libdeno: add file utilities Dirname() and ExePath()

libdeno/file_util.cc

@@ -1,10 +1,21 @@
 // Copyright 2018 the Deno authors. All rights reserved. MIT license.
 #include <inttypes.h>
+#include <limits.h>
+#include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <fstream>
 #include <iterator>
 #include <string>
 
+#ifdef __APPLE__
+#include <mach-o/dyld.h>
+#endif
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
 #include "file_util.h"
 
 namespace deno {
@@ -28,4 +39,52 @@ std::string Basename(std::string const& filename) {
   return filename;
 }
 
+// Returns the directory component from a filename. The returned path always
+// ends with a slash. This function does not understand Windows drive letters.
+std::string Dirname(std::string const& filename) {
+  for (auto it = filename.rbegin(); it != filename.rend(); ++it) {
+    char ch = *it;
+    if (ch == '\\' || ch == '/') {
+      return std::string(filename.begin(), it.base());
+    }
+  }
+  return std::string("./");
+}
+
+// Returns the full path the currently running executable.
+// This implementation is very basic. Caveats:
+//   * OS X: fails if buffer is too small, does not retry with a bigger buffer.
+//   * Windows: ANSI only, no unicode. Fails if path is longer than 260 chars.
+bool ExePath(std::string* path) {
+#ifdef _WIN32
+  // Windows only.
+  char exe_buf[MAX_PATH];
+  DWORD len = GetModuleFileNameA(NULL, exe_buf, sizeof exe_buf);
+  if (len == 0 || len == sizeof exe_buf) {
+    return false;
+  }
+#else
+#ifdef __APPLE__
+  // OS X only.
+  char link_buf[PATH_MAX * 2];  // Exe may be longer than MAX_PATH, says Apple.
+  uint32_t len = sizeof link_buf;
+  if (_NSGetExecutablePath(link_buf, &len) < 0) {
+    return false;
+  }
+#else
+  // Linux only.
+  static const char* link_buf = "/proc/self/exe";
+#endif
+  // Linux and OS X.
+  char exe_buf[PATH_MAX];
+  char* r = realpath(link_buf, exe_buf);
+  if (r == NULL) {
+    return false;
+  }
+#endif
+  // All platforms.
+  path->assign(exe_buf);
+  return true;
+}
+
 }  // namespace deno

libdeno/file_util.h

@@ -7,6 +7,8 @@
 namespace deno {
 bool ReadFileToString(const char* fn, std::string* contents);
 std::string Basename(std::string const& filename);
+std::string Dirname(std::string const& filename);
+bool ExePath(std::string* path);
 }  // namespace deno
 
 #endif  // FILE_UTIL_H_

libdeno/file_util_test.cc

@@ -11,11 +11,36 @@ TEST(FileUtilTest, ReadFileToStringFileNotExist) {
 TEST(FileUtilTest, Basename) {
   EXPECT_EQ("foo.txt", deno::Basename("foo.txt"));
   EXPECT_EQ("foo.txt", deno::Basename("/foo.txt"));
+  EXPECT_EQ("", deno::Basename("/foo/"));
+  EXPECT_EQ("", deno::Basename("foo/"));
   EXPECT_EQ("", deno::Basename("/"));
   EXPECT_EQ("foo.txt", deno::Basename(".\\foo.txt"));
   EXPECT_EQ("foo.txt", deno::Basename("/home/ryan/foo.txt"));
   EXPECT_EQ("foo.txt", deno::Basename("C:\\home\\ryan\\foo.txt"));
 }
 
-// TODO(ry) success unit test. Needs a tempfile or fixture.
-// TEST(FileUtilTest, ReadFileToStringSuccess) { }
+TEST(FileUtilTest, Dirname) {
+  EXPECT_EQ("home/dank/", deno::Dirname("home/dank/memes.gif"));
+  EXPECT_EQ("/home/dank/", deno::Dirname("/home/dank/memes.gif"));
+  EXPECT_EQ("/home/dank/", deno::Dirname("/home/dank/"));
+  EXPECT_EQ("home/dank/", deno::Dirname("home/dank/memes.gif"));
+  EXPECT_EQ("/", deno::Dirname("/"));
+  EXPECT_EQ(".\\", deno::Dirname(".\\memes.gif"));
+  EXPECT_EQ("c:\\", deno::Dirname("c:\\stuff"));
+  EXPECT_EQ("./", deno::Dirname("nothing"));
+  EXPECT_EQ("./", deno::Dirname(""));
+}
+
+TEST(FileUtilTest, ExePath) {
+  std::string exe_path;
+  EXPECT_TRUE(deno::ExePath(&exe_path));
+  // Path is absolute.
+  EXPECT_TRUE(exe_path.find("/") == 0 || exe_path.find(":\\") == 1);
+  // FIlename is the name of the test binary.
+  std::string exe_filename = deno::Basename(exe_path);
+  EXPECT_EQ(exe_filename.find("test_cc"), 0);
+  // Path exists (also tests ReadFileToString).
+  std::string contents;
+  EXPECT_TRUE(deno::ReadFileToString(exe_path.c_str(), &contents));
+  EXPECT_NE(contents.find("Inception :)"), std::string::npos);
+}