From 2dd125048dedbae3fbad6ae4b89f4b9b6e44b9b1 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Rafa=C5=82=20Mi=C5=82ecki?= <zajec5@gmail.com>
Date: Mon, 9 May 2016 19:00:53 +0200
Subject: [PATCH] mtd: trx: use separated buffer for TRX header
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We plan to adjust usage of the main buffer to allow reading custom
amount of data for CRC32. This means we need another buffer that will be
always block aligned.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
---
 package/system/mtd/src/trx.c | 23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/package/system/mtd/src/trx.c b/package/system/mtd/src/trx.c
index 00c4d6c0b50b..f310f51087e5 100644
--- a/package/system/mtd/src/trx.c
+++ b/package/system/mtd/src/trx.c
@@ -152,6 +152,7 @@ mtd_fixtrx(const char *mtd, size_t offset)
 {
 	int fd;
 	struct trx_header *trx;
+	char *first_block;
 	char *buf;
 	ssize_t res;
 	size_t block_offset;
@@ -173,19 +174,19 @@ mtd_fixtrx(const char *mtd, size_t offset)
 		exit(1);
 	}
 
-	buf = malloc(erasesize);
-	if (!buf) {
+	first_block = malloc(erasesize);
+	if (!first_block) {
 		perror("malloc");
 		exit(1);
 	}
 
-	res = pread(fd, buf, erasesize, block_offset);
+	res = pread(fd, first_block, erasesize, block_offset);
 	if (res != erasesize) {
 		perror("pread");
 		exit(1);
 	}
 
-	trx = (struct trx_header *) (buf + offset);
+	trx = (struct trx_header *)(first_block + offset);
 	if (trx->magic != STORE32_LE(0x30524448)) {
 		fprintf(stderr, "No trx magic found\n");
 		exit(1);
@@ -198,6 +199,18 @@ mtd_fixtrx(const char *mtd, size_t offset)
 		return 0;
 	}
 
+	buf = malloc(erasesize);
+	if (!buf) {
+		perror("malloc");
+		exit(1);
+	}
+
+	res = pread(fd, buf, erasesize, block_offset);
+	if (res != erasesize) {
+		perror("pread");
+		exit(1);
+	}
+
 	trx->len = STORE32_LE(erasesize - offset);
 
 	trx->crc32 = STORE32_LE(crc32buf((char*) &trx->flag_version, erasesize - offset - 3*4));
@@ -209,7 +222,7 @@ mtd_fixtrx(const char *mtd, size_t offset)
 	if (quiet < 2)
 		fprintf(stderr, "New crc32: 0x%x, rewriting block\n", trx->crc32);
 
-	if (pwrite(fd, buf, erasesize, block_offset) != erasesize) {
+	if (pwrite(fd, first_block, erasesize, block_offset) != erasesize) {
 		fprintf(stderr, "Error writing block (%s)\n", strerror(errno));
 		exit(1);
 	}
-- 
2.30.2