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/* ----------------------------------------------------------------------- *
*
* Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
* Copyright 2009 Intel Corporation; author: H. Peter Anvin
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* syslinux/setadv.c
*
* (Over)write a data item in the auxilliary data vector. To
* delete an item, set its length to zero.
*
* Return 0 on success, -1 on error, and set errno.
*
* NOTE: Data is not written to disk unless
* syslinux_adv_write() is called.
*/
#include <syslinux/adv.h>
#include <klibc/compiler.h>
#include <inttypes.h>
#include <string.h>
#include <errno.h>
#include <alloca.h>
__export int syslinux_setadv(int tag, size_t size, const void *data)
{
uint8_t *p, *advtmp;
size_t rleft, left;
if ((unsigned)tag - 1 > 254) {
errno = EINVAL;
return -1; /* Impossible tag value */
}
if (size > 255) {
errno = ENOSPC; /* Max 255 bytes for a data item */
return -1;
}
rleft = left = syslinux_adv_size();
p = advtmp = alloca(left);
memcpy(p, syslinux_adv_ptr(), left); /* Make working copy */
while (rleft >= 2) {
uint8_t ptag = p[0];
size_t plen = p[1] + 2;
if (ptag == ADV_END)
break;
if (ptag == tag) {
/* Found our tag. Delete it. */
if (plen >= rleft) {
/* Entire remainder is our tag */
break;
}
memmove(p, p + plen, rleft - plen);
rleft -= plen; /* Fewer bytes to read, but not to write */
} else {
/* Not our tag */
if (plen > rleft)
break; /* Corrupt tag (overrun) - overwrite it */
left -= plen;
rleft -= plen;
p += plen;
}
}
/* Now (p, left) reflects the position to write in and how much space
we have for our data. */
if (size) {
if (left < size + 2) {
errno = ENOSPC; /* Not enough space for data */
return -1;
}
*p++ = tag;
*p++ = size;
memcpy(p, data, size);
p += size;
left -= size + 2;
}
memset(p, 0, left);
/* If we got here, everything went OK, commit the write to low memory */
memcpy(syslinux_adv_ptr(), advtmp, syslinux_adv_size());
return 0;
}
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