X-Git-Url: https://git.ozlabs.org/?p=ccan;a=blobdiff_plain;f=ccan%2Fcrcsync%2Fcrcsync.c;h=2301bc103c1fce4952dbb14cd88057416d62339c;hp=87f513ea90cc74576b2f5854ccd68431f8ed5e65;hb=9fc013b29af595852c1cc53fdb365a06dd5e7d49;hpb=4df5a75fd90bfcd42dedb3bfa83e85b57fd9f63c

diff --git a/ccan/crcsync/crcsync.c b/ccan/crcsync/crcsync.c
index 87f513ea..2301bc10 100644
--- a/ccan/crcsync/crcsync.c
+++ b/ccan/crcsync/crcsync.c
@@ -192,7 +192,11 @@ size_t crc_read_block(struct crc_context *ctx, long *result,
 		if (ctx->literal_bytes > ctx->block_size) {
 			*result = ctx->literal_bytes - ctx->block_size;
 			ctx->literal_bytes -= *result;
-			ctx->buffer_start += *result;
+			/* Advance buffer. */
+			if (*result >= buffer_size(ctx))
+				ctx->buffer_start = ctx->buffer_end = 0;
+			else
+				ctx->buffer_start += *result;
 		} else
 			*result = 0;
 
@@ -206,7 +210,9 @@ size_t crc_read_block(struct crc_context *ctx, long *result,
 			ctx->buffer_end -= ctx->buffer_start;
 			ctx->buffer_start = 0;
 		}
-		memcpy(ctx->buffer + ctx->buffer_end, buf, len);
+
+		/* Copy len bytes from tail of buffer. */
+		memcpy(ctx->buffer + ctx->buffer_end, buf + buflen - len, len);
 		ctx->buffer_end += len;
 		assert(buffer_size(ctx) <= ctx->block_size);
 	}