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glibc/sysdeps/unix/sysv/linux/dl-sysdep.c
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/* Dynamic linker system dependencies for Linux. | |
Copyright (C) 1995-2016 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, see | |
<http://www.gnu.org/licenses/>. */ | |
/* Linux needs some special initialization, but otherwise uses | |
the generic dynamic linker system interface code. */ | |
#include <string.h> | |
#include <fcntl.h> | |
#include <unistd.h> | |
#include <sys/param.h> | |
#include <sys/utsname.h> | |
#include <ldsodefs.h> | |
#ifdef SHARED | |
# define DL_SYSDEP_INIT frob_brk () | |
static inline void | |
frob_brk (void) | |
{ | |
__brk (0); /* Initialize the break. */ | |
} | |
# include <elf/dl-sysdep.c> | |
#endif | |
int | |
attribute_hidden | |
_dl_discover_osversion (void) | |
{ | |
#if 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; | |
} |