gecko-dev/dom/system/gonk/OpenFileFinder.cpp

248 строки
6.9 KiB
C++

/* 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 "OpenFileFinder.h"
#include "mozilla/FileUtils.h"
#include "nsPrintfCString.h"
#include <sys/stat.h>
#include <errno.h>
#define USE_DEBUG 0
#undef LOG
#define LOG(args...) __android_log_print(ANDROID_LOG_INFO, "OpenFileFinder", ## args)
#define LOGW(args...) __android_log_print(ANDROID_LOG_WARN, "OpenFileFinder", ## args)
#define ERR(args...) __android_log_print(ANDROID_LOG_ERROR, "OpenFileFinder", ## args)
#if USE_DEBUG
#define DBG(args...) __android_log_print(ANDROID_LOG_DEBUG, "OpenFileFinder" , ## args)
#else
#define DBG(args...)
#endif
namespace mozilla {
namespace system {
OpenFileFinder::OpenFileFinder(const nsACString& aPath,
bool aCheckIsB2gOrDescendant /* = true */)
: mPath(aPath),
mProcDir(nullptr),
mFdDir(nullptr),
mPid(0),
mCheckIsB2gOrDescendant(aCheckIsB2gOrDescendant)
{
// We assume that we're running in the parent process
mMyPid = getpid();
}
OpenFileFinder::~OpenFileFinder()
{
Close();
}
bool
OpenFileFinder::First(OpenFileFinder::Info* aInfo)
{
Close();
mProcDir = opendir("/proc");
if (!mProcDir) {
return false;
}
mState = NEXT_PID;
return Next(aInfo);
}
bool
OpenFileFinder::Next(OpenFileFinder::Info* aInfo)
{
// NOTE: This function calls readdir and readlink, neither of which should
// block since we're using the proc filesystem, which is a purely
// kernel in-memory filesystem and doesn't depend on external driver
// behaviour.
while (mState != DONE) {
switch (mState) {
case NEXT_PID: {
struct dirent *pidEntry;
pidEntry = readdir(mProcDir);
if (!pidEntry) {
mState = DONE;
break;
}
char *endPtr;
mPid = strtol(pidEntry->d_name, &endPtr, 10);
if (mPid == 0 || *endPtr != '\0') {
// Not a +ve number - ignore
continue;
}
// We've found a /proc/PID directory. Scan open file descriptors.
if (mFdDir) {
closedir(mFdDir);
}
nsPrintfCString fdDirPath("/proc/%d/fd", mPid);
mFdDir = opendir(fdDirPath.get());
if (!mFdDir) {
continue;
}
mState = CHECK_FDS;
}
// Fall through
case CHECK_FDS: {
struct dirent *fdEntry;
while((fdEntry = readdir(mFdDir))) {
if (!strcmp(fdEntry->d_name, ".") ||
!strcmp(fdEntry->d_name, "..")) {
continue;
}
nsPrintfCString fdSymLink("/proc/%d/fd/%s", mPid, fdEntry->d_name);
nsCString resolvedPath;
if (ReadSymLink(fdSymLink, resolvedPath) && PathMatches(resolvedPath)) {
// We found an open file contained within the directory tree passed
// into the constructor.
FillInfo(aInfo, resolvedPath);
// If sCheckIsB2gOrDescendant is set false, the caller cares about
// all processes which have open files. If sCheckIsB2gOrDescendant
// is set false, we only care about the b2g proccess or its descendants.
if (!mCheckIsB2gOrDescendant || aInfo->mIsB2gOrDescendant) {
return true;
}
LOG("Ignore process(%d), not a b2g process or its descendant.",
aInfo->mPid);
}
}
// We've checked all of the files for this pid, move onto the next one.
mState = NEXT_PID;
continue;
}
case DONE:
default:
mState = DONE; // covers the default case
break;
}
}
return false;
}
void
OpenFileFinder::Close()
{
if (mFdDir) {
closedir(mFdDir);
}
if (mProcDir) {
closedir(mProcDir);
}
}
void
OpenFileFinder::FillInfo(OpenFileFinder::Info* aInfo, const nsACString& aPath)
{
aInfo->mFileName = aPath;
aInfo->mPid = mPid;
nsPrintfCString exePath("/proc/%d/exe", mPid);
ReadSymLink(exePath, aInfo->mExe);
aInfo->mComm.Truncate();
aInfo->mAppName.Truncate();
nsPrintfCString statPath("/proc/%d/stat", mPid);
nsCString statString;
statString.SetLength(200);
char *stat = statString.BeginWriting();
if (!stat) {
return;
}
ReadSysFile(statPath.get(), stat, statString.Length());
// The stat line includes the comm field, surrounded by parenthesis.
// However, the contents of the comm field itself is arbitrary and
// and can include ')', so we search for the rightmost ) as being
// the end of the comm field.
char *closeParen = strrchr(stat, ')');
if (!closeParen) {
return;
}
char *openParen = strchr(stat, '(');
if (!openParen) {
return;
}
if (openParen >= closeParen) {
return;
}
nsDependentCSubstring comm(&openParen[1], closeParen - openParen - 1);
aInfo->mComm = comm;
// There is a single character field after the comm and then
// the parent pid (the field we're interested in).
// ) X ppid
// 01234
int ppid = atoi(&closeParen[4]);
if (mPid == mMyPid) {
// This is chrome process
aInfo->mIsB2gOrDescendant = true;
DBG("Chrome process has open file(s)");
return;
}
// For the rest (non-chrome process), we recursively check the ppid to know
// it is a descendant of b2g or not. See bug 931456.
while (ppid != mMyPid && ppid != 1) {
DBG("Process(%d) is not forked from b2g(%d) or Init(1), keep looking",
ppid, mMyPid);
nsPrintfCString ppStatPath("/proc/%d/stat", ppid);
ReadSysFile(ppStatPath.get(), stat, statString.Length());
closeParen = strrchr(stat, ')');
if (!closeParen) {
return;
}
ppid = atoi(&closeParen[4]);
}
if (ppid == 1) {
// This is a not a b2g process.
DBG("Non-b2g process has open file(s)");
aInfo->mIsB2gOrDescendant = false;
return;
}
if (ppid == mMyPid) {
// This is a descendant of b2g.
DBG("Child process of chrome process has open file(s)");
aInfo->mIsB2gOrDescendant = true;
}
// This looks like a content process. The comm field will be the
// app name.
aInfo->mAppName = aInfo->mComm;
}
bool
OpenFileFinder::ReadSymLink(const nsACString& aSymLink, nsACString& aOutPath)
{
aOutPath.Truncate();
const char *symLink = aSymLink.BeginReading();
// Verify that we actually have a symlink.
struct stat st;
if (lstat(symLink, &st)) {
return false;
}
if ((st.st_mode & S_IFMT) != S_IFLNK) {
return false;
}
// Contrary to the documentation st.st_size doesn't seem to be a reliable
// indication of the length when reading from /proc, so we use a fixed
// size buffer instead.
char resolvedSymLink[PATH_MAX];
ssize_t pathLength = readlink(symLink, resolvedSymLink,
sizeof(resolvedSymLink) - 1);
if (pathLength <= 0) {
return false;
}
resolvedSymLink[pathLength] = '\0';
aOutPath.Assign(resolvedSymLink);
return true;
}
} // system
} // mozilla