Add a tool to extract pakfiles

Makefile

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+# The compiler
+CC := gcc
+
+# ----------
+
+# Base CFLAGS
+CFLAGS := -O2 -Wall -ansi -pedantic
+
+# ----------
+
+# When make is invoked by "make VERBOSE=1" print
+# the compiler and linker commands.
+ifdef VERBOSE
+Q :=
+else
+Q := @
+endif
+
+# ----------
+
+# The converter rule
+%.o: %.c
+	@echo '===> CC $<'
+	${Q}$(CC) -c $(CFLAGS) -o $@ $<
+
+# ----------
+
+PAK_OBJS = \
+	pakextract.o
+
+# ----------
+
+pakextract: $(PAK_OBJS)
+	@echo '===> LD $@'
+	${Q}$(CC) $(PAK_OBJS) -o $@
+               
+# ----------
+
+clean:
+	@echo "===> CLEAN"
+	${Q}rm -Rf pakextract.o pakextract
+

README

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+                      pakextract
+                      ----------
+
+pakextract is a small tool to extract the contents of 
+a Quake II pak file into the current directory. Usage:
+ 
+ ./pakextract /path/to/pakfile.pak
+
+Only Quake II paks are supported. Other pak formats may
+work but it's untested and unsupported.
+
+-------------------------------------------------------
+
+            The Quake II Pak File Format
+            ----------------------------
+
+A Quake II pak file consists of 3 parts:
+ - Header
+ - Directory
+ - Data
+
+The header is written right after the start
+of the file and consists of 3 parts in the
+following order:
+ - A 4 byte identification string "PACK" (in ASCII)
+ - A 4 byte integer value defining the offset to the
+   directory in bytes
+ - A 4 byte iteger giving the length of the directory
+   in bytes. Since every directory entry is 64 bytes 
+   long this value modulo 64 must be 0: 
+     (dir_length % 64) == 0;
+
+The directory can be anywere in the file but most times
+it's written to the end. In consists of datablocks, 
+written one after the other without any space between
+them. A directory entry is 64 bytes long has entries
+in the following order:
+ - A 56 byte file name (in ASCII)
+ - A 4 byte value defining the position if the file
+   as an offset in bytes to the start of the pak file.
+ - A 4 byte integer giving the length of the file
+   in bytes.

pakextract.c

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+/*-
+ * Copyright (c) 2012 Yamagi Burmeister
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+
+/* Holds the pak header */
+struct
+{
+	char signature[4];
+	int dir_offset;
+	int dir_length;
+} header;
+
+/* A directory entry */
+struct directory_s
+{
+	char file_name[56];
+	int file_pos;
+	int file_length;
+	struct directory_s *next;
+};
+typedef struct directory_s directory;
+ 
+/*
+ * Creates a directory tree.
+ *
+ *  *s -> The path to create. The last
+ *        part (the file itself) is
+ *        ommitted
+ */
+void
+mktree(char *s)
+{
+	char *dir;
+	char *elements[28];
+	char *path;
+	char *token;
+	int i, j;
+
+	path = calloc(56, sizeof(char));
+	dir = malloc(sizeof(char) * 56);
+
+	strncpy(dir, s, sizeof(char) * 56);
+
+	for (i = 0; (token = strsep(&dir, "/")) != NULL; i++)
+	{
+		elements[i] = token;
+	}
+
+	for (j = 0; j < i - 1; j++)
+	{
+		strcat(path, elements[j]);
+		strcat(path, "/");
+
+		mkdir(path, 0700);
+	}
+
+	free(path);
+	free(dir);
+}
+
+/*
+ * Reads the pak file header and
+ * stores it into the global struct
+ * "header".
+ *
+ *  *fd -> A file descriptor holding
+ *         the pack to be read.
+ */
+int
+read_header(FILE *fd)
+{
+    if (fread(&header, sizeof(header), 1, fd) != 1)
+	{
+		perror("Could not read the pak file header");
+		return -1;
+	}
+
+	if (strncmp(header.signature, "PACK", 4))
+	{
+		fprintf(stderr, "Not a pak file\n");
+		return -1;
+	}
+
+	if ((header.dir_length % 64) != 0)
+	{
+		fprintf(stderr, "Corrupt pak file\n");
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Reads the directory of a pak file
+ * into a linked list and returns 
+ * a pointer to the first element.
+ *
+ *  *fd -> a file descriptor holding
+ *         holding the pak to be read
+ */ 
+directory *
+read_directory(FILE *fd)
+{
+	int i;
+	directory *head, *cur;
+
+	head = NULL;
+
+	/* Navigate to the directory */
+	fseek(fd, header.dir_offset, SEEK_SET);
+
+	for (i = 0; i < (header.dir_length / 64); i++)
+	{
+		cur = malloc(sizeof(directory));
+
+		if (fread(cur, sizeof(directory) - sizeof(directory *), 1, fd) != 1)
+		{
+			perror("Could not read directory entry");
+			return NULL;
+		}
+
+		cur->next = head;
+		head = cur;
+	}
+
+	return head;
+}
+
+/* 
+ * Extract the files from a pak.
+ *
+ *  *d -> a pointer to the first element
+ *        of the pak directory
+ *
+ *  *fd -> a file descriptor holding
+ *         the pak to be extracted
+ */
+void
+extract_files(FILE *fd, directory *d)
+{
+	char b;
+	directory *old_d;
+	FILE *out;
+	int i;
+
+	while (d != NULL)
+	{
+	    mktree(d->file_name);
+
+        out = fopen(d->file_name, "w");
+		if (out == NULL)
+		{
+			perror("Could open the outputfile");
+			return;
+		}
+
+		fseek(fd, d->file_pos, SEEK_SET);
+
+		for (i = 0; i < d->file_length; i++)
+		{
+			fread(&b, sizeof(char), 1, fd);
+			fwrite(&b, sizeof(char), 1, out);
+		}
+
+		fclose(out);
+
+		old_d = d;
+		d = d->next;
+		free(old_d);
+	}
+}
+
+/*
+ * A small programm to extract a Quake II pak file.
+ * The pak file is given as the first an only 
+ * argument.
+ */
+int
+main(int argc, char *argv[])
+{
+	directory *d;
+	FILE *fd;
+
+	/* Correct usage? */
+	if (argc != 2)
+	{
+		fprintf(stderr, "Usage: %s pakfile\n", argv[0]);
+		exit(-1);
+	}
+
+	/* Open the pak file */
+	fd = fopen(argv[1], "r");
+	if (fd == NULL)
+	{
+		perror("Could not open the pak file");
+		exit(-1);
+	}
+
+	/* Read the header */
+    if (read_header(fd) < 0)
+	{
+		fclose(fd);
+		exit(-1);
+	}
+
+	/* Read the directory */
+	d = read_directory(fd);
+	if (d == NULL)
+	{
+		fclose(fd);
+		exit(-1);
+	}
+
+	/* And now extract the files */
+	extract_files(fd, d);
+
+	/* cleanup */
+	fclose(fd);
+
+	return 0;
+}
+