From 30b4b7ee0961033ef4b25215c38fd5aa8af459bd Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Wed, 15 May 2019 22:37:25 +0200 Subject: [PATCH] mtd: Make fixwrgg command work on DIR-685 The D-Link DIR-685 has the same problem as the D-Link DAP-2695: when flashing the factory image, the checksum includes the whole flashed image, even the rootfs_data part with the end of filesystem mark. Also the whole flashed image is stored in the flash, so on the first boot, the whole rootfs image is loaded into memory with the kernel. This is fixed using the fixwrgg command to mtd, but for this to work we need to make fixwrgg work with the Little-Endian ARM DIR-685. The code tries to be endian agnostic but this fails because the WRGG image loader doesn't. On ARM, the file size is stored in little endian format, and on big-endian systems it is stored in big endian format, so we can just drop all the friendly htonl() that will make the shdr->size big endian: this will actually break the little endian systems, and on the big endian systems the native endianness will still be correct. The magic number is always stored in little endian format however, so make sure this is always read in LE32 format. I chose to create a straight-forward le32_to_cpu() static inline that IMO is simple and easy to read. Cc: Stijn Tintel Signed-off-by: Linus Walleij --- package/system/mtd/src/wrgg.c | 27 +++++++++++++-------------- 1 file changed, 13 insertions(+), 14 deletions(-) diff --git a/package/system/mtd/src/wrgg.c b/package/system/mtd/src/wrgg.c index e0b5ca172d..c62f9f5507 100644 --- a/package/system/mtd/src/wrgg.c +++ b/package/system/mtd/src/wrgg.c @@ -39,13 +39,10 @@ #include "wrgg.h" #include "md5.h" -#if __BYTE_ORDER == __BIG_ENDIAN -#define STORE32_LE(X) ((((X) & 0x000000FF) << 24) | (((X) & 0x0000FF00) << 8) | (((X) & 0x00FF0000) >> 8) | (((X) & 0xFF000000) >> 24)) -#elif __BYTE_ORDER == __LITTLE_ENDIAN -#define STORE32_LE(X) (X) -#else -#error unknown endianness! -#endif +static inline uint32_t le32_to_cpu(uint8_t *buf) +{ + return buf[0] | buf[1] << 8 | buf[2] << 16 | buf[3] << 24; +} ssize_t pread(int fd, void *buf, size_t count, off_t offset); ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset); @@ -94,7 +91,7 @@ wrgg_fix_md5(struct wrgg03_header *shdr, int fd, size_t data_offset, size_t data } /* update the size in the image */ - shdr->size = htonl(data_size); + shdr->size = data_size; /* update the checksum in the image */ memcpy(shdr->digest, digest, sizeof(digest)); @@ -147,12 +144,14 @@ mtd_fixwrgg(const char *mtd, size_t offset, size_t data_size) } shdr = (struct wrgg03_header *)(first_block + offset); - if (shdr->magic1 != htonl(STORE32_LE(WRGG03_MAGIC))) { - fprintf(stderr, "magic1 %x\n", shdr->magic1); - fprintf(stderr, "htonl(WRGG03_MAGIC) %x\n", WRGG03_MAGIC); + + /* The magic is always stored in little-endian byte order */ + if (le32_to_cpu((uint8_t *)&shdr->magic1) != WRGG03_MAGIC) { + fprintf(stderr, "magic1 = %x\n", shdr->magic1); + fprintf(stderr, "WRGG03_MAGIC = %x\n", WRGG03_MAGIC); fprintf(stderr, "No WRGG header found\n"); exit(1); - } else if (!ntohl(shdr->size)) { + } else if (!shdr->size) { fprintf(stderr, "WRGG entity with empty image\n"); exit(1); } @@ -160,8 +159,8 @@ mtd_fixwrgg(const char *mtd, size_t offset, size_t data_size) data_offset = offset + sizeof(struct wrgg03_header); if (!data_size) data_size = mtdsize - data_offset; - if (data_size > ntohl(shdr->size)) - data_size = ntohl(shdr->size); + if (data_size > shdr->size) + data_size = shdr->size; if (wrgg_fix_md5(shdr, fd, data_offset, data_size)) goto out; -- 2.30.2