Change in coreboot[master]: cbfstool: Add helper function `buffer_from_file_aligned_size`

[Furquan Shaikh (Code Review)]

Furquan Shaikh has submitted this change. ( https://review.coreboot.org/c/coreboot/+/55989 )

Change subject: cbfstool: Add helper function `buffer_from_file_aligned_size`
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cbfstool: Add helper function `buffer_from_file_aligned_size`

This change adds a helper function `buffer_from_file_aligned_size`
that loads a file into memory buffer by creating a memory buffer of
size rounded up to the provided `size_granularity` parameter.

BUG=b:189177186,b:189167923

Change-Id: Iad3430d476abcdad850505ac50e36cd5d5deecb4
Signed-off-by: Furquan Shaikh 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55989
Tested-by: build bot (Jenkins) 
Reviewed-by: Felix Held 
Reviewed-by: Tim Wawrzynczak 
---
M util/cbfstool/common.c
M util/cbfstool/common.h
2 files changed, 18 insertions(+), 3 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Felix Held: Looks good to me, but someone else must approve
  Tim Wawrzynczak: Looks good to me, approved

diff --git a/util/cbfstool/common.c b/util/cbfstool/common.c
index 539d0ba..5889e2a 100644
--- a/util/cbfstool/common.c
+++ b/util/cbfstool/common.c
@@ -49,7 +49,8 @@
    return (buffer->data == NULL);
 }

-int buffer_from_file(struct buffer *buffer, const char *filename)
+int buffer_from_file_aligned_size(struct buffer *buffer, const char *filename,
+				  size_t size_granularity)
 {
    FILE *fp = fopen(filename, "rb");
    if (!fp) {
@@ -63,20 +64,29 @@
    	fclose(fp);
    	return -1;
    }
-	buffer->size = file_size;
+	buffer->size = ALIGN_UP(file_size, size_granularity);
    buffer->name = strdup(filename);
    buffer->data = (char *)malloc(buffer->size);
    assert(buffer->data);
-	if (fread(buffer->data, 1, buffer->size, fp) != buffer->size) {
+	if (fread(buffer->data, 1, file_size, fp) != (size_t)file_size) {
    	fprintf(stderr, "incomplete read: %s\n", filename);
    	fclose(fp);
    	buffer_delete(buffer);
    	return -1;
    }
    fclose(fp);
+
+	if (buffer->size > (size_t)file_size)
+		memset(buffer->data + file_size, 0xff, buffer->size - file_size);
+
    return 0;
 }

+int buffer_from_file(struct buffer *buffer, const char *filename)
+{
+	return buffer_from_file_aligned_size(buffer, filename, 1);
+}
+
 int buffer_write_file(struct buffer *buffer, const char *filename)
 {
    FILE *fp = fopen(filename, "wb");
diff --git a/util/cbfstool/common.h b/util/cbfstool/common.h
index 07ffdf8..b23c8d2 100644
--- a/util/cbfstool/common.h
+++ b/util/cbfstool/common.h
@@ -132,6 +132,11 @@
 /* Loads a file into memory buffer. Returns 0 on success, otherwise non-zero. */
 int buffer_from_file(struct buffer *buffer, const char *filename);

+/* Loads a file into memory buffer (with buffer size rounded up to a multiple of
+   size_granularity). Returns 0 on success, otherwise non-zero. */
+int buffer_from_file_aligned_size(struct buffer *buffer, const char *filename,
+				  size_t size_granularity);
+
 /* Writes memory buffer content into file.
  * Returns 0 on success, otherwise non-zero. */
 int buffer_write_file(struct buffer *buffer, const char *filename);