Add path::home()

3 files changed, 134 insertions, 20 deletions

diff --git a/butl/path b/butl/path
index 472e421..193eae4 100644
--- a/butl/path
+++ b/butl/path
@@ -167,6 +167,12 @@ namespace butl
     static void
     current (string_type const&);
 
+    // Return the user home directory. Throw std::system_error to report the
+    // underlying OS errors.
+    //
+    static string_type
+    home ();
+
     // Return the temporary directory. Throw std::system_error to report the
     // underlying OS errors.
     //
@@ -273,9 +279,9 @@ namespace butl
     //
     basic_path () {};
 
-    // Constructors that take a path string as an argument throw
-    // invalid_basic_path if the string is not a valid path (e.g. uses
-    // unsupported notation on Windows).
+    // Constructors that initialize a path from a string argument throw the
+    // invalid_path exception if the string is not a valid path (e.g., uses
+    // unsupported path notations on Windows).
     //
     explicit
     basic_path (C const* s): base_type (s) {init (this->path_);}
@@ -292,11 +298,11 @@ namespace butl
     basic_path (const string_type& s, size_type p, size_type n)
         : base_type (string_type (s, p, n)) {init (this->path_);}
 
-    // Create a path using the exact string representation. If
-    // the string is not a valid path or if it would require a
-    // modification, then empty path is created instead and the
-    // passed string rvalue-reference is left untouched. See
-    // also string() && below.
+    // Create a path using the exact string representation. If the string is
+    // not a valid path or if it would require a modification, then empty path
+    // is created instead and the passed string rvalue-reference is left
+    // untouched. Note that no exception is thrown if the path is invalid. See
+    // also string()&& below.
     //
     enum exact_type {exact};
     basic_path (string_type&& s, exact_type)
@@ -328,6 +334,12 @@ namespace butl
     static void
     current (basic_path const&);
 
+    // Return the user home directory. Throw std::system_error to report the
+    // underlying OS errors.
+    //
+    static dir_type
+    home () {return dir_type (traits::home ());}
+
     // Return the temporary directory. Throw std::system_error to report the
     // underlying OS errors.
     //
@@ -617,10 +629,10 @@ namespace butl
     template <class P, class C1, class K1>
     friend P butl::path_cast (basic_path<C1, K1>&&);
 
-    // If exact is true, return whether the initialization was
-    // successful, that is, the passed string is a valid path
-    // and no modifications were necessary. Throw invalid_basic_path
-    // if the string is not a valid path (e.g. uses unsupported notation on
+    // If exact is true, return whether the initialization was successful,
+    // that is, the passed string is a valid path and no modifications were
+    // necessary. Otherwise (extact is false), throw invalid_path if the
+    // string is not a valid path (e.g., uses an unsupported path notation on
     // Windows).
     //
     bool
diff --git a/butl/path.cxx b/butl/path.cxx
index 0ec71d1..92b0d6c 100644
--- a/butl/path.cxx
+++ b/butl/path.cxx
@@ -5,14 +5,17 @@
 #include <butl/path>
 
 #ifdef _WIN32
-#  include <stdlib.h>  // _MAX_PATH
+#  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*()
-#  include <memory>    // unique_ptr
+#  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
 #  include <stdlib.h>    // mbstowcs(), wcstombs(), realpath(), getenv()
 #  include <limits.h>    // PATH_MAX
@@ -20,6 +23,7 @@
 #  include <string.h>    // strlen(), strcpy()
 #  include <sys/stat.h>  // stat(), S_IS*
 #  include <sys/types.h> // stat
+#  include <vector>
 #endif
 
 #include <atomic>
@@ -87,9 +91,8 @@ namespace butl
   };
 
   static string
-  last_error ()
+  error_msg (DWORD e)
   {
-    DWORD e (GetLastError ());
     char* msg;
     if (!FormatMessageA (
           FORMAT_MESSAGE_ALLOCATE_BUFFER |
@@ -107,6 +110,12 @@ namespace butl
     unique_ptr<char, msg_deleter> m (msg);
     return msg;
   }
+
+  inline static string
+  last_error ()
+  {
+    return error_msg (GetLastError ());
+  }
 #else
   static const char*
   temp_directory ()
@@ -129,6 +138,35 @@ namespace butl
 
     return dir;
   }
+
+  static string
+  home ()
+  {
+    if (const char* h = getenv ("HOME"))
+      return h;
+
+    // Struct passwd has 5 members that will use this buffer. Two are the
+    // home directory and shell paths. The other three are the user login
+    // name, password, and real name (comment). We expect them to fit into
+    // PATH_MAX * 2.
+    //
+    char buf[PATH_MAX * 4];
+
+    passwd pw;
+    passwd* rpw;
+
+    int r (getpwuid_r (getuid (), &pw, buf, sizeof (buf), &rpw));
+    if (r == -1)
+      throw system_error (errno, system_category ());
+
+    if (r == 0 && rpw == nullptr)
+      // According to POSIX errno should be left unchanged if an entry is not
+      // found.
+      //
+      throw system_error (ENOENT, system_category ());
+
+    return pw.pw_dir;
+  }
 #endif
 
   template <>
@@ -162,6 +200,31 @@ namespace butl
       + "-" + to_string (temp_name_count++);
   }
 
+  template <>
+  path_traits<char>::string_type path_traits<char>::
+  home ()
+  {
+#ifndef _WIN32
+    return string_type (butl::home ());
+#else
+    // Could be set by, e.g., MSYS and Cygwin shells.
+    //
+    if (const char* h = getenv ("HOME"))
+      return string_type (h);
+
+    char h[_MAX_PATH];
+    HRESULT r (SHGetFolderPathA (NULL, CSIDL_PROFILE, NULL, 0, h));
+
+    if (!SUCCEEDED (r))
+    {
+      string e (error_msg (r));
+      throw system_error (ENOTDIR, system_category (), e);
+    }
+
+    return string_type (h);
+#endif
+  }
+
 #ifndef _WIN32
   template <>
   void path_traits<char>::
@@ -270,6 +333,40 @@ namespace butl
       L"-" + to_wstring (temp_name_count++);
   }
 
+  template <>
+  path_traits<wchar_t>::string_type path_traits<wchar_t>::
+  home ()
+  {
+#ifndef _WIN32
+    wchar_t d[PATH_MAX];
+    size_t r (mbstowcs (d, butl::home ().c_str (), PATH_MAX));
+
+    if (r == size_t (-1))
+      throw system_error (EINVAL, system_category ());
+
+    if (r == PATH_MAX)
+      throw system_error (ENOTSUP, system_category ());
+
+    return string_type (d);
+#else
+    // Could be set by, e.g., MSYS and Cygwin shells.
+    //
+    if (const wchar_t* h = _wgetenv (L"HOME"))
+      return string_type (h);
+
+    wchar_t h[_MAX_PATH];
+    HRESULT r (SHGetFolderPathW (NULL, CSIDL_PROFILE, NULL, 0, h));
+
+    if (!SUCCEEDED (r))
+    {
+      string e (error_msg (r));
+      throw system_error (ENOTDIR, system_category (), e);
+    }
+
+    return string_type (h);
+#endif
+  }
+
 #ifndef _WIN32
   template <>
   void path_traits<wchar_t>::
diff --git a/butl/path.txx b/butl/path.txx
index 383f7fe..35c6956 100644
--- a/butl/path.txx
+++ b/butl/path.txx
@@ -255,11 +255,16 @@ namespace butl
     //
     if ((n > 2 && s[1] == ':' && s[2] != '\\' && s[2] != '/') ||
         (n > 1 && s[0] == '\\' && s[1] == '\\'))
-      throw invalid_basic_path<C> (s);
+    {
+      if (exact)
+        return false;
+      else
+        throw invalid_basic_path<C> (s);
+    }
 #endif
 
-    // Strip trailing slashes except for the case where the single
-    // slash represents the root directory.
+    // Strip trailing slashes except for the case where the single slash
+    // represents the root directory.
     //
     for (; n > 1 && traits::is_separator (s[n - 1]); --n) ;