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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
/* Macro to check if a wrapper is defined, if not
* then try to resolve it again. */
#define check_dlsym(_name, _symname, _symver) \
{ \
int old_errno = errno; \
if (NULL == _name) \
_name = get_dlsym(_symname, _symver); \
errno = old_errno; \
}
static void *libc_handle = NULL;
extern char sandbox_lib[SB_PATH_MAX];
extern bool sandbox_on;
/* Need to include the function wrappers here, as they are needed below */
#include "symbols.h"
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!
*/
#define INVALID_LIBC_HANDLE(x) (!x || NULL == x || (void *)-1UL == x)
if (INVALID_LIBC_HANDLE(libc_handle)) {
libc_handle = dlopen(LIBC_VERSION, RTLD_LAZY);
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;
}
int libsb_open(const char *pathname, int flags, ...)
{
va_list ap;
int mode = 0;
int result = -1;
if (flags & O_CREAT) {
va_start(ap, flags);
mode = va_arg(ap, int);
va_end(ap);
}
check_dlsym(true_open_DEFAULT, symname_open_DEFAULT,
symver_open_DEFAULT);
if (flags & O_CREAT)
result = true_open_DEFAULT(pathname, flags, mode);
else
result = true_open_DEFAULT(pathname, flags);
return result;
}
char *libsb_getcwd(char *buf, size_t size)
{
check_dlsym(true_getcwd_DEFAULT, symname_getcwd_DEFAULT,
symver_getcwd_DEFAULT);
return true_getcwd_DEFAULT(buf, size);
}
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