cbfstool: decompress stage files on extraction

In order to actually do something useful with the
resulting file after being extracted decompress stage
files' content. That way one can interrogate the
resulting file w/o having to decompress on the fly.

Note: This change will cause an unexpected change to
Chrome OS devices which package up individual stage
files in the RW slots w/o using cbfs. The result will
be that compressed stages are now decompressed.

Longer term is to turn these files into proper ELF
files on the way out.

Change-Id: I373ecc7b924ea21af8d891a8cb8f01fd64467360
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: http://review.coreboot.org/12174
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

util/cbfstool/cbfs_image.c

@@ -657,6 +657,73 @@ struct cbfs_file *cbfs_get_entry(struct cbfs_image *image, const char *name)
 	return NULL;
 }
 
+static int cbfs_stage_decompress(struct buffer *buff)
+{
+	struct buffer reader;
+	struct buffer writer;
+	struct cbfs_stage metadata;
+	char *orig_buffer;
+	char *new_buffer;
+	size_t new_buff_sz;
+	decomp_func_ptr decompress;
+
+	buffer_clone(&reader, buff);
+
+	/* The stage metadata is in little endian. */
+	metadata.compression = xdr_le.get32(&reader);
+	metadata.entry = xdr_le.get64(&reader);
+	metadata.load = xdr_le.get64(&reader);
+	metadata.len = xdr_le.get32(&reader);
+	metadata.memlen = xdr_le.get32(&reader);
+
+	if (metadata.compression == CBFS_COMPRESS_NONE)
+		return 0;
+
+	decompress = decompression_function(metadata.compression);
+	if (decompress == NULL)
+		return -1;
+
+	orig_buffer = buffer_get(buff);
+
+	/* This can be too big of a buffer needed, but there's no current
+	 * field indicating decompressed size of data. */
+	new_buff_sz = metadata.memlen + sizeof(struct cbfs_stage);
+	new_buffer = calloc(1, new_buff_sz);
+
+	if (decompress(orig_buffer + sizeof(struct cbfs_stage),
+			(int)(buffer_size(buff) - sizeof(struct cbfs_stage)),
+			new_buffer + sizeof(struct cbfs_stage),
+			(int)(new_buff_sz - sizeof(struct cbfs_stage)),
+			&new_buff_sz)) {
+		ERROR("Couldn't decompress stage.\n");
+		free(new_buffer);
+		return -1;
+	}
+
+	/* Include correct size for full stage info. */
+	new_buff_sz += sizeof(struct cbfs_stage);
+	buffer_init(buff, buff->name, new_buffer, new_buff_sz);
+	buffer_clone(&writer, buff);
+	/* Set size to 0 to please xdr. */
+	buffer_set_size(&writer, 0);
+
+	/* True decompressed size is just the data size -- no metadata. */
+	metadata.len = new_buff_sz - sizeof(struct cbfs_stage);
+	/* Stage is not compressed. */
+	metadata.compression = CBFS_COMPRESS_NONE;
+
+	/* Write back out the stage metadata. */
+	xdr_le.put32(&writer, metadata.compression);
+	xdr_le.put32(&writer, metadata.entry);
+	xdr_le.put32(&writer, metadata.load);
+	xdr_le.put32(&writer, metadata.len);
+	xdr_le.put32(&writer, metadata.memlen);
+
+	free(orig_buffer);
+
+	return 0;
+}
+
 int cbfs_export_entry(struct cbfs_image *image, const char *entry_name,
 		      const char *filename)
 {
@@ -689,22 +756,40 @@ int cbfs_export_entry(struct cbfs_image *image, const char *entry_name,
 		WARN("Payloads are extracted in SELF format.\n");
 	}
 
+	buffer_init(&buffer, strdup("(cbfs_export_entry)"), NULL, 0);
+
 	buffer.data = malloc(decompressed_size);
 	buffer.size = decompressed_size;
 	if (decompress(CBFS_SUBHEADER(entry), ntohl(entry->len),
 		buffer.data, buffer.size, NULL)) {
 		ERROR("decompression failed for %s\n", entry_name);
+		buffer_delete(&buffer);
 		return -1;
 	}
-	buffer.name = strdup("(cbfs_export_entry)");
+
+	/*
+	 * The stage metadata is never compressed proper for cbfs_stage
+	 * files. The contents of the stage data can be though. Therefore
+	 * one has to do a second pass for stages to potentially decompress
+	 * the stage data to make it more meaningful.
+	 */
+	if (ntohl(entry->type) == CBFS_COMPONENT_STAGE) {
+		if (cbfs_stage_decompress(&buffer)) {
+			ERROR("Failed to write %s into %s.\n",
+			      entry_name, filename);
+			buffer_delete(&buffer);
+			return -1;
+		}
+	}
+
 	if (buffer_write_file(&buffer, filename) != 0) {
 		ERROR("Failed to write %s into %s.\n",
 		      entry_name, filename);
-		free(buffer.name);
+		buffer_delete(&buffer);
 		return -1;
 	}
-	free(buffer.data);
+
-	free(buffer.name);
+	buffer_delete(&buffer);
 	INFO("Successfully dumped the file to: %s\n", filename);
 	return 0;
 }