pbzx2.c

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <lzma.h>


int main(int argc, const char * argv[])
{

    // Dumps a pbzx to stdout. Can work as a filter if no argument is specified

    char buffer[1024];
    int fd = 0;

    if (argc < 2) { fd  = 0 ;}
    else { fd = open (argv[1], O_RDONLY);
           if (fd < 0) { perror (argv[1]); exit(5); }
         }


    read (fd, buffer, 4);
    if (strncmp(buffer, "pbzx", 4)) { fprintf(stderr, "Can't find pbzx magic\n"); exit(0);}

    // Now, if it IS a pbzx

    uint64_t length = 0, flags = 0;

    read (fd, &flags, sizeof (uint64_t));
    flags = __builtin_bswap64(flags);

    fprintf(stderr,"Flags: 0x%llx\n", flags);

    int i = 0;
    int off = 0;

    while (flags &   0x01000000) { // have more chunks
    int cat = 0;
    i++;
    read (fd, &flags, sizeof (uint64_t));
    flags = __builtin_bswap64(flags);
    read (fd, &length, sizeof (uint64_t));
    length = __builtin_bswap64(length);

    fprintf(stderr,"Chunk #%d (flags: %llx, length: %lld bytes)\n",i, flags,length);
     
    // Let's ignore the fact I'm allocating based on user input, etc..
    char *buf = malloc (length);
    read (fd, buf, length);

   // We want the XZ header/footer if it's the payload, but prepare_payload doesn't have that, 
    // so just warn.
    

    if (strncmp(buf, "\xfd""7zXZ\0", 6))  { cat = 1; fprintf (stderr, "Warning: Can't find XZ header. This is likely not XZ data.\n"); }
    else // if we have the header, we had better have a footer, too
    if (strncmp(buf + length -2, "YZ", 2)) { fprintf (stderr, "Warning: Can't find XZ footer. This is bad.\n"); exit(1); }

    // [xerub] cat/unxz here
    if (cat) {
        write (1, buf, length);
    } else {
        uint64_t memlimit = -1;
        size_t max = ((length > 16 * 1024 * 1024) ? length : (16 * 1024 * 1024)) * 10;
        size_t in_pos = 0;
        size_t out_pos = 0;
        unsigned char *output = malloc(max);
        if (!output) {
            fprintf(stderr, "out of memory. abort\n");
            exit(1);
        }
        int rv = lzma_stream_buffer_decode(&memlimit, 0, NULL, (void *)buf, &in_pos, length, output, &out_pos, max);
        if (rv) {
            fprintf(stderr, "xz returned %d. abort\n", rv);
            exit(1);
        }
        write(1, output, out_pos);
        free(output);
    }

    }

    return 0;
}