Comply with the stream read protocol in flate decoder: always fill the output buffer with all available data.

1 files changed, 33 insertions, 27 deletions

diff --git a/fitz/filt_flate.c b/fitz/filt_flate.c
index acda8c49..0d14a75c 100644
--- a/fitz/filt_flate.c
+++ b/fitz/filt_flate.c
@@ -10,7 +10,7 @@ struct fz_flate_s
 	z_stream z;
 };
 
-static void *zmalloc(void *opaque, unsigned int items, unsigned int size)
+static void *zalloc(void *opaque, unsigned int items, unsigned int size)
 {
 	return fz_calloc(items, size);
 }
@@ -28,36 +28,42 @@ readflated(fz_stream *stm, unsigned char *outbuf, int outlen)
 	z_streamp zp = &state->z;
 	int code;
 
-	if (chain->rp == chain->wp)
-		fz_fillbuffer(chain);
-
-	zp->next_in = chain->rp;
-	zp->avail_in = chain->wp - chain->rp;
 	zp->next_out = outbuf;
 	zp->avail_out = outlen;
 
-	code = inflate(zp, Z_SYNC_FLUSH);
-
-	chain->rp = chain->wp - zp->avail_in;
-
-	if (code == Z_STREAM_END || code == Z_OK)
-	{
-		return outlen - zp->avail_out;
-	}
-	else if (code == Z_BUF_ERROR)
+	while (zp->avail_out > 0)
 	{
-		fz_warn("premature end of data in flate filter");
-		return outlen - zp->avail_out;
-	}
-	else if (code == Z_DATA_ERROR && zp->avail_in == 0)
-	{
-		fz_warn("ignoring zlib error: %s", zp->msg);
-		return outlen - zp->avail_out;
-	}
-	else
-	{
-		return fz_throw("zlib error: %s", zp->msg);
+		if (chain->rp == chain->wp)
+			fz_fillbuffer(chain);
+
+		zp->next_in = chain->rp;
+		zp->avail_in = chain->wp - chain->rp;
+
+		code = inflate(zp, Z_SYNC_FLUSH);
+
+		chain->rp = chain->wp - zp->avail_in;
+
+		if (code == Z_STREAM_END)
+		{
+			return outlen - zp->avail_out;
+		}
+		else if (code == Z_BUF_ERROR)
+		{
+			fz_warn("premature end of data in flate filter");
+			return outlen - zp->avail_out;
+		}
+		else if (code == Z_DATA_ERROR && zp->avail_in == 0)
+		{
+			fz_warn("ignoring zlib error: %s", zp->msg);
+			return outlen - zp->avail_out;
+		}
+		else if (code != Z_OK)
+		{
+			return fz_throw("zlib error: %s", zp->msg);
+		}
 	}
+
+	return outlen - zp->avail_out;
 }
 
 static void
@@ -83,7 +89,7 @@ fz_openflated(fz_stream *chain)
 	state = fz_malloc(sizeof(fz_flate));
 	state->chain = chain;
 
-	state->z.zalloc = zmalloc;
+	state->z.zalloc = zalloc;
 	state->z.zfree = zfree;
 	state->z.opaque = nil;
 	state->z.next_in = nil;