1 files changed, 251 insertions, 0 deletions
diff --git a/dom/system/gonk/OpenFileFinder.cpp b/dom/system/gonk/OpenFileFinder.cpp
new file mode 100644
index 000000000..388e813e1
--- /dev/null
+++ b/dom/system/gonk/OpenFileFinder.cpp
@@ -0,0 +1,251 @@
+/* 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>
+
+#undef USE_DEBUG
+#define USE_DEBUG 0
+
+#undef LOG
+#undef LOGW
+#undef ERR
+#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)
+
+#undef DBG
+#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