Bug 1851095 - Step 2: Connect setproctitle to the fork server. r=nika

This adds a small function that concatenates the args (because not
only does the BSD `setproctitle` take a single string, but also the
Linux kernel code that implements `/proc/{pid}/cmdline` won't allow the
"arguments" to extend past their original length unless it's a single
string), and connects it to the fork server.

Differential Revision: https://phabricator.services.mozilla.com/D187635

ipc/chromium/src/base/process_util_linux.cc

@@ -27,6 +27,7 @@
 #  include "mozilla/Unused.h"
 #  include "mozilla/ScopeExit.h"
 #  include "mozilla/ipc/ProcessUtils.h"
+#  include "mozilla/ipc/SetProcessTitle.h"
 
 using namespace mozilla::ipc;
 #endif
@@ -142,6 +143,7 @@ void AppProcessBuilder::ReplaceArguments(int* argcp, char*** argvp) {
   *p = nullptr;
   *argvp = argv;
   *argcp = argv_.size();
+  mozilla::SetProcessTitle(argv_);
 }
 
 void AppProcessBuilder::InitAppProcess(int* argcp, char*** argvp) {

ipc/glue/ForkServer.cpp

@@ -14,6 +14,7 @@
 #include "mozilla/ipc/FileDescriptor.h"
 #include "mozilla/ipc/IPDLParamTraits.h"
 #include "mozilla/ipc/ProtocolMessageUtils.h"
+#include "mozilla/ipc/SetProcessTitle.h"
 #include "nsTraceRefcnt.h"
 
 #include <fcntl.h>
@@ -256,6 +257,8 @@ bool ForkServer::RunForkServer(int* aArgc, char*** aArgv) {
   bool sleep_newproc = !!getenv("MOZ_FORKSERVER_WAIT_GDB_NEWPROC");
 #endif
 
+  SetProcessTitleInit(*aArgv);
+
   // Do this before NS_LogInit() to avoid log files taking lower
   // FDs.
   ForkServer forkserver;

ipc/glue/SetProcessTitle.cpp

@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/ipc/SetProcessTitle.h"
+
+#include "nsString.h"
+
+#ifdef XP_LINUX
+
+#  include "base/set_process_title_linux.h"
+#  define HAVE_SETPROCTITLE
+#  define HAVE_SETPROCTITLE_INIT
+
+#elif defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || \
+    defined(__DragonFly__)
+
+#  include <sys/types.h>
+#  include <unistd.h>
+#  define HAVE_SETPROCTITLE
+
+#endif
+
+namespace mozilla {
+
+void SetProcessTitle(const std::vector<std::string>& aNewArgv) {
+#ifdef HAVE_SETPROCTITLE
+  nsAutoCStringN<1024> buf;
+
+  bool firstArg = true;
+  for (const std::string& arg : aNewArgv) {
+    if (firstArg) {
+      firstArg = false;
+    } else {
+      buf.Append(' ');
+    }
+    buf.Append(arg.c_str());
+  }
+
+  setproctitle("-%s", buf.get());
+#endif
+}
+
+void SetProcessTitleInit(char** aOrigArgv) {
+#ifdef HAVE_SETPROCTITLE_INIT
+  setproctitle_init(aOrigArgv);
+#endif
+}
+
+}  // namespace mozilla

ipc/glue/SetProcessTitle.h

@@ -0,0 +1,19 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ipc_SetProcessTitle_h
+#define mozilla_ipc_SetProcessTitle_h
+
+#include <string>
+#include <vector>
+
+namespace mozilla {
+
+void SetProcessTitle(const std::vector<std::string>& aNewArgv);
+void SetProcessTitleInit(char** aOrigArgv);
+
+}  // namespace mozilla
+
+#endif  // mozilla_ipc_SetProcessTitle_h

ipc/glue/moz.build

@@ -125,9 +125,19 @@ else:
 if CONFIG["OS_ARCH"] == "Linux":
     UNIFIED_SOURCES += [
         "ProcessUtils_linux.cpp",
+        "SetProcessTitle.cpp",
+    ]
+    EXPORTS.mozilla.ipc += [
+        "SetProcessTitle.h",
     ]
 elif CONFIG["OS_ARCH"] in ("DragonFly", "FreeBSD", "NetBSD", "OpenBSD"):
-    UNIFIED_SOURCES += ["ProcessUtils_bsd.cpp"]
+    UNIFIED_SOURCES += [
+        "ProcessUtils_bsd.cpp",
+        "SetProcessTitle.cpp",
+    ]
+    EXPORTS.ipc += [
+        "SetProcessTitle.h",
+    ]
 elif CONFIG["OS_ARCH"] == "Darwin":
     UNIFIED_SOURCES += ["ProcessUtils_mac.mm"]
 else: