gecko-dev/b2g/app/B2GLoader.cpp

299 lines
7.6 KiB
C++

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set sw=2 ts=2 autoindent cindent expandtab: */
/* 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 "nsXULAppAPI.h"
#include "application.ini.h"
#include "nsXPCOMGlue.h"
#include "nsStringGlue.h"
#include "nsCOMPtr.h"
#include "nsIFile.h"
#include "BinaryPath.h"
#include "nsAutoPtr.h"
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <dlfcn.h>
#include "nsXPCOMPrivate.h" // for MAXPATHLEN and XPCOM_DLL
#define ASSERT(x) if (!(x)) { MOZ_CRASH(); }
// Functions being loaded by XPCOMGlue
XRE_ProcLoaderServiceRunType XRE_ProcLoaderServiceRun;
XRE_ProcLoaderClientInitType XRE_ProcLoaderClientInit;
XRE_ProcLoaderPreloadType XRE_ProcLoaderPreload;
extern XRE_CreateAppDataType XRE_CreateAppData;
extern XRE_GetFileFromPathType XRE_GetFileFromPath;
static const nsDynamicFunctionLoad kXULFuncs[] = {
{ "XRE_ProcLoaderServiceRun", (NSFuncPtr*) &XRE_ProcLoaderServiceRun },
{ "XRE_ProcLoaderClientInit", (NSFuncPtr*) &XRE_ProcLoaderClientInit },
{ "XRE_ProcLoaderPreload", (NSFuncPtr*) &XRE_ProcLoaderPreload },
{ "XRE_CreateAppData", (NSFuncPtr*) &XRE_CreateAppData },
{ "XRE_GetFileFromPath", (NSFuncPtr*) &XRE_GetFileFromPath },
{ nullptr, nullptr }
};
typedef mozilla::Vector<int> FdArray;
static const int kReservedFileDescriptors = 5;
static const int kBeginReserveFileDescriptor = STDERR_FILENO + 1;
static int
GetDirnameSlash(const char *aPath, char *aOutDir, int aMaxLen)
{
char *lastSlash = strrchr(aPath, XPCOM_FILE_PATH_SEPARATOR[0]);
if (lastSlash == nullptr) {
return 0;
}
int cpsz = lastSlash - aPath + 1; // include slash
if (aMaxLen <= cpsz) {
return 0;
}
strncpy(aOutDir, aPath, cpsz);
aOutDir[cpsz] = 0;
return cpsz;
}
static bool
GetXPCOMPath(const char *aProgram, char *aOutPath, int aMaxLen)
{
nsAutoArrayPtr<char> progBuf(new char[aMaxLen]);
nsresult rv = mozilla::BinaryPath::Get(aProgram, progBuf);
NS_ENSURE_SUCCESS(rv, false);
int len = GetDirnameSlash(progBuf, aOutPath, aMaxLen);
NS_ENSURE_TRUE(!!len, false);
NS_ENSURE_TRUE((len + sizeof(XPCOM_DLL)) < (unsigned)aMaxLen, false);
char *afterSlash = aOutPath + len;
strcpy(afterSlash, XPCOM_DLL);
return true;
}
static bool
LoadLibxul(const char *aXPCOMPath)
{
nsresult rv;
XPCOMGlueEnablePreload();
rv = XPCOMGlueStartup(aXPCOMPath);
NS_ENSURE_SUCCESS(rv, false);
rv = XPCOMGlueLoadXULFunctions(kXULFuncs);
NS_ENSURE_SUCCESS(rv, false);
return true;
}
/**
* Return true if |arg| matches the given argument name.
*/
static bool
IsArg(const char* arg, const char* s)
{
if (*arg == '-') {
if (*++arg == '-') {
++arg;
}
return !strcasecmp(arg, s);
}
#if defined(XP_WIN)
if (*arg == '/') {
return !strcasecmp(++arg, s);
}
#endif
return false;
}
static already_AddRefed<nsIFile>
GetAppIni(int argc, const char *argv[])
{
nsCOMPtr<nsIFile> appini;
nsresult rv;
// Allow firefox.exe to launch XULRunner apps via -app <application.ini>
// Note that -app must be the *first* argument.
const char *appDataFile = getenv("XUL_APP_FILE");
if (appDataFile && *appDataFile) {
rv = XRE_GetFileFromPath(appDataFile, getter_AddRefs(appini));
NS_ENSURE_SUCCESS(rv, nullptr);
} else if (argc > 1 && IsArg(argv[1], "app")) {
if (argc == 2) {
return nullptr;
}
rv = XRE_GetFileFromPath(argv[2], getter_AddRefs(appini));
NS_ENSURE_SUCCESS(rv, nullptr);
char appEnv[MAXPATHLEN];
snprintf(appEnv, MAXPATHLEN, "XUL_APP_FILE=%s", argv[2]);
if (putenv(appEnv)) {
return nullptr;
}
}
return appini.forget();
}
static bool
LoadStaticData(int argc, const char *argv[])
{
char xpcomPath[MAXPATHLEN];
bool ok = GetXPCOMPath(argv[0], xpcomPath, MAXPATHLEN);
NS_ENSURE_TRUE(ok, false);
ok = LoadLibxul(xpcomPath);
NS_ENSURE_TRUE(ok, false);
char progDir[MAXPATHLEN];
ok = GetDirnameSlash(xpcomPath, progDir, MAXPATHLEN);
NS_ENSURE_TRUE(ok, false);
nsCOMPtr<nsIFile> appini = GetAppIni(argc, argv);
const nsXREAppData *appData;
if (appini) {
nsresult rv =
XRE_CreateAppData(appini, const_cast<nsXREAppData**>(&appData));
NS_ENSURE_SUCCESS(rv, false);
} else {
appData = &sAppData;
}
XRE_ProcLoaderPreload(progDir, appData);
if (appini) {
XRE_FreeAppData(const_cast<nsXREAppData*>(appData));
}
return true;
}
/**
* Fork and run parent and child process.
*
* The parent is the b2g process and child for Nuwa.
*/
static int
RunProcesses(int argc, const char *argv[], FdArray& aReservedFds)
{
/*
* The original main() of the b2g process. It is renamed to
* b2g_main() for the b2g loader.
*/
int b2g_main(int argc, const char *argv[]);
int ipcSockets[2] = {-1, -1};
int r = socketpair(AF_LOCAL, SOCK_STREAM, 0, ipcSockets);
ASSERT(r == 0);
int parentSock = ipcSockets[0];
int childSock = ipcSockets[1];
r = fcntl(parentSock, F_SETFL, O_NONBLOCK);
ASSERT(r != -1);
r = fcntl(childSock, F_SETFL, O_NONBLOCK);
ASSERT(r != -1);
pid_t pid = fork();
ASSERT(pid >= 0);
bool isChildProcess = pid == 0;
close(isChildProcess ? parentSock : childSock);
if (isChildProcess) {
/* The Nuwa process */
/* This provides the IPC service of loading Nuwa at the process.
* The b2g process would send a IPC message of loading Nuwa
* as the replacement of forking and executing plugin-container.
*/
return XRE_ProcLoaderServiceRun(getppid(), childSock, argc, argv,
aReservedFds);
}
// Reap zombie child process.
struct sigaction sa;
sa.sa_handler = SIG_IGN;
sigemptyset(&sa.sa_mask);
sa.sa_flags = 0;
sigaction(SIGCHLD, &sa, nullptr);
// The b2g process
int childPid = pid;
XRE_ProcLoaderClientInit(childPid, parentSock, aReservedFds);
return b2g_main(argc, argv);
}
/**
* Reserve the file descriptors that shouldn't be taken for other use for the
* child process.
*/
static void
ReserveFileDescriptors(FdArray& aReservedFds)
{
for (int i = 0; i < kReservedFileDescriptors; i++) {
struct stat fileState;
int target = kBeginReserveFileDescriptor + i;
if (fstat(target, &fileState) == 0) {
MOZ_CRASH("ProcLoader error: a magic file descriptor is occupied.");
}
int fd = open("/dev/null", O_RDWR);
if (fd == -1) {
MOZ_CRASH("ProcLoader error: failed to reserve a magic file descriptor.");
}
aReservedFds.append(target);
if (fd == target) {
// No need to call dup2(). We already occupy the desired file descriptor.
continue;
}
if (dup2(fd, target)) {
MOZ_CRASH("ProcLoader error: failed to reserve a magic file descriptor.");
}
close(fd);
}
}
/**
* B2G Loader is responsible for loading the b2g process and the
* Nuwa process. It forks into the parent process, for the b2g
* process, and the child process, for the Nuwa process.
*
* The loader loads libxul and performs initialization of static data
* before forking, so relocation of libxul and static data can be
* shared between the b2g process, the Nuwa process, and the content
* processes.
*/
int
main(int argc, const char* argv[])
{
/**
* Reserve file descriptors before loading static data.
*/
FdArray reservedFds;
ReserveFileDescriptors(reservedFds);
/*
* Before fork(), libxul and static data of Gecko are loaded for
* sharing.
*/
bool ok = LoadStaticData(argc, argv);
if (!ok) {
return 255;
}
return RunProcesses(argc, argv, reservedFds);
}