mex: symlink reuse code

Author: scivision

private/get_mex_sources.m

@@ -10,16 +10,18 @@
 
 mac = fullfile(top, "src/macos.cpp");
 
+sym = fullfile(top, "src/symlink_fs.cpp");
+
 srcs = {fullfile(top, "src/is_char_device.cpp"), ...
   fullfile(top, "src/set_permissions.cpp"), ...
-  fullfile(top, "src/create_symlink.cpp"), ...
   [fullfile(top, "src/is_rosetta.cpp"), mac], ...
   [fullfile(top, "src/windows_shortname.cpp"), win]
 };
 
-%% isSymbolicLink() new in R2024b
-if ~isMATLABReleaseOlderThan("R2024b")
-srcs{end+1} = [fullfile(top, "src/is_symlink.cpp"), win];
+%%  new in R2024b
+if isMATLABReleaseOlderThan("R2024b")
+srcs{end+1} = [fullfile(top, "src/is_symlink.cpp"), win, sym];
+srcs{end+1} = [fullfile(top, "src/create_symlink.cpp"), win, sym];
 end
 
 end

src/create_symlink.cpp

@@ -7,63 +7,7 @@
 #include <vector>
 #include <memory>
 
-#if defined(_WIN32)
-# define WIN32_LEAN_AND_MEAN
-# include <windows.h>
-#else
-# include <unistd.h> // for symlink()
-#endif
-
-#if __has_include(<filesystem>)
-# include <filesystem>
-# include <system_error>
-#endif
-
-
-bool fs_create_symlink(std::string target, std::string link)
-{
-  // confusing program errors if target is "" -- we'd never make such a symlink in real use.
-  if(target.empty())
-    return false;
-
-  // macOS needs empty check to avoid SIGABRT
-  if(link.empty())
-    return false;
-
-#if defined(__MINGW32__) || (defined(_WIN32) && !defined(__cpp_lib_filesystem))
-
-  const DWORD attr = GetFileAttributesA(target.data());
-// https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getfileattributesa
-// https://learn.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants
-
-  if (attr == INVALID_FILE_ATTRIBUTES)
-    return false;
-
-  DWORD p = SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE;
-  if(attr & FILE_ATTRIBUTE_DIRECTORY)
-    p |= SYMBOLIC_LINK_FLAG_DIRECTORY;
-
-  return CreateSymbolicLinkA(link.data(), target.data(), p);
-#elif defined(__cpp_lib_filesystem)
-  std::error_code ec;
-  std::filesystem::path t(target);
-
-  bool isdir = std::filesystem::is_directory(t, ec);
-  if (ec)
-    return false;
-
-  isdir
-    ? std::filesystem::create_directory_symlink(t, link, ec)
-    : std::filesystem::create_symlink(t, link, ec);
-
-  return !ec;
-#else
-  // https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/symlink.2.html
-  // https://linux.die.net/man/3/symlink
-  return symlink(target.data(), link.data()) == 0;
-#endif
-
-}
+#include "symlink_fs.h"
 
 
 class MexFunction : public matlab::mex::Function {

src/is_symlink.cpp

@@ -10,35 +10,7 @@
 #include <vector>
 #include <memory>
 
-#if defined(_WIN32)
-# include "win32_fs.h"
-#endif
-
-#if __has_include(<filesystem>)
-# include <filesystem>
-# include <system_error>
-#endif
-
-#include <sys/types.h>
-#include <sys/stat.h>
-
-
-static bool fs_is_symlink(std::string path)
-{
-
-#if defined(__MINGW32__) || (defined(_WIN32) && !defined(__cpp_lib_filesystem))
-  return fs_win32_is_symlink(path);
-#elif defined(__cpp_lib_filesystem)
-// std::filesystem::symlink_status doesn't detect symlinks on MinGW
-  std::error_code ec;
-  const auto s = std::filesystem::symlink_status(path, ec);
-  return !ec && std::filesystem::is_symlink(s);
-#else
-  struct stat s;
-  return lstat(path.data(), &s) == 0 && S_ISLNK(s.st_mode);
-#endif
-}
-
+#include "symlink_fs.h"
 
 class MexFunction : public matlab::mex::Function {
 public:

src/symlink_fs.cpp

@@ -0,0 +1,79 @@
+#if defined(_WIN32)
+# include "win32_fs.h"
+#else
+# include "unistd.h" // for symlink()
+#endif
+
+#include <string>
+
+#if __has_include(<filesystem>)
+# include <filesystem>
+# include <system_error>
+#endif
+
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "symlink_fs.h"
+
+
+bool fs_create_symlink(std::string target, std::string link)
+{
+  // confusing program errors if target is "" -- we'd never make such a symlink in real use.
+  if(target.empty())
+    return false;
+
+  // macOS needs empty check to avoid SIGABRT
+  if(link.empty())
+    return false;
+
+#if defined(__MINGW32__) || (defined(_WIN32) && !defined(__cpp_lib_filesystem))
+
+  const DWORD attr = GetFileAttributesA(target.data());
+// https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-getfileattributesa
+// https://learn.microsoft.com/en-us/windows/win32/fileio/file-attribute-constants
+
+  if (attr == INVALID_FILE_ATTRIBUTES)
+    return false;
+
+  DWORD p = SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE;
+  if(attr & FILE_ATTRIBUTE_DIRECTORY)
+    p |= SYMBOLIC_LINK_FLAG_DIRECTORY;
+
+  return CreateSymbolicLinkA(link.data(), target.data(), p);
+#elif defined(__cpp_lib_filesystem)
+  std::error_code ec;
+  std::filesystem::path t(target);
+
+  bool isdir = std::filesystem::is_directory(t, ec);
+  if (ec)
+    return false;
+
+  isdir
+    ? std::filesystem::create_directory_symlink(t, link, ec)
+    : std::filesystem::create_symlink(t, link, ec);
+
+  return !ec;
+#else
+  // https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man2/symlink.2.html
+  // https://linux.die.net/man/3/symlink
+  return symlink(target.data(), link.data()) == 0;
+#endif
+}
+
+
+bool fs_is_symlink(std::string path)
+{
+
+#if defined(__MINGW32__) || (defined(_WIN32) && !defined(__cpp_lib_filesystem))
+  return fs_win32_is_symlink(path);
+#elif defined(__cpp_lib_filesystem)
+// std::filesystem::symlink_status doesn't detect symlinks on MinGW
+  std::error_code ec;
+  const auto s = std::filesystem::symlink_status(path, ec);
+  return !ec && std::filesystem::is_symlink(s);
+#else
+  struct stat s;
+  return lstat(path.data(), &s) == 0 && S_ISLNK(s.st_mode);
+#endif
+}

src/symlink_fs.h

@@ -0,0 +1,4 @@
+#include <string>
+
+bool fs_is_symlink(std::string);
+bool fs_create_symlink(std::string, std::string);