Implement process.title for cygwin

src/platform_cygwin.cc

@@ -3,11 +3,31 @@
 
 #include <sys/param.h> // for MAXPATHLEN
 #include <unistd.h> // getpagesize
+#include <windows.h>
 
 
 namespace node {
 
 static char buf[MAXPATHLEN + 1];
+static char *process_title = NULL;
+
+
+// Does the about the same as perror(), but for windows api functions
+static void _winapi_perror(const char* prefix = NULL) {
+  DWORD errno = GetLastError();
+  char *errmsg;
+
+  FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS,
+                NULL, errno, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPTSTR)&errmsg, 0, NULL);
+
+  // FormatMessage messages include a newline character
+
+  if (prefix) {
+    fprintf(stderr, "%s: %s", prefix, errmsg);
+  } else {
+    fputs(errmsg, stderr);
+  }
+}
 
 
 char** OS::SetupArgs(int argc, char *argv[]) {
@@ -16,13 +36,123 @@ char** OS::SetupArgs(int argc, char *argv[]) {
 
 
 void OS::SetProcessTitle(char *title) {
-  ;
+  // We need to convert _title_ to UTF-16 first, because that's what windows uses internally.
+  // It would be more efficient to use the UTF-16 value that we can obtain from v8,
+  // but it's not accessible from here.
+
+  // Max title length; according to the specs it should be 64K but in practice it's a little over 30000,
+  // but who needs titles that long anyway?
+  const int MAX_TITLE_LENGTH = 30001;
+
+  int length;
+  WCHAR *title_w;
+
+  // Find out how big the buffer for the wide-char title must be
+  length = MultiByteToWideChar(CP_UTF8, 0, title, -1, NULL, 0);
+  if (!length) {
+    _winapi_perror("MultiByteToWideChar");
+    return;
+  }
+
+  // Convert to wide-char string
+  title_w = new WCHAR[length];
+  length = MultiByteToWideChar(CP_UTF8, 0, title, -1, title_w, length);
+  if (!length) {
+    _winapi_perror("MultiByteToWideChar");
+    delete title_w;
+    return;
+  };
+
+  // If the title must be truncated insert a \0 terminator there
+  if (length > MAX_TITLE_LENGTH) {
+    title_w[MAX_TITLE_LENGTH - 1] = *L"\0";
+  }
+
+  if (!SetConsoleTitleW(title_w)) {
+    _winapi_perror("SetConsoleTitleW");
+  }
+
+  free(process_title);
+  process_title = strdup(title);
+
+  delete title_w;
+}
+
+
+static inline char* _getProcessTitle() {
+  WCHAR *title_w;
+  char *title;
+  int length, length_w;
+
+  length_w = GetConsoleTitleW(L"\0", sizeof(WCHAR));
+
+  // If length is zero, there may be an error or the title may be empty
+  if (!length_w) {
+    if (GetLastError()) {
+      _winapi_perror("GetConsoleTitleW");
+      return NULL;
+    }
+    else {
+      // The title is empty, so return empty string
+      process_title = strdup("\0");
+      return process_title;
+    }
+  }
+
+  // Room for \0 terminator
+  length_w++;
+
+  title_w = new WCHAR[length_w];
+
+  if (!GetConsoleTitleW(title_w, length_w * sizeof(WCHAR))) {
+    _winapi_perror("GetConsoleTitleW");
+    delete title_w;
+    return NULL;
+  }
+
+  // Find out what the size of the buffer is that we need
+  length = WideCharToMultiByte(CP_UTF8, 0, title_w, length_w, NULL, 0, NULL, NULL);
+  if (!length) {
+    _winapi_perror("WideCharToMultiByte");
+    delete title_w;
+    return NULL;
+  }
+
+  title = (char *) malloc(length);
+  if (!title) {
+    perror("malloc");
+    delete title_w;
+    return NULL;
+  }
+
+  // Do utf16 -> utf8 conversion here
+  if (!WideCharToMultiByte(CP_UTF8, 0, title_w, -1, title, length, NULL, NULL)) {
+    _winapi_perror("WideCharToMultiByte");
+    delete title_w;
+    free(title);
+    return NULL;
+  }
+
+  delete title_w;
+
+  return title;
 }
 
 
 const char* OS::GetProcessTitle(int *len) {
-  *len = 0;
-  return NULL;
+  // If the process_title was never read before nor explicitly set,
+  // we must query it with getConsoleTitleW
+  if (!process_title) {
+    process_title = _getProcessTitle();
+  }
+
+  if (process_title) {
+    *len = strlen(process_title);
+    return process_title;
+  } else {
+    *len = 0;
+    return NULL;
+  }
 }