1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/dom/system/gonk/OpenFileFinder.cpp Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,247 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.6 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +#include "OpenFileFinder.h"
1.9 +
1.10 +#include "mozilla/FileUtils.h"
1.11 +#include "nsPrintfCString.h"
1.12 +
1.13 +#include <sys/stat.h>
1.14 +#include <errno.h>
1.15 +
1.16 +#define USE_DEBUG 0
1.17 +
1.18 +#undef LOG
1.19 +#define LOG(args...) __android_log_print(ANDROID_LOG_INFO, "OpenFileFinder", ## args)
1.20 +#define LOGW(args...) __android_log_print(ANDROID_LOG_WARN, "OpenFileFinder", ## args)
1.21 +#define ERR(args...) __android_log_print(ANDROID_LOG_ERROR, "OpenFileFinder", ## args)
1.22 +
1.23 +#if USE_DEBUG
1.24 +#define DBG(args...) __android_log_print(ANDROID_LOG_DEBUG, "OpenFileFinder" , ## args)
1.25 +#else
1.26 +#define DBG(args...)
1.27 +#endif
1.28 +
1.29 +namespace mozilla {
1.30 +namespace system {
1.31 +
1.32 +OpenFileFinder::OpenFileFinder(const nsACString& aPath,
1.33 + bool aCheckIsB2gOrDescendant /* = true */)
1.34 + : mPath(aPath),
1.35 + mProcDir(nullptr),
1.36 + mFdDir(nullptr),
1.37 + mPid(0),
1.38 + mCheckIsB2gOrDescendant(aCheckIsB2gOrDescendant)
1.39 +{
1.40 + // We assume that we're running in the parent process
1.41 + mMyPid = getpid();
1.42 +}
1.43 +
1.44 +OpenFileFinder::~OpenFileFinder()
1.45 +{
1.46 + Close();
1.47 +}
1.48 +
1.49 +bool
1.50 +OpenFileFinder::First(OpenFileFinder::Info* aInfo)
1.51 +{
1.52 + Close();
1.53 +
1.54 + mProcDir = opendir("/proc");
1.55 + if (!mProcDir) {
1.56 + return false;
1.57 + }
1.58 + mState = NEXT_PID;
1.59 + return Next(aInfo);
1.60 +}
1.61 +
1.62 +bool
1.63 +OpenFileFinder::Next(OpenFileFinder::Info* aInfo)
1.64 +{
1.65 + // NOTE: This function calls readdir and readlink, neither of which should
1.66 + // block since we're using the proc filesystem, which is a purely
1.67 + // kernel in-memory filesystem and doesn't depend on external driver
1.68 + // behaviour.
1.69 + while (mState != DONE) {
1.70 + switch (mState) {
1.71 + case NEXT_PID: {
1.72 + struct dirent *pidEntry;
1.73 + pidEntry = readdir(mProcDir);
1.74 + if (!pidEntry) {
1.75 + mState = DONE;
1.76 + break;
1.77 + }
1.78 + char *endPtr;
1.79 + mPid = strtol(pidEntry->d_name, &endPtr, 10);
1.80 + if (mPid == 0 || *endPtr != '\0') {
1.81 + // Not a +ve number - ignore
1.82 + continue;
1.83 + }
1.84 + // We've found a /proc/PID directory. Scan open file descriptors.
1.85 + if (mFdDir) {
1.86 + closedir(mFdDir);
1.87 + }
1.88 + nsPrintfCString fdDirPath("/proc/%d/fd", mPid);
1.89 + mFdDir = opendir(fdDirPath.get());
1.90 + if (!mFdDir) {
1.91 + continue;
1.92 + }
1.93 + mState = CHECK_FDS;
1.94 + }
1.95 + // Fall through
1.96 + case CHECK_FDS: {
1.97 + struct dirent *fdEntry;
1.98 + while((fdEntry = readdir(mFdDir))) {
1.99 + if (!strcmp(fdEntry->d_name, ".") ||
1.100 + !strcmp(fdEntry->d_name, "..")) {
1.101 + continue;
1.102 + }
1.103 + nsPrintfCString fdSymLink("/proc/%d/fd/%s", mPid, fdEntry->d_name);
1.104 + nsCString resolvedPath;
1.105 + if (ReadSymLink(fdSymLink, resolvedPath) && PathMatches(resolvedPath)) {
1.106 + // We found an open file contained within the directory tree passed
1.107 + // into the constructor.
1.108 + FillInfo(aInfo, resolvedPath);
1.109 + // If sCheckIsB2gOrDescendant is set false, the caller cares about
1.110 + // all processes which have open files. If sCheckIsB2gOrDescendant
1.111 + // is set false, we only care about the b2g proccess or its descendants.
1.112 + if (!mCheckIsB2gOrDescendant || aInfo->mIsB2gOrDescendant) {
1.113 + return true;
1.114 + }
1.115 + LOG("Ignore process(%d), not a b2g process or its descendant.",
1.116 + aInfo->mPid);
1.117 + }
1.118 + }
1.119 + // We've checked all of the files for this pid, move onto the next one.
1.120 + mState = NEXT_PID;
1.121 + continue;
1.122 + }
1.123 + case DONE:
1.124 + default:
1.125 + mState = DONE; // covers the default case
1.126 + break;
1.127 + }
1.128 + }
1.129 + return false;
1.130 +}
1.131 +
1.132 +void
1.133 +OpenFileFinder::Close()
1.134 +{
1.135 + if (mFdDir) {
1.136 + closedir(mFdDir);
1.137 + }
1.138 + if (mProcDir) {
1.139 + closedir(mProcDir);
1.140 + }
1.141 +}
1.142 +
1.143 +void
1.144 +OpenFileFinder::FillInfo(OpenFileFinder::Info* aInfo, const nsACString& aPath)
1.145 +{
1.146 + aInfo->mFileName = aPath;
1.147 + aInfo->mPid = mPid;
1.148 + nsPrintfCString exePath("/proc/%d/exe", mPid);
1.149 + ReadSymLink(exePath, aInfo->mExe);
1.150 + aInfo->mComm.Truncate();
1.151 + aInfo->mAppName.Truncate();
1.152 + nsPrintfCString statPath("/proc/%d/stat", mPid);
1.153 + nsCString statString;
1.154 + statString.SetLength(200);
1.155 + char *stat = statString.BeginWriting();
1.156 + if (!stat) {
1.157 + return;
1.158 + }
1.159 + ReadSysFile(statPath.get(), stat, statString.Length());
1.160 + // The stat line includes the comm field, surrounded by parenthesis.
1.161 + // However, the contents of the comm field itself is arbitrary and
1.162 + // and can include ')', so we search for the rightmost ) as being
1.163 + // the end of the comm field.
1.164 + char *closeParen = strrchr(stat, ')');
1.165 + if (!closeParen) {
1.166 + return;
1.167 + }
1.168 + char *openParen = strchr(stat, '(');
1.169 + if (!openParen) {
1.170 + return;
1.171 + }
1.172 + if (openParen >= closeParen) {
1.173 + return;
1.174 + }
1.175 + nsDependentCSubstring comm(&openParen[1], closeParen - openParen - 1);
1.176 + aInfo->mComm = comm;
1.177 + // There is a single character field after the comm and then
1.178 + // the parent pid (the field we're interested in).
1.179 + // ) X ppid
1.180 + // 01234
1.181 + int ppid = atoi(&closeParen[4]);
1.182 +
1.183 + if (mPid == mMyPid) {
1.184 + // This is chrome process
1.185 + aInfo->mIsB2gOrDescendant = true;
1.186 + DBG("Chrome process has open file(s)");
1.187 + return;
1.188 + }
1.189 + // For the rest (non-chrome process), we recursively check the ppid to know
1.190 + // it is a descendant of b2g or not. See bug 931456.
1.191 + while (ppid != mMyPid && ppid != 1) {
1.192 + DBG("Process(%d) is not forked from b2g(%d) or Init(1), keep looking",
1.193 + ppid, mMyPid);
1.194 + nsPrintfCString ppStatPath("/proc/%d/stat", ppid);
1.195 + ReadSysFile(ppStatPath.get(), stat, statString.Length());
1.196 + closeParen = strrchr(stat, ')');
1.197 + if (!closeParen) {
1.198 + return;
1.199 + }
1.200 + ppid = atoi(&closeParen[4]);
1.201 + }
1.202 + if (ppid == 1) {
1.203 + // This is a not a b2g process.
1.204 + DBG("Non-b2g process has open file(s)");
1.205 + aInfo->mIsB2gOrDescendant = false;
1.206 + return;
1.207 + }
1.208 + if (ppid == mMyPid) {
1.209 + // This is a descendant of b2g.
1.210 + DBG("Child process of chrome process has open file(s)");
1.211 + aInfo->mIsB2gOrDescendant = true;
1.212 + }
1.213 +
1.214 + // This looks like a content process. The comm field will be the
1.215 + // app name.
1.216 + aInfo->mAppName = aInfo->mComm;
1.217 +}
1.218 +
1.219 +bool
1.220 +OpenFileFinder::ReadSymLink(const nsACString& aSymLink, nsACString& aOutPath)
1.221 +{
1.222 + aOutPath.Truncate();
1.223 + const char *symLink = aSymLink.BeginReading();
1.224 +
1.225 + // Verify that we actually have a symlink.
1.226 + struct stat st;
1.227 + if (lstat(symLink, &st)) {
1.228 + return false;
1.229 + }
1.230 + if ((st.st_mode & S_IFMT) != S_IFLNK) {
1.231 + return false;
1.232 + }
1.233 +
1.234 + // Contrary to the documentation st.st_size doesn't seem to be a reliable
1.235 + // indication of the length when reading from /proc, so we use a fixed
1.236 + // size buffer instead.
1.237 +
1.238 + char resolvedSymLink[PATH_MAX];
1.239 + ssize_t pathLength = readlink(symLink, resolvedSymLink,
1.240 + sizeof(resolvedSymLink) - 1);
1.241 + if (pathLength <= 0) {
1.242 + return false;
1.243 + }
1.244 + resolvedSymLink[pathLength] = '\0';
1.245 + aOutPath.Assign(resolvedSymLink);
1.246 + return true;
1.247 +}
1.248 +
1.249 +} // system
1.250 +} // mozilla
