fw_env.c

	if (rc < 0)
		return rc;

	if (environment.flag_scheme == FLAG_BOOLEAN) {
		/* Have to set obsolete flag */
		off_t offset = DEVOFFSET (dev_current) +
			offsetof (struct env_image_redundant, flags);
#ifdef DEBUG
		fprintf(stderr,
			"Setting obsolete flag in environment at 0x%lx on %s\n",
			DEVOFFSET (dev_current), DEVNAME (dev_current));
#endif
		flash_flag_obsolete (dev_current, fd_current, offset);
	}

	return 0;
}

static int flash_read (int fd)
{
	struct mtd_info_user mtdinfo;
	struct stat st;
	int rc;

	rc = fstat(fd, &st);
	if (rc < 0) {
		fprintf(stderr, "Cannot stat the file %s\n",
			DEVNAME(dev_current));
		return -1;
	}

	if (S_ISCHR(st.st_mode)) {
		rc = ioctl(fd, MEMGETINFO, &mtdinfo);
		if (rc < 0) {
			fprintf(stderr, "Cannot get MTD information for %s\n",
				DEVNAME(dev_current));
			return -1;
		}
		if (mtdinfo.type != MTD_NORFLASH &&
		    mtdinfo.type != MTD_NANDFLASH &&
		    mtdinfo.type != MTD_DATAFLASH &&
		    mtdinfo.type != MTD_UBIVOLUME) {
			fprintf (stderr, "Unsupported flash type %u on %s\n",
				 mtdinfo.type, DEVNAME(dev_current));
			return -1;
		}
	} else {
		memset(&mtdinfo, 0, sizeof(mtdinfo));
		mtdinfo.type = MTD_ABSENT;
	}

	DEVTYPE(dev_current) = mtdinfo.type;

	rc = flash_read_buf(dev_current, fd, environment.image, CUR_ENVSIZE,
			     DEVOFFSET (dev_current), mtdinfo.type);
	if (rc != CUR_ENVSIZE)
		return -1;

	return 0;
}

static int flash_io (int mode)
{
	int fd_current, fd_target, rc, dev_target;

	/* dev_current: fd_current, erase_current */
	fd_current = open (DEVNAME (dev_current), mode);
	if (fd_current < 0) {
		fprintf (stderr,
			 "Can't open %s: %s\n",
			 DEVNAME (dev_current), strerror (errno));
		return -1;
	}

	if (mode == O_RDWR) {
		if (HaveRedundEnv) {
			/* switch to next partition for writing */
			dev_target = !dev_current;
			/* dev_target: fd_target, erase_target */
			fd_target = open (DEVNAME (dev_target), mode);
			if (fd_target < 0) {
				fprintf (stderr,
					 "Can't open %s: %s\n",
					 DEVNAME (dev_target),
					 strerror (errno));
				rc = -1;
				goto exit;
			}
		} else {
			dev_target = dev_current;
			fd_target = fd_current;
		}

		rc = flash_write (fd_current, fd_target, dev_target);

		if (HaveRedundEnv) {
			if (close (fd_target)) {
				fprintf (stderr,
					"I/O error on %s: %s\n",
					DEVNAME (dev_target),
					strerror (errno));
				rc = -1;
			}
		}
	} else {
		rc = flash_read (fd_current);
	}

exit:
	if (close (fd_current)) {
		fprintf (stderr,
			 "I/O error on %s: %s\n",
			 DEVNAME (dev_current), strerror (errno));
		return -1;
	}

	return rc;
}

/*
 * s1 is either a simple 'name', or a 'name=value' pair.
 * s2 is a 'name=value' pair.
 * If the names match, return the value of s2, else NULL.
 */

static char *envmatch (char * s1, char * s2)
{
	if (s1 == NULL || s2 == NULL)
		return NULL;

	while (*s1 == *s2++)
		if (*s1++ == '=')
			return s2;
	if (*s1 == '\0' && *(s2 - 1) == '=')
		return s2;
	return NULL;
}

/*
 * Prevent confusion if running from erased flash memory
 */
int fw_env_open(void)
{
	int crc0, crc0_ok;
	unsigned char flag0;
	void *addr0;

	int crc1, crc1_ok;
	unsigned char flag1;
	void *addr1;

	int ret;

	struct env_image_single *single;
	struct env_image_redundant *redundant;

	if (parse_config ())		/* should fill envdevices */
		return -1;

	addr0 = calloc(1, CUR_ENVSIZE);
	if (addr0 == NULL) {
		fprintf(stderr,
			"Not enough memory for environment (%ld bytes)\n",
			CUR_ENVSIZE);
		return -1;
	}

	/* read environment from FLASH to local buffer */
	environment.image = addr0;

	if (HaveRedundEnv) {
		redundant = addr0;
		environment.crc		= &redundant->crc;
		environment.flags	= &redundant->flags;
		environment.data	= redundant->data;
	} else {
		single = addr0;
		environment.crc		= &single->crc;
		environment.flags	= NULL;
		environment.data	= single->data;
	}

	dev_current = 0;
	if (flash_io (O_RDONLY))
		return -1;

	crc0 = crc32 (0, (uint8_t *) environment.data, ENV_SIZE);

	if (common_args.aes_flag) {
		ret = env_aes_cbc_crypt(environment.data, 0,
					common_args.aes_key);
		if (ret)
			return ret;
	}

	crc0_ok = (crc0 == *environment.crc);
	if (!HaveRedundEnv) {
		if (!crc0_ok) {
			fprintf (stderr,
				"Warning: Bad CRC, using default environment\n");
			memcpy(environment.data, default_environment, sizeof default_environment);
		}
	} else {
		flag0 = *environment.flags;

		dev_current = 1;
		addr1 = calloc(1, CUR_ENVSIZE);
		if (addr1 == NULL) {
			fprintf(stderr,
				"Not enough memory for environment (%ld bytes)\n",
				CUR_ENVSIZE);
			return -1;
		}
		redundant = addr1;

		/*
		 * have to set environment.image for flash_read(), careful -
		 * other pointers in environment still point inside addr0
		 */
		environment.image = addr1;
		if (flash_io (O_RDONLY))
			return -1;

		/* Check flag scheme compatibility */
		if (DEVTYPE(dev_current) == MTD_NORFLASH &&
		    DEVTYPE(!dev_current) == MTD_NORFLASH) {
			environment.flag_scheme = FLAG_BOOLEAN;
		} else if (DEVTYPE(dev_current) == MTD_NANDFLASH &&
			   DEVTYPE(!dev_current) == MTD_NANDFLASH) {
			environment.flag_scheme = FLAG_INCREMENTAL;
		} else if (DEVTYPE(dev_current) == MTD_DATAFLASH &&
			   DEVTYPE(!dev_current) == MTD_DATAFLASH) {
			environment.flag_scheme = FLAG_BOOLEAN;
		} else if (DEVTYPE(dev_current) == MTD_UBIVOLUME &&
			   DEVTYPE(!dev_current) == MTD_UBIVOLUME) {
			environment.flag_scheme = FLAG_INCREMENTAL;
		} else if (DEVTYPE(dev_current) == MTD_ABSENT &&
			   DEVTYPE(!dev_current) == MTD_ABSENT) {
			environment.flag_scheme = FLAG_INCREMENTAL;
		} else {
			fprintf (stderr, "Incompatible flash types!\n");
			return -1;
		}

		crc1 = crc32 (0, (uint8_t *) redundant->data, ENV_SIZE);

		if (common_args.aes_flag) {
			ret = env_aes_cbc_crypt(redundant->data, 0,
						common_args.aes_key);
			if (ret)
				return ret;
		}

		crc1_ok = (crc1 == redundant->crc);
		flag1 = redundant->flags;

		if (crc0_ok && !crc1_ok) {
			dev_current = 0;
		} else if (!crc0_ok && crc1_ok) {
			dev_current = 1;
		} else if (!crc0_ok && !crc1_ok) {
			fprintf (stderr,
				"Warning: Bad CRC, using default environment\n");
			memcpy (environment.data, default_environment,
				sizeof default_environment);
			dev_current = 0;
		} else {
			switch (environment.flag_scheme) {
			case FLAG_BOOLEAN:
				if (flag0 == active_flag &&
				    flag1 == obsolete_flag) {
					dev_current = 0;
				} else if (flag0 == obsolete_flag &&
					   flag1 == active_flag) {
					dev_current = 1;
				} else if (flag0 == flag1) {
					dev_current = 0;
				} else if (flag0 == 0xFF) {
					dev_current = 0;
				} else if (flag1 == 0xFF) {
					dev_current = 1;
				} else {
					dev_current = 0;
				}
				break;
			case FLAG_INCREMENTAL:
				if (flag0 == 255 && flag1 == 0)
					dev_current = 1;
				else if ((flag1 == 255 && flag0 == 0) ||
					 flag0 >= flag1)
					dev_current = 0;
				else /* flag1 > flag0 */
					dev_current = 1;
				break;
			default:
				fprintf (stderr, "Unknown flag scheme %u \n",
					 environment.flag_scheme);
				return -1;
			}
		}

		/*
		 * If we are reading, we don't need the flag and the CRC any
		 * more, if we are writing, we will re-calculate CRC and update
		 * flags before writing out
		 */
		if (dev_current) {
			environment.image	= addr1;
			environment.crc		= &redundant->crc;
			environment.flags	= &redundant->flags;
			environment.data	= redundant->data;
			free (addr0);
		} else {
			environment.image	= addr0;
			/* Other pointers are already set */
			free (addr1);
		}
#ifdef DEBUG
		fprintf(stderr, "Selected env in %s\n", DEVNAME(dev_current));
#endif
	}
	return 0;
}


static int parse_config ()
{
	struct stat st;

#if defined(CONFIG_FILE)
	if (!common_args.config_file)
		common_args.config_file = CONFIG_FILE;

	/* Fills in DEVNAME(), ENVSIZE(), DEVESIZE(). Or don't. */
	if (get_config(common_args.config_file)) {
		fprintf(stderr, "Cannot parse config file '%s': %m\n",
			common_args.config_file);
		return -1;
	}
#else
	DEVNAME (0) = DEVICE1_NAME;
	DEVOFFSET (0) = DEVICE1_OFFSET;
	ENVSIZE (0) = ENV1_SIZE;
	/* Default values are: erase-size=env-size */
	DEVESIZE (0) = ENVSIZE (0);
	/* #sectors=env-size/erase-size (rounded up) */
	ENVSECTORS (0) = (ENVSIZE(0) + DEVESIZE(0) - 1) / DEVESIZE(0);
#ifdef DEVICE1_ESIZE
	DEVESIZE (0) = DEVICE1_ESIZE;
#endif
#ifdef DEVICE1_ENVSECTORS
	ENVSECTORS (0) = DEVICE1_ENVSECTORS;
#endif

#ifdef HAVE_REDUND
	DEVNAME (1) = DEVICE2_NAME;
	DEVOFFSET (1) = DEVICE2_OFFSET;
	ENVSIZE (1) = ENV2_SIZE;
	/* Default values are: erase-size=env-size */
	DEVESIZE (1) = ENVSIZE (1);
	/* #sectors=env-size/erase-size (rounded up) */
	ENVSECTORS (1) = (ENVSIZE(1) + DEVESIZE(1) - 1) / DEVESIZE(1);
#ifdef DEVICE2_ESIZE
	DEVESIZE (1) = DEVICE2_ESIZE;
#endif
#ifdef DEVICE2_ENVSECTORS
	ENVSECTORS (1) = DEVICE2_ENVSECTORS;
#endif
	HaveRedundEnv = 1;
#endif
#endif
	if (stat (DEVNAME (0), &st)) {
		fprintf (stderr,
			"Cannot access MTD device %s: %s\n",
			DEVNAME (0), strerror (errno));
		return -1;
	}

	if (HaveRedundEnv && stat (DEVNAME (1), &st)) {
		fprintf (stderr,
			"Cannot access MTD device %s: %s\n",
			DEVNAME (1), strerror (errno));
		return -1;
	}
	return 0;
}

#if defined(CONFIG_FILE)
static int get_config (char *fname)
{
	FILE *fp;
	int i = 0;
	int rc;
	char dump[128];
	char *devname;

	fp = fopen (fname, "r");
	if (fp == NULL)
		return -1;

	while (i < 2 && fgets (dump, sizeof (dump), fp)) {
		/* Skip incomplete conversions and comment strings */
		if (dump[0] == '#')
			continue;

		rc = sscanf (dump, "%ms %lx %lx %lx %lx",
			     &devname,
			     &DEVOFFSET (i),
			     &ENVSIZE (i),
			     &DEVESIZE (i),
			     &ENVSECTORS (i));

		if (rc < 3)
			continue;

		DEVNAME(i) = devname;

		if (rc < 4)
			/* Assume the erase size is the same as the env-size */
			DEVESIZE(i) = ENVSIZE(i);

		if (rc < 5)
			/* Assume enough env sectors to cover the environment */
			ENVSECTORS (i) = (ENVSIZE(i) + DEVESIZE(i) - 1) / DEVESIZE(i);

		i++;
	}
	fclose (fp);

	HaveRedundEnv = i - 1;
	if (!i) {			/* No valid entries found */
		errno = EINVAL;
		return -1;
	} else
		return 0;
}
#endif