add unicode compatible file_lock for Windows

boost::interprocess::file_lock cannot open the files that contain characters which cannot be parsed by the user's code page on Windows.
This commit add a new class to handle those specific file for Windows.

1 files changed, 85 insertions, 0 deletions

diff --git a/src/fs.cpp b/src/fs.cpp
index 570ed3e2ee..e7d06e45ab 100644
--- a/src/fs.cpp
+++ b/src/fs.cpp
@@ -1,5 +1,12 @@
 #include <fs.h>
 
+#ifndef WIN32
+#include <fcntl.h>
+#else
+#include <codecvt>
+#include <windows.h>
+#endif
+
 namespace fsbridge {
 
 FILE *fopen(const fs::path& p, const char *mode)
@@ -12,4 +19,82 @@ FILE *freopen(const fs::path& p, const char *mode, FILE *stream)
     return ::freopen(p.string().c_str(), mode, stream);
 }
 
+#ifndef WIN32
+
+static std::string GetErrorReason() {
+    return std::strerror(errno);
+}
+
+FileLock::FileLock(const fs::path& file)
+{
+    fd = open(file.string().c_str(), O_RDWR);
+    if (fd == -1) {
+        reason = GetErrorReason();
+    }
+}
+
+FileLock::~FileLock()
+{
+    if (fd != -1) {
+        close(fd);
+    }
+}
+
+bool FileLock::TryLock()
+{
+    if (fd == -1) {
+        return false;
+    }
+    struct flock lock;
+    lock.l_type = F_WRLCK;
+    lock.l_whence = SEEK_SET;
+    lock.l_start = 0;
+    lock.l_len = 0;
+    if (fcntl(fd, F_SETLK, &lock) == -1) {
+        reason = GetErrorReason();
+        return false;
+    }
+    return true;
+}
+#else
+
+static std::string GetErrorReason() {
+    wchar_t* err;
+    FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+        nullptr, GetLastError(), MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), reinterpret_cast<WCHAR*>(&err), 0, nullptr);
+    std::wstring err_str(err);
+    LocalFree(err);
+    return std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>>().to_bytes(err_str);
+}
+
+FileLock::FileLock(const fs::path& file)
+{
+    hFile = CreateFileW(file.wstring().c_str(),  GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+        nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);
+    if (hFile == INVALID_HANDLE_VALUE) {
+        reason = GetErrorReason();
+    }
+}
+
+FileLock::~FileLock()
+{
+    if (hFile != INVALID_HANDLE_VALUE) {
+        CloseHandle(hFile);
+    }
+}
+
+bool FileLock::TryLock()
+{
+    if (hFile == INVALID_HANDLE_VALUE) {
+        return false;
+    }
+    _OVERLAPPED overlapped = {0};
+    if (!LockFileEx(hFile, LOCKFILE_EXCLUSIVE_LOCK | LOCKFILE_FAIL_IMMEDIATELY, 0, 0, 0, &overlapped)) {
+        reason = GetErrorReason();
+        return false;
+    }
+    return true;
+}
+#endif
+
 } // fsbridge