Write-blocking cleanup, largely thanks to Colin Percival (cperciva@).

   * If write block size is zero, don't block at all.
     This supports the unusual requirement of applications
     that need "no-delay" writes.
   * Expose _write_finish_entry() to give such applications more
     control over write boundaries.  (Normal applications do not
     need this, as entries are completed automatically.)
   * Correct the type of write callbacks; this is a minor API
     change that does not affect the ABI.
   * Correct the error handling in _write_next_header() around
     completing the previous entry.
   * Correct the documentation for block-size markers:  Remove
     docs for the long-defunct _read_set_block_size(); document
     all of the write block size manipulators.

MFC after: 14 days

1 files changed, 29 insertions, 8 deletions

diff --git a/lib/libarchive/archive_write_set_compression_none.c b/lib/libarchive/archive_write_set_compression_none.c
index 9e43365..3fdaa67 100644
--- a/lib/libarchive/archive_write_set_compression_none.c
+++ b/lib/libarchive/archive_write_set_compression_none.c
@@ -89,13 +89,14 @@ archive_compressor_none_init(struct archive *a)
 	memset(state, 0, sizeof(*state));
 
 	state->buffer_size = a->bytes_per_block;
-	state->buffer = (char *)malloc(state->buffer_size);
-
-	if (state->buffer == NULL) {
-		archive_set_error(a, ENOMEM,
-		    "Can't allocate output buffer");
-		free(state);
-		return (ARCHIVE_FATAL);
+	if (state->buffer_size != 0) {
+		state->buffer = (char *)malloc(state->buffer_size);
+		if (state->buffer == NULL) {
+			archive_set_error(a, ENOMEM,
+			    "Can't allocate output buffer");
+			free(state);
+			return (ARCHIVE_FATAL);
+		}
 	}
 
 	state->next = state->buffer;
@@ -129,7 +130,27 @@ archive_compressor_none_write(struct archive *a, const void *vbuff,
 	}
 
 	remaining = length;
-	while (remaining > 0) {
+
+	/*
+	 * If there is no buffer for blocking, just pass the data
+	 * straight through to the client write callback.  In
+	 * particular, this supports "no write delay" operation for
+	 * special applications.  Just set the block size to zero.
+	 */
+	if (state->buffer_size == 0) {
+		while (remaining > 0) {
+			bytes_written = (a->client_writer)(a, a->client_data,
+			    buff, remaining);
+			if (bytes_written <= 0)
+				return (ARCHIVE_FATAL);
+			remaining -= bytes_written;
+			buff += bytes_written;
+		}
+		a->file_position += length;
+		return (ARCHIVE_OK);
+	}
+
+	while ((remaining > 0) || (state->avail == 0)) {
 		/*
 		 * If we have a full output block, write it and reset the
 		 * output buffer.