Odin/core/compress/gzip/example.odin

//+ignore
package gzip

/*
	Copyright 2021 Jeroen van Rijn <nom@duclavier.com>.
	Made available under Odin's BSD-2 license.

	List of contributors:
		Jeroen van Rijn: Initial implementation.
		Ginger Bill:     Cosmetic changes.

	A small GZIP implementation as an example.
*/

import "core:bytes"
import "core:os"
import "core:compress"
import "core:fmt"

// Small GZIP file with fextra, fname and fcomment present.
@private
TEST: []u8 = {
	0x1f, 0x8b, 0x08, 0x1c, 0xcb, 0x3b, 0x3a, 0x5a,
	0x02, 0x03, 0x07, 0x00, 0x61, 0x62, 0x03, 0x00,
	0x63, 0x64, 0x65, 0x66, 0x69, 0x6c, 0x65, 0x6e,
	0x61, 0x6d, 0x65, 0x00, 0x54, 0x68, 0x69, 0x73,
	0x20, 0x69, 0x73, 0x20, 0x61, 0x20, 0x63, 0x6f,
	0x6d, 0x6d, 0x65, 0x6e, 0x74, 0x00, 0x2b, 0x48,
	0xac, 0xcc, 0xc9, 0x4f, 0x4c, 0x01, 0x00, 0x15,
	0x6a, 0x2c, 0x42, 0x07, 0x00, 0x00, 0x00,
};

main :: proc() {
	// Set up output buffer.
	buf := bytes.Buffer{};

	stdout :: proc(s: string) {
		os.write_string(os.stdout, s);
	}
	stderr :: proc(s: string) {
		os.write_string(os.stderr, s);
	}

	args := os.args;

	if len(args) < 2 {
		stderr("No input file specified.\n");
		err := load(slice=TEST, buf=&buf, known_gzip_size=len(TEST));
		if err == nil {
			stdout("Displaying test vector: ");
			stdout(bytes.buffer_to_string(&buf));
			stdout("\n");
		} else {
			fmt.printf("gzip.load returned %v\n", err);
		}
		bytes.buffer_destroy(&buf);
		os.exit(0);
	}

	// The rest are all files.
	args = args[1:];
	err: Error;

	for file in args {
		if file == "-" {
			// Read from stdin
			s := os.stream_from_handle(os.stdin);
			ctx := &compress.Context_Stream_Input{
				input = s,
			};
			err = load(ctx, &buf);
		} else {
			err = load(file, &buf);
		}
		if err != nil {
			if err != E_General.File_Not_Found {
				stderr("File not found: ");
				stderr(file);
				stderr("\n");
				os.exit(1);
			}
			stderr("GZIP returned an error.\n");
				bytes.buffer_destroy(&buf);
			os.exit(2);
		}
		stdout(bytes.buffer_to_string(&buf));
	}
	bytes.buffer_destroy(&buf);
}