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Commit 694948c0 authored by Jing Ji's avatar Jing Ji Committed by Automerger Merge Worker
Browse files

Keep reading until end-of-file in reading procfs am: 7c5b6d11 

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/3171623



Change-Id: I8fadfe281fd01e47fb7a2cc0fafc5b544b2d7544
Signed-off-by: default avatarAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
parents f491ad5e 7c5b6d11

core/jni/android_util_Process.cpp

+31 −21
Original line number Diff line number Diff line
@@ -1063,8 +1063,8 @@ jboolean android_os_Process_readProcFile(JNIEnv* env, jobject clazz, 
    }

    env->ReleaseStringUTFChars(file, file8);



    // Most proc files we read are small, so we only go through the

    // loop once and use the stack buffer.  We allocate a buffer big

    // Most proc files we read are small, so we go through the loop

    // with the stack buffer firstly. We allocate a buffer big

    // enough for the whole file.



    char readBufferStack[kProcReadStackBufferSize];
@@ -1072,30 +1072,38 @@ jboolean android_os_Process_readProcFile(JNIEnv* env, jobject clazz, 
    char* readBuffer = &readBufferStack[0];

    ssize_t readBufferSize = kProcReadStackBufferSize;

    ssize_t numberBytesRead;

    off_t offset = 0;

    for (;;) {

        ssize_t requestedBufferSize = readBufferSize - offset;

        // By using pread, we can avoid an lseek to rewind the FD

        // before retry, saving a system call.

        numberBytesRead = pread(fd, readBuffer, readBufferSize, 0);

        if (numberBytesRead < 0 && errno == EINTR) {

            continue;

        }

        numberBytesRead =

                TEMP_FAILURE_RETRY(pread(fd, readBuffer + offset, requestedBufferSize, offset));

        if (numberBytesRead < 0) {

            if (kDebugProc) {

                ALOGW("Unable to open process file: %s fd=%d\n", file8, fd.get());

                ALOGW("Unable to read process file err: %s file: %s fd=%d\n",

                      strerror_r(errno, &readBufferStack[0], sizeof(readBufferStack)), file8,

                      fd.get());

            }

            return JNI_FALSE;

        }

        if (numberBytesRead < readBufferSize) {

        if (numberBytesRead == 0) {

            // End of file.

            numberBytesRead = offset;

            break;

        }

        if (numberBytesRead < requestedBufferSize) {

            // Read less bytes than requested, it's not an error per pread(2).

            offset += numberBytesRead;

        } else {

            // Buffer is fully used, try to grow it.

            if (readBufferSize > std::numeric_limits<ssize_t>::max() / 2) {

                if (kDebugProc) {

                    ALOGW("Proc file too big: %s fd=%d\n", file8, fd.get());

                }

                return JNI_FALSE;

            }

        readBufferSize = std::max(readBufferSize * 2,

                                  kProcReadMinHeapBufferSize);

            readBufferSize = std::max(readBufferSize * 2, kProcReadMinHeapBufferSize);

            readBufferHeap.reset(); // Free address space before getting more.

            readBufferHeap = std::make_unique<char[]>(readBufferSize);

            if (!readBufferHeap) {
@@ -1103,6 +1111,8 @@ jboolean android_os_Process_readProcFile(JNIEnv* env, jobject clazz, 
                return JNI_FALSE;

            }

            readBuffer = readBufferHeap.get();

            offset = 0;

        }

    }



    // parseProcLineArray below modifies the buffer while parsing!