
-	return (char *) b;
-}
-INLINE char *memory_arena_strdup_len(const char *s, size_t len, char *(*dup)(const char *, size_t)) {
-	char *r;
+INLINE char *memory_arena_strdup_len(const char *s, size_t len, void *arena) {
 	if (!s)
 		return NULL;
-	dup = dup ?: memory_arena_dup;
-	r = dup(s, len);
-	return r;
+	if (arena == memory_arena)
+		return (char *) s;
+	return memory_arena_dup(s, len);
 }
 
 INLINE char *memory_arena_strdup(const char *s) {
@@ -49,24 +45,24 @@ INLINE char *memory_arena_strdup(const char *s) {
 INLINE char *memory_arena_strdup_str(const str *s) {
 	if (!s)
 		return NULL;
-	return memory_arena_strdup_len(s->s, s->len, s->dup);
+	return memory_arena_strdup_len(s->s, s->len, s->arena);
 }
-INLINE str memory_arena_str_cpy_fn(const char *in, size_t len, char *(*dup)(const char *, size_t)) {
+INLINE str memory_arena_str_cpy_fn(const char *in, size_t len, void *arena) {
 	str out;
 	if (!in) {
 		out = STR_NULL;
 		return out;
 	}
-	out.s = memory_arena_strdup_len(in, len, dup);
+	out.s = memory_arena_strdup_len(in, len, arena);
 	out.len = len;
-	out.dup = memory_arena_ref;
+	out.arena = memory_arena;
 	return out;
 }
 INLINE str memory_arena_str_cpy_len(const char *in, size_t len) {
 	return memory_arena_str_cpy_fn(in, len, NULL);
 }
 INLINE str memory_arena_str_cpy(const str *in) {
-	return memory_arena_str_cpy_fn((in ? in->s : NULL), (in ? in->len : 0), (in ? in->dup : NULL));
+	return memory_arena_str_cpy_fn((in ? in->s : NULL), (in ? in->len : 0), (in ? in->arena : NULL));
 }
 INLINE str memory_arena_str_cpy_c(const char *in) {
 	return memory_arena_str_cpy_len(in, in ? strlen(in) : 0);

include/call.h

@@ -924,7 +924,6 @@ const rtp_payload_type *__rtp_stats_codec(struct call_media *m);
 
 #define call_malloc memory_arena_alloc
 #define call_dup memory_arena_dup
-#define call_ref memory_arena_ref
 
 #define call_strdup memory_arena_strdup
 #define call_strdup_str memory_arena_strdup_str

lib/str.h

@@ -15,7 +15,7 @@
 struct _str {
 	char *s;
 	size_t len;
-	char *(*dup)(const char *, size_t);
+	void *arena;
 };
 
 typedef struct _str str;
@@ -325,7 +325,7 @@ INLINE str *str_alloc(size_t len) {
 	r = malloc(sizeof(*r) + len + 1);
 	r->s = ((char *) r) + sizeof(*r);
 	r->len = 0;
-	r->dup = NULL;
+	r->arena = NULL;
 	return r;
 }
 INLINE str *str_dup(const str *s) {