#!/bin/sh
: "
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"

# gtagallery - a shell script to extract JPEG images from the GALLERY.DAT
# file in a PS2 "Grand Theft Auto: San Andreas" save on a *ix system.
#
# Copyright © 2009 Ben Winslow <gtagallery at t dot themuffin dot net>
# Version 0.2, 2009-07-13
#
# Released under a Creative Commons Attribution-Noncommercial-
# Share Alike 3.0 United States License.

# GTA:SA's GALLERY.DAT is composed of 80 KiB chunks, each starting with
# JPEG image data followed by unknown data for the remainder of the chunk.
# This script uses dd to pull out the the chunks, and jpegtran (part of
# libjpeg) to losslessly remove the unknown data and optimize the Huffman
# tables in an attempt to get a smaller image.

trap 'exit 1' INT

imgpos=0
imgex=0
imgok=0

INFILE="$1"
OUTFMT="$2"

# Default output format
if [ -z "$OUTFMT" ]; then
	OUTFMT="gtasa-%03d.jpg"
fi

# Display help if no file is specified or it's unreadable
if [ "$#" -lt 1 -o ! -r "$INFILE" ]; then
	echo "Usage: $0 <gallery.dat> [outputfmt]" >&2
	echo "Parameters: " >&2
	echo "  <gallery.dat>: the file name of a GALLERY.DAT extracted from a" >&2
	echo "    Grand Theft Auto: San Andreas (PS2) save." >&2
	echo "  [outputfmt]: (default \`gtasa-%03d'): a printf(3) style format string" >&2
	echo "    for the output file names." >&2
	exit 1
fi

# Check for jpegtran
if ! which jpegtran > /dev/null; then
	echo "Warning: Unable to find the \`jpegtran' utility from libjpeg/libjpeg-progs!" >&2
	echo "Without this utility, all JPEG images extracted will be exactly 80KiB and" >&2
	echo "contain superfluous data at the end of the file." >&2
	echo >&2
	HAVE_JPEGTRAN=0
else
	HAVE_JPEGTRAN=1
fi

# Verify $OUTFMT actually has a proper format character
if [ "`printf "$OUTFMT" 1`" = "`printf "$OUTFMT" 2`" ]; then
	echo "Warning: The specified output format ($OUTFMT) does not provide" >&2
	echo "unique file names!  Only the first image will be extracted." >&2
fi

INFILE_SIZE="`du -k "$INFILE" | awk '{print $1}'`"
imgcnt=$((INFILE_SIZE / 80))

echo "Processing file: ${INFILE} (${imgcnt} images)..."

while [ $imgpos -lt $imgcnt ]; do
	OUTFILE="`printf "$OUTFMT" $((imgpos + 1))`"

	printf "\rImage %3d: extracting...              " $((imgpos + 1))

	if [ -e "$OUTFILE" ]; then
		printf "\rSkipping image %3d (output file \`%s' already exists!)\n" $((imgpos + 1)) "$OUTFILE" >&2
		imgpos=$((imgpos + 1))
		continue
	fi

	dd if="$INFILE" of="$OUTFILE" bs=81920 count=1 skip=$imgpos >/dev/null 2>&1
	# If dd spits out a 0-byte file, assume EOF
	if [ -e "$OUTFILE" -a ! -s "$OUTFILE" ]; then
		printf "\rImage %3d: not present (end of file)\n" $((imgpos + 1))
		rm -f "$OUTFILE"
		break
	fi

	imgex=$((imgex + 1))

	# Use jpegtran to drop the extra data after the image and optimize
	# the image's Huffman table.
	if [ "x$HAVE_JPEGTRAN" = "x1" ]; then
		printf "\rImage %3d: extracting... optimizing..." $((imgpos + 1))
		jpegtran -copy none -optimize -progressive -outfile "$OUTFILE" "$OUTFILE" 2>/dev/null
		if [ "x$?" != "x0" ]; then
			printf "\nWarning: image %3d (%s) may be corrupt!\n" $((imgpos + 1)) $OUTFILE >&2
		else
			imgok=$((imgok + 1))
		fi
	fi
	imgpos=$((imgpos + 1))
done
printf "\rDone.  Extracted %d of %d images (%d verified OK.)\n" $imgex $imgcnt $imgok
exit 0
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