From 3b22def34cb8b19c4bdc2dd237374a536c21fa71 Mon Sep 17 00:00:00 2001
From: Andre Noll <maan@tuebingen.mpg.de>
Date: Mon, 9 Aug 2021 21:08:16 +0200
Subject: [PATCH] mp4: Introduce min_body_size() helper.

This increases readability a lot and brings the line length of
mp4ff_parse_tag() down to a reasonable number of characters.
---
 mp4.c | 90 ++++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 55 insertions(+), 35 deletions(-)

diff --git a/mp4.c b/mp4.c
index 80acf41a..e66fcea2 100644
--- a/mp4.c
+++ b/mp4.c
@@ -952,6 +952,29 @@ static int32_t mp4ff_set_metadata_name(const uint8_t atom_type, char **name)
 	return 0;
 }
 
+static uint32_t min_body_size(const uint8_t atom_type)
+{
+	switch(atom_type) {
+	case ATOM_GENRE2:
+	case ATOM_TEMPO:
+		return 10;
+	case ATOM_TRACK:
+		return sizeof (char) /* version */
+			+ sizeof(uint8_t) * 3 /* flags */
+			+ sizeof(uint32_t) /* reserved */
+			+ sizeof(uint16_t) /* leading uint16_t */
+			+ sizeof(uint16_t) /* track */
+			+ sizeof(uint16_t); /* totaltracks */
+	case ATOM_DISC:
+		return sizeof (char) /* version */
+			+ sizeof(uint8_t) * 3 /* flags */
+			+ sizeof(uint32_t) /* reserved */
+			+ sizeof(uint16_t) /* disc */
+			+ sizeof(uint16_t); /* totaldiscs */
+	default: assert(false);
+	}
+}
+
 static int32_t mp4ff_parse_tag(mp4ff_t * f, const uint8_t parent,
 		const int32_t size)
 {
@@ -988,45 +1011,42 @@ static int32_t mp4ff_parse_tag(mp4ff_t * f, const uint8_t parent,
 
 		/* some need special attention */
 		if (parent == ATOM_GENRE2 || parent == ATOM_TEMPO) {
-			if (subsize - header_size >= 8 + 2) {
-				uint16_t val = mp4ff_read_int16(f);
-
-				if (parent == ATOM_TEMPO) {
-					char temp[16];
-					sprintf(temp, "%.5u BPM", val);
-					mp4ff_tag_add_field(&(f-> tags), "tempo", temp, -1);
-				} else {
-					const char *temp = mp4ff_meta_index_to_genre(val);
-					if (temp)
-						mp4ff_tag_add_field (&(f->tags), "genre", temp, -1);
-				}
-				done = 1;
+			uint16_t val;
+			if (subsize - header_size < min_body_size(parent))
+				continue;
+			val = mp4ff_read_int16(f);
+			if (parent == ATOM_TEMPO) {
+				char temp[16];
+				sprintf(temp, "%.5u BPM", val);
+				mp4ff_tag_add_field(&(f-> tags), "tempo",
+					temp, -1);
+			} else {
+				const char *tmp = mp4ff_meta_index_to_genre(val);
+				if (tmp)
+					mp4ff_tag_add_field (&(f->tags),
+						"genre", tmp, -1);
 			}
+			done = 1;
 		} else if (parent == ATOM_TRACK || parent == ATOM_DISC) {
-			if (subsize - header_size >= (sizeof (char) + sizeof (uint8_t) * 3 + sizeof (uint32_t) +	/* version + flags + reserved */
-								 +(parent == ATOM_TRACK ? sizeof (uint16_t) : 0)	/* leading uint16_t if ATOM_TRACK */
-								 +sizeof (uint16_t)	/* track / disc */
-								 +sizeof (uint16_t))	/* totaltracks / totaldiscs */) {
-				uint16_t index, total;
-				char temp[32];
+			uint16_t index, total;
+			char temp[32];
+			if (subsize - header_size < min_body_size(parent))
+				continue;
+			mp4ff_read_int16(f);
+			index = mp4ff_read_int16(f);
+			total = mp4ff_read_int16(f);
+			if (parent == ATOM_TRACK)
 				mp4ff_read_int16(f);
-				index = mp4ff_read_int16(f);
-				total = mp4ff_read_int16(f);
-				if (parent == ATOM_TRACK)
-					mp4ff_read_int16(f);
-
-				sprintf(temp, "%d", index);
-				mp4ff_tag_add_field(&(f->tags), parent == ATOM_TRACK ?
-					"track" : "disc", temp, -1);
-				if (total > 0) {
-					sprintf(temp, "%d",
-						total);
-					mp4ff_tag_add_field(& (f-> tags),
-						parent == ATOM_TRACK?
-						"totaltracks" : "totaldiscs", temp, -1);
-				}
-				done = 1;
+			sprintf(temp, "%d", index);
+			mp4ff_tag_add_field(&(f->tags), parent == ATOM_TRACK?
+				"track" : "disc", temp, -1);
+			if (total > 0) {
+				sprintf(temp, "%d", total);
+				mp4ff_tag_add_field(& (f-> tags),
+					parent == ATOM_TRACK?
+					"totaltracks" : "totaldiscs", temp, -1);
 			}
+			done = 1;
 		} else {
 			free(data);
 			data = mp4ff_read_string(f, subsize - (header_size + 8));
-- 
2.39.5