pacextractor.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/stat.h>

typedef struct {
    int16_t someField[24];
    int32_t someInt;
    int16_t productName[256];
    int16_t firmwareName[256];
    int32_t partitionCount;
    int32_t partitionsListStart;
    int32_t someIntFields1[5];
    int16_t productName2[50];
    int16_t someIntFields2[6];
    int16_t someIntFields3[2];
} PacHeader;

typedef struct {
    uint32_t length;
    int16_t partitionName[256];
    int16_t fileName[512];
    uint32_t partitionSize;
    int32_t someFileds1[2];
    uint32_t partitionAddrInPac;
    int32_t someFileds2[3];
    int32_t dataArray[];
} PartitionHeader;

void getString(int16_t* baseString, char* resString) {
    if(*baseString == 0) {
        *resString = 0;
        return;
    }
    int length = 0;
    do {
        *resString = 0xFF & *baseString;
        resString++;
        baseString++;
        if(++length > 256)
            break;
    } while(baseString > 0);
    *resString = 0;
}

int main(int argc, char** argv) {
    if(argc < 2) {
        printf("command format:\n   capextractor <firmware name>.pac");
        exit(EXIT_FAILURE);
    }
    
    int fd = open(argv[1], O_RDONLY);
    if (fd == -1) {
        printf("file %s is not find", argv[1]);
        exit(EXIT_FAILURE);
    }
    
//    fseek(fd, 0, SEEK_END);
//    int firmwareSize = (fd);
//    fseek(fd, 0, SEEK_SET);
    struct stat st;
    stat(argv[1], &st);
    int firmwareSize = st.st_size;
    if(firmwareSize < sizeof(PacHeader)) {
        printf("file %s is not firmware", argv[1]);
        exit(EXIT_FAILURE);
    }
    
    PacHeader pacHeader;
    size_t rb =read(fd, &pacHeader, sizeof(PacHeader));
    if(rb <= 0) {
        printf("Error while parsing PAC header");
        exit(EXIT_FAILURE);
    }

    char buffer[256];
    char buffer1[256];
    getString(pacHeader.firmwareName, buffer);
    printf("Firmware name: %s\n", buffer);
    uint32_t curPos = pacHeader.partitionsListStart;
    PartitionHeader** partHeaders = malloc(sizeof(PartitionHeader**)*pacHeader.partitionCount);
    int i;
    for(i = 0; i < pacHeader.partitionCount; i++) {
        lseek(fd, curPos, SEEK_SET);
        uint32_t length;
        rb =read(fd, &length, sizeof(uint32_t));
        if(rb <= 0) {
            printf("Partition header error");
            exit(EXIT_FAILURE);
        }
        partHeaders[i] = malloc(length);
        lseek(fd, curPos, SEEK_SET);
        curPos += length;
        rb =read(fd, partHeaders[i], length);
        if(rb <= 0) {
            printf("Partition header error");
            exit(EXIT_FAILURE);
        }
        getString(partHeaders[i]->partitionName, buffer);
        getString(partHeaders[i]->fileName, buffer1);
        printf("Partition name: %s\n\twith file name: %s\n\twith size %u\n", buffer, buffer1, partHeaders[i]->partitionSize);
    }
    
    for(i = 0; i < pacHeader.partitionCount; i++) {
        if(partHeaders[i]->partitionSize == 0) {
            free(partHeaders[i]);
            continue;
        }
        lseek(fd, partHeaders[i]->partitionAddrInPac, SEEK_SET);
        getString(partHeaders[i]->fileName, buffer);
        remove(buffer);
        int fd_new = open(buffer, O_WRONLY | O_CREAT, 0666);
        printf("Extract %s\n", buffer);
        uint32_t dataSizeLeft = partHeaders[i]->partitionSize;
        while(dataSizeLeft > 0) {
            uint32_t copyLength = (dataSizeLeft > 256) ? 256 : dataSizeLeft;
            dataSizeLeft -= copyLength;
            rb =read(fd, buffer, copyLength);
            if(rb != copyLength) {
                printf("Partition image extraction error");
                exit(EXIT_FAILURE);
            }
            rb = write(fd_new, buffer, copyLength);
            if(rb != copyLength) {
                printf("Partition image extraction error");
                exit(EXIT_FAILURE);
            }
            printf("\r\t%02d%%", (uint64_t)100 - (uint64_t)100*dataSizeLeft/partHeaders[i]->partitionSize);
        }
        printf("\n");
        close(fd_new);
        free(partHeaders[i]);
    }
    free(partHeaders);
    close(fd);
    
    return EXIT_SUCCESS;
}