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cgpt_wrapper: Only write rw_gpt back if changed

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We always wrote back the rw_gpt file to NOR flash. This operation is too
slow. This CL compares if the original file has been changed by cgpt.bin
before writing the file back to NOR.

BUG=None
BRANCH=None
TEST=/usr/bin/cgpt show /dev/mtd0 now does not write back to NOR

Change-Id: I4c63f0d4da72f3674e06a896fa329f5fc964a885
Reviewed-on: https://chromium-review.googlesource.com/242293
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Tested-by: Nam Nguyen <namnguyen@chromium.org>
Commit-Queue: Nam Nguyen <namnguyen@google.com>
This commit is contained in:
Nam T. Nguyen
2015-01-21 11:18:32 -08:00
committed by ChromeOS Commit Bot
parent 4e1a9569c3
commit c67b061cb5
1 changed files with 12 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
cgpt/cgpt_wrapper.c
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@@ -22,6 +22,7 @@
#include "cgpt.h"
#include "cgpt_nor.h"
#include "cryptolib.h"
// Check if cmdline |argv| has "-D". "-D" signifies that GPT structs are stored
// off device, and hence we should not wrap around cgpt.
@@ -64,6 +65,8 @@ static const char *find_mtd_device(int argc, const char *const argv[]) {
static int wrap_cgpt(int argc,
const char *const argv[],
const char *mtd_device) {
uint8_t *original_hash = NULL;
uint8_t *modified_hash = NULL;
int ret = 0;
// Create a temp dir to work in.
@@ -76,6 +79,7 @@ static int wrap_cgpt(int argc,
if (snprintf(rw_gpt_path, sizeof(rw_gpt_path), "%s/rw_gpt", temp_dir) < 0) {
goto cleanup;
}
original_hash = DigestFile(rw_gpt_path, SHA1_DIGEST_ALGORITHM);
// Obtain the MTD size.
ret++;
@@ -120,11 +124,17 @@ static int wrap_cgpt(int argc,
// Write back "rw_gpt" to NOR flash in two chunks.
ret++;
if (WriteNorFlash(temp_dir) == 0) {
ret = 0;
modified_hash = DigestFile(rw_gpt_path, SHA1_DIGEST_ALGORITHM);
if (original_hash != NULL && modified_hash != NULL &&
memcmp(original_hash, modified_hash, SHA1_DIGEST_SIZE) != 0) {
if (WriteNorFlash(temp_dir) == 0) {
ret = 0;
}
}
cleanup:
free(original_hash);
free(modified_hash);
RemoveDir(temp_dir);
return ret;
}