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//===-- interception_linux.cpp ----------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Linux-specific interception methods.
//===----------------------------------------------------------------------===//
#include "interception.h"
#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
SANITIZER_SOLARIS
#include <dlfcn.h> // for dlsym() and dlvsym()
namespace __interception {
#if SANITIZER_NETBSD
static int StrCmp(const char *s1, const char *s2) {
while (true) {
if (*s1 != *s2)
return false;
if (*s1 == 0)
return true;
s1++;
s2++;
}
}
#endif
static void *GetFuncAddr(const char *name, uptr trampoline) {
#if SANITIZER_NETBSD
// FIXME: Find a better way to handle renames
if (StrCmp(name, "sigaction"))
name = "__sigaction14";
#endif
void *addr = dlsym(RTLD_NEXT, name);
if (!addr) {
// If the lookup using RTLD_NEXT failed, the sanitizer runtime library is
// later in the library search order than the DSO that we are trying to
// intercept, which means that we cannot intercept this function. We still
// want the address of the real definition, though, so look it up using
// RTLD_DEFAULT.
addr = dlsym(RTLD_DEFAULT, name);
// In case `name' is not loaded, dlsym ends up finding the actual wrapper.
// We don't want to intercept the wrapper and have it point to itself.
if ((uptr)addr == trampoline)
addr = nullptr;
}
return addr;
}
bool InterceptFunction(const char *name, uptr *ptr_to_real, uptr func,
uptr trampoline) {
void *addr = GetFuncAddr(name, trampoline);
*ptr_to_real = (uptr)addr;
return addr && (func == trampoline);
}
// dlvsym is a GNU extension supported by some other platforms.
#if SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
static void *GetFuncAddr(const char *name, const char *ver) {
return dlvsym(RTLD_NEXT, name, ver);
}
bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
uptr func, uptr trampoline) {
void *addr = GetFuncAddr(name, ver);
*ptr_to_real = (uptr)addr;
return addr && (func == trampoline);
}
# endif // SANITIZER_GLIBC || SANITIZER_FREEBSD || SANITIZER_NETBSD
} // namespace __interception
#endif // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
// SANITIZER_SOLARIS
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