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/*
* wrappers.c
*
* Function wrapping functions.
*
* Copyright 1999-2008 Gentoo Foundation
* Licensed under the GPL-2
*
* Partly Copyright (C) 1998-9 Pancrazio `Ezio' de Mauro <p@demauro.net>,
* as some of the InstallWatch code was used.
*/
#include "headers.h"
#include "sbutil.h"
#include "libsandbox.h"
#include "wrappers.h"
#if !defined(BROKEN_RTLD_NEXT) && defined(HAVE_RTLD_NEXT)
# define USE_RTLD_NEXT
#endif
static void *libc_handle = NULL;
static void *get_dlsym(const char *symname, const char *symver)
{
void *symaddr = NULL;
#if defined(USE_RTLD_NEXT)
libc_handle = RTLD_NEXT;
#endif
/* Checking for -1UL is significant on hardened!
* USE_RTLD_NEXT returns it as a sign of being unusable.
* However using !x or NULL checks does NOT pick it up!
* That is also why we need to save/restore errno #260765.
*/
#define INVALID_LIBC_HANDLE(x) (!x || NULL == x || (void *)-1UL == x)
if (INVALID_LIBC_HANDLE(libc_handle)) {
save_errno();
libc_handle = dlopen(LIBC_VERSION, RTLD_LAZY);
restore_errno();
if (INVALID_LIBC_HANDLE(libc_handle)) {
fprintf(stderr, "libsandbox: Can't dlopen libc: %s\n",
dlerror());
exit(EXIT_FAILURE);
}
}
#undef INVALID_LIBC_HANDLE
if (NULL == symver)
symaddr = dlsym(libc_handle, symname);
else
symaddr = dlvsym(libc_handle, symname, symver);
if (!symaddr) {
fprintf(stderr, "libsandbox: Can't resolve %s: %s\n",
symname, dlerror());
exit(EXIT_FAILURE);
}
return symaddr;
}
/* Macro to check if a wrapper is defined, if not
* then try to resolve it again.
*/
#define check_dlsym(_name, _symname, _symver) \
{ \
if (NULL == _name) \
_name = get_dlsym(_symname, _symver); \
}
/* Need to include the function wrappers here, as they are needed below */
#include "symbols.h"
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