The Tor Browser: dom/system/gonk/OpenFileFinder.cpp@b8a032363ba2 (annotated)

dom/system/gonk/OpenFileFinder.cpp@b8a032363ba2 (annotated)

dom/system/gonk/OpenFileFinder.cpp

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* 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

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dom/system/gonk/OpenFileFinder.cpp@b8a032363ba2 (annotated)

dom/system/gonk/OpenFileFinder.cpp