michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
michael@0:  * You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "OpenFileFinder.h"
michael@0: 
michael@0: #include "mozilla/FileUtils.h"
michael@0: #include "nsPrintfCString.h"
michael@0: 
michael@0: #include <sys/stat.h>
michael@0: #include <errno.h>
michael@0: 
michael@0: #define USE_DEBUG 0
michael@0: 
michael@0: #undef LOG
michael@0: #define LOG(args...)  __android_log_print(ANDROID_LOG_INFO,  "OpenFileFinder", ## args)
michael@0: #define LOGW(args...) __android_log_print(ANDROID_LOG_WARN,  "OpenFileFinder", ## args)
michael@0: #define ERR(args...)  __android_log_print(ANDROID_LOG_ERROR, "OpenFileFinder", ## args)
michael@0: 
michael@0: #if USE_DEBUG
michael@0: #define DBG(args...)  __android_log_print(ANDROID_LOG_DEBUG, "OpenFileFinder" , ## args)
michael@0: #else
michael@0: #define DBG(args...)
michael@0: #endif
michael@0: 
michael@0: namespace mozilla {
michael@0: namespace system {
michael@0: 
michael@0: OpenFileFinder::OpenFileFinder(const nsACString& aPath,
michael@0:                                bool aCheckIsB2gOrDescendant /* = true */)
michael@0:   : mPath(aPath),
michael@0:     mProcDir(nullptr),
michael@0:     mFdDir(nullptr),
michael@0:     mPid(0),
michael@0:     mCheckIsB2gOrDescendant(aCheckIsB2gOrDescendant)
michael@0: {
michael@0:   // We assume that we're running in the parent process
michael@0:   mMyPid = getpid();
michael@0: }
michael@0: 
michael@0: OpenFileFinder::~OpenFileFinder()
michael@0: {
michael@0:   Close();
michael@0: }
michael@0: 
michael@0: bool
michael@0: OpenFileFinder::First(OpenFileFinder::Info* aInfo)
michael@0: {
michael@0:   Close();
michael@0: 
michael@0:   mProcDir = opendir("/proc");
michael@0:   if (!mProcDir) {
michael@0:     return false;
michael@0:   }
michael@0:   mState = NEXT_PID;
michael@0:   return Next(aInfo);
michael@0: }
michael@0: 
michael@0: bool
michael@0: OpenFileFinder::Next(OpenFileFinder::Info* aInfo)
michael@0: {
michael@0:   // NOTE: This function calls readdir and readlink, neither of which should
michael@0:   //       block since we're using the proc filesystem, which is a purely
michael@0:   // kernel in-memory filesystem and doesn't depend on external driver
michael@0:   // behaviour.
michael@0:   while (mState != DONE) {
michael@0:     switch (mState) {
michael@0:       case NEXT_PID: {
michael@0:         struct dirent *pidEntry;
michael@0:         pidEntry = readdir(mProcDir);
michael@0:         if (!pidEntry) {
michael@0:           mState = DONE;
michael@0:           break;
michael@0:         }
michael@0:         char *endPtr;
michael@0:         mPid = strtol(pidEntry->d_name, &endPtr, 10);
michael@0:         if (mPid == 0 || *endPtr != '\0') {
michael@0:           // Not a +ve number - ignore
michael@0:           continue;
michael@0:         }
michael@0:         // We've found a /proc/PID directory. Scan open file descriptors.
michael@0:         if (mFdDir) {
michael@0:           closedir(mFdDir);
michael@0:         }
michael@0:         nsPrintfCString fdDirPath("/proc/%d/fd", mPid);
michael@0:         mFdDir = opendir(fdDirPath.get());
michael@0:         if (!mFdDir) {
michael@0:           continue;
michael@0:         }
michael@0:         mState = CHECK_FDS;
michael@0:       }
michael@0:       // Fall through
michael@0:       case CHECK_FDS: {
michael@0:         struct dirent *fdEntry;
michael@0:         while((fdEntry = readdir(mFdDir))) {
michael@0:           if (!strcmp(fdEntry->d_name, ".") ||
michael@0:               !strcmp(fdEntry->d_name, "..")) {
michael@0:             continue;
michael@0:           }
michael@0:           nsPrintfCString fdSymLink("/proc/%d/fd/%s", mPid, fdEntry->d_name);
michael@0:           nsCString resolvedPath;
michael@0:           if (ReadSymLink(fdSymLink, resolvedPath) && PathMatches(resolvedPath)) {
michael@0:             // We found an open file contained within the directory tree passed
michael@0:             // into the constructor.
michael@0:             FillInfo(aInfo, resolvedPath);
michael@0:             // If sCheckIsB2gOrDescendant is set false, the caller cares about
michael@0:             // all processes which have open files. If sCheckIsB2gOrDescendant
michael@0:             // is set false, we only care about the b2g proccess or its descendants.
michael@0:             if (!mCheckIsB2gOrDescendant || aInfo->mIsB2gOrDescendant) {
michael@0:               return true;
michael@0:             }
michael@0:             LOG("Ignore process(%d), not a b2g process or its descendant.",
michael@0:                 aInfo->mPid);
michael@0:           }
michael@0:         }
michael@0:         // We've checked all of the files for this pid, move onto the next one.
michael@0:         mState = NEXT_PID;
michael@0:         continue;
michael@0:       }
michael@0:       case DONE:
michael@0:       default:
michael@0:         mState = DONE;  // covers the default case
michael@0:         break;
michael@0:     }
michael@0:   }
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: void
michael@0: OpenFileFinder::Close()
michael@0: {
michael@0:   if (mFdDir) {
michael@0:     closedir(mFdDir);
michael@0:   }
michael@0:   if (mProcDir) {
michael@0:     closedir(mProcDir);
michael@0:   }
michael@0: }
michael@0: 
michael@0: void
michael@0: OpenFileFinder::FillInfo(OpenFileFinder::Info* aInfo, const nsACString& aPath)
michael@0: {
michael@0:   aInfo->mFileName = aPath;
michael@0:   aInfo->mPid = mPid;
michael@0:   nsPrintfCString exePath("/proc/%d/exe", mPid);
michael@0:   ReadSymLink(exePath, aInfo->mExe);
michael@0:   aInfo->mComm.Truncate();
michael@0:   aInfo->mAppName.Truncate();
michael@0:   nsPrintfCString statPath("/proc/%d/stat", mPid);
michael@0:   nsCString statString;
michael@0:   statString.SetLength(200);
michael@0:   char *stat = statString.BeginWriting();
michael@0:   if (!stat) {
michael@0:     return;
michael@0:   }
michael@0:   ReadSysFile(statPath.get(), stat, statString.Length());
michael@0:   // The stat line includes the comm field, surrounded by parenthesis.
michael@0:   // However, the contents of the comm field itself is arbitrary and
michael@0:   // and can include ')', so we search for the rightmost ) as being
michael@0:   // the end of the comm field.
michael@0:   char *closeParen = strrchr(stat, ')');
michael@0:   if (!closeParen) {
michael@0:     return;
michael@0:   }
michael@0:   char *openParen = strchr(stat, '(');
michael@0:   if (!openParen) {
michael@0:     return;
michael@0:   }
michael@0:   if (openParen >= closeParen) {
michael@0:     return;
michael@0:   }
michael@0:   nsDependentCSubstring comm(&openParen[1], closeParen - openParen - 1);
michael@0:   aInfo->mComm = comm;
michael@0:   // There is a single character field after the comm and then
michael@0:   // the parent pid (the field we're interested in).
michael@0:   // ) X ppid
michael@0:   // 01234
michael@0:   int ppid = atoi(&closeParen[4]);
michael@0: 
michael@0:   if (mPid == mMyPid) {
michael@0:     // This is chrome process
michael@0:     aInfo->mIsB2gOrDescendant = true;
michael@0:     DBG("Chrome process has open file(s)");
michael@0:     return;
michael@0:   }
michael@0:   // For the rest (non-chrome process), we recursively check the ppid to know
michael@0:   // it is a descendant of b2g or not. See bug 931456.
michael@0:   while (ppid != mMyPid && ppid != 1) {
michael@0:     DBG("Process(%d) is not forked from b2g(%d) or Init(1), keep looking",
michael@0:         ppid, mMyPid);
michael@0:     nsPrintfCString ppStatPath("/proc/%d/stat", ppid);
michael@0:     ReadSysFile(ppStatPath.get(), stat, statString.Length());
michael@0:     closeParen = strrchr(stat, ')');
michael@0:     if (!closeParen) {
michael@0:       return;
michael@0:     }
michael@0:     ppid = atoi(&closeParen[4]);
michael@0:   }
michael@0:   if (ppid == 1) {
michael@0:     // This is a not a b2g process.
michael@0:     DBG("Non-b2g process has open file(s)");
michael@0:     aInfo->mIsB2gOrDescendant = false;
michael@0:     return;
michael@0:   }
michael@0:   if (ppid == mMyPid) {
michael@0:     // This is a descendant of b2g.
michael@0:     DBG("Child process of chrome process has open file(s)");
michael@0:     aInfo->mIsB2gOrDescendant = true;
michael@0:   }
michael@0: 
michael@0:   // This looks like a content process. The comm field will be the
michael@0:   // app name.
michael@0:   aInfo->mAppName = aInfo->mComm;
michael@0: }
michael@0: 
michael@0: bool
michael@0: OpenFileFinder::ReadSymLink(const nsACString& aSymLink, nsACString& aOutPath)
michael@0: {
michael@0:   aOutPath.Truncate();
michael@0:   const char *symLink = aSymLink.BeginReading();
michael@0: 
michael@0:   // Verify that we actually have a symlink.
michael@0:   struct stat st;
michael@0:   if (lstat(symLink, &st)) {
michael@0:       return false;
michael@0:   }
michael@0:   if ((st.st_mode & S_IFMT) != S_IFLNK) {
michael@0:       return false;
michael@0:   }
michael@0: 
michael@0:   // Contrary to the documentation st.st_size doesn't seem to be a reliable
michael@0:   // indication of the length when reading from /proc, so we use a fixed
michael@0:   // size buffer instead.
michael@0: 
michael@0:   char resolvedSymLink[PATH_MAX];
michael@0:   ssize_t pathLength = readlink(symLink, resolvedSymLink,
michael@0:                                 sizeof(resolvedSymLink) - 1);
michael@0:   if (pathLength <= 0) {
michael@0:       return false;
michael@0:   }
michael@0:   resolvedSymLink[pathLength] = '\0';
michael@0:   aOutPath.Assign(resolvedSymLink);
michael@0:   return true;
michael@0: }
michael@0: 
michael@0: } // system
michael@0: } // mozilla