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