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Commit a56245f3 authored by Pawan Wagh's avatar Pawan Wagh
Browse files

Block align start and length while punching holes 

If hole punching offset is within block, kernel will write
zeros forcefully. Block align offset and length used for punching
to avoid unnecessary write to the disk while punching.

Test: acloud delete --all && m && acloud create --local-instance --local-image && adb logcat -c && m FileSystemUtilsTests && atest -c FileSystemUtilsTests
Bug: 301631861
Change-Id: Ib65e4fb9419125e89e9253bec769fce53304649a
parent bd836d4c

core/jni/com_android_internal_content_FileSystemUtils.cpp

+40 −13
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <android-base/file.h>

#include <android-base/hex.h>

#include <android-base/unique_fd.h>

#include <bionic/macros.h>

#include <elf.h>

#include <errno.h>

#include <fcntl.h>
@@ -35,10 +36,45 @@ 
#include <fstream>

#include <vector>



using android::base::borrowed_fd;

using android::base::HexString;

using android::base::ReadFullyAtOffset;



namespace android {



bool punchWithBlockAlignment(borrowed_fd fd, uint64_t start, uint64_t length, uint64_t blockSize) {

    uint64_t end;

    if (__builtin_add_overflow(start, length, &end)) {

        ALOGE("Overflow occurred when calculating end");

        return false;

    }



    start = align_up(start, blockSize);

    end = align_down(end, blockSize);



    uint64_t alignedLength;

    if (__builtin_sub_overflow(end, start, &alignedLength)) {

        ALOGE("Overflow occurred when calculating length");

        return false;

    }



    if (alignedLength < blockSize) {

        ALOGW("Skipping punching hole as aligned length is less than block size");

        return false;

    }



    ALOGD("Punching hole in file - start: %" PRIu64 " len:%" PRIu64 "", start, alignedLength);



    int result =

            fallocate(fd.get(), FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, start, alignedLength);

    if (result < 0) {

        ALOGE("fallocate failed to punch hole, error:%d", errno);

        return false;

    }



    return true;

}



bool punchHoles(const char *filePath, const uint64_t offset,

                const std::vector<Elf64_Phdr> &programHeaders) {

    struct stat64 beforePunch;
@@ -96,6 +132,8 @@ bool punchHoles(const char *filePath, const uint64_t offset, 
            continue;

        }



        // if we have a uncompressed file which is being opened from APK, use the offset to

        // punch native lib inside Apk.

        uint64_t punchStartOffset;

        if (__builtin_add_overflow(offset, punchOffset, &punchStartOffset)) {

            ALOGE("Overflow occurred when calculating length");
@@ -144,12 +182,7 @@ bool punchHoles(const char *filePath, const uint64_t offset, 
            position = uncheckedChunkEnd;

        }



        // if we have a uncompressed file which is being opened from APK, use the offset to

        // punch native lib inside Apk.

        int result = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, punchStartOffset,

                               punchLen);

        if (result < 0) {

            ALOGE("fallocate failed to punch hole, error:%d", errno);

        if (!punchWithBlockAlignment(fd, punchStartOffset, punchLen, blockSize)) {

            return false;

        }

    }
@@ -298,13 +331,7 @@ bool punchHolesInZip(const char *filePath, uint64_t offset, uint16_t extraFieldL 
                return false;

            }



            ALOGD("Punching hole in apk start: %" PRIu64 " len:%" PRIu64 "", punchOffset, punchLen);



            // Punch hole for this entire stretch.

            int result = fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, punchOffset,

                                   punchLen);

            if (result < 0) {

                ALOGE("fallocate failed to punch hole inside apk, error:%d", errno);

            if (!punchWithBlockAlignment(fd, punchOffset, punchLen, blockSize)) {

                return false;

            }

        }