/*
 * dselect - Debian package maintenance user interface
 * method.cc - access method handling
 *
 * Copyright © 1995 Ian Jackson <ijackson@chiark.greenend.org.uk>
 * Copyright © 2001,2002 Wichert Akkerman <wakkerma@debian.org>
 *
 * This 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; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This 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, see <https://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <compat.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/wait.h>

#include <errno.h>
#include <limits.h>
#include <string.h>
#include <fcntl.h>
#include <dirent.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

#include <dpkg/i18n.h>
#include <dpkg/dpkg.h>
#include <dpkg/dpkg-db.h>
#include <dpkg/subproc.h>
#include <dpkg/command.h>

#include "dselect.h"
#include "method.h"

static const char *const methoddirectories[] = {
	LIBDIR "/" METHODSDIR,
	LOCALLIBDIR "/" METHODSDIR,
	nullptr
};

static char *methodlockfile = nullptr;
static int methlockfd = -1;

static void
sthfailed(const char * reasoning)
{
	curseson();
	clear();
	printw("\n\n%s: %s\n", DSELECT, reasoning);
	attrset(A_BOLD);
	addstr(_("\nPress <enter> to continue."));
	attrset(A_NORMAL);
	refresh();
	getch();
}

static void
cu_unlockmethod(int, void**)
{
	struct flock fl;

	if (methodlockfile == nullptr)
		internerr("method lock file is nullptr");
	if (methlockfd < 0)
		internerr("method lock fd is %d < 0", methlockfd);
	fl.l_type = F_UNLCK;
	fl.l_whence = SEEK_SET;
	fl.l_start = 0;
	fl.l_len = 0;
	if (fcntl(methlockfd, F_SETLK, &fl) < 0)
		sthfailed(_("cannot unlock access method area"));
}

static enum urqresult
ensureoptions(void)
{
	dselect_option *newoptions;
	int nread;

	if (!options) {
		newoptions = nullptr;
		nread = 0;
		for (const char *const *ccpp = methoddirectories; *ccpp; ccpp++)
			readmethods(*ccpp, &newoptions, &nread);
		if (!newoptions) {
			sthfailed(_("no access methods are available"));
			return urqr_fail;
		}
		options = newoptions;
		noptions = nread;
	}
	return urqr_normal;
}

static enum urqresult
lockmethod(void)
{
	struct flock fl;

	if (methodlockfile == nullptr)
		methodlockfile = dpkg_db_get_path(METHLOCKFILE);

	if (methlockfd < 0) {
		methlockfd = open(methodlockfile, O_RDWR|O_CREAT|O_TRUNC, 0660);
		if (methlockfd < 0) {
			if ((errno == EPERM) || (errno == EACCES)) {
				sthfailed(_("requested operation requires superuser privilege"));
				return urqr_fail;
			}
			sthfailed(_("cannot open or create access method lockfile"));
			return urqr_fail;
		}
	}
	fl.l_type = F_WRLCK;
	fl.l_whence = SEEK_SET;
	fl.l_start = 0;
	fl.l_len = 0;
	if (fcntl(methlockfd, F_SETLK, &fl) < 0) {
		if (errno == EACCES || errno == EAGAIN) {
			sthfailed(_("the access method area is already locked"));
			return urqr_fail;
		}
		sthfailed(_("cannot lock access method area"));
		return urqr_fail;
	}
	push_cleanup(cu_unlockmethod, ~0, 0);

	return urqr_normal;
}

static urqresult
falliblesubprocess(struct command *cmd)
{
	pid_t pid;
	int i, c;

	cursesoff();

	subproc_signals_ignore(cmd->name);

	pid = subproc_fork();
	if (pid == 0) {
		subproc_signals_cleanup(0, nullptr);
		command_exec(cmd);
	}

	fprintf(stderr, "\n");

	i = subproc_reap(pid, cmd->name, SUBPROC_WARN);

	subproc_signals_restore();

	if (i == 0) {
		sleep(1);
		return urqr_normal;
	}

	fprintf(stderr, _("Press <enter> to continue.\n"));
	m_output(stderr, _("<standard error>"));
	do {
		c = fgetc(stdin);
	} while ((c == EOF && errno == EINTR) || (c != '\n' && c != EOF));
	if (c == EOF)
		ohshite(_("error reading acknowledgement of program failure message"));

	return urqr_fail;
}

static urqresult
runscript(const char *exepath, const char *name)
{
	urqresult ur;

	ur = ensureoptions();
	if (ur != urqr_normal)
		return ur;
	ur = lockmethod();
	if (ur != urqr_normal)
		return ur;
	getcurrentopt();

	if (coption) {
		struct command cmd;
		varbuf cmdpath;

		cmdpath += coption->meth->path;
		cmdpath += exepath;

		command_init(&cmd, cmdpath.str(), name);
		command_add_args(&cmd, exepath, dpkg_db_get_dir(),
		                 coption->meth->name.str(),
		                 coption->name.str(), nullptr);
		ur = falliblesubprocess(&cmd);
		command_destroy(&cmd);
	} else {
		sthfailed(_("no access method is selected or configured"));
		ur = urqr_fail;
	}
	pop_cleanup(ehflag_normaltidy);

	return ur;
}

urqresult
urq_update(void)
{
	return runscript(METHODUPDATESCRIPT, _("update available list script"));
}

urqresult
urq_install(void)
{
	return runscript(METHODINSTALLSCRIPT, _("installation script"));
}

static urqresult
rundpkgauto(const char *name, const char *dpkgmode)
{
	urqresult ur;
	struct command cmd;

	command_init(&cmd, DPKG, name);
	command_add_args(&cmd, DPKG, "--admindir", dpkg_db_get_dir(), "--pending",
	                 dpkgmode, nullptr);

	cursesoff();
	printf(_("running %s %s ...\n"), "dpkg --pending", dpkgmode);
	fflush(stdout);
	ur = falliblesubprocess(&cmd);
	command_destroy(&cmd);

	return ur;
}

urqresult
urq_remove(void)
{
	return rundpkgauto("dpkg --remove", "--remove");
}

urqresult
urq_config(void)
{
	return rundpkgauto("dpkg --configure", "--configure");
}

urqresult
urq_setup(void)
{
	quitaction qa;
	urqresult ur;

	ur = ensureoptions();
	if (ur != urqr_normal)
		return ur;
	ur = lockmethod();
	if (ur != urqr_normal)
		return ur;
	getcurrentopt();

	curseson();
	methodlist *l = new methodlist();
	qa = l->display();
	delete l;

	if (qa == qa_quitchecksave) {
		struct command cmd;
		varbuf cmdpath;

		cmdpath += coption->meth->path;
		cmdpath += METHODSETUPSCRIPT;

		command_init(&cmd, cmdpath.str(), _("query/setup script"));
		command_add_args(&cmd, METHODSETUPSCRIPT, dpkg_db_get_dir(),
		                 coption->meth->name.str(), coption->name.str(), nullptr);
		ur = falliblesubprocess(&cmd);
		command_destroy(&cmd);
		if (ur == urqr_normal)
			writecurrentopt();
	} else {
		ur = urqr_fail;
	}
	pop_cleanup(ehflag_normaltidy);

	return ur;
}