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Commit 0e3f47e4 authored by Colin Cross's avatar Colin Cross
Browse files

append2simg: write to temporary file 

append2simg causes libsparse to write mmapped data from a file
back to that same file.  On btrfs, this sometimes causes a page
of zeroes to be written instead of the file data.  Work around
the issue by writing the output to a temporary file and then
renaming it over the original file.

Change-Id: Ia194b6ba0ddb8548747b63292b523756f544706a
parent 9fdc8156

libsparse/Android.mk

+3 −0
Original line number Diff line number Diff line
@@ -81,6 +81,8 @@ LOCAL_STATIC_LIBRARIES := \ 
include $(BUILD_EXECUTABLE)





ifneq ($(HOST_OS),windows)



include $(CLEAR_VARS)

LOCAL_SRC_FILES := append2simg.c

LOCAL_MODULE := append2simg
@@ -89,6 +91,7 @@ LOCAL_STATIC_LIBRARIES := \ 
    libz

include $(BUILD_HOST_EXECUTABLE)



endif



include $(CLEAR_VARS)

LOCAL_MODULE := simg_dump.py

libsparse/append2simg.c

+29 −1
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 


#define _FILE_OFFSET_BITS 64

#define _LARGEFILE64_SOURCE 1

#define _GNU_SOURCE



#include <errno.h>

#include <fcntl.h>
@@ -56,6 +57,11 @@ int main(int argc, char *argv[]) 
    char *input_path;

    off64_t input_len;



    int tmp_fd;

    char *tmp_path;



    int ret;



    if (argc == 3) {

        output_path = argv[1];

        input_path = argv[2];
@@ -64,6 +70,12 @@ int main(int argc, char *argv[]) 
        exit(-1);

    }



    ret = asprintf(&tmp_path, "%s.append2simg", output_path);

    if (ret < 0) {

        fprintf(stderr, "Couldn't allocate filename\n");

        exit(-1);

    }



    output = open(output_path, O_RDWR | O_BINARY);

    if (output < 0) {

        fprintf(stderr, "Couldn't open output file (%s)\n", strerror(errno));
@@ -99,14 +111,30 @@ int main(int argc, char *argv[]) 
    }

    sparse_output->len += input_len;



    tmp_fd = open(tmp_path, O_WRONLY | O_CREAT | O_BINARY, 0664);

    if (tmp_fd < 0) {

        fprintf(stderr, "Couldn't open temporary file (%s)\n", strerror(errno));

        exit(-1);

    }



    lseek64(output, 0, SEEK_SET);

    if (sparse_file_write(sparse_output, output, false, true, false) < 0) {

    if (sparse_file_write(sparse_output, tmp_fd, false, true, false) < 0) {

        fprintf(stderr, "Failed to write sparse file\n");

        exit(-1);

    }



    sparse_file_destroy(sparse_output);

    close(tmp_fd);

    close(output);

    close(input);



    ret = rename(tmp_path, output_path);

    if (ret < 0) {

        fprintf(stderr, "Failed to rename temporary file (%s)\n", strerror(errno));

        exit(-1);

    }



    free(tmp_path);



    exit(0);

}