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#define _XOPEN_SOURCE 500
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
static inline int
elf16(unsigned char *buf, int le)
{
if (le)
return buf[0] | buf[1] << 8;
return buf[0] << 8 | buf[1];
}
static inline unsigned int
elf32(unsigned char *buf, int le)
{
if (le)
return buf[0] | buf[1] << 8 | buf[2] << 16 | buf[3] << 24;
return buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
static inline unsigned int
elf64(unsigned char *buf, int le, int is64)
{
if (is64)
{
buf += le ? 4 : 0;
if (buf[0] || buf[1] || buf[2] || buf[3])
return ~0;
buf += le ? -4 : 4;
}
if (le)
return buf[0] | buf[1] << 8 | buf[2] << 16 | buf[3] << 24;
return buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
}
int
is_prelinked(int fd, unsigned char *buf, int l)
{
int le, is64;
off_t soff;
int snum, ssiz;
int i, stridx;
unsigned char *sects, *strsect;
unsigned int slen;
unsigned int o;
if (l < 0x34)
return 0;
if (buf[0] != 0x7f || buf[1] != 'E' || buf[2] != 'L' || buf[3] != 'F')
return 0;
is64 = buf[4] == 2;
le = buf[5] != 2;
if (is64 && l < 0x40)
return 0;
soff = elf64(is64 ? buf + 40 : buf + 32, le, is64);
if (soff == (off_t)~0)
return 0;
ssiz = elf16(buf + (is64 ? 0x40 - 6 : 0x34 - 6), le);
if (ssiz < (is64 ? 64 : 40) || ssiz >= 32768)
return 0;
snum = elf16(buf + (is64 ? 0x40 - 4 : 0x34 - 4), le);
stridx = elf16(buf + (is64 ? 0x40 - 2 : 0x34 - 2), le);
if (stridx >= snum)
return 0;
sects = malloc(snum * ssiz);
if (!sects)
return 0;
if (pread(fd, sects, snum * ssiz, soff) != snum * ssiz)
{
free(sects);
return 0;
}
strsect = sects + stridx * ssiz;
if (elf32(strsect + 4, le) != 3)
{
free(sects);
return 0;
}
soff = elf64(is64 ? strsect + 24 : strsect + 16, le, is64);
slen = elf64(is64 ? strsect + 32 : strsect + 20, le, is64);
if (soff == (off_t)~0 || slen == ~0 || (int)slen < 0)
{
free(sects);
return 0;
}
strsect = malloc(slen);
if (!strsect)
{
free(sects);
return 0;
}
if (pread(fd, strsect, slen, soff) != slen)
{
free(sects);
free(strsect);
return 0;
}
for (i = 0; i < snum; i++)
{
o = elf32(sects + i * ssiz, le);
if (o > slen)
continue;
/* printf("sect #%d %s\n", i, strsect + o); */
if (o + 18 <= slen && memcmp(strsect + o, ".gnu.prelink_undo", 18) == 0)
break;
}
free(strsect);
free(sects);
return i == snum ? 0 : 1;
}
pid_t prelink_pid;
int
prelinked_open(char *name)
{
pid_t pid;
int fd, status;
struct stat stb;
char template[21];
if (stat("/usr/sbin/prelink", &stb))
{
perror("/usr/sbin/prelink");
fprintf(stderr, "prelink not installed, cannot undo prelinking");
exit(1);
}
strcpy(template, "/tmp/deltarpm.XXXXXX");
if ((fd = mkstemp(template)) == -1)
{
perror("mkstemp");
exit(1);
}
close(fd); /* prelink renames another tmpfile over our file */
pid = fork();
if (pid == (pid_t)(-1))
{
perror("fork");
exit(1);
}
if (!pid)
{
execl("/usr/sbin/prelink", "prelink", "-o", template, "-u", name, (char *)0);
perror("/usr/sbin/prelink");
_exit(1);
}
while (waitpid(pid, &status, 0) == (pid_t)-1)
;
if ((fd = open(template, O_RDONLY)) == -1)
{
perror(template);
exit(1);
}
unlink(template);
return fd;
}
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