nvram: fix regression in finding NVRAM beginning

The loop was giving up too early as it never expected NVRAM smaller
than 0x10000.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

SVN-Revision: 45578

package/utils/nvram/src/nvram.c

@@ -364,7 +364,12 @@ nvram_handle_t * nvram_open(const char *file, int rdonly)
 
 		if( mmap_area != MAP_FAILED )
 		{
-			for( i = 0; i <= ((nvram_part_size - NVRAM_SPACE) / sizeof(uint32_t)); i++ )
+			/*
+			 * Start looking for NVRAM_MAGIC at beginning of MTD
+			 * partition. Stop if there is less than NVRAM_MIN_SPACE
+			 * to check, that was the lowest used size.
+			 */
+			for( i = 0; i <= ((nvram_part_size - NVRAM_MIN_SPACE) / sizeof(uint32_t)); i++ )
 			{
 				if( ((uint32_t *)mmap_area)[i] == NVRAM_MAGIC )
 				{

package/utils/nvram/src/nvram.h

@@ -113,6 +113,7 @@ char * nvram_find_staging(void);
 #define	NVRAM_ROUNDUP(x, y)	((((x)+((y)-1))/(y))*(y))
 
 /* NVRAM constants */
+#define NVRAM_MIN_SPACE			0x8000
 #define NVRAM_SPACE			0x10000
 #define NVRAM_MAGIC			0x48534C46	/* 'FLSH' */
 #define NVRAM_VERSION		1