From 2e753fa3d7ebdc6ff142680461610c9db6cac947 Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sesse@debian.org>
Date: Sat, 3 Jan 2009 12:10:40 +0100
Subject: [PATCH 1/1] More issues with overlong returns.

---
 bytesource.c      | 44 +++++++++++++++++++++++---------------------
 bytesource_test.c | 11 ++++++++---
 2 files changed, 31 insertions(+), 24 deletions(-)

diff --git a/bytesource.c b/bytesource.c
index fed7551..ca260a1 100644
--- a/bytesource.c
+++ b/bytesource.c
@@ -44,7 +44,7 @@ uint8_t byte_source_read_marker(struct byte_source* src)
 	uint8_t ret = src->bytes[1];
 	memmove(src->bytes, src->bytes + 2, src->bytes_available - 2);
 	src->bytes_available -= 2;
-
+	
 	return ret;
 }
 
@@ -81,7 +81,7 @@ ssize_t byte_source_input_func(void* source, uint8_t* buf, size_t len)
 
 		src->bytes_available += bytes_read;
 	}
-	
+
 	// Now unstuff as much as we can. First of all, if there's a 0xFF at the
 	// end of the buffer, we don't include it this time; the unstuff function
 	// will only give us an error since it can't decide if it's a marker or
@@ -94,45 +94,47 @@ ssize_t byte_source_input_func(void* source, uint8_t* buf, size_t len)
 		end_marker = true;
 	}
 
-	int unstuffed_bytes = (*unstuff_choice)(buf, src->bytes, bytes_to_unstuff);
-	assert(unstuffed_bytes != 0);
-	if (unstuffed_bytes > 0) {
-		// Fast path: No markers in the data. We can basically just
-		// return it.
-		if (end_marker) {
-			src->bytes_available = 1;
-			src->bytes[0] = 0xff;
-		} else {
-			src->bytes_available = 0;
-			src->bytes[0] = 0;
+	// Fast path: No markers in the data, we don't have more data than we
+	// need. We can basically just return it.
+	if (bytes_to_unstuff <= len) {
+		int unstuffed_bytes = (*unstuff_choice)(buf, src->bytes, bytes_to_unstuff);
+		assert(unstuffed_bytes != 0);
+		if (unstuffed_bytes > 0) {
+			// Fast path: No markers in the data. We can basically just
+			// return it.
+			if (end_marker) {
+				src->bytes_available = 1;
+				src->bytes[0] = 0xff;
+			} else {
+				src->bytes_available = 0;
+			}
+			return unstuffed_bytes;
 		}
-		return unstuffed_bytes;
 	}
 
 	// Slow path: There was a marker in the data. Unstuff manually until
 	// we hit the marker, then return that.
-	assert(unstuffed_bytes == -1);
 	unsigned bytes_read;
 	unsigned bytes_written = 0;
-	for (bytes_read = 0; bytes_read < src->bytes_available; ++bytes_read) {
-		buf[bytes_written++] = src->bytes[bytes_read];
+	for (bytes_read = 0; bytes_read < bytes_to_unstuff && bytes_written < len; ++bytes_read) {
 		if (src->bytes[bytes_read] != MARKER_CHAR) {
+			buf[bytes_written++] = src->bytes[bytes_read];
 			continue;
 		}
 
 		assert(bytes_read < src->bytes_available);
 		if (src->bytes[bytes_read + 1] == STUFF_MARKER) {
+			src->bytes[bytes_written++] = MARKER_CHAR;
+
 			// Skip the stuff byte.
 			++bytes_read;
-			continue;
 		} else {
 			// OK, this is our marker.
 			break;
-		}	
+		}
 	}
 
 	memmove(src->bytes, src->bytes + bytes_read, src->bytes_available - bytes_read);
 	src->bytes_available -= bytes_read;
-	assert(bytes_written >= 1);
-	return bytes_written - 1;
+	return bytes_written;
 }
diff --git a/bytesource_test.c b/bytesource_test.c
index 36c6da2..6c692cb 100644
--- a/bytesource_test.c
+++ b/bytesource_test.c
@@ -161,18 +161,23 @@ void test_small_reads()
 	struct byte_source source;
 	init_byte_source(&source, custom_read, &ud);
 
+	uint8_t buf[4096];
+	ssize_t ret;
+
+	ret = byte_source_input_func(&source, buf, 4096);
+	assert(ret == 0);	
+
 	uint8_t marker = byte_source_read_marker(&source);
 	assert(marker == 0x80);
 
-	uint8_t buf[4096];
 	for (unsigned i = 0; i < 8; ++i) {
-		ssize_t ret = byte_source_input_func(&source, buf, 1);
+		ret = byte_source_input_func(&source, buf, 1);
 		assert(ret == 1);
 		assert(buf[0] == i);
 	}
 	
 	// Now EOF.
-	ssize_t ret = byte_source_input_func(&source, buf, 4096);
+	ret = byte_source_input_func(&source, buf, 4096);
 	assert(ret == 0);
 }
 
-- 
2.39.2