| /* ----------------------------------------------------------------------- * |
| * |
| * 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; |
| } |