Use stat structure to keep oldest mtime.

// Must match the path defined in NativeCrashListener.java

#define NCRASH_SOCKET_PATH "/data/system/ndebugsocket"

#define typecheck(x,y) {    \

  typeof(x) __dummy1;     \

  typeof(y) __dummy2;     \

  (void)(&__dummy1 == &__dummy2); }

static bool signal_has_address(int sig) {

  switch (sig) {

    case SIGILL:

//

// Returns the path of the tombstone file, allocated using malloc().  Caller must free() it.

static char* find_and_open_tombstone(int* fd) {

#ifdef __aarch64__

  long mtime = LONG_MAX;

#else

  unsigned long mtime = ULONG_MAX;

#endif

  struct stat sb;

  // XXX: Our stat.st_mtime isn't time_t. If it changes, as it probably ought

  // to, our logic breaks. This check will generate a warning if that happens.

  typecheck(mtime, sb.st_mtime);

  // In a single wolf-like pass, find an available slot and, in case none

  // In a single pass, find an available slot and, in case none

  // exist, find and record the least-recently-modified file.

  char path[128];

  int oldest = 0;

  int oldest = -1;

  struct stat oldest_sb;

  for (int i = 0; i < MAX_TOMBSTONES; i++) {

    snprintf(path, sizeof(path), TOMBSTONE_TEMPLATE, i);

    struct stat sb;

    if (!stat(path, &sb)) {

      if (sb.st_mtime < mtime) {

      if (oldest < 0 || sb.st_mtime < oldest_sb.st_mtime) {

        oldest = i;

        mtime = sb.st_mtime;

        oldest_sb.st_mtime = sb.st_mtime;

      }

      continue;

    }

    return strdup(path);

  }

  if (oldest < 0) {

    LOG("Failed to find a valid tombstone, default to using tombstone 0.\n");

    oldest = 0;

  }

  // we didn't find an available file, so we clobber the oldest one

  snprintf(path, sizeof(path), TOMBSTONE_TEMPLATE, oldest);

  *fd = open(path, O_CREAT | O_TRUNC | O_WRONLY, 0600);