Introduced internal pseudo-random generators iso_random_uuid() and
iso_random_8byte().
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3e2479c095
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1ed3ba7933
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@ -23,17 +23,6 @@
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/* for gettimeofday() */
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#include <sys/time.h>
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/* >>> ISOHYBRID : Need ./configure test for uuid_generate() which checks for:
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uuid_t, uuid_generate, the need for -luuid
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*/
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/* <<<
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#define Libisofs_with_uuid_generatE 1
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*/
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#ifdef Libisofs_with_uuid_generatE
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#include <uuid/uuid.h>
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#endif
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#include "filesrc.h"
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#include "ecma119.h"
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#include "eltorito.h"
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@ -455,106 +444,6 @@ static int insert_apm_head(uint8_t *buf, int apm_count)
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}
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#ifdef Libisofs_with_uuid_generatE
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static void swap_uuid(void *u_pt)
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{
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uint8_t tr, *u;
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u = (uint8_t *) u_pt;
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tr = u[0]; u[0] = u[3]; u[3] = tr;
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tr = u[1]; u[1] = u[2]; u[2] = tr;
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tr = u[4]; u[4] = u[5]; u[5] = tr;
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tr = u[6]; u[6] = u[7]; u[7] = tr;
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}
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#endif /* Libisofs_with_uuid_generatE */
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/* CRC-32 as of GPT and Ethernet.
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Parameters are deduced from a table driven implementation in isohybrid.c
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*/
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static unsigned int crc32_gpt(unsigned char *data, int count, int flag)
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{
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unsigned int acc, top, result = 0;
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long int i;
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/* Chosen so that the CRC of 0 bytes of input is 0x00000000 */
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acc = 0x46af6449;
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/* Process data bits and flush numerator by 32 zero bits */
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for (i = 0; i < count * 8 + 32; i++) {
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top = acc & 0x80000000;
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acc = (acc << 1);
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if (i < count * 8)
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/* The least significant bits of input bytes get processed first */
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acc |= ((data[i / 8] >> (i % 8)) & 1);
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if (top)
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/* Division by the generating polynomial */
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acc ^= 0x04c11db7;
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}
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/* Mirror residue bits */
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for (i = 0; i < 32; i++)
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if (acc & (1 << i))
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result |= 1 << (31 - i);
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/* Return bit complement */
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return result ^ 0xffffffff;
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}
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static void random_uuid(Ecma119Image *t, uint8_t *uuid)
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{
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#ifdef Libisofs_with_uuid_generatE
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uuid_t u;
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#else
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uint8_t u[16];
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/* produced by uuidgen(1) by Andreas Dilger */
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static uint8_t uuid_template[16] = {
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0x6e, 0xf5, 0xa3, 0x8b, 0xcb, 0xfa, 0xdd, 0x4e,
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0x36, 0x9f, 0x0b, 0x12, 0x51, 0xc3, 0x7d, 0x1a
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};
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uint32_t rnd, salt;
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struct timeval tv;
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struct timezone tz;
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static int counter = 0;
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int i;
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#endif
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#ifdef Libisofs_with_uuid_generatE
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uuid_generate(u);
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swap_uuid((void *) u);
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memcpy(wpt, u, 16);
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#else
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salt = crc32_gpt((unsigned char *) t, sizeof(Ecma119Image), 0);
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/* This relies on the uniqueness of the template and the rareness of
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bootable ISO image production via libisofs. Estimated 53 bits of
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entropy should influence the production of a single day.
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So first collisions are to be expected with about 100 million images
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per day.
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*/
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memcpy(u, uuid_template, 16);
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gettimeofday(&tv, &tz);
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for (i = 0; i < 4; i++)
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u[3 + i] = (salt >> (8 * i)) & 0xff;
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u[8] = (salt >> 8) & 0xff;
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rnd = ((0xffffffffff & tv.tv_sec) << 8) |
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(((tv.tv_usec >> 16) ^ (salt & 0xf0)) & 0xff);
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u[9] ^= counter & 0xff;
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for (i = 0; i < 4; i++)
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u[10 + i] ^= (rnd >> (8 * i)) & 0xff;
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u[14] ^= (tv.tv_usec >> 8) & 0xff;
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u[15] ^= tv.tv_usec & 0xff;
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counter++;
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#endif /* ! Libisofs_with_uuid_generatE */
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}
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/* Describe the first three GPT boot images as MBR partitions */
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static int gpt_images_as_mbr_partitions(Ecma119Image *t, char *wpt,
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int gpt_idx[128], int *gpt_cursor)
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@ -598,7 +487,7 @@ static void write_gpt_entry(Ecma119Image *t, char *buf, uint8_t type_guid[16],
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memcpy(wpt, type_guid, 16);
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wpt += 16;
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random_uuid(t, (uint8_t *) wpt);
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iso_random_uuid(t, (uint8_t *) wpt);
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wpt += 16;
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lsb_to_buf(&wpt, start_lba & 0xffffffff, 32, 0);
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lsb_to_buf(&wpt, (start_lba >> 32) & 0xffffffff, 32, 0);
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@ -692,7 +581,7 @@ static int write_gpt_header_block(Ecma119Image *t, char *buf,
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lsb_to_buf(&wpt, (uint32_t) ((back_lba - 32) >> 32), 32, 1);
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/* Disk GUID */
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random_uuid(t, (uint8_t *) wpt);
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iso_random_uuid(t, (uint8_t *) wpt);
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wpt += 16;
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/* Partition entries start */
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@ -720,7 +609,7 @@ static int write_gpt_header_block(Ecma119Image *t, char *buf,
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/* CRC-32 of this header while head_crc is 0 */
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wpt = buf + 16;
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crc = crc32_gpt((unsigned char *) buf, wpt - buf, 0);
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crc = iso_crc32_gpt((unsigned char *) buf, wpt - buf, 0);
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lsb_to_buf(&wpt, crc, 32, 0);
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return ISO_SUCCESS;
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@ -27,6 +27,19 @@
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#include <sys/stat.h>
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#include <unistd.h>
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/* for gettimeofday() */
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#include <sys/time.h>
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/* >>> Need ./configure test for uuid_generate() which checks for:
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uuid_t, uuid_generate, the need for -luuid
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*/
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/*
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#define Libisofs_with_uuid_generatE 1
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*/
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#ifdef Libisofs_with_uuid_generatE
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#include <uuid/uuid.h>
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#endif
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/*
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* Create a MBR for an isohybrid enabled ISOLINUX boot image.
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@ -834,7 +847,8 @@ static int iso_write_apm(Ecma119Image *t, uint32_t img_blocks, uint8_t *buf)
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}
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if (part_end > goal) {
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/* >>> Overlapping partition. ??? Warn ??? Bail out ??? */;
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/* >>> Overlapping partition. */;
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/* >>> Vladimir: "Throw error." */;
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}
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if (part_end < goal) {
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@ -924,14 +938,6 @@ int iso_write_system_area(Ecma119Image *t, uint8_t *buf)
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Note that Block0 of the APM is not written but is in the responsibility
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of the MBR template. Its block size MUST match t->apm_block_size.
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>>> ts B20526
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>>> ??? Shall i check t->system_area_data whether there are the first
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>>> ??? four bytes of a Block0 and what block size they announce ?
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>>> pro: That would prevent cruel mishaps
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>>> con: t->system_area_data is totally opaque up to now.
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>>> I cannot easily predict whether the first bytes get altered
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>>> in the course of processing.
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>>> ts B20526
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>>> This does not care for eventual image enlargements in last minute.
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>>> A sa_type, that does this, will have to adjust the last APM entry
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@ -1170,3 +1176,123 @@ int iso_register_apm_entry(Ecma119Image *t,
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return ISO_SUCCESS;
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}
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#ifdef Libisofs_with_uuid_generatE
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static void swap_uuid(void *u_pt)
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{
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uint8_t tr, *u;
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u = (uint8_t *) u_pt;
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tr = u[0]; u[0] = u[3]; u[3] = tr;
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tr = u[1]; u[1] = u[2]; u[2] = tr;
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tr = u[4]; u[4] = u[5]; u[5] = tr;
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tr = u[6]; u[6] = u[7]; u[7] = tr;
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}
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#endif /* Libisofs_with_uuid_generatE */
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/* CRC-32 as of GPT and Ethernet.
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Parameters are deduced from a table driven implementation in isohybrid.c
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*/
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unsigned int iso_crc32_gpt(unsigned char *data, int count, int flag)
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{
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unsigned int acc, top, result = 0;
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long int i;
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/* Chosen so that the CRC of 0 bytes of input is 0x00000000 */
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acc = 0x46af6449;
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/* Process data bits and flush numerator by 32 zero bits */
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for (i = 0; i < count * 8 + 32; i++) {
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top = acc & 0x80000000;
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acc = (acc << 1);
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if (i < count * 8)
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/* The least significant bits of input bytes get processed first */
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acc |= ((data[i / 8] >> (i % 8)) & 1);
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if (top)
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/* Division by the generating polynomial */
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acc ^= 0x04c11db7;
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}
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/* Mirror residue bits */
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for (i = 0; i < 32; i++)
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if (acc & (1 << i))
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result |= 1 << (31 - i);
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/* Return bit complement */
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return result ^ 0xffffffff;
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}
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void iso_random_uuid(Ecma119Image *t, uint8_t uuid[16])
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{
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#ifdef Libisofs_with_uuid_generatE
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uuid_t u;
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#else
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uint8_t u[16];
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/* produced by uuid_generate() and byte-swapped to isohybrid.c habits */
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static uint8_t uuid_template[16] = {
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0xee, 0x29, 0x9d, 0xfc, 0x65, 0xcc, 0x7c, 0x40,
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0x92, 0x61, 0x5b, 0xcd, 0x6f, 0xed, 0x08, 0x34
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};
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uint32_t rnd, salt;
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struct timeval tv;
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struct timezone tz;
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pid_t pid;
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static int counter = 0;
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int i;
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#endif
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#ifdef Libisofs_with_uuid_generatE
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uuid_generate(u);
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swap_uuid((void *) u);
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memcpy(uuid, u, 16);
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#else
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salt = iso_crc32_gpt((unsigned char *) t, sizeof(Ecma119Image), 0);
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salt ^= getpid();
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/* This relies on the uniqueness of the template and the rareness of
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bootable ISO image production via libisofs. Estimated 53 bits of
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entropy should influence the production of a single day.
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So first collisions are to be expected with about 100 million images
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per day.
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*/
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memcpy(u, uuid_template, 16);
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gettimeofday(&tv, &tz);
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for (i = 0; i < 4; i++)
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u[i] = (salt >> (8 * i)) & 0xff;
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for (i = 0; i < 2; i++)
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u[4 + i] = (pid >> (8 * i)) & 0xff;
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u[6] = ((salt >> 8) | (pid >> 16)) & 0xff;
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rnd = ((0xffffffffff & tv.tv_sec) << 8) |
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(((tv.tv_usec >> 16) ^ (salt & 0xf0)) & 0xff);
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u[9] ^= counter & 0xff;
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for (i = 0; i < 4; i++)
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u[10 + i] ^= (rnd >> (8 * i)) & 0xff;
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u[14] ^= (tv.tv_usec >> 8) & 0xff;
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u[15] ^= tv.tv_usec & 0xff;
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counter++;
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memcpy(uuid, u, 16);
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#endif /* ! Libisofs_with_uuid_generatE */
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}
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void iso_random_8byte(Ecma119Image *t, uint8_t result[8])
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{
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uint8_t uuid[16];
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int i;
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iso_random_uuid(t, uuid);
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for (i = 0; i < 8; i++) {
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if (i == 1)
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result[i] = uuid[9]; /* The intra-process counter */
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else
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result[i] = uuid[i] ^ uuid[i + 8];
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}
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}
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@ -103,4 +103,27 @@ int iso_quick_apm_entry(Ecma119Image *t,
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uint32_t start_block, uint32_t block_count, char *name, char *type);
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/* CRC-32 as of GPT and Ethernet.
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*/
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unsigned int iso_crc32_gpt(unsigned char *data, int count, int flag);
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/* These two pseudo-random generators produce byte strings which will
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surely not duplicate in the first 256 calls. If more calls are necessary
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in the same process, then one must wait until the output of
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gettimeofday(2) changes.
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It is advised to obtain them as late as possible, so that Ecma119Image *t
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can distinguish itself from other image production setups which might be
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run on other machines with the same process number at the same time.
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*/
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/* Produces a weakly random variation of a hardcoded real random uuid
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*/
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void iso_random_uuid(Ecma119Image *t, uint8_t uuid[16]);
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/* Produces a weakly random variation of a hardcoded real random template
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*/
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void iso_random_8byte(Ecma119Image *t, uint8_t result[8]);
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#endif /* SYSTEM_AREA_H_ */
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