tools/env: allow negative offsets
A negative value for the offset is treated as a backwards offset for
from the end of the device/partition for block devices. This aligns
the behavior of the config file with the syntax of CONFIG_ENV_OFFSET
where the functionality has been introduced with
commit 5c088ee841f9 ("env_mmc: allow negative CONFIG_ENV_OFFSET").
Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c
index 06d6865..be338a5b 100644
--- a/tools/env/fw_env.c
+++ b/tools/env/fw_env.c
@@ -14,6 +14,7 @@
#include <errno.h>
#include <env_flags.h>
#include <fcntl.h>
+#include <linux/fs.h>
#include <linux/stringify.h>
#include <ctype.h>
#include <stdio.h>
@@ -51,7 +52,7 @@
struct envdev_s {
const char *devname; /* Device name */
- ulong devoff; /* Device offset */
+ long long devoff; /* Device offset */
ulong env_size; /* environment size */
ulong erase_size; /* device erase size */
ulong env_sectors; /* number of environment sectors */
@@ -994,7 +995,7 @@
}
#ifdef DEBUG
- fprintf(stderr, "Writing new environment at 0x%lx on %s\n",
+ fprintf(stderr, "Writing new environment at 0x%llx on %s\n",
DEVOFFSET (dev_target), DEVNAME (dev_target));
#endif
@@ -1010,7 +1011,7 @@
offsetof (struct env_image_redundant, flags);
#ifdef DEBUG
fprintf(stderr,
- "Setting obsolete flag in environment at 0x%lx on %s\n",
+ "Setting obsolete flag in environment at 0x%llx on %s\n",
DEVOFFSET (dev_current), DEVNAME (dev_current));
#endif
flash_flag_obsolete (dev_current, fd_current, offset);
@@ -1335,7 +1336,27 @@
}
DEVTYPE(dev) = mtdinfo.type;
} else {
+ uint64_t size;
DEVTYPE(dev) = MTD_ABSENT;
+
+ /*
+ * Check for negative offsets, treat it as backwards offset
+ * from the end of the block device
+ */
+ if (DEVOFFSET(dev) < 0) {
+ rc = ioctl(fd, BLKGETSIZE64, &size);
+ if (rc < 0) {
+ fprintf(stderr, "Could not get block device size on %s\n",
+ DEVNAME(dev));
+ goto err;
+ }
+
+ DEVOFFSET(dev) = DEVOFFSET(dev) + size;
+#ifdef DEBUG
+ fprintf(stderr, "Calculated device offset 0x%llx on %s\n",
+ DEVOFFSET(dev), DEVNAME(dev));
+#endif
+ }
}
err:
@@ -1434,12 +1455,12 @@
if (dump[0] == '#')
continue;
- rc = sscanf (dump, "%ms %lx %lx %lx %lx",
- &devname,
- &DEVOFFSET (i),
- &ENVSIZE (i),
- &DEVESIZE (i),
- &ENVSECTORS (i));
+ rc = sscanf(dump, "%ms %lli %lx %lx %lx",
+ &devname,
+ &DEVOFFSET(i),
+ &ENVSIZE(i),
+ &DEVESIZE(i),
+ &ENVSECTORS(i));
if (rc < 3)
continue;
diff --git a/tools/env/fw_env.config b/tools/env/fw_env.config
index 776e16f..7916ebd 100644
--- a/tools/env/fw_env.config
+++ b/tools/env/fw_env.config
@@ -4,6 +4,7 @@
# Notice, that the "Number of sectors" is not required on NOR and SPI-dataflash.
# Futhermore, if the Flash sector size is omitted, this value is assumed to
# be the same as the Environment size, which is valid for NOR and SPI-dataflash
+# Device offset must be prefixed with 0x to be parsed as a hexadecimal value.
# NOR example
# MTD device name Device offset Env. size Flash sector size Number of sectors
@@ -18,8 +19,12 @@
# NAND example
#/dev/mtd0 0x4000 0x4000 0x20000 2
+# On a block device a negative offset is treated as a backwards offset from the
+# end of the device/partition, rather than a forwards offset from the start.
+
# Block device example
#/dev/mmcblk0 0xc0000 0x20000
+#/dev/mmcblk0 -0x20000 0x20000
# VFAT example
#/boot/uboot.env 0x0000 0x4000