First step to create application shortcuts on Linux.

chrome/browser/shell_integration_linux.cc

 // Copyright (c) 2006-2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/shell_integration.h"
 
 #include <fcntl.h>
 #include <stdlib.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <unistd.h>
 
 #include <vector>
 
+#include "base/file_path.h"
+#include "base/file_util.h"
+#include "base/message_loop.h"
+#include "base/path_service.h"
 #include "base/process_util.h"
+#include "base/string_tokenizer.h"
+#include "base/string_util.h"
+#include "base/task.h"
+#include "base/thread.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/common/chrome_paths.h"
+#include "googleurl/src/gurl.h"
 
-static const char* GetDesktopName() {
+namespace {
+
+const char* GetDesktopName() {
 #if defined(GOOGLE_CHROME_BUILD)
   return "google-chrome.desktop";
 #else  // CHROMIUM_BUILD
   static const char* name = NULL;
   if (!name) {
     // Allow $CHROME_DESKTOP to override the built-in value, so that development
     // versions can set themselves as the default without interfering with
     // non-official, packaged versions using the built-in value.
     name = getenv("CHROME_DESKTOP");
     if (!name)
       name = "chromium-browser.desktop";
   }
   return name;
 #endif
 }
 
+bool GetDesktopShortcutTemplate(std::string* output) {
+  std::vector<std::string> search_paths;
+
+  const char* xdg_data_home = getenv("XDG_DATA_HOME");

[Lei Zhang, 2009/08/14 20:18:33]

This will not work because almost nobody has $XDG_DATA_HOME set. If you can't
get this env variable, you should default to $HOME/.local/share. Same for
XDG_DATA_DIRS below - defaults to /usr/local/share:/usr/share. (per XDG basedir
specs)

+  if (xdg_data_home)
+    search_paths.push_back(xdg_data_home);
+
+  const char* xdg_data_dirs = getenv("XDG_DATA_DIRS");
+  if (xdg_data_dirs) {
+    StringTokenizer tokenizer(xdg_data_dirs, ":");
+    while (tokenizer.GetNext()) {
+      search_paths.push_back(tokenizer.token());
+    }
+  }
+
+  std::string template_filename(GetDesktopName());
+  for (std::vector<std::string>::const_iterator i = search_paths.begin();
+       i != search_paths.end(); ++i) {
+    FilePath path = FilePath(*i).Append(template_filename);

[Lei Zhang, 2009/08/14 20:18:33]

Are you expecting to find /usr/share/google-chrome.desktop? You should be
looking in path.Append('applications') followed by path.Append('applnk').

Applnk is a legacy directory, but we seem to be putting our
google-chrome.desktop there?! I'll look into that.

[Mike Mammarella, 2009/08/14 20:56:22]

I'm not sure we need to check applnk, but definitely we need to append
"applications" before template_filename.

+    if (file_util::PathExists(path))
+      return file_util::ReadFileToString(path, output);
+  }
+
+  return false;
+}
+
+class CreateDesktopShortcutTask : public Task {
+ public:
+  CreateDesktopShortcutTask(const GURL& url, const string16& title)
+      : url_(url),
+        title_(title) {
+  }
+
+  virtual void Run() {
+    // TODO(phajdan.jr): Report errors from this function, possibly as infobars.
+    FilePath desktop_path;
+    if (!PathService::Get(chrome::DIR_USER_DESKTOP, &desktop_path))
+      return;
+    desktop_path =
+        desktop_path.Append(ShellIntegration::GetDesktopShortcutFilename(url_));
+
+    if (file_util::PathExists(desktop_path))
+      return;
+
+    std::string template_contents;
+    if (!GetDesktopShortcutTemplate(&template_contents))
+      return;
+
+    std::string contents = ShellIntegration::GetDesktopFileContents(
+        template_contents, url_, title_);
+    int bytes_written = file_util::WriteFile(desktop_path, contents.data(),
+                                             contents.length());
+    if (bytes_written != static_cast<int>(contents.length())) {
+      file_util::Delete(desktop_path, false);
+    }
+  }
+
+ private:
+  const GURL url_;  // URL of the web application.
+  const string16 title_;  // Title displayed to the user.
+
+  DISALLOW_COPY_AND_ASSIGN(CreateDesktopShortcutTask);
+};
+
+}  // namespace
+
 // We delegate the difficult of setting the default browser in Linux desktop
 // environments to a new xdg utility, xdg-settings. We'll have to include a copy
 // of it for this to work, obviously, but that's actually the suggested approach
 // for xdg utilities anyway.
 
 bool ShellIntegration::SetAsDefaultBrowser() {
   std::vector<std::string> argv;
   argv.push_back("xdg-settings");
   argv.push_back("set");
   argv.push_back("default-web-browser");
@@ skipping 47 matching lines @@
   std::vector<std::string> argv;
   argv.push_back("xdg-settings");
   argv.push_back("get");
   argv.push_back("default-web-browser");
 
   std::string browser;
   // We don't care about the return value here.
   base::GetAppOutput(CommandLine(argv), &browser);
   return browser.find("irefox") != std::string::npos;
 }
+
+FilePath ShellIntegration::GetDesktopShortcutFilename(const GURL& url) {
+  std::wstring filename = UTF8ToWide(url.spec()) + L".desktop";
+  file_util::ReplaceIllegalCharacters(&filename, '_');
+
+  // Return BaseName to be absolutely sure we're not vulnerable to a directory
+  // traversal attack.
+  return FilePath::FromWStringHack(filename).BaseName();
+}
+
+std::string ShellIntegration::GetDesktopFileContents(
+    const std::string& template_contents, const GURL& url,
+    const string16& title) {
+  // See http://standards.freedesktop.org/desktop-entry-spec/latest/
+  std::string output_buffer;
+  StringTokenizer tokenizer(template_contents, "\n");
+  while (tokenizer.GetNext()) {
+    // TODO(phajdan.jr): Add the icon.
+
+    if (tokenizer.token().substr(0, 5) == "Exec=") {
+      std::string exec_path = tokenizer.token().substr(5);
+      StringTokenizer exec_tokenizer(exec_path, " ");
+      std::string final_path;
+      while (exec_tokenizer.GetNext()) {
+        if (exec_tokenizer.token() != "%U")
+          final_path += exec_tokenizer.token() + " ";
+      }
+      std::string app_switch(StringPrintf("\"--app=%s\"",

[Mike Mammarella, 2009/08/14 20:56:22]

This should use switches::kApp.

+                                          url.spec().c_str()));

[Evan Martin, 2009/08/18 14:43:08]

Does this make us vulnerable to some sort of command line escaping attack?  What
if url.spec() includes quotes?

+      ReplaceSubstringsAfterOffset(&app_switch, 0, "%", "%%");
+      output_buffer += std::string("Exec=") + final_path + app_switch + "\n";
+    } else if (tokenizer.token().substr(0, 5) == "Name=") {
+      std::string final_title = UTF16ToUTF8(title);
+      // Make sure no endline characters can slip in and possibly introduce
+      // additional lines (like Exec, which makes it a security risk). Also
+      // use the URL as a default when the title is empty.
+      if (final_title.empty() ||
+          final_title.find("\n") != std::string::npos ||
+          final_title.find("\r") != std::string::npos)
+        final_title = url.spec();
+      output_buffer += StringPrintf("Name=%s\n", final_title.c_str());
+    } else if (tokenizer.token().substr(0, 8) == "Comment=") {
+      // Skip the line.
+    } else {
+      output_buffer += tokenizer.token() + "\n";
+    }
+  }
+  return output_buffer;
+}
+
+void ShellIntegration::CreateDesktopShortcut(const GURL& url,
+                                             const string16& title) {
+  g_browser_process->file_thread()->message_loop()->PostTask(FROM_HERE,
+      new CreateDesktopShortcutTask(url, title));
+}