glibc/elf/dl-minimal.c

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/* Minimal replacements for basic facilities used in the dynamic linker.
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/>. */
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <string.h>
#include <tls.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/types.h>
#include <ldsodefs.h>
#include <_itoa.h>
#include <assert.h>
/* Minimal `malloc' allocator for use while loading shared libraries.
No block is ever freed. */
static void *alloc_ptr, *alloc_end, *alloc_last_block;
/* Declarations of global functions. */
extern void weak_function free (void *ptr);
extern void * weak_function realloc (void *ptr, size_t n);
extern unsigned long int weak_function __strtoul_internal (const char *nptr,
char **endptr,
int base,
int group);
extern unsigned long int weak_function strtoul (const char *nptr,
char **endptr, int base);
/* Allocate an aligned memory block. */
void * weak_function
__libc_memalign (size_t align, size_t n)
{
if (alloc_end == 0)
{
/* Consume any unused space in the last page of our data segment. */
extern int _end attribute_hidden;
alloc_ptr = &_end;
alloc_end = (void *) 0 + (((alloc_ptr - (void *) 0)
+ GLRO(dl_pagesize) - 1)
& ~(GLRO(dl_pagesize) - 1));
}
/* Make sure the allocation pointer is ideally aligned. */
alloc_ptr = (void *) 0 + (((alloc_ptr - (void *) 0) + align - 1)
& ~(align - 1));
if (alloc_ptr + n >= alloc_end || n >= -(uintptr_t) alloc_ptr)
{
/* Insufficient space left; allocate another page. */
caddr_t page;
size_t nup = (n + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1);
if (__glibc_unlikely (nup == 0))
{
if (n)
return NULL;
nup = GLRO(dl_pagesize);
}
page = __mmap (0, nup, PROT_READ|PROT_WRITE,
MAP_ANON|MAP_PRIVATE, -1, 0);
if (page == MAP_FAILED)
return NULL;
if (page != alloc_end)
alloc_ptr = page;
alloc_end = page + nup;
}
alloc_last_block = (void *) alloc_ptr;
alloc_ptr += n;
return alloc_last_block;
}
void * weak_function
malloc (size_t n)
{
return __libc_memalign (sizeof (double), n);
}
/* We use this function occasionally since the real implementation may
be optimized when it can assume the memory it returns already is
set to NUL. */
void * weak_function
calloc (size_t nmemb, size_t size)
{
/* New memory from the trivial malloc above is always already cleared.
(We make sure that's true in the rare occasion it might not be,
by clearing memory in free, below.) */
size_t bytes = nmemb * size;
#define HALF_SIZE_T (((size_t) 1) << (8 * sizeof (size_t) / 2))
if (__builtin_expect ((nmemb | size) >= HALF_SIZE_T, 0)
&& size != 0 && bytes / size != nmemb)
return NULL;
return malloc (bytes);
}
/* This will rarely be called. */
void weak_function
free (void *ptr)
{
/* We can free only the last block allocated. */
if (ptr == alloc_last_block)
{
/* Since this is rare, we clear the freed block here
so that calloc can presume malloc returns cleared memory. */
memset (alloc_last_block, '\0', alloc_ptr - alloc_last_block);
alloc_ptr = alloc_last_block;
}
}
/* This is only called with the most recent block returned by malloc. */
void * weak_function
realloc (void *ptr, size_t n)
{
if (ptr == NULL)
return malloc (n);
assert (ptr == alloc_last_block);
size_t old_size = alloc_ptr - alloc_last_block;
alloc_ptr = alloc_last_block;
void *new = malloc (n);
return new != ptr ? memcpy (new, ptr, old_size) : new;
}
/* Avoid signal frobnication in setjmp/longjmp. Keeps things smaller. */
#include <setjmp.h>
int weak_function
__sigjmp_save (sigjmp_buf env, int savemask __attribute__ ((unused)))
{
env[0].__mask_was_saved = 0;
return 0;
}
/* Define our own version of the internal function used by strerror. We
only provide the messages for some common errors. This avoids pulling
in the whole error list. */
char * weak_function
__strerror_r (int errnum, char *buf, size_t buflen)
{
char *msg;
switch (errnum)
{
case ENOMEM:
msg = (char *) "Cannot allocate memory";
break;
case EINVAL:
msg = (char *) "Invalid argument";
break;
case ENOENT:
msg = (char *) "No such file or directory";
break;
case EPERM:
msg = (char *) "Operation not permitted";
break;
case EIO:
msg = (char *) "Input/output error";
break;
case EACCES:
msg = (char *) "Permission denied";
break;
default:
/* No need to check buffer size, all calls in the dynamic linker
provide enough space. */
buf[buflen - 1] = '\0';
msg = _itoa (errnum, buf + buflen - 1, 10, 0);
msg = memcpy (msg - (sizeof ("Error ") - 1), "Error ",
sizeof ("Error ") - 1);
break;
}
return msg;
}
void
__libc_fatal (const char *message)
{
_dl_fatal_printf ("%s", message);
}
rtld_hidden_def (__libc_fatal)
void
__attribute__ ((noreturn))
__chk_fail (void)
{
_exit (127);
}
rtld_hidden_def (__chk_fail)
#ifndef NDEBUG
/* Define (weakly) our own assert failure function which doesn't use stdio.
If we are linked into the user program (-ldl), the normal __assert_fail
defn can override this one. */
void weak_function
__assert_fail (const char *assertion,
const char *file, unsigned int line, const char *function)
{
_dl_fatal_printf ("\
Inconsistency detected by ld.so: %s: %u: %s%sAssertion `%s' failed!\n",
file, line, function ?: "", function ? ": " : "",
assertion);
}
rtld_hidden_weak (__assert_fail)
void weak_function
__assert_perror_fail (int errnum,
const char *file, unsigned int line,
const char *function)
{
char errbuf[400];
_dl_fatal_printf ("\
Inconsistency detected by ld.so: %s: %u: %s%sUnexpected error: %s.\n",
file, line, function ?: "", function ? ": " : "",
__strerror_r (errnum, errbuf, sizeof errbuf));
}
rtld_hidden_weak (__assert_perror_fail)
#endif
unsigned long int weak_function
__strtoul_internal (const char *nptr, char **endptr, int base, int group)
{
unsigned long int result = 0;
long int sign = 1;
unsigned max_digit;
while (*nptr == ' ' || *nptr == '\t')
++nptr;
if (*nptr == '-')
{
sign = -1;
++nptr;
}
else if (*nptr == '+')
++nptr;
if (*nptr < '0' || *nptr > '9')
{
if (endptr != NULL)
*endptr = (char *) nptr;
return 0UL;
}
assert (base == 0);
base = 10;
max_digit = 9;
if (*nptr == '0')
{
if (nptr[1] == 'x' || nptr[1] == 'X')
{
base = 16;
nptr += 2;
}
else
{
base = 8;
max_digit = 7;
}
}
while (1)
{
unsigned long int digval;
if (*nptr >= '0' && *nptr <= '0' + max_digit)
digval = *nptr - '0';
else if (base == 16)
{
if (*nptr >= 'a' && *nptr <= 'f')
digval = *nptr - 'a' + 10;
else if (*nptr >= 'A' && *nptr <= 'F')
digval = *nptr - 'A' + 10;
else
break;
}
else
break;
if (result > ULONG_MAX / base
|| (result == ULONG_MAX / base && digval > ULONG_MAX % base))
{
errno = ERANGE;
if (endptr != NULL)
*endptr = (char *) nptr;
return ULONG_MAX;
}
result *= base;
result += digval;
++nptr;
}
if (endptr != NULL)
*endptr = (char *) nptr;
return result * sign;
}
#undef _itoa
/* We always use _itoa instead of _itoa_word in ld.so since the former
also has to be present and it is never about speed when these
functions are used. */
char *
_itoa (unsigned long long int value, char *buflim, unsigned int base,
int upper_case)
{
assert (! upper_case);
do
*--buflim = _itoa_lower_digits[value % base];
while ((value /= base) != 0);
return buflim;
}
/* The '_itoa_lower_digits' variable in libc.so is able to handle bases
up to 36. We don't need this here. */
const char _itoa_lower_digits[16] = "0123456789abcdef";
rtld_hidden_data_def (_itoa_lower_digits)
/* The following is not a complete strsep implementation. It cannot
handle empty delimiter strings. But this isn't necessary for the
execution of ld.so. */
#undef strsep
#undef __strsep
char *
__strsep (char **stringp, const char *delim)
{
char *begin;
assert (delim[0] != '\0');
begin = *stringp;
if (begin != NULL)
{
char *end = begin;
while (*end != '\0' || (end = NULL))
{
const char *dp = delim;
do
if (*dp == *end)
break;
while (*++dp != '\0');
if (*dp != '\0')
{
*end++ = '\0';
break;
}
++end;
}
*stringp = end;
}
return begin;
}
weak_alias (__strsep, strsep)
strong_alias (__strsep, __strsep_g)