[PATCH v2] fit_image: Use calloc() to fix reproducibility issue

[Fabio Estevam <festevam@gmail.com>]

Vagrant Cascadian reported that mx6cuboxi target no longer builds
reproducibility on Debian.

One example of builds mismatches:

00096680: 696e 6700 736f 756e 642d 6461 6900 6465  ing.sound-dai.de
-00096690: 7465 6374 2d67 7069 6f73 0000            tect-gpios..
+00096690: 7465 6374 2d67 7069 6f73 0061            tect-gpios.a

This problem happens because all the buffers in fit_image.c are
allocated via malloc(), which does not zero out the allocated buffer.

Using calloc() fixes this unpredictable behaviour as it guarantees
that the allocated buffer are zero initialized.

Reported-by: Vagrant Cascadian <vagrant@reproducible-builds.org>
Suggested-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
---
Changes since v1:
- Improve the commit log description by stating why calloc() helps.

 tools/fit_image.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/fit_image.c b/tools/fit_image.c
index a082d9386d..0c6185d892 100644
--- a/tools/fit_image.c
+++ b/tools/fit_image.c
@@ -388,7 +388,7 @@ static int fit_build(struct image_tool_params *params, const char *fname)
 	size = fit_calc_size(params);
 	if (size < 0)
 		return -1;
-	buf = malloc(size);
+	buf = calloc(1, size);
 	if (!buf) {
 		fprintf(stderr, "%s: Out of memory (%d bytes)\n",
 			params->cmdname, size);
@@ -467,7 +467,7 @@ static int fit_extract_data(struct image_tool_params *params, const char *fname)
 	 * Allocate space to hold the image data we will extract,
 	 * extral space allocate for image alignment to prevent overflow.
 	 */
-	buf = malloc(fit_size + (align_size * image_number));
+	buf = calloc(1, fit_size + (align_size * image_number));
 	if (!buf) {
 		ret = -ENOMEM;
 		goto err_munmap;
@@ -572,7 +572,7 @@ static int fit_import_data(struct image_tool_params *params, const char *fname)
 
 	/* Allocate space to hold the new FIT */
 	size = sbuf.st_size + 16384;
-	fdt = malloc(size);
+	fdt = calloc(1, size);
 	if (!fdt) {
 		fprintf(stderr, "%s: Failed to allocate memory (%d bytes)\n",
 			__func__, size);
@@ -673,7 +673,7 @@ static int copyfile(const char *src, const char *dst)
 		goto out;
 	}
 
-	buf = malloc(512);
+	buf = calloc(1, 512);
 	if (!buf) {
 		printf("Can't allocate buffer to copy file\n");
 		goto out;
-- 
2.17.1