1 files changed, 157 insertions, 0 deletions
diff --git a/gitstatus/src/check_dir_mtime.cc b/gitstatus/src/check_dir_mtime.cc
new file mode 100644
index 00000000..bb60ffe5
--- /dev/null
+++ b/gitstatus/src/check_dir_mtime.cc
@@ -0,0 +1,157 @@
+// Copyright 2019 Roman Perepelitsa.
+//
+// This file is part of GitStatus.
+//
+// GitStatus is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// GitStatus is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with GitStatus. If not, see <https://www.gnu.org/licenses/>.
+
+#include "check_dir_mtime.h"
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <cerrno>
+#include <cstring>
+#include <ctime>
+#include <string>
+#include <vector>
+
+#include "check.h"
+#include "dir.h"
+#include "logging.h"
+#include "print.h"
+#include "scope_guard.h"
+#include "stat.h"
+
+namespace gitstatus {
+
+namespace {
+
+constexpr char kDirPrefix[] = ".gitstatus.";
+
+void Touch(const char* path) {
+  int fd = creat(path, 0444);
+  VERIFY(fd >= 0) << Errno();
+  CHECK(!close(fd)) << Errno();
+}
+
+bool StatChanged(const char* path, const struct stat& prev) {
+  struct stat cur;
+  VERIFY(!lstat(path, &cur)) << Errno();
+  return !StatEq(prev, cur);
+}
+
+void RemoveStaleDirs(const char* root_dir) {
+  int dir_fd = open(root_dir, O_DIRECTORY | O_CLOEXEC);
+  if (dir_fd < 0) return;
+  ON_SCOPE_EXIT(&) { CHECK(!close(dir_fd)) << Errno(); };
+
+  Arena arena;
+  std::vector<char*> entries;
+  const std::time_t now = std::time(nullptr);
+  if (!ListDir(dir_fd, arena, entries,
+               /* precompose_unicode = */ false,
+               /* case_sensitive = */ true)) {
+    return;
+  }
+
+  std::string path = root_dir;
+  const size_t root_dir_len = path.size();
+
+  for (const char* entry : entries) {
+    if (std::strlen(entry) < std::strlen(kDirPrefix)) continue;
+    if (std::memcmp(entry, kDirPrefix, std::strlen(kDirPrefix))) continue;
+
+    struct stat st;
+    if (fstatat(dir_fd, entry, &st, AT_SYMLINK_NOFOLLOW)) {
+      LOG(WARN) << "Cannot stat " << Print(entry) << " in " << Print(root_dir) << ": " << Errno();
+      continue;
+    }
+    if (MTim(st).tv_sec + 10 > now) continue;
+
+    path.resize(root_dir_len);
+    path += entry;
+    size_t dir_len = path.size();
+
+    path += "/b/1";
+    if (unlink(path.c_str()) && errno != ENOENT) {
+      LOG(WARN) << "Cannot unlink " << Print(path) << ": " << Errno();
+      continue;
+    }
+
+    for (const char* d : {"/a/1", "/a", "/b", ""}) {
+      path.resize(dir_len);
+      path += d;
+      if (rmdir(path.c_str()) && errno != ENOENT) {
+        LOG(WARN) << "Cannot remove " << Print(path) << ": " << Errno();
+        break;
+      }
+    }
+  }
+}
+
+}  // namespace
+
+bool CheckDirMtime(const char* root_dir) {
+  try {
+    RemoveStaleDirs(root_dir);
+
+    std::string tmp = std::string() + root_dir + kDirPrefix + "XXXXXX";
+    VERIFY(mkdtemp(&tmp[0])) << Errno();
+    ON_SCOPE_EXIT(&) { rmdir(tmp.c_str()); };
+
+    std::string a_dir = tmp + "/a";
+    VERIFY(!mkdir(a_dir.c_str(), 0755)) << Errno();
+    ON_SCOPE_EXIT(&) { rmdir(a_dir.c_str()); };
+    struct stat a_st;
+    VERIFY(!lstat(a_dir.c_str(), &a_st)) << Errno();
+
+    std::string b_dir = tmp + "/b";
+    VERIFY(!mkdir(b_dir.c_str(), 0755)) << Errno();
+    ON_SCOPE_EXIT(&) { rmdir(b_dir.c_str()); };
+    struct stat b_st;
+    VERIFY(!lstat(b_dir.c_str(), &b_st)) << Errno();
+
+    while (sleep(1)) {
+      // zzzz
+    }
+
+    std::string a1 = a_dir + "/1";
+    VERIFY(!mkdir(a1.c_str(), 0755)) << Errno();
+    ON_SCOPE_EXIT(&) { rmdir(a1.c_str()); };
+    if (!StatChanged(a_dir.c_str(), a_st)) {
+      LOG(WARN) << "Creating a directory doesn't change mtime of the parent: " << Print(root_dir);
+      return false;
+    }
+
+    std::string b1 = b_dir + "/1";
+    Touch(b1.c_str());
+    ON_SCOPE_EXIT(&) { unlink(b1.c_str()); };
+    if (!StatChanged(b_dir.c_str(), b_st)) {
+      LOG(WARN) << "Creating a file doesn't change mtime of the parent: " << Print(root_dir);
+      return false;
+    }
+
+    LOG(INFO) << "All mtime checks have passes. Enabling untracked cache: " << Print(root_dir);
+    return true;
+  } catch (const Exception&) {
+    LOG(WARN) << "Error while testing for mtime capability: " << Print(root_dir);
+    return false;
+  }
+}
+
+}  // namespace gitstatus