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/* Operating system specific code for generic dynamic loader functions. Linux.
Copyright (C) 2000,2001,2002,2004,2005,2006,2007
Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <string.h>
#include <fcntl.h>
#include <sys/utsname.h>
#include <kernel-features.h>
#include <dl-sysdep.h>
#include <stdint.h>
#ifndef MIN
# define MIN(a,b) (((a)<(b))?(a):(b))
#endif
#ifdef SHARED
/* This is the function used in the dynamic linker to print the fatal error
message. */
static inline void
__attribute__ ((__noreturn__))
dl_fatal (const char *str)
{
_dl_dprintf (2, str);
_exit (1);
}
#endif
static inline int __attribute__ ((always_inline))
_dl_discover_osversion (void)
{
#if (defined NEED_DL_SYSINFO || defined NEED_DL_SYSINFO_DSO) && defined SHARED
if (GLRO(dl_sysinfo_map) != NULL)
{
/* If the kernel-supplied DSO contains a note indicating the kernel's
version, we don't need to call uname or parse any strings. */
static const struct
{
ElfW(Nhdr) hdr;
char vendor[8];
} expected_note = { { sizeof "Linux", sizeof (ElfW(Word)), 0 }, "Linux" };
const ElfW(Phdr) *const phdr = GLRO(dl_sysinfo_map)->l_phdr;
const ElfW(Word) phnum = GLRO(dl_sysinfo_map)->l_phnum;
for (uint_fast16_t i = 0; i < phnum; ++i)
if (phdr[i].p_type == PT_NOTE)
{
const ElfW(Addr) start = (phdr[i].p_vaddr
+ GLRO(dl_sysinfo_map)->l_addr);
const ElfW(Nhdr) *note = (const void *) start;
while ((ElfW(Addr)) (note + 1) - start < phdr[i].p_memsz)
{
if (!memcmp (note, &expected_note, sizeof expected_note))
return *(const ElfW(Word) *) ((const void *) note
+ sizeof expected_note);
#define ROUND(len) (((len) + sizeof note->n_type - 1) & -sizeof note->n_type)
note = ((const void *) (note + 1)
+ ROUND (note->n_namesz) + ROUND (note->n_descsz));
#undef ROUND
}
}
}
#endif
char bufmem[64];
char *buf = bufmem;
unsigned int version;
int parts;
char *cp;
struct utsname uts;
/* Try the uname system call. */
if (__uname (&uts))
{
/* This was not successful. Now try reading the /proc filesystem. */
int fd = __open ("/proc/sys/kernel/osrelease", O_RDONLY);
if (fd < 0)
return -1;
ssize_t reslen = __read (fd, bufmem, sizeof (bufmem));
__close (fd);
if (reslen <= 0)
/* This also didn't work. We give up since we cannot
make sure the library can actually work. */
return -1;
buf[MIN (reslen, (ssize_t) sizeof (bufmem) - 1)] = '\0';
}
else
buf = uts.release;
/* Now convert it into a number. The string consists of at most
three parts. */
version = 0;
parts = 0;
cp = buf;
while ((*cp >= '0') && (*cp <= '9'))
{
unsigned int here = *cp++ - '0';
while ((*cp >= '0') && (*cp <= '9'))
{
here *= 10;
here += *cp++ - '0';
}
++parts;
version <<= 8;
version |= here;
if (*cp++ != '.' || parts == 3)
/* Another part following? */
break;
}
if (parts < 3)
version <<= 8 * (3 - parts);
return version;
}
#define DL_SYSDEP_OSCHECK(FATAL) \
do { \
/* Test whether the kernel is new enough. This test is only performed \
if the library is not compiled to run on all kernels. */ \
\
int version = _dl_discover_osversion (); \
if (__builtin_expect (version >= 0, 1)) \
{ \
if (__builtin_expect (GLRO(dl_osversion) == 0, 1) \
|| GLRO(dl_osversion) > version) \
GLRO(dl_osversion) = version; \
\
/* Now we can test with the required version. */ \
if (__LINUX_KERNEL_VERSION > 0 && version < __LINUX_KERNEL_VERSION) \
/* Not sufficent. */ \
FATAL ("FATAL: kernel too old\n"); \
} \
else if (__LINUX_KERNEL_VERSION > 0) \
FATAL ("FATAL: cannot determine kernel version\n"); \
} while (0)
static inline uintptr_t __attribute__ ((always_inline))
_dl_setup_stack_chk_guard (void)
{
uintptr_t ret;
#ifdef ENABLE_STACKGUARD_RANDOMIZE
int fd = __open ("/dev/urandom", O_RDONLY);
if (fd >= 0)
{
ssize_t reslen = __read (fd, &ret, sizeof (ret));
__close (fd);
if (reslen == (ssize_t) sizeof (ret))
return ret;
}
#endif
ret = 0;
unsigned char *p = (unsigned char *) &ret;
p[sizeof (ret) - 1] = 255;
p[sizeof (ret) - 2] = '\n';
return ret;
}
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