Support: Provide a function to get the home directory of an arbitrary user

[zturner]

Summary

llvm::sys::path already provides a function home_directory() which returns the current user's home directory.

This patch extends this by implementing a function which returns the home directory of an arbitrary user. This satisfies a use case in LLDB where we need to resolve paths of the form ~username/path, and since it is similar in nature to the existing home_directory() function, seems generally useful for llvm

[rnk]

lib/Support/Unix/Path.inc

683

StringRef doesn't have a c_str() method, but you can do .str().c_str() to convert to std::string first. *yawn*, excessive copies in C++. :(

lib/Support/Windows/Path.inc

880–882

I'd sink these declarations to the point of first use.

886

there's a bunch of micro 80cols stuff that clang-format can fix here.

905

Can we avoid the copy by resizing result directly and passing it into the query?

[majnemer]

lib/Support/Unix/Path.inc

683

This doesn't follow LLVM's coding style.

Variables should be CamelCase and there is no space between the identifier and the parenthesis.

lib/Support/Windows/Path.inc

873

Pointers on the right side.

890

Can we get away with using reserve instead of resize?

[zturner]

Updated with review changes.

[zturner]

Ran clang-format over the patch.

[rnk]

lgtm

lib/Support/Unix/Path.inc

683

Yeah, but we're in the sys::filesystem API. The STL-like function names usually come with hacker_style_underscore variable names. This is consistent with the code around it, too.

lib/Support/Windows/Path.inc

887–888

I guess this can be .reserve() instead of .resize() and .data() instead of &result[0].

890

+1

907

ditto

include/llvm/Support/Path.h

 void system_temp_directory(bool erasedOnReboot, SmallVectorImpl<char> &result);
 
 /// @brief Get the user's home directory.
 ///
 /// @param result Holds the resulting path name.
 /// @result True if a home directory is set, false otherwise.
 bool home_directory(SmallVectorImpl<char> &result);
 
+/// @brief Get the home directory of an arbitrary user.
+///
+/// @param user The username to look up the home directory for.  Must be null
+/// terminated.
+/// @param result Holds the resulting path name.
+/// @result True if a home directory is set, false otherwise.
+bool home_directory(StringRef user, SmallVectorImpl<char> &result);
+
 /// @brief Has root name?
 ///
 /// root_name != ""
 ///
 /// @param path Input path.
 /// @result True if the path has a root name, false otherwise.
 bool has_root_name(const Twine &path);
 

lib/Support/Unix/Path.inc

if (char *RequestedDir = getenv("HOME")) {
     result.clear();
     result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
     return true;
   }
 
   return false;
 }
 
+bool home_directory(StringRef user, SmallVectorImpl<char> &result) {
+  result.clear();
+  struct passwd *user_entry = ::getpwnam(user.data());
+  if (user_entry == nullptr)
+    return false;
+
+  result.append(user_entry->pw_dir);
+  return true;
+}
+
 } // end namespace path
 
 } // end namespace sys
 } // end namespace llvm

lib/Support/Windows/Path.inc

 #include <io.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 
 // These two headers must be included last, and make sure shlobj is required
 // after Windows.h to make sure it picks up our definition of _WIN32_WINNT
 #include "WindowsSupport.h"
 #include <shlobj.h>
+#include <sddl.h>
 
 #undef max
 
 // MinGW doesn't define this.
 #ifndef _ERRNO_T_DEFINED
 #define _ERRNO_T_DEFINED
 typedef int errno_t;
 #endif
if (::SHGetFolderPathW(0, CSIDL_APPDATA | CSIDL_FLAG_CREATE, 0,
     return false;
 
   if (UTF16ToUTF8(Path, ::wcslen(Path), result))
     return false;
 
   return true;
 }
 
+bool home_directory(StringRef user, SmallVectorImpl<char> &result) {
+  char sid_buf[SECURITY_MAX_SID_SIZE];
+  SID *sid = reinterpret_cast<SID *>(sid_buf);
+  DWORD sid_size = SECURITY_MAX_SID_SIZE;
+  DWORD cch_referenced_domain = 0;
+  SID_NAME_USE sid_name_use;
+  bool success = false;
+  char *string_sid = nullptr;
+  std::string reg_path;
+  HKEY hkey = nullptr;
+
+  ::LookupAccountName(nullptr, user.data(), sid, &sid_size, nullptr,
+                      &cch_referenced_domain, &sid_name_use);
+  if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+    goto finish;
+
+  result.resize(cch_referenced_domain);
+  if (!::LookupAccountName(nullptr, user.data(), sid, &sid_size, &result[0],
+                           &cch_referenced_domain, &sid_name_use))
+    goto finish;
+
+  if (!ConvertSidToStringSid(sid, &string_sid))
+    goto finish;
+
+  reg_path.assign(
+      "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\ProfileList\\");
+  reg_path.append(string_sid);
+  if (RegOpenKey(HKEY_LOCAL_MACHINE, reg_path.c_str(), &hkey) != ERROR_SUCCESS)
+    goto finish;
+
+  DWORD cbData = 0;
+  DWORD key_type;
+  if (RegQueryValueEx(hkey, "ProfileImagePath", NULL, &key_type, NULL,
+                      &cbData) != ERROR_SUCCESS)
+    goto finish;
+
+  result.resize(cbData);
+  uint8_t *buf_data = reinterpret_cast<uint8_t *>(result.data());
+  if (RegQueryValueEx(hkey, "ProfileImagePath", NULL, &key_type, buf_data,
+                      &cbData) != ERROR_SUCCESS)
+    goto finish;
+
+  success = true;
+
+finish:
+  if (string_sid)
+    ::LocalFree(string_sid);
+  if (hkey)
+    ::RegCloseKey(hkey);
+
+  return success;
+}
+
 } // end namespace path
 
 namespace windows {
 std::error_code UTF8ToUTF16(llvm::StringRef utf8,
                             llvm::SmallVectorImpl<wchar_t> &utf16) {
   if (!utf8.empty()) {
     int len = ::MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, utf8.begin(),
                                     utf8.size(), utf16.begin(), 0);