Binary Patch Extractor

#include <stdio.h>

struct header
{
    int action;
    long size;
    char filename[512];
};

int main( int argc, char *argv[] )
{
    FILE *input;
    FILE *output;
    int size=13049;
    long fs=0;
    long count=0;
    char inbyte='\0';
    struct header index[256];
    long pos=0;
    char csize[512];
    int d=0;
    int end=0;
    char cmd[512];
    int fpos=0;

    if ( ( input = fopen(argv[0],"rb") ) == NULL ) exit(-1);
    //output=fopen("out.txt","wb");

    fseek(input,0L,SEEK_END);
    fs=ftell(input);
    fseek(input,size,SEEK_SET);

    while ( ! end )
    {
        inbyte='\0';
        fread(&inbyte,1,1,input);

        if ( inbyte == 'A' )
        {
            // ADD
            index[pos].action=0;

            for(d=0;d<3;d++)
                fread(&inbyte,1,1,input);

            inbyte='\0';
            fread(&inbyte,1,1,input);

            for(d=0;d<512;d++)
                csize[d]='\0';

            while ( inbyte != 32 )
            {
                csize[count]=inbyte;
                inbyte='\0';
                fread(&inbyte,1,1,input);
                count++;
            }count=0;

            // convert string to number
            index[pos].size=strtol(csize,NULL,10);
            printf("%s %d\n",csize, index[pos].size);

            inbyte='\0';
            fread(&inbyte,1,1,input);

            while ( inbyte != '\n' )
            {
                index[pos].filename[count]=inbyte;
                inbyte='\0';
                fread(&inbyte,1,1,input);
                count++;
            }count=0;

            printf("%d %s %d\n",index[pos].action, index[pos].filename, index[pos].size);

        }
        else if ( inbyte == 'U' )
        {
            // UPDATE
            for(d=0;d<6;d++)
                fread(&inbyte,1,1,input);

            index[pos].action=1;

            inbyte='\0';
            fread(&inbyte,1,1,input);

            for(d=0;d<512;d++)
                csize[d]='\0';

            while ( inbyte != 32 )
            {
                csize[count]=inbyte;
                inbyte='\0';
                fread(&inbyte,1,1,input);
                count++;
            }count=0;

            // convert string to number
            index[pos].size=strtol(csize,NULL,10);

            inbyte='\0';
            fread(&inbyte,1,1,input);

            while ( inbyte != '\n' )
            {
                index[pos].filename[count]=inbyte;
                inbyte='\0';
                fread(&inbyte,1,1,input);
                count++;
            }count=0;

            printf("%d %s %d\n",index[pos].action, index[pos].filename, index[pos].size);

        }
        else if ( inbyte == 'D' )
        {
            // DELETE
            for(d=0;d<6;d++)
                fread(&inbyte,1,1,input);

            index[pos].action=2;

            inbyte='\0';
            fread(&inbyte,1,1,input);

            while ( inbyte != '\n' )
            {
                index[pos].filename[count]=inbyte;
                inbyte='\0';
                fread(&inbyte,1,1,input);
                count++;
            }count=0;

            printf("%d %s\n",index[pos].action, index[pos].filename);

        }else{
            while ( inbyte != '\n' )
                fread(&inbyte,1,1,input);
            end=1;
        }


        pos++;
    }

    for(d=0;d<pos-1;d++)
    {
        if ( index[d].action == 2 )
        {
            strcpy(cmd,"rm ");
            strcat(cmd,index[d].filename);
            printf("Removing %s\n",index[d].filename);
            system(cmd);
        }
        else if ( index[d].action == 0 )
        {
            fpos=0;
            printf("Adding %s with size of %d bytes\n",index[d].filename, index[d].size);
            output=fopen(index[d].filename,"wb");
            while ( fpos < index[d].size )
            {
                inbyte='\0';
                fread(&inbyte,1,1,input);
                fwrite(&inbyte,1,1,output);
                fpos++;
            }
            fclose(output);
        }
        else if ( index[d].action == 1 )
        {
            strcpy(cmd,"rm ");
            strcat(cmd,index[d].filename);
            printf("Updating %s with size of %d bytes\n",index[d].filename, index[d].size);
            system(cmd);

            fpos=0;
            output=fopen(index[d].filename,"wb");
            while ( fpos < index[d].size )
            {
                inbyte='\0';
                fread(&inbyte,1,1,input);
                fwrite(&inbyte,1,1,output);
                fpos++;
            }
            fclose(output);


        }

    }

    fclose(input);
}