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[ C ] multidemensional array pass to functions

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# 1  
Old 12-05-2008
[ C ] multidemensional array pass to functions
Please excuse my ineptitude for a bit as I've been spoiled for the past few months with only writing perl code instead of C.

So ok, I've been thinking about some code to change the crc32 values that are held within central directory headers of zip files.

Because I'm lazy I decided to just hack up some archive repair tool to write the desired crc32.

What I figured I could do was make a multidimensional array of ints to pass to the function that will do all the messy work.


Here is the relevant code:

Code:
int crcSpoof( char* file, char* fileOut, char* fileOutTmp, ulong* nRecovered, ulong* bytesRecovered, int** CRC_Array )

...

int main( int argc, char** argv )
{
    int i = 3; // start with the 3rd value of argv
    int** crc_s; 
    
    // Some argument testing here

    while( argv[ i ] )
       crc_s = argv[ i ];
    
    crcSpoof( argv[1], argv[2], "fileOutTmp", NULL, NULL, crc_s );

I feel that this is probably ok but I really can't test it until I baseline some units around here.


Thanks!
# 2  
Old 12-06-2008
Most of the source code looks alright with the exception of one statement. Dual-level pointer crc_s cannot be equated to uni-level pointer argv[i] as they are incompatible in terms of the pointer levels. crc_s is of type char** while argv[i] is of type char*.
Quote:
Originally Posted by VRoemer
Code:
int crcSpoof( char* file, char* fileOut, char* fileOutTmp, ulong* nRecovered, ulong* bytesRecovered, int** CRC_Array )

...

int main( int argc, char** argv )
{
    int i = 3; // start with the 3rd value of argv
    int** crc_s; 
    
    // Some argument testing here

    while( argv[ i ] )
       crc_s = argv[ i ]; /* the compiler will complain about this line */ 
    
    crcSpoof( argv[1], argv[2], "fileOutTmp", NULL, NULL, crc_s );

# 3  
Old 12-06-2008
Ow yes that does look like an issue

Alright so here are my updates, I was also thinking that I need to change my command line ascii codes to actual integers like this.

Now I'm coming to think that this could perhaps lead to some memory issues, so I might also be obligated to throw in a *alloc.

Code:
int main( int argc, char** argv )
{
    int i = 3; // start with the 3rd value of argv
    int** crc_s; 
    
    // Some argument testing here

    while( argv[ i ] ) {
       crc_s[ i ] = malloc( sizeof(argv[i]) );
       if( crc_s[ i ] == NULL )
           exit( -1 );
       crc_s[ i ] = atoi( argv[ i ] ); // Perhaps this is a better way of doing it
    }

    crcSpoof( argv[1], argv[2], "fileOutTmp", NULL, NULL, crc_s );

Hopefully thats the proper way to allocate memory ( I have never really done much with allocating memory )
Last edited by VRoemer; 12-06-2008 at 06:19 PM..
# 4  
Old 12-08-2008
Well there is one major point in your code that I completely missed before. I mistakenly thought crc_s was of type char** when it actually is of type int**. Casting char** to int** won't work (most likely crash the program with a SIGBUS) as char** addresses are not guaranted to be aligned on a word boundary.
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