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/******************************************************************************
* Copyright (c) 2004, 2008 IBM Corporation
* All rights reserved.
* This program and the accompanying materials
* are made available under the terms of the BSD License
* which accompanies this distribution, and is available at
* http://www.opensource.org/licenses/bsd-license.php
*
* Contributors:
* IBM Corporation - initial implementation
*****************************************************************************/
#include <stdint.h>
#include "../libc/include/stdio.h"
#include "../libc/include/string.h"
#include "../libc/include/stdlib.h"
#include "nvram.h"
/* returns the offset of the first byte after the searched envvar */
static int get_past_env_pos(partition_t part, char *envvar, int evlen)
{
int offset, len;
static char temp[256];
uint8_t data;
offset=part.addr;
memset(temp, 0, 256);
do {
len=0;
while((data=nvram_read_byte(offset++)) && len < 256) {
temp[len++]=data;
}
if (!strncmp(envvar, temp, evlen)) {
return offset;
}
} while (len);
return -1;
}
/**
* @param partition name of the envvar partition
* @param envvar name of the environment variable
* @param evlen string length of the envvar parameter
* @return pointer to temporary string containing the value of envvar
*/
char *nvram_get_env(partition_t part, char *envvar, int evlen)
{
static char temp[256+1];
int len, offset;
uint8_t data;
DEBUG("nvram_get_env %p... ", envvar);
if(!part.addr) {
/* ERROR: No environment variable partition */
DEBUG("invalid partition.\n");
return NULL;
}
offset=part.addr;
do {
len=0;
while((data=nvram_read_byte(offset++)) && len < 256) {
temp[len++]=data;
}
temp[len]=0;
if (!strncmp(envvar, temp, evlen)) {
int pos=0;
while (temp[pos]!='=' && pos < len) pos++;
// DEBUG("value='%s'\n", temp+pos+1);
return temp+pos+1;
}
} while (len);
DEBUG("not found\n");
return NULL;
}
static int find_last_envvar(partition_t part)
{
uint8_t last, current;
int offset;
offset=part.addr;
last=nvram_read_byte(part.addr);
for (offset=part.addr; offset<(int)(part.addr+part.len); offset++) {
current=nvram_read_byte(offset);
if(!last && !current)
return offset;
last=current;
}
return -1;
}
int nvram_add_env(partition_t part, char *envvar, int evlen, char *value, int vallen)
{
int freespace, last, len, offset;
unsigned int i;
/* Find offset where we can write */
last = find_last_envvar(part);
/* How much space do we have left? */
freespace = part.addr+part.len-last;
/* how long is the entry we want to write? */
len = evlen + vallen + 2;
if(freespace<len) {
// TODO try to increase partition size
return -1;
}
offset=last;
for (i = 0; i < evlen; i++)
nvram_write_byte(offset++, envvar[i]);
nvram_write_byte(offset++, '=');
for (i = 0; i < vallen; i++)
nvram_write_byte(offset++, value[i]);
return 0;
}
int nvram_del_env(partition_t part, char *envvar, int evlen)
{
int last, current, pos, i;
char *buffer;
if(!part.addr)
return -1;
last=find_last_envvar(part);
current = pos = get_past_env_pos(part, envvar, evlen);
// TODO is this really required?
/* go back to non-0 value */
current--;
while (nvram_read_byte(current))
current--;
// TODO is this required?
current++;
buffer=get_nvram_buffer(last-pos);
for (i=0; i<last-pos; i++)
buffer[i]=nvram_read_byte(i+pos);
for (i=0; i<last-pos; i++)
nvram_write_byte(i+current, buffer[i]);
free_nvram_buffer(buffer);
erase_nvram(last, current+last-pos);
return 0;
}
int nvram_set_env(partition_t part, char *envvar, int evlen, char *value, int vallen)
{
char *oldvalue, *buffer;
int last, current, buffersize, i;
DEBUG("nvram_set_env %lx[%lx]: %p=>%p\n", part.addr, part.len, envvar, value);
if(!part.addr)
return -1;
/* Check whether the environment variable exists already */
oldvalue = nvram_get_env(part, envvar, evlen);
if (oldvalue == NULL)
return nvram_add_env(part, envvar, evlen, value, vallen);
/* The value did not change. So we succeeded! */
if (strlen(oldvalue) == vallen && !strncmp(oldvalue, value, vallen))
return 0;
/* we need to overwrite environment variables, back them up first */
// DEBUG("overwriting existing environment variable\n");
/* allocate a buffer */
last=find_last_envvar(part);
current = get_past_env_pos(part, envvar, evlen);
buffersize = last - current;
buffer=get_nvram_buffer(buffersize);
if(!buffer)
return -1;
for (i=0; i<buffersize; i++) {
buffer[i] = nvram_read_byte(current+i);
}
/* walk back until the = */
while (nvram_read_byte(current)!='=') {
current--;
}
/* Start at envvar= */
current++;
/* Write the new value */
for(i = 0; i < vallen; i++) {
nvram_write_byte(current++, value[i]);
}
/* Write end of string marker */
nvram_write_byte(current++, 0);
/* Copy back the buffer */
for (i=0; i<buffersize; i++) {
nvram_write_byte(current++, buffer[i]);
}
free_nvram_buffer(buffer);
/* If the new environment variable content is shorter than the old one,
* we need to erase the rest of the bytes
*/
if (current<last) {
for(i=current; i<last; i++) {
nvram_write_byte(i, 0);
}
}
return 0; /* success */
}
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