/* $Id$
 * UDP Gateway single-file bundle utility functions
 * Copyright (C) 2004 Jan Kratochvil <project-udpgate@jankratochvil.net>
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; exactly version 2 of June 1991 is required
 * 
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */


#include "config.h"

#include <glib/gmessages.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <glib/gmem.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <stdio.h>
#include <glib/gstrfuncs.h>

#include "bundle-util.h"	/* self */
#include "bundle.h"
#include "main.h"


static G_CONST_RETURN guint8 *bundle_util_file_retrieve(guint32 *data_length_return,const gchar *basename)
{
const guint8 *data;

	g_return_val_if_fail(data_length_return!=NULL,NULL);
	g_return_val_if_fail(basename!=NULL,NULL);

	if (optarg_verbose)
		g_message(_("Retrieving internally stored: %s"),basename);
	data=g_hash_table_lookup(bundle_hash_new(),basename);
	g_return_val_if_fail(data!=NULL,NULL);
	*data_length_return=GUINT32_FROM_BE(*(guint32 *)data);
	data+=sizeof(*data_length_return);

	return data;
}

void bundle_util_file_insert(const void *data,gsize data_length,const gchar *basename)
{
guint8 *buffer;

	g_return_if_fail(data!=NULL);
	g_return_if_fail(basename!=NULL);

	if (optarg_verbose)
		g_message(_("Internally storing autogenerated: %s"),basename);
	udpgate_newn(buffer,sizeof(guint32)+data_length);
	*((guint32 *)buffer)=GUINT32_TO_BE(data_length);
	g_assert(data_length==GUINT32_FROM_BE(*(guint32 *)buffer));
	memcpy(buffer+sizeof(data_length),data,data_length);
	/* FIXME: Missing duplicity check! */
	/* FIXME: Missing g_free() on the element removal! */
	g_hash_table_insert(bundle_hash_new(),g_strdup(basename),buffer);
}

/* Returns TRUE if it safe to overwrite/unlink the file.
 */
static gboolean bundle_util_file_backup_conditional(const gchar *pathname,const gchar *basename)
{
const guint8 *data;
guint32 data_length;
int fd;
guint8 *data_found;
int got;
char strftime_buffer[LINE_MAX];
const gchar *destination;
time_t time_current;

	g_return_val_if_fail(pathname!=NULL,FALSE);
	g_return_val_if_fail(basename!=NULL,FALSE);

	if (!(data=bundle_util_file_retrieve(&data_length,basename)))
		return FALSE;

	if (-1==(fd=open(pathname,O_RDONLY))) {
		if (errno==ENOENT)
			return TRUE;
		else {
			g_warning(_("Error checking file modifications of \"%s\": %m"),pathname);
			return FALSE;
			}
		}

	/* WARNING: 'data_found' allocated in this block! */
	data_found=g_malloc(data_length+1);
	if (-1==(got=read(fd,data_found,data_length+1)))
		g_warning(_("Error reading during the check of file modifications of \"%s\": %m"),pathname);
	if (close(fd))
		g_warning(_("Error closing the file \"%s\" during the check of its modifications: %m"),pathname);
	/* memcmp(3) requires 'data_found'! */
	if (got==(int)data_length && !memcmp(data_found,data,data_length)) {
		g_free(data_found);
		return TRUE;
		}
	g_free(data_found);

	time_current=time(NULL);	/* It is segfault to gmtime(NULL). */
	if (!strftime(strftime_buffer,sizeof(strftime_buffer),"GMT%FT%T",gmtime(&time_current))) {
		g_warning("strftime(3): %m");	/* shouldn't happen */
		return FALSE;
		}
	destination=udpgate_printf_alloca("%s-%s-%d",pathname,strftime_buffer,(int)getpid());
	if (rename(pathname,destination)) {
		g_warning(_("Error renaming your modified file \"%s\" to the backup \"%s\", giving up: %m"),
				pathname,destination);
		return FALSE;
		}

	return TRUE;
}

gboolean bundle_util_file_remove(const gchar *pathname,const gchar *basename)
{
	g_return_val_if_fail(pathname!=NULL,FALSE);
	g_return_val_if_fail(basename!=NULL,FALSE);

	if (!bundle_util_file_backup_conditional(pathname,basename))
		return FALSE;

	if (unlink(pathname) && errno!=ENOENT) {
		g_warning(_("Error removing the file \"%s\": %m"),pathname);
		return FALSE;
		}
	
	return TRUE;
}

struct dir_stack {
	struct dir_stack *next;
	gchar *dirname;	/* in fact 'pathname' */
	};

/* Always creates up to 'dirname(pathname)', never 'pathname' itself! */
static struct dir_stack *pathname_mkdirs(const gchar *pathname,mode_t mode)
{
gchar *dirname;
struct dir_stack *r;

	g_return_val_if_fail(pathname!=NULL,NULL);

	dirname=g_path_get_dirname(pathname);
	if (!strcmp(dirname,pathname)) {
		g_free(dirname);
		dirname=NULL;
		}
	if (!dirname)
		return NULL;
	r=pathname_mkdirs(dirname,mode);
	if (mkdir(dirname,mode))
		g_free(dirname);
	else {
struct dir_stack *dir_stack;

		udpgate_new(dir_stack);
		dir_stack->dirname=dirname;
		dir_stack->next=r;
		r=dir_stack;
		}
	return r;
}

static struct dir_stack *bundle_util_file_write_atexit_dir_stack_head;
struct file_stack {
	struct file_stack *next;
	gchar *pathname;
	gchar *basename;
	};
static struct file_stack *bundle_util_file_write_atexit_file_stack_head;

static void bundle_util_file_write_atexit(void)
{
struct file_stack *file_stack;
struct dir_stack *dir_stack;

	/* Always remove files first before their directories! */
	while ((file_stack=bundle_util_file_write_atexit_file_stack_head)) {
		/* Errors already reported: */
		bundle_util_file_remove(file_stack->pathname,file_stack->basename);
		g_free(file_stack->pathname);
		g_free(file_stack->basename);
		bundle_util_file_write_atexit_file_stack_head=file_stack->next;
		g_free(file_stack);
		}

	while ((dir_stack=bundle_util_file_write_atexit_dir_stack_head)) {
		if (rmdir(dir_stack->dirname))
			g_warning(_("Error cleaning up created temporary directory: %s"),dir_stack->dirname);
		g_free(dir_stack->dirname);
		bundle_util_file_write_atexit_dir_stack_head=dir_stack->next;
		g_free(dir_stack);
		}
}

gboolean bundle_util_file_write(const gchar *pathname,const gchar *basename,mode_t pathname_mode,
		enum bundle_util_flags flags)
{
const guint8 *data;
guint32 data_length;
int fd;
struct dir_stack *mkdirs=NULL;
static gboolean atexited=FALSE;

	g_return_val_if_fail(pathname!=NULL,FALSE);
	g_return_val_if_fail(basename!=NULL,FALSE);
	g_return_val_if_fail(flags&(BUNDLE_UTIL_BACKUP_MASK|BUNDLE_UTIL_MKDIRS_MASK|BUNDLE_UTIL_TEMPORARY_MASK),FALSE);
	/* Currently just unsupported: */
	g_return_val_if_fail((flags&(BUNDLE_UTIL_MKDIRS_MASK|BUNDLE_UTIL_TEMPORARY_MASK))!=BUNDLE_UTIL_MKDIRS_MASK,FALSE);

	if (!(data=bundle_util_file_retrieve(&data_length,basename)))
		return FALSE;

	if ((flags&BUNDLE_UTIL_BACKUP_MASK) && !bundle_util_file_backup_conditional(pathname,basename))
		return FALSE;
	
	if (flags&BUNDLE_UTIL_MKDIRS_MASK) {
mode_t dir_mode=pathname_mode;

		dir_mode|=(pathname_mode&0444)>>2;	/* mode|=('r'->'x') */
		mkdirs=pathname_mkdirs(pathname,dir_mode);
		}

	if (!atexited) {
		atexited=TRUE;
		g_atexit(bundle_util_file_write_atexit);
		}

	if (flags&BUNDLE_UTIL_TEMPORARY_MASK) {
struct dir_stack **mkdirs_tail_pointer;

		/* Stack current 'mkdirs' in front of the current: bundle_util_file_write_atexit_dir_stack_head
		 * to remove them in the reverse order than created.
		 * Removal ordering of the current 'mkdirs' stack is preserved
		 * as it is already reversed.
		 */
		for (mkdirs_tail_pointer=&mkdirs;*mkdirs_tail_pointer;mkdirs_tail_pointer=&(*mkdirs_tail_pointer)->next);
		*mkdirs_tail_pointer=bundle_util_file_write_atexit_dir_stack_head;
		bundle_util_file_write_atexit_dir_stack_head=mkdirs;
		mkdirs=NULL;
		}
	/* Currently just unsupported: */
	g_assert(!mkdirs);

	if (-1==(fd=open(pathname,O_WRONLY|O_CREAT|O_TRUNC,pathname_mode))) {
		g_warning(_("Error opening the file \"%s\" for rewrite: %m"),pathname);
		return FALSE;
		}
	/* Register the file only if it got already created.
	 * Do not atempt to remove files which are not ours!
	 */
	if (flags&BUNDLE_UTIL_TEMPORARY_MASK) {
struct file_stack *file_stack;

		/* Register also the file itself. */
		udpgate_new(file_stack);
		file_stack->pathname=g_strdup(pathname);
		file_stack->basename=g_strdup(basename);
		file_stack->next=bundle_util_file_write_atexit_file_stack_head;
		bundle_util_file_write_atexit_file_stack_head=file_stack;
		}

	if ((int)data_length!=write(fd,data,data_length)) {
		g_warning(_("Error writing the data of the file \"%s\" being overwritten: %m"),pathname);
		close(fd);	/* errors ignored */
		return FALSE;
		}
	if (close(fd)) {
		g_warning(_("Error closing the file \"%s\" after its rewrite: %m"),pathname);
		return FALSE;
		}
	return TRUE;
}