/*

SPDX-License-Identifier: BSD-3-Clause

Copyright (c) 2026
 Project Tick. All rights reserved.

This code is derived from software contributed to Berkeley by
the Institute of Electrical and Electronics Engineers, Inc.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
3. Neither the name of the University nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
SUCH DAMAGE.

*/

#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

#include "compat.h"
#include "signames.h"

struct signal_entry {
	const char *name;
	int number;
};

#define SIGNAL_ENTRY(name) { #name, SIG##name }
#define SIGNAL_ALIAS(name, signal) { name, signal }

static const struct signal_entry canonical_signals[] = {
#ifdef SIGHUP
	SIGNAL_ENTRY(HUP),
#endif
#ifdef SIGINT
	SIGNAL_ENTRY(INT),
#endif
#ifdef SIGQUIT
	SIGNAL_ENTRY(QUIT),
#endif
#ifdef SIGILL
	SIGNAL_ENTRY(ILL),
#endif
#ifdef SIGTRAP
	SIGNAL_ENTRY(TRAP),
#endif
#ifdef SIGABRT
	SIGNAL_ENTRY(ABRT),
#endif
#ifdef SIGBUS
	SIGNAL_ENTRY(BUS),
#endif
#ifdef SIGFPE
	SIGNAL_ENTRY(FPE),
#endif
#ifdef SIGKILL
	SIGNAL_ENTRY(KILL),
#endif
#ifdef SIGUSR1
	SIGNAL_ENTRY(USR1),
#endif
#ifdef SIGSEGV
	SIGNAL_ENTRY(SEGV),
#endif
#ifdef SIGUSR2
	SIGNAL_ENTRY(USR2),
#endif
#ifdef SIGPIPE
	SIGNAL_ENTRY(PIPE),
#endif
#ifdef SIGALRM
	SIGNAL_ENTRY(ALRM),
#endif
#ifdef SIGTERM
	SIGNAL_ENTRY(TERM),
#endif
#ifdef SIGSTKFLT
	SIGNAL_ENTRY(STKFLT),
#endif
#ifdef SIGCHLD
	SIGNAL_ENTRY(CHLD),
#endif
#ifdef SIGCONT
	SIGNAL_ENTRY(CONT),
#endif
#ifdef SIGSTOP
	SIGNAL_ENTRY(STOP),
#endif
#ifdef SIGTSTP
	SIGNAL_ENTRY(TSTP),
#endif
#ifdef SIGTTIN
	SIGNAL_ENTRY(TTIN),
#endif
#ifdef SIGTTOU
	SIGNAL_ENTRY(TTOU),
#endif
#ifdef SIGURG
	SIGNAL_ENTRY(URG),
#endif
#ifdef SIGXCPU
	SIGNAL_ENTRY(XCPU),
#endif
#ifdef SIGXFSZ
	SIGNAL_ENTRY(XFSZ),
#endif
#ifdef SIGVTALRM
	SIGNAL_ENTRY(VTALRM),
#endif
#ifdef SIGPROF
	SIGNAL_ENTRY(PROF),
#endif
#ifdef SIGWINCH
	SIGNAL_ENTRY(WINCH),
#endif
#ifdef SIGIO
	SIGNAL_ENTRY(IO),
#endif
#ifdef SIGPWR
	SIGNAL_ENTRY(PWR),
#endif
#ifdef SIGSYS
	SIGNAL_ENTRY(SYS),
#endif
};

static const struct signal_entry signal_aliases[] = {
#ifdef SIGIOT
	SIGNAL_ALIAS("IOT", SIGIOT),
#endif
#ifdef SIGCLD
	SIGNAL_ALIAS("CLD", SIGCLD),
#endif
#ifdef SIGPOLL
	SIGNAL_ALIAS("POLL", SIGPOLL),
#endif
#ifdef SIGUNUSED
	SIGNAL_ALIAS("UNUSED", SIGUNUSED),
#endif
};

static bool
parse_nonnegative_number(const char *text, int *value)
{
	long parsed;
	char *end;

	if (text[0] == '\0')
		return (false);

	errno = 0;
	parsed = strtol(text, &end, 10);
	if (errno != 0 || *end != '\0' || parsed < 0 || parsed > INT_MAX)
		return (false);

	*value = (int)parsed;
	return (true);
}

static char *
normalize_signal_name(const char *token)
{
	size_t i;
	size_t length;
	size_t offset;
	char *name;

	length = strlen(token);
	name = malloc(length + 1);
	if (name == NULL)
		return (NULL);

	for (i = 0; i < length; i++) {
		unsigned char ch;

		ch = (unsigned char)token[i];
		if (ch >= 'a' && ch <= 'z')
			name[i] = (char)(ch - ('a' - 'A'));
		else
			name[i] = (char)ch;
	}
	name[length] = '\0';

	offset = 0;
	if (length > 3 && name[0] == 'S' && name[1] == 'I' && name[2] == 'G')
		offset = 3;
	if (offset != 0)
		memmove(name, name + offset, length - offset + 1);

	return (name);
}

bool
sh_signal_name(int signum, char *buffer, size_t buffer_size)
{
	size_t i;

	if (signum == 0) {
		if (buffer != NULL && buffer_size > 0) {
			buffer[0] = '0';
			if (buffer_size > 1)
				buffer[1] = '\0';
		}
		return (true);
	}

	for (i = 0; i < nitems(canonical_signals); i++) {
		if (canonical_signals[i].number != signum)
			continue;
		if (buffer != NULL && buffer_size > 0)
			strlcpy(buffer, canonical_signals[i].name, buffer_size);
		return (true);
	}

#ifdef SIGRTMIN
#ifdef SIGRTMAX
	if (signum == SIGRTMIN) {
		if (buffer != NULL && buffer_size > 0)
			strlcpy(buffer, "RTMIN", buffer_size);
		return (true);
	}
	if (signum == SIGRTMAX) {
		if (buffer != NULL && buffer_size > 0)
			strlcpy(buffer, "RTMAX", buffer_size);
		return (true);
	}
	if (signum > SIGRTMIN && signum < SIGRTMAX) {
		if (buffer != NULL && buffer_size > 0)
			snprintf(buffer, buffer_size, "RTMIN+%d", signum - SIGRTMIN);
		return (true);
	}
#endif
#endif

	return (false);
}

bool
sh_signal_number(const char *token, int *signum)
{
	char *name;
	char *end;
	int offset;
	size_t i;

	if (parse_nonnegative_number(token, signum))
		return (true);

	name = normalize_signal_name(token);
	if (name == NULL)
		return (false);

	for (i = 0; i < nitems(canonical_signals); i++) {
		if (strcmp(name, canonical_signals[i].name) == 0) {
			*signum = canonical_signals[i].number;
			free(name);
			return (true);
		}
	}

	for (i = 0; i < nitems(signal_aliases); i++) {
		if (strcmp(name, signal_aliases[i].name) == 0) {
			*signum = signal_aliases[i].number;
			free(name);
			return (true);
		}
	}

#ifdef SIGRTMIN
#ifdef SIGRTMAX
	if (strcmp(name, "RTMIN") == 0) {
		*signum = SIGRTMIN;
		free(name);
		return (true);
	}
	if (strncmp(name, "RTMIN+", 6) == 0) {
		errno = 0;
		offset = (int)strtol(name + 6, &end, 10);
		if (errno == 0 && *end == '\0' && offset >= 0 &&
		    SIGRTMIN + offset <= SIGRTMAX) {
			*signum = SIGRTMIN + offset;
			free(name);
			return (true);
		}
	}
	if (strcmp(name, "RTMAX") == 0) {
		*signum = SIGRTMAX;
		free(name);
		return (true);
	}
	if (strncmp(name, "RTMAX-", 6) == 0) {
		errno = 0;
		offset = (int)strtol(name + 6, &end, 10);
		if (errno == 0 && *end == '\0' && offset >= 0 &&
		    SIGRTMAX - offset >= SIGRTMIN) {
			*signum = SIGRTMAX - offset;
			free(name);
			return (true);
		}
	}
#endif
#endif

	free(name);
	return (false);
}

int
sh_signal_max(void)
{
	size_t i;
	int maxsig;

	maxsig = 0;
	for (i = 0; i < nitems(canonical_signals); i++) {
		if (canonical_signals[i].number > maxsig)
			maxsig = canonical_signals[i].number;
	}
#ifdef SIGRTMAX
	if (SIGRTMAX > maxsig)
		maxsig = SIGRTMAX;
#endif
	return (maxsig);
}