Add mkslink(), mkhlink()

12 files changed, 385 insertions, 112 deletions

diff --git a/.gitignore b/.gitignore
index f01859a..a0c7e80 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,4 +5,5 @@
 *.so
 *.a
 *.exe
+*.dll
 core
diff --git a/butl/buildfile b/butl/buildfile
index db33ef7..5c939af 100644
--- a/butl/buildfile
+++ b/butl/buildfile
@@ -2,26 +2,27 @@
 # copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
 # license   : MIT; see accompanying LICENSE file
 
-lib{butl}:                        \
-{hxx         cxx}{ base64       } \
-{hxx         cxx}{ char-scanner } \
-{hxx         cxx}{ fdstream     } \
-{hxx ixx     cxx}{ filesystem   } \
-{hxx            }{ multi-index  } \
-{hxx            }{ optional     } \
-{hxx         cxx}{ pager        } \
-{hxx ixx txx cxx}{ path         } \
-{hxx            }{ path-io      } \
-{hxx            }{ path-map     } \
-{hxx     txx    }{ prefix-map   } \
-{hxx ixx     cxx}{ process      } \
-{hxx         cxx}{ sha256       } \
-{hxx     txx    }{ string-table } \
-{hxx         cxx}{ timestamp    } \
-{hxx         cxx}{ triplet      } \
-{hxx            }{ utility      } \
-{hxx            }{ vector-view  } \
-{hxx            }{ version      }
+lib{butl}:                         \
+{hxx         cxx}{ base64        } \
+{hxx         cxx}{ char-scanner  } \
+{hxx         cxx}{ fdstream      } \
+{hxx ixx     cxx}{ filesystem    } \
+{hxx            }{ multi-index   } \
+{hxx            }{ optional      } \
+{hxx         cxx}{ pager         } \
+{hxx ixx txx cxx}{ path          } \
+{hxx            }{ path-io       } \
+{hxx            }{ path-map      } \
+{hxx     txx    }{ prefix-map    } \
+{hxx ixx     cxx}{ process       } \
+{hxx         cxx}{ sha256        } \
+{hxx     txx    }{ string-table  } \
+{hxx         cxx}{ timestamp     } \
+{hxx         cxx}{ triplet       } \
+{hxx            }{ utility       } \
+{hxx            }{ vector-view   } \
+{hxx            }{ version       } \
+{hxx         cxx}{ win32-utility }
 
 # This one is included into sha256.cxx so treat it as file to exclude
 # from the compilation.
diff --git a/butl/filesystem b/butl/filesystem
index ab39f36..565f465 100644
--- a/butl/filesystem
+++ b/butl/filesystem
@@ -120,6 +120,41 @@ namespace butl
   using auto_rmfile = auto_rm<path>;
   using auto_rmdir = auto_rm<dir_path>; // Note: recursive (rm_r).
 
+  // Create a symbolic link to a file (default) or directory (third argument
+  // is true). Throw std::system_error on failures.
+  //
+  // Note that Windows symlinks are currently not supported.
+  //
+  void
+  mksymlink (const path& target, const path& link, bool dir = false);
+
+  // Create a symbolic link to a directory. Throw std::system_error on
+  // failures.
+  //
+  inline void
+  mksymlink (const dir_path& target, const dir_path& link)
+  {
+    mksymlink (target, link, true);
+  }
+
+  // Create a hard link to a file (default) or directory (third argument is
+  // true). Throw std::system_error on failures.
+  //
+  // Note that on Linix, FreeBSD and some other platforms the target can not
+  // be a directory. While Windows support directories (via junktions), this
+  // is currently not implemented.
+  //
+  void
+  mkhardlink (const path& target, const path& link, bool dir = false);
+
+  // Create a hard link to a directory. Throw std::system_error on failures.
+  //
+  inline void
+  mkhardlink (const dir_path& target, const dir_path& link)
+  {
+    mkhardlink (target, link, true);
+  }
+
   // Return timestamp_nonexistent if the entry at the specified path
   // does not exist or is not a path. All other errors are reported
   // by throwing std::system_error. Note that this function resolves
diff --git a/butl/filesystem.cxx b/butl/filesystem.cxx
index a2d6434..c3d21cd 100644
--- a/butl/filesystem.cxx
+++ b/butl/filesystem.cxx
@@ -4,18 +4,23 @@
 
 #include <butl/filesystem>
 
-#include <errno.h>     // errno, E*
-#include <unistd.h>    // stat, rmdir(), unlink()
-#include <sys/types.h> // stat
-#include <sys/stat.h>  // stat(), lstat(), S_IS*, mkdir()
-
 #ifndef _WIN32
 #  include <dirent.h> // struct dirent, *dir()
+#  include <unistd.h> // symlink(), link()
 #else
-#  include <io.h>     // _find*()
-#  include <direct.h> // _mkdir()
+#  include <butl/win32-utility>
+
+#  include <io.h>       // _find*()
+#  include <direct.h>   // _mkdir()
+
+#  include <cassert>
 #endif
 
+#include <errno.h>     // errno, E*
+#include <unistd.h>    // stat, rmdir(), unlink()
+#include <sys/types.h> // stat
+#include <sys/stat.h>  // stat(), lstat(), S_IS*, mkdir()
+
 #include <memory>       // unique_ptr
 #include <system_error>
 
@@ -152,6 +157,48 @@ namespace butl
     return r;
   }
 
+#ifndef _WIN32
+  void
+  mksymlink (const path& target, const path& link, bool)
+  {
+    if (symlink (target.string ().c_str (), link.string ().c_str ()) == -1)
+      throw system_error (errno, system_category ());
+  }
+
+  void
+  mkhardlink (const path& target, const path& link, bool)
+  {
+    if (::link (target.string ().c_str (), link.string ().c_str ()) == -1)
+      throw system_error (errno, system_category ());
+  }
+
+#else
+
+  void
+  mksymlink (const path&, const path&, bool)
+  {
+    throw system_error (ENOSYS, system_category (), "symlinks not supported");
+  }
+
+  void
+  mkhardlink (const path& target, const path& link, bool dir)
+  {
+    if (!dir)
+    {
+      if (!CreateHardLinkA (link.string ().c_str (),
+                            target.string ().c_str (),
+                            nullptr))
+      {
+        string e (win32::last_error_msg ());
+        throw system_error (EIO, system_category (), e);
+      }
+    }
+    else
+      throw system_error (
+        ENOSYS, system_category (), "directory hard links not supported");
+  }
+#endif
+
   // Figuring out whether we have the nanoseconds in struct stat. Some
   // platforms (e.g., FreeBSD), may provide some "compatibility" #define's,
   // so use the second argument to not end up with the same signatures.
diff --git a/butl/pager.cxx b/butl/pager.cxx
index 9999bb0..0f29bb4 100644
--- a/butl/pager.cxx
+++ b/butl/pager.cxx
@@ -11,11 +11,8 @@
 #  include <chrono>
 #  include <thread> // this_thread::sleep_for()
 #else
-#  ifndef WIN32_LEAN_AND_MEAN
-#    define WIN32_LEAN_AND_MEAN
-#  endif
-#  include <windows.h>  // GetConsoleScreenBufferInfo(), GetStdHandle(),
-                        // Sleep()
+#  include <butl/win32-utility>
+
 #  include <io.h>       // _close()
 #endif
 
diff --git a/butl/path.cxx b/butl/path.cxx
index 92b0d6c..1693c86 100644
--- a/butl/path.cxx
+++ b/butl/path.cxx
@@ -5,15 +5,12 @@
 #include <butl/path>
 
 #ifdef _WIN32
+#  include <butl/win32-utility>
+
 #  include <stdlib.h>  // _MAX_PATH, _wgetenv()
 #  include <direct.h>  // _[w]getcwd(), _[w]chdir()
-#  ifndef WIN32_LEAN_AND_MEAN
-#    define WIN32_LEAN_AND_MEAN
-#  endif
-#  include <windows.h>  // GetTempPath*(), FormatMessageA(), LocalFree()
 #  include <shlobj.h>   // SHGetFolderPath*(), CSIDL_PROFILE
 #  include <winerror.h> // SUCCEEDED()
-#  include <memory>     // unique_ptr
 #else
 #  include <pwd.h>       // struct passwd, getpwuid_r()
 #  include <errno.h>     // EINVAL
@@ -23,6 +20,7 @@
 #  include <string.h>    // strlen(), strcpy()
 #  include <sys/stat.h>  // stat(), S_IS*
 #  include <sys/types.h> // stat
+
 #  include <vector>
 #endif
 
@@ -40,6 +38,10 @@
 
 using namespace std;
 
+#ifdef _WIN32
+using namespace butl::win32;
+#endif
+
 namespace butl
 {
   char const* invalid_path_base::
@@ -84,39 +86,7 @@ namespace butl
 #endif
   }
 
-#ifdef _WIN32
-  struct msg_deleter
-  {
-    void operator() (char* p) const {LocalFree (p);}
-  };
-
-  static string
-  error_msg (DWORD e)
-  {
-    char* msg;
-    if (!FormatMessageA (
-          FORMAT_MESSAGE_ALLOCATE_BUFFER |
-          FORMAT_MESSAGE_FROM_SYSTEM |
-          FORMAT_MESSAGE_IGNORE_INSERTS |
-          FORMAT_MESSAGE_MAX_WIDTH_MASK,
-          0,
-          e,
-          MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT),
-          (char*)&msg,
-          0,
-          0))
-      return "unknown error code " + to_string (e);
-
-    unique_ptr<char, msg_deleter> m (msg);
-    return msg;
-  }
-
-  inline static string
-  last_error ()
-  {
-    return error_msg (GetLastError ());
-  }
-#else
+#ifndef _WIN32
   static const char*
   temp_directory ()
   {
@@ -179,7 +149,7 @@ namespace butl
 
     if (r == 0)
     {
-      string e (last_error ());
+      string e (last_error_msg ());
       throw system_error (ENOTDIR, system_category (), e);
     }
 
@@ -301,7 +271,7 @@ namespace butl
 
     if (r == 0)
     {
-      string e (last_error ());
+      string e (last_error_msg ());
       throw system_error (ENOTDIR, system_category (), e);
     }
 #else
diff --git a/butl/process.cxx b/butl/process.cxx
index 588c0b6..aaab915 100644
--- a/butl/process.cxx
+++ b/butl/process.cxx
@@ -8,10 +8,8 @@
 #  include <unistd.h>    // execvp, fork, dup2, pipe, chdir, *_FILENO, getpid
 #  include <sys/wait.h>  // waitpid
 #else
-#  ifndef WIN32_LEAN_AND_MEAN
-#    define WIN32_LEAN_AND_MEAN
-#  endif
-#  include <windows.h>   // CreatePipe(), CreateProcess()
+#  include <butl/win32-utility>
+
 #  include <io.h>        // _open_osfhandle(), _get_osfhandle(), _close()
 #  include <fcntl.h>     // _O_TEXT
 #  include <stdlib.h>    // getenv()
@@ -21,6 +19,7 @@
 #  include <memory>    // unique_ptr
 
 #  include <butl/path>
+#  include <butl/win32-utility>
 #endif
 
 #include <cassert>
@@ -29,6 +28,10 @@
 
 using namespace std;
 
+#ifdef _WIN32
+using namespace butl::win32;
+#endif
+
 namespace butl
 {
   class auto_fd
@@ -226,38 +229,6 @@ namespace butl
 
 #else // _WIN32
 
-  struct msg_deleter
-  {
-    void operator() (char* p) const {LocalFree (p);}
-  };
-
-  static string
-  error (DWORD e)
-  {
-    char* msg;
-    if (!FormatMessageA (
-          FORMAT_MESSAGE_ALLOCATE_BUFFER |
-          FORMAT_MESSAGE_FROM_SYSTEM |
-          FORMAT_MESSAGE_IGNORE_INSERTS |
-          FORMAT_MESSAGE_MAX_WIDTH_MASK,
-          0,
-          e,
-          MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT),
-          (char*)&msg,
-          0,
-          0))
-      return "unknown error code " + to_string (e);
-
-    unique_ptr<char, msg_deleter> m (msg);
-    return msg;
-  }
-
-  static inline string
-  last_error ()
-  {
-    return error (GetLastError ());
-  }
-
   static path
   path_search (const path& f)
   {
@@ -383,7 +354,7 @@ namespace butl
 
     auto fail = [](const char* m = nullptr)
     {
-      throw process_error (m == nullptr ? last_error () : m);
+      throw process_error (m == nullptr ? last_error_msg () : m);
     };
 
     // Create a pipe and clear the inherit flag on the parent side.
@@ -605,7 +576,7 @@ namespace butl
       handle = 0; // We have tried.
 
       if (e != NO_ERROR)
-        throw process_error (error (e));
+        throw process_error (error_msg (e));
 
       status = s;
     }
@@ -631,7 +602,7 @@ namespace butl
       handle = 0; // We have tried.
 
       if (e != NO_ERROR)
-        throw process_error (error (e));
+        throw process_error (error_msg (e));
 
       status = s;
     }
diff --git a/butl/win32-utility b/butl/win32-utility
new file mode 100644
index 0000000..c74eb66
--- /dev/null
+++ b/butl/win32-utility
@@ -0,0 +1,52 @@
+// file      : butl/win32-utility -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef BUTL_WIN32_UTILITY
+#define BUTL_WIN32_UTILITY
+
+// Use this header to include <windows.h> and a couple of Win32-specific
+// utilities.
+//
+
+#ifdef _WIN32
+
+// Try to include <windows.h> so that it doesn't mess other things up.
+//
+#ifndef WIN32_LEAN_AND_MEAN
+#  define WIN32_LEAN_AND_MEAN
+#  ifndef NOMINMAX // No min and max macros.
+#    define NOMINMAX
+#    include <windows.h>
+#    undef NOMINMAX
+#  else
+#    include <windows.h>
+#  endif
+#  undef WIN32_LEAN_AND_MEAN
+#else
+#  ifndef NOMINMAX
+#    define NOMINMAX
+#    include <windows.h>
+#    undef NOMINMAX
+#  else
+#    include <windows.h>
+#  endif
+#endif
+
+#include <string>
+
+namespace butl
+{
+  namespace win32
+  {
+    std::string
+    error_msg (DWORD code);
+
+    std::string
+    last_error_msg ();
+  }
+};
+
+#endif // _WIN32
+
+#endif // BUTL_WIN32_UTILITY
diff --git a/butl/win32-utility.cxx b/butl/win32-utility.cxx
new file mode 100644
index 0000000..cf44d4d
--- /dev/null
+++ b/butl/win32-utility.cxx
@@ -0,0 +1,51 @@
+// file      : butl/win32-utility.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <butl/win32-utility>
+
+#ifdef _WIN32
+
+#include <memory> // unique_ptr
+
+using namespace std;
+
+namespace butl
+{
+  namespace win32
+  {
+    struct msg_deleter
+    {
+      void operator() (char* p) const {LocalFree (p);}
+    };
+
+    string
+    error_msg (DWORD code)
+    {
+      char* msg;
+      if (!FormatMessageA (
+            FORMAT_MESSAGE_ALLOCATE_BUFFER |
+            FORMAT_MESSAGE_FROM_SYSTEM |
+            FORMAT_MESSAGE_IGNORE_INSERTS |
+            FORMAT_MESSAGE_MAX_WIDTH_MASK,
+            0,
+            code,
+            MAKELANGID (LANG_NEUTRAL, SUBLANG_DEFAULT),
+            (char*)&msg,
+            0,
+            0))
+        return "unknown error code " + to_string (code);
+
+      unique_ptr<char, msg_deleter> m (msg);
+      return msg;
+    }
+
+    string
+    last_error_msg ()
+    {
+      return error_msg (GetLastError ());
+    }
+  }
+}
+
+#endif // _WIN32
diff --git a/tests/buildfile b/tests/buildfile
index e6670ca..311a290 100644
--- a/tests/buildfile
+++ b/tests/buildfile
@@ -2,7 +2,7 @@
 # copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
 # license   : MIT; see accompanying LICENSE file
 
-d = base64/ dir-iterator/ pager/ path/ prefix-map/ process/ sha256/ \
+d = base64/ dir-iterator/ link/ pager/ path/ prefix-map/ process/ sha256/ \
     timestamp/ triplet/
 
 .: $d
diff --git a/tests/link/buildfile b/tests/link/buildfile
new file mode 100644
index 0000000..860f0fc
--- /dev/null
+++ b/tests/link/buildfile
@@ -0,0 +1,7 @@
+# file      : tests/link/buildfile
+# copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+# license   : MIT; see accompanying LICENSE file
+
+exe{driver}: cxx{driver} ../../butl/lib{butl}
+
+include ../../butl/
diff --git a/tests/link/driver.cxx b/tests/link/driver.cxx
new file mode 100644
index 0000000..7ec4ac2
--- /dev/null
+++ b/tests/link/driver.cxx
@@ -0,0 +1,141 @@
+// file      : tests/link/driver.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <set>
+#include <cassert>
+#include <fstream>
+#include <utility>      // pair
+#include <system_error>
+
+#include <butl/path>
+#include <butl/filesystem>
+
+using namespace std;
+using namespace butl;
+
+static const char text[] = "ABCDEF";
+
+static bool
+link_file (const path& target, const path& link, bool hard, bool check_content)
+{
+  try
+  {
+    if (hard)
+      mkhardlink (target, link);
+    else
+      mksymlink (target, link);
+  }
+  catch (const system_error&)
+  {
+    return false;
+  }
+
+  if (!check_content)
+    return true;
+
+  string s;
+  ifstream ifs;
+  ifs.exceptions (fstream::badbit | fstream::failbit);
+  ifs.open (link.string ());
+  ifs >> s;
+  return s == text;
+}
+
+#ifndef _WIN32
+static bool
+link_dir (
+  const dir_path& target, const dir_path& link, bool hard, bool check_content)
+{
+  try
+  {
+    if (hard)
+      mkhardlink (target, link);
+    else
+      mksymlink (target, link);
+  }
+  catch (const system_error&)
+  {
+    return false;
+  }
+
+  if (!check_content)
+    return true;
+
+  dir_path tp (target.absolute () ? target : link.directory () / target);
+  set<pair<entry_type, path>> te;
+  for (const dir_entry& de: dir_iterator (tp))
+    te.emplace (de.ltype (), de.path ());
+
+  set<pair<entry_type, path>> le;
+  for (const dir_entry& de: dir_iterator (link))
+    le.emplace (de.ltype (), de.path ());
+
+  return te == le;
+}
+#endif
+
+int
+main ()
+{
+  dir_path td (dir_path::temp_directory () / dir_path ("butl-link"));
+
+  // Recreate the temporary directory (that possibly exists from the previous
+  // faulty run) for the test files. Delete the directory only if the test
+  // succeeds to simplify the failure research.
+  //
+  try_rmdir_r (td);
+  assert (try_mkdir (td) == mkdir_status::success);
+
+  // Prepare the target file.
+  //
+  path fn ("target");
+  path fp (td / fn);
+
+  {
+    ofstream ofs;
+    ofs.exceptions (fstream::badbit | fstream::failbit);
+    ofs.open (fp.string ());
+    ofs << text;
+  }
+
+  // Create the file hard link.
+  //
+  assert (link_file (fp, td / path ("hlink"), true, true));
+
+#ifndef _WIN32
+  // Create the file symlink using an absolute path.
+  //
+  assert (link_file (fp, td / path ("slink"), false, true));
+
+  // Create the file symlink using a relative path.
+  //
+  assert (link_file (fn, td / path ("rslink"), false, true));
+
+  // Create the file symlink using an unexistent file path.
+  //
+  assert (link_file (fp / path ("a"), td / path ("sa"), false, false));
+
+  // Prepare the target directory.
+  //
+  dir_path dn ("dir");
+  dir_path dp (td / dn);
+  assert (try_mkdir (dp) == mkdir_status::success);
+  assert (link_file (fp, dp / path ("hlink"), true, true));
+  assert (link_file (fp, dp / path ("slink"), false, true));
+
+  // Create the directory symlink using an absolute path.
+  //
+  assert (link_dir (dp, td / dir_path ("dslink"), false, true));
+
+  // Create the directory symlink using a relative path.
+  //
+  assert (link_dir (dn, td / dir_path ("rdslink"), false, true));
+
+  // Create the directory symlink using an unexistent directory path.
+  //
+  assert (link_dir (dp / dir_path ("a"), td / dir_path ("dsa"), false, false));
+#endif
+
+  rmdir_r (td);
+}