From f813a693fd5e07c60c042a0b11ae8e15144fc960 Mon Sep 17 00:00:00 2001
From: Jo-Philipp Wich <jow@openwrt.org>
Date: Mon, 19 Jul 2010 22:20:07 +0000
Subject: nvram: handle nvram at varying offsets within the eraseblock (fixes
 Edimax PS-1208mfg with FLSH at offset 0)

SVN-Revision: 22299
---
 package/nvram/Makefile    |  2 +-
 package/nvram/src/cli.c   |  1 +
 package/nvram/src/nvram.c | 21 ++++++++++++++++++---
 package/nvram/src/nvram.h |  4 ++--
 4 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/package/nvram/Makefile b/package/nvram/Makefile
index c47f1c7bbb..7fc9cc8a41 100644
--- a/package/nvram/Makefile
+++ b/package/nvram/Makefile
@@ -8,7 +8,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=nvram
-PKG_RELEASE:=7
+PKG_RELEASE:=8
 
 PKG_BUILD_DIR := $(BUILD_DIR)/$(PKG_NAME)
 
diff --git a/package/nvram/src/cli.c b/package/nvram/src/cli.c
index 44d4b88fde..66ef904885 100644
--- a/package/nvram/src/cli.c
+++ b/package/nvram/src/cli.c
@@ -111,6 +111,7 @@ static int do_info(nvram_handle_t *nvram)
 	/* Show info */
 	printf("Magic:         0x%08X\n",   hdr->magic);
 	printf("Length:        0x%08X\n",   hdr->len);
+	printf("Offset:        0x%08X\n",   nvram->offset);
 
 	printf("CRC8:          0x%02X (calculated: 0x%02X)\n",
 		hdr->crc_ver_init & 0xFF, crc);
diff --git a/package/nvram/src/nvram.c b/package/nvram/src/nvram.c
index 7ab8c81ab0..a0bc006d15 100644
--- a/package/nvram/src/nvram.c
+++ b/package/nvram/src/nvram.c
@@ -142,7 +142,7 @@ static int _nvram_rehash(nvram_handle_t *h)
 /* Get nvram header. */
 nvram_header_t * nvram_header(nvram_handle_t *h)
 {
-	return (nvram_header_t *) &h->mmap[NVRAM_START(nvram_erase_size)];
+	return (nvram_header_t *) &h->mmap[h->offset];
 }
 
 /* Get the value of an NVRAM variable. */
@@ -337,10 +337,12 @@ int nvram_commit(nvram_handle_t *h)
 /* Open NVRAM and obtain a handle. */
 nvram_handle_t * nvram_open(const char *file, int rdonly)
 {
+	int i;
 	int fd;
 	char *mtd = NULL;
 	nvram_handle_t *h;
 	nvram_header_t *header;
+	int offset = -1;
 
 	/* If erase size or file are undefined then try to define them */
 	if( (nvram_erase_size == 0) || (file == NULL) )
@@ -361,15 +363,28 @@ nvram_handle_t * nvram_open(const char *file, int rdonly)
 
 		if( mmap_area != MAP_FAILED )
 		{
-			memset(mmap_area, 0xFF, NVRAM_START(nvram_erase_size));
+			for( i = 0; i <= ((nvram_erase_size - NVRAM_SPACE) / sizeof(uint32_t)); i++ )
+			{
+				if( ((uint32_t *)mmap_area)[i] == NVRAM_MAGIC )
+				{
+					offset = i * sizeof(uint32_t);
+					break;
+				}
+			}
 
-			if((h = (nvram_handle_t *) malloc(sizeof(nvram_handle_t))) != NULL)
+			if( offset < 0 )
+			{
+				free(mtd);
+				return NULL;
+			}
+			else if( (h = malloc(sizeof(nvram_handle_t))) != NULL )
 			{
 				memset(h, 0, sizeof(nvram_handle_t));
 
 				h->fd     = fd;
 				h->mmap   = mmap_area;
 				h->length = nvram_erase_size;
+				h->offset = offset;
 
 				header = nvram_header(h);
 
diff --git a/package/nvram/src/nvram.h b/package/nvram/src/nvram.h
index e3d64613d4..c72f67e9a8 100644
--- a/package/nvram/src/nvram.h
+++ b/package/nvram/src/nvram.h
@@ -46,7 +46,8 @@ struct nvram_tuple {
 struct nvram_handle {
 	int fd;
 	char *mmap;
-	unsigned long length;
+	unsigned int length;
+	unsigned int offset;
 	struct nvram_tuple *nvram_hash[257];
 	struct nvram_tuple *nvram_dead;
 };
@@ -113,7 +114,6 @@ char * nvram_find_staging(void);
 
 /* NVRAM constants */
 #define NVRAM_SPACE			0x8000
-#define NVRAM_START(x)		x - NVRAM_SPACE
 #define NVRAM_MAGIC			0x48534C46	/* 'FLSH' */
 #define NVRAM_VERSION		1
 
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