Simple utility to extract all files from an Unreal umod file.

slumod.c

// slumod
// simple utility to extract all files from an Unreal umod file
// only tested with UT99 umods
// reference: http://wiki.beyondunreal.com/Legacy:UMOD/File_Format
// doesn't preserve directories. extracts to same dir as executable
// umod file needs to be renamed to pack.umod and placed in same dir
// public domain

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>

uint8_t i = 0;

FILE* umodFile = NULL;

typedef struct
{
	char filename[64];
	uint32_t offs;
	uint32_t size;
	uint32_t flags; // Unused
} dirEntry_t;

dirEntry_t* entries = NULL;
uint32_t numEntries = 0;

void DumpFile( const char* filename, uint32_t offs, uint32_t size ) {
	printf( "Dumping %s...\n", filename );

	uint8_t* data = (uint8_t*)malloc( size );
	fseek( umodFile, offs, SEEK_SET );
	fread( data, size, 1, umodFile );

	FILE* dumpedFile = fopen( filename, "wb" );
	fwrite( data, size, 1, dumpedFile );

	fclose( dumpedFile );
	free( data );
}

int main( int argc, char** argv ) {
	umodFile = fopen( "pack.umod", "rb" );
	if ( umodFile == NULL ) {
		fprintf( stderr, "Could not open file.\n" );
		exit( EXIT_FAILURE );
	}

	// Seek to "header". 20 bytes from end
	fseek( umodFile, -20, SEEK_END ); // SEEK_END aint portable bro
	uint32_t HED = ftell( umodFile ); // Beggining of header marker
	uint32_t magic = 0;
	fread( &magic, 4, 1, umodFile );
	printf( "0x%0x\n", magic );
	uint32_t dirOffs = 0;
	fread( &dirOffs, 4, 1, umodFile );
	printf( "Dir offs: 0x%0x\n", dirOffs );

	// Seek to dir offs. +1 because first byte isnt really the first filename size
	fseek( umodFile, dirOffs + 1, SEEK_SET );
	//uint32_t EOD = ftell( umodFile ) - 1; // End of data marker

	// Read entries
	while ( ftell( umodFile ) < HED ) {
		numEntries++;
		entries = (dirEntry_t*)realloc( entries, sizeof(dirEntry_t) * numEntries );
		uint8_t fnl = 0;
		fread( &fnl, 1, 1, umodFile );
		fread( entries[numEntries-1].filename, 1, fnl, umodFile );
		fread( &entries[numEntries-1].offs, 4, 1, umodFile );
		fread( &entries[numEntries-1].size, 4, 1, umodFile );
		fread( &entries[numEntries-1].flags, 4, 1, umodFile ); // Silly flags
	}

	/*for ( i = 0; i < numEntries; ++i ) {
		printf( "Filename: %s\n", entries[i].filename );
		printf( "Offset: %0x\n", entries[i].offs );
		printf( "Size: %d\n", entries[i].size );
	}*/
	for ( i = 0; i < numEntries; ++i ) {
		// trim this bitch
		char* fname = strchr( entries[i].filename, '\\' ) + 1;

		DumpFile( fname, entries[i].offs, entries[i].size );
	}
	printf( "%d entries.\n", numEntries );

	free( entries );
	fclose( umodFile );

	return 0;
}