//===-- asan_linux.cc -----------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of AddressSanitizer, an address sanity checker.
//
// Linux-specific details.
//===----------------------------------------------------------------------===//

#include "sanitizer_common/sanitizer_platform.h"
#if SANITIZER_FREEBSD || SANITIZER_LINUX

#include "asan_interceptors.h"
#include "asan_internal.h"
#include "asan_thread.h"
#include "sanitizer_common/sanitizer_flags.h"
#include "sanitizer_common/sanitizer_freebsd.h"
#include "sanitizer_common/sanitizer_libc.h"
#include "sanitizer_common/sanitizer_procmaps.h"

#include <sys/time.h>
#include <sys/resource.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <dlfcn.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
#include <unwind.h>

#if SANITIZER_FREEBSD
#include <sys/link_elf.h>
#endif

#if SANITIZER_ANDROID || SANITIZER_FREEBSD
#include <ucontext.h>
extern "C" void* _DYNAMIC;
#else
#include <sys/ucontext.h>
#include <link.h>
#endif

// x86-64 FreeBSD 9.2 and older define 'ucontext_t' incorrectly in
// 32-bit mode.
#if SANITIZER_FREEBSD && (SANITIZER_WORDSIZE == 32) && \
  __FreeBSD_version <= 902001  // v9.2
#define ucontext_t xucontext_t
#endif

typedef enum {
  ASAN_RT_VERSION_UNDEFINED = 0,
  ASAN_RT_VERSION_DYNAMIC,
  ASAN_RT_VERSION_STATIC,
} asan_rt_version_t;

// FIXME: perhaps also store abi version here?
extern "C" {
SANITIZER_INTERFACE_ATTRIBUTE
asan_rt_version_t  __asan_rt_version;
}

namespace __asan {

void InitializePlatformInterceptors() {}

void DisableReexec() {
  // No need to re-exec on Linux.
}

void MaybeReexec() {
  // No need to re-exec on Linux.
}

void *AsanDoesNotSupportStaticLinkage() {
  // This will fail to link with -static.
  return &_DYNAMIC;  // defined in link.h
}

#if SANITIZER_ANDROID
// FIXME: should we do anything for Android?
void AsanCheckDynamicRTPrereqs() {}
void AsanCheckIncompatibleRT() {}
#else
static int FindFirstDSOCallback(struct dl_phdr_info *info, size_t size,
                                void *data) {
  // Continue until the first dynamic library is found
  if (!info->dlpi_name || info->dlpi_name[0] == 0)
    return 0;

  // Ignore vDSO
  if (internal_strncmp(info->dlpi_name, "linux-", sizeof("linux-") - 1) == 0)
    return 0;

  *(const char **)data = info->dlpi_name;
  return 1;
}

static bool IsDynamicRTName(const char *libname) {
  return internal_strstr(libname, "libclang_rt.asan") ||
    internal_strstr(libname, "libasan.so");
}

static void ReportIncompatibleRT() {
  Report("Your application is linked against incompatible ASan runtimes.\n");
  Die();
}

void AsanCheckDynamicRTPrereqs() {
  if (!ASAN_DYNAMIC)
    return;

  // Ensure that dynamic RT is the first DSO in the list
  const char *first_dso_name = nullptr;
  dl_iterate_phdr(FindFirstDSOCallback, &first_dso_name);
  if (first_dso_name && !IsDynamicRTName(first_dso_name)) {
    Report("ASan runtime does not come first in initial library list; "
           "you should either link runtime to your application or "
           "manually preload it with LD_PRELOAD.\n");
    Die();
  }
}

void AsanCheckIncompatibleRT() {
  if (ASAN_DYNAMIC) {
    if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) {
      __asan_rt_version = ASAN_RT_VERSION_DYNAMIC;
    } else if (__asan_rt_version != ASAN_RT_VERSION_DYNAMIC) {
      ReportIncompatibleRT();
    }
  } else {
    if (__asan_rt_version == ASAN_RT_VERSION_UNDEFINED) {
      // Ensure that dynamic runtime is not present. We should detect it
      // as early as possible, otherwise ASan interceptors could bind to
      // the functions in dynamic ASan runtime instead of the functions in
      // system libraries, causing crashes later in ASan initialization.
      MemoryMappingLayout proc_maps(/*cache_enabled*/true);
      char filename[128];
      while (proc_maps.Next(nullptr, nullptr, nullptr, filename,
                            sizeof(filename), nullptr)) {
        if (IsDynamicRTName(filename)) {
          Report("Your application is linked against "
                 "incompatible ASan runtimes.\n");
          Die();
        }
      }
      __asan_rt_version = ASAN_RT_VERSION_STATIC;
    } else if (__asan_rt_version != ASAN_RT_VERSION_STATIC) {
      ReportIncompatibleRT();
    }
  }
}
#endif // SANITIZER_ANDROID

#if !SANITIZER_ANDROID
void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
  ucontext_t *ucp = (ucontext_t*)context;
  *stack = (uptr)ucp->uc_stack.ss_sp;
  *ssize = ucp->uc_stack.ss_size;
}
#else
void ReadContextStack(void *context, uptr *stack, uptr *ssize) {
  UNIMPLEMENTED();
}
#endif

void *AsanDlSymNext(const char *sym) {
  return dlsym(RTLD_NEXT, sym);
}

} // namespace __asan

#endif // SANITIZER_FREEBSD || SANITIZER_LINUX
