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u-boot/include/environment.h
Wolfgang Denk ea882baf9c New implementation for internal handling of environment variables. 
Motivation:

* Old environment code used a pessimizing implementation:
  - variable lookup used linear search => slow
  - changed/added variables were added at the end, i. e. most
    frequently used variables had the slowest access times => slow
  - each setenv() would calculate the CRC32 checksum over the whole
    environment block => slow
* "redundant" envrionment was locked down to two copies
* No easy way to implement features like "reset to factory defaults",
  or to select one out of several pre-defined (previously saved) sets
  of environment settings ("profiles")
* No easy way to import or export environment settings

======================================================================

API Changes:

- Variable names starting with '#' are no longer allowed

  I didn't find any such variable names being used; it is highly
  recommended to follow standard conventions and start variable names
  with an alphanumeric character

- "printenv" will now print a backslash at the end of all but the last
  lines of a multi-line variable value.

  Multi-line variables have never been formally defined, allthough
  there is no reason not to use them. Now we define rules how to deal
  with them, allowing for import and export.

- Function forceenv() and the related code in saveenv() was removed.
  At the moment this is causing build problems for the only user of
  this code (schmoogie - which has no entry in MAINTAINERS); may be
  fixed later by implementing the "env set -f" feature.

Inconsistencies:

- "printenv" will '\\'-escape the '\n' in multi-line variables, while
  "printenv var" will not do that.

======================================================================

Advantages:

- "printenv" output much better readable (sorted)
- faster!
- extendable (additional variable properties can be added)
- new, powerful features like "factory reset" or easy switching
  between several different environment settings ("profiles")

Disadvantages:

- Image size grows by typically 5...7 KiB (might shrink a bit again on
  systems with redundant environment with a following patch series)

======================================================================

Implemented:

- env command with subcommands:

  - env print [arg ...]

    same as "printenv": print environment

  - env set [-f] name [arg ...]

    same as "setenv": set (and delete) environment variables

    ["-f" - force setting even for read-only variables - not
    implemented yet.]

  - end delete [-f] name

    not implemented yet

    ["-f" - force delete even for read-only variables]

  - env save

    same as "saveenv": save environment

  - env export [-t | -b | -c] addr [size]

    export internal representation (hash table) in formats usable for
    persistent storage or processing:

	-t:	export as text format; if size is given, data will be
		padded with '\0' bytes; if not, one terminating '\0'
		will be added (which is included in the "filesize"
		setting so you can for exmple copy this to flash and
		keep the termination).
	-b:	export as binary format (name=value pairs separated by
		'\0', list end marked by double "\0\0")
	-c:	export as checksum protected environment format as
		used for example by "saveenv" command
	addr:	memory address where environment gets stored
	size:	size of output buffer

	With "-c" and size is NOT given, then the export command will
	format the data as currently used for the persistent storage,
	i. e. it will use CONFIG_ENV_SECT_SIZE as output block size and
	prepend a valid CRC32 checksum and, in case of resundant
	environment, a "current" redundancy flag. If size is given, this
	value will be used instead of CONFIG_ENV_SECT_SIZE; again, CRC32
	checksum and redundancy flag will be inserted.

	With "-b" and "-t", always only the real data (including a
	terminating '\0' byte) will be written; here the optional size
	argument will be used to make sure not to overflow the user
	provided buffer; the command will abort if the size is not
	sufficient. Any remainign space will be '\0' padded.

        On successful return, the variable "filesize" will be set.
        Note that filesize includes the trailing/terminating '\0'
        byte(s).

        Usage szenario: create a text snapshot/backup of the current
	settings:

		=> env export -t 100000
		=> era ${backup_addr} +${filesize}
		=> cp.b 100000 ${backup_addr} ${filesize}

	Re-import this snapshot, deleting all other settings:

		=> env import -d -t ${backup_addr}

  - env import [-d] [-t | -b | -c] addr [size]

    import external format (text or binary) into hash table,
    optionally deleting existing values:

	-d:	delete existing environment before importing;
		otherwise overwrite / append to existion definitions
	-t:	assume text format; either "size" must be given or the
		text data must be '\0' terminated
	-b:	assume binary format ('\0' separated, "\0\0" terminated)
	-c:	assume checksum protected environment format
	addr:	memory address to read from
	size:	length of input data; if missing, proper '\0'
		termination is mandatory

  - env default -f

    reset default environment: drop all environment settings and load
    default environment

  - env ask name [message] [size]

    same as "askenv": ask for environment variable

  - env edit name

    same as "editenv": edit environment variable

  - env run

    same as "run": run commands in an environment variable

======================================================================

TODO:

- drop default env as implemented now; provide a text file based
  initialization instead (eventually using several text files to
  incrementally build it from common blocks) and a tool to convert it
  into a binary blob / object file.

- It would be nice if we could add wildcard support for environment
  variables; this is needed for variable name auto-completion,
  but it would also be nice to be able to say "printenv ip*" or
  "printenv *addr*"

- Some boards don't link any more due to the grown code size:
  DU405, canyonlands, sequoia, socrates.

	=> cc: Matthias Fuchs <matthias.fuchs@esd-electronics.com>,
	       Stefan Roese <sr@denx.de>,
	       Heiko Schocher <hs@denx.de>

- Dropping forceenv() causes build problems on schmoogie

	=> cc: Sergey Kubushyn <ksi@koi8.net>

- Build tested on PPC and ARM only; runtime tested with NOR and NAND
  flash only => needs testing!!

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Matthias Fuchs <matthias.fuchs@esd-electronics.com>,
Cc: Stefan Roese <sr@denx.de>,
Cc: Heiko Schocher <hs@denx.de>
Cc: Sergey Kubushyn <ksi@koi8.net>
2010-09-19 19:29:48 +02:00

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/*
* (C) Copyright 2002
* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#ifndef _ENVIRONMENT_H_
#define _ENVIRONMENT_H_ 1
/**************************************************************************
*
* The "environment" is stored as a list of '\0' terminated
* "name=value" strings. The end of the list is marked by a double
* '\0'. New entries are always added at the end. Deleting an entry
* shifts the remaining entries to the front. Replacing an entry is a
* combination of deleting the old value and adding the new one.
*
* The environment is preceeded by a 32 bit CRC over the data part.
*
**************************************************************************
*/
#if defined(CONFIG_ENV_IS_IN_FLASH)
# ifndef CONFIG_ENV_ADDR
# define CONFIG_ENV_ADDR (CONFIG_SYS_FLASH_BASE + CONFIG_ENV_OFFSET)
# endif
# ifndef CONFIG_ENV_OFFSET
# define CONFIG_ENV_OFFSET (CONFIG_ENV_ADDR - CONFIG_SYS_FLASH_BASE)
# endif
# if !defined(CONFIG_ENV_ADDR_REDUND) && defined(CONFIG_ENV_OFFSET_REDUND)
# define CONFIG_ENV_ADDR_REDUND (CONFIG_SYS_FLASH_BASE + CONFIG_ENV_OFFSET_REDUND)
# endif
# if defined(CONFIG_ENV_SECT_SIZE) || defined(CONFIG_ENV_SIZE)
# ifndef CONFIG_ENV_SECT_SIZE
# define CONFIG_ENV_SECT_SIZE CONFIG_ENV_SIZE
# endif
# ifndef CONFIG_ENV_SIZE
# define CONFIG_ENV_SIZE CONFIG_ENV_SECT_SIZE
# endif
# else
# error "Both CONFIG_ENV_SECT_SIZE and CONFIG_ENV_SIZE undefined"
# endif
# if defined(CONFIG_ENV_ADDR_REDUND) && !defined(CONFIG_ENV_SIZE_REDUND)
# define CONFIG_ENV_SIZE_REDUND CONFIG_ENV_SIZE
# endif
# if (CONFIG_ENV_ADDR >= CONFIG_SYS_MONITOR_BASE) && \
(CONFIG_ENV_ADDR+CONFIG_ENV_SIZE) <= (CONFIG_SYS_MONITOR_BASE + CONFIG_SYS_MONITOR_LEN)
# define ENV_IS_EMBEDDED 1
# endif
# if defined(CONFIG_ENV_ADDR_REDUND) || defined(CONFIG_ENV_OFFSET_REDUND)
# define CONFIG_SYS_REDUNDAND_ENVIRONMENT 1
# endif
# ifdef CONFIG_ENV_IS_EMBEDDED
# error "do not define CONFIG_ENV_IS_EMBEDDED in your board config"
# error "it is calculated automatically for you"
# endif
#endif /* CONFIG_ENV_IS_IN_FLASH */
#if defined(CONFIG_ENV_IS_IN_NAND)
# if defined(CONFIG_ENV_OFFSET_OOB)
# ifdef CONFIG_ENV_OFFSET_REDUND
# error "CONFIG_ENV_OFFSET_REDUND is not supported when CONFIG_ENV_OFFSET_OOB"
# error "is set"
# endif
extern unsigned long nand_env_oob_offset;
# define CONFIG_ENV_OFFSET nand_env_oob_offset
# else
# ifndef CONFIG_ENV_OFFSET
# error "Need to define CONFIG_ENV_OFFSET when using CONFIG_ENV_IS_IN_NAND"
# endif
# ifdef CONFIG_ENV_OFFSET_REDUND
# define CONFIG_SYS_REDUNDAND_ENVIRONMENT
# endif
# endif /* CONFIG_ENV_OFFSET_OOB */
# ifndef CONFIG_ENV_SIZE
# error "Need to define CONFIG_ENV_SIZE when using CONFIG_ENV_IS_IN_NAND"
# endif
#endif /* CONFIG_ENV_IS_IN_NAND */
#if defined(CONFIG_ENV_IS_IN_MG_DISK)
# ifndef CONFIG_ENV_ADDR
# error "Need to define CONFIG_ENV_ADDR when using CONFIG_ENV_IS_IN_MG_DISK"
# endif
# ifndef CONFIG_ENV_SIZE
# error "Need to define CONFIG_ENV_SIZE when using CONFIG_ENV_IS_IN_MG_DISK"
# endif
#endif /* CONFIG_ENV_IS_IN_MG_DISK */
/* Embedded env is only supported for some flash types */
#ifdef CONFIG_ENV_IS_EMBEDDED
# if !defined(CONFIG_ENV_IS_IN_FLASH) && \
!defined(CONFIG_ENV_IS_IN_NAND) && \
!defined(CONFIG_ENV_IS_IN_ONENAND)
# error "CONFIG_ENV_IS_EMBEDDED not supported for your flash type"
# endif
#endif
/*
* For the flash types where embedded env is supported, but it cannot be
* calculated automatically (i.e. NAND), take the board opt-in.
*/
#if defined(CONFIG_ENV_IS_EMBEDDED) && !defined(ENV_IS_EMBEDDED)
# define ENV_IS_EMBEDDED 1
#endif
/* The build system likes to know if the env is embedded */
#ifdef DO_DEPS_ONLY
# ifdef ENV_IS_EMBEDDED
# define CONFIG_ENV_IS_EMBEDDED
# endif
#endif
#include "compiler.h"
#ifdef CONFIG_SYS_REDUNDAND_ENVIRONMENT
# define ENV_HEADER_SIZE (sizeof(uint32_t) + 1)
# define ACTIVE_FLAG 1
# define OBSOLETE_FLAG 0
#else
# define ENV_HEADER_SIZE (sizeof(uint32_t))
#endif
#define ENV_SIZE (CONFIG_ENV_SIZE - ENV_HEADER_SIZE)
typedef struct environment_s {
uint32_t crc; /* CRC32 over data bytes */
#ifdef CONFIG_SYS_REDUNDAND_ENVIRONMENT
unsigned char flags; /* active/obsolete flags */
#endif
unsigned char data[ENV_SIZE]; /* Environment data */
} env_t;
/* Function that returns a character from the environment */
unsigned char env_get_char (int);
/* Function that returns a pointer to a value from the environment */
unsigned char *env_get_addr(int);
unsigned char env_get_char_memory (int index);
/* Function that updates CRC of the enironment */
void env_crc_update (void);
/* [re]set to the default environment */
void set_default_env(const char *s);
/* Import from binary representation into hash table */
int env_import(const char *buf, int check);
#endif /* _ENVIRONMENT_H_ */
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