// SPDX-License-Identifier: GPL-2.0-or-later
// SPDX-FileCopyrightText: 2021 Alyssa Ross <hi@alyssa.is>

#define _GNU_SOURCE

#include <argz.h>
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdnoreturn.h>
#include <sysexits.h>
#include <unistd.h>

#include "config.h"
#include "exec.h"
#include "log.h"

noreturn static void ex_usage(void)
{
	if (verbosity)
		fprintf(stderr,
		        "Usage: %s [ -1 ] [ -q | -Q | -v ] cid port prog...\n",
		        program_invocation_short_name);
	exit(EX_USAGE);
}

int main(int argc, char *argv[])
{
	int opt;
	bool alloc_failed = false;
	size_t binder_opts_len = 0, daemon_opts_len = 0;
	char *binder_opts = NULL, *daemon_opts = NULL;

	// The heavy lifting here is done by vsockserver-socketbinder
	// and vsockserverd.  All this program does is munge argv
	// appropriately to set the right options for each of those
	// programs, and then exec into vsockserver-socketbinder.

	// If allocation fails, we need to keep going until after
	// we've parsed the arguments, so we know what our verbosity
	// setting is, and consequently whether we should print an
	// error message about the allocation failure.
	alloc_failed |= argz_add(&binder_opts, &binder_opts_len,
	                         BINDIR "/vsockserver-socketbinder")
		|| argz_add(&daemon_opts, &daemon_opts_len,
	                    BINDIR "/vsockserverd");

	while ((opt = getopt(argc, argv, "+1qQv")) != -1) {
		char *arg = NULL;

		switch (opt) {
		case '1':
		case 'q':
		case 'Q':
		case 'v':
			set_verbosity(opt);
			alloc_failed |= asprintf(&arg, "-%c", opt) == -1
				|| argz_add(&daemon_opts, &daemon_opts_len,
			                    arg);
			free(arg);
			break;
		default:
			ex_usage();
		}
	}

	// Now that verbosity is set, we can whether we were sitting
	// on an allocation failure.
	if (alloc_failed)
		diee(EX_OSERR, "malloc");
	// Now we don't have to keep checking alloc_failed before
	// doing anything, and we can deal with allocation failures
	// after this point by just terminating immediately.

	// Check there are `cid' and `port' arguments to pass to
	// vsockserver-socketbinder, and at least one `prog' argument
	// to pass to vsockserverd.
	if (optind > argc - 3)
		ex_usage();

	// Add `cid' and `port' arguments to binder options.
	if (argz_add(&binder_opts, &binder_opts_len, "--")
	    || argz_add(&binder_opts, &binder_opts_len, argv[optind++])
	    || argz_add(&binder_opts, &binder_opts_len, argv[optind++]))
		diee(EX_OSERR, "malloc");

	// Add all of daemon_opts onto the end of binder_opts.  It's
	// okay to multiply to find the size because if it would
	// overflow calloc would have failed earlier.
	if (argz_append(&binder_opts, &binder_opts_len, daemon_opts,
	                daemon_opts_len))
		diee(EX_OSERR, "malloc");
	free(daemon_opts);

	// Append `prog' to binder_opts.  Technically this should be
	// part of daemon_opts, but then we'd just be copying it into
	// one place to immediately copy it elsewhere.
	for (int i = optind; i < argc; i++)
		if (argz_add(&binder_opts, &binder_opts_len, argv[i]))
			diee(EX_OSERR, "malloc");

	if (verbosity == all) {
		char *opt = 0;

		// Log the full argv before we exec it.
		fprintf(stderr, "%s: executing", program_invocation_short_name);
		while ((opt = argz_next(binder_opts, binder_opts_len, opt)))
			fprintf(stderr, " %s", opt);
		fputc('\n', stderr);
	}

	execzp(binder_opts, binder_opts, binder_opts_len);
	diee(EX_OSERR, "execvp");
}