/*  This file is part of "reprepro"
 *  Copyright (C) 2006 Bernhard R. Link
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02111-1301  USA
 */
#include <config.h>

#include <errno.h>
#include <assert.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <malloc.h>
#include <string.h>
#include <ctype.h>
#include <archive.h>
#include <archive_entry.h>
#include "error.h"
#include "uncompression.h"
#include "ar.h"
#include "chunks.h"
#include "debfile.h"

#ifndef HAVE_LIBARCHIVE
#error Why did this file got compiled instead of extractcontrol.c?
#endif

static retvalue read_control_file(char **control, const char *debfile, struct archive *tar, struct archive_entry *entry) {
	int64_t size;
	char *buffer, *afterchanges, *n;
	size_t len, controllen;
	ssize_t got;

	size = archive_entry_size(entry);
	if( size <= 0 ) {
		fprintf(stderr, "Error: Empty control file within %s!\n", debfile);
		return RET_ERROR;
	}
	if( size > 10*1024*1024 ) {
		fprintf(stderr, "Error: Ridiculously long control file within %s!\n", debfile);
		return RET_ERROR;
	}
	buffer = malloc(size+2);
	len = 0;
	while( (got = archive_read_data(tar, buffer+len, ((size_t)size+1)-len)) > 0
			&& !interrupted() ) {
		len += got;
		if( len > (size_t)size ) {
			fprintf(stderr, "Internal Error: libarchive miscalculated length of the control file inside '%s',\n"
			" perhaps the file is corrupt, perhaps libarchive!\n", debfile);
			free(buffer);
			return RET_ERROR;
		}
	}
	if( interrupted() ) {
		free(buffer);
		return RET_ERROR_INTERRUPTED;
	}
	if( got < 0 ) {
		free(buffer);
		fprintf(stderr, "Error reading control file from %s\n", debfile);
		return RET_ERROR;
	}
	if( len < (size_t)size )
		fprintf(stderr, "Warning: libarchive miscalculated length of the control file inside '%s'.\n"
			"Maybe the file is corrupt, perhaps libarchive!\n", debfile);
	buffer[len] = '\0';

	controllen = chunk_extract(buffer, buffer, &afterchanges);

	if( controllen == 0 ) {
		fprintf(stderr,"Could only find spaces within control file of '%s'!\n",
				debfile);
		free(buffer);
		return RET_ERROR;
	}
	if( (size_t)(afterchanges - buffer) < len ) {
		if( *afterchanges == '\0' )
			fprintf(stderr,
"Unexpected \\0 character within control file of '%s'!\n", debfile);
		else
			fprintf(stderr,
"Unexpected data after ending empty line in control file of '%s'!\n", debfile);
		free(buffer);
		return RET_ERROR;
	}
	assert( buffer[controllen] == '\0' );
	n = realloc(buffer, controllen+1);
	if( n == NULL ) {
		free(buffer);
		return RET_ERROR_OOM;
	}
	*control = n;
	return RET_OK;
}

static retvalue read_control_tar(char **control, const char *debfile, struct ar_archive *ar, struct archive *tar) {
	struct archive_entry *entry;
	int a;
	retvalue r;

	archive_read_support_format_tar(tar);
	archive_read_support_format_gnutar(tar);
	a = archive_read_open(tar, ar,
			ar_archivemember_open,
			ar_archivemember_read,
			ar_archivemember_close);
	if( a != ARCHIVE_OK ) {
		fprintf(stderr,"open control.tar.gz within '%s' failed: %d:%d:%s\n",
				debfile,
				a,archive_errno(tar),
				archive_error_string(tar));
		return RET_ERROR;
	}
	while( (a=archive_read_next_header(tar, &entry)) == ARCHIVE_OK ) {
		if( strcmp(archive_entry_pathname(entry),"./control") != 0 &&
		    strcmp(archive_entry_pathname(entry),"control") != 0 ) {
			a = archive_read_data_skip(tar);
			if( a != ARCHIVE_OK ) {
				int e = archive_errno(tar);
				printf("Error skipping %s within data.tar.gz from %s: %d=%s\n",
						archive_entry_pathname(entry),
						debfile,
						e, archive_error_string(tar));
				return (e!=0)?(RET_ERRNO(e)):RET_ERROR;
			}
			if( interrupted() )
				return RET_ERROR_INTERRUPTED;
		} else {
			r = read_control_file(control, debfile, tar, entry);
			if( r != RET_NOTHING )
				return r;
		}
	}
	if( a != ARCHIVE_EOF ) {
		int e = archive_errno(tar);
		printf("Error reading control.tar.gz from %s: %d=%s\n",
				debfile,
				e, archive_error_string(tar));
		return (e!=0)?(RET_ERRNO(e)):RET_ERROR;
	}
	fprintf(stderr,"Could not find a control file within control.tar.gz within '%s'!\n",debfile);
	return RET_ERROR_MISSING;
}

retvalue extractcontrol(char **control,const char *debfile) {
	struct ar_archive *ar;
	retvalue r;
	bool hadcandidate = false;

	r = ar_open(&ar,debfile);
	if( RET_WAS_ERROR(r) )
		return r;
	assert( r != RET_NOTHING);
	do {
		char *filename;
		enum compression c;

		r = ar_nextmember(ar, &filename);
		if( RET_IS_OK(r) ) {
			if( strncmp(filename, "control.tar", 11) != 0 ) {
				free(filename);
				continue;
			}
			hadcandidate = true;
			for( c = 0 ; c < c_COUNT ; c++ ) {
				if( strcmp(filename + 11,
						uncompression_suffix[c]) == 0)
					break;
			}
			if( c >= c_COUNT ) {
				free(filename);
				continue;
			}
			ar_archivemember_setcompression(ar, c);
			if( uncompression_supported(c) ) {
				struct archive *tar;

				tar = archive_read_new();
				r = read_control_tar(control, debfile, ar, tar);
				// TODO run archive_read_close to get error messages?
				archive_read_finish(tar);
				if( r != RET_NOTHING ) {
					ar_close(ar);
					free(filename);
					return r;
				}

			}
			free(filename);
		}
	} while( RET_IS_OK(r) );
	ar_close(ar);
	if( hadcandidate )
		fprintf(stderr,
"Could not find a suitable control.tar file within '%s'!\n", debfile);
	else
		fprintf(stderr,
"Could not find a control.tar file within '%s'!\n", debfile);
	return RET_ERROR_MISSING;
}