diff options
Diffstat (limited to 'contrib/syslinux-4.02/libinstaller/setadv.c')
| -rw-r--r-- | contrib/syslinux-4.02/libinstaller/setadv.c | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/libinstaller/setadv.c b/contrib/syslinux-4.02/libinstaller/setadv.c new file mode 100644 index 0000000..9cf6f18 --- /dev/null +++ b/contrib/syslinux-4.02/libinstaller/setadv.c @@ -0,0 +1,167 @@ +/* ----------------------------------------------------------------------- * + * + * Copyright 2007-2008 H. Peter Anvin - All Rights Reserved + * Copyright 2010 Intel Corporation; author: H. Peter Anvin + * + * 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, Inc., 53 Temple Place Ste 330, + * Boston MA 02111-1307, USA; either version 2 of the License, or + * (at your option) any later version; incorporated herein by reference. + * + * ----------------------------------------------------------------------- */ + +/* + * 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. + * + */ +#define _GNU_SOURCE + +#include <stdio.h> +#include <stdlib.h> +#include <stddef.h> +#include <stdint.h> +#include <string.h> +#include <errno.h> +#include "syslxint.h" +#include "syslxcom.h" + +unsigned char syslinux_adv[2 * ADV_SIZE]; + +#define ADV_MAGIC1 0x5a2d2fa5 /* Head signature */ +#define ADV_MAGIC2 0xa3041767 /* Total checksum */ +#define ADV_MAGIC3 0xdd28bf64 /* Tail signature */ + +static void cleanup_adv(unsigned char *advbuf) +{ + int i; + uint32_t csum; + + /* Make sure both copies agree, and update the checksum */ + set_32((uint32_t *) advbuf, ADV_MAGIC1); + + csum = ADV_MAGIC2; + for (i = 8; i < ADV_SIZE - 4; i += 4) + csum -= get_32((uint32_t *) (advbuf + i)); + + set_32((uint32_t *) (advbuf + 4), csum); + set_32((uint32_t *) (advbuf + ADV_SIZE - 4), ADV_MAGIC3); + + memcpy(advbuf + ADV_SIZE, advbuf, ADV_SIZE); +} + +int syslinux_setadv(int tag, size_t size, const void *data) +{ + uint8_t *p; + size_t left; + uint8_t advtmp[ADV_SIZE]; + + 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; + } + + left = ADV_LEN; + p = advtmp; + memcpy(p, syslinux_adv + 2 * 4, left); /* Make working copy */ + + while (left >= 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 >= left) { + /* Entire remainder is our tag */ + break; + } + memmove(p, p + plen, left - plen); + } else { + /* Not our tag */ + if (plen > left) + break; /* Corrupt tag (overrun) - overwrite it */ + + left -= 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 */ + memcpy(syslinux_adv + 2 * 4, advtmp, ADV_LEN); + cleanup_adv(syslinux_adv); + + return 0; +} + +void syslinux_reset_adv(unsigned char *advbuf) +{ + /* Create an all-zero ADV */ + memset(advbuf + 2 * 4, 0, ADV_LEN); + cleanup_adv(advbuf); +} + +static int adv_consistent(const unsigned char *p) +{ + int i; + uint32_t csum; + + if (get_32((uint32_t *) p) != ADV_MAGIC1 || + get_32((uint32_t *) (p + ADV_SIZE - 4)) != ADV_MAGIC3) + return 0; + + csum = 0; + for (i = 4; i < ADV_SIZE - 4; i += 4) + csum += get_32((uint32_t *) (p + i)); + + return csum == ADV_MAGIC2; +} + +/* + * Verify that an in-memory ADV is consistent, making the copies consistent. + * If neither copy is OK, return -1 and call syslinux_reset_adv(). + */ +int syslinux_validate_adv(unsigned char *advbuf) +{ + if (adv_consistent(advbuf + 0 * ADV_SIZE)) { + memcpy(advbuf + ADV_SIZE, advbuf, ADV_SIZE); + return 0; + } else if (adv_consistent(advbuf + 1 * ADV_SIZE)) { + memcpy(advbuf, advbuf + ADV_SIZE, ADV_SIZE); + return 0; + } else { + syslinux_reset_adv(advbuf); + return -1; + } +} |