/*
 *  Error handling for libcdecl.
 *  Copyright © 2011-2012, 2021 Nick Bowler
 *
 *  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, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  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, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <stdarg.h>

#include "cdecl.h"
#include "cdecl-internal.h"

#include <glthread/lock.h>
#include <glthread/tls.h>

gl_once_define(static, tls_initialized);
static gl_tls_key_t tls_key;

struct err_state {
	struct cdecl_error err;
	size_t nstr;
	char str[FLEXIBLE_ARRAY_MEMBER];
};

/* This error is reserved for extremely dire out-of-memory conditions. */
static struct err_state err_no_mem = {
	.err = {
		.code = CDECL_ENOMEM,
		.str  = NULL,
	},
};

static void free_err(void *err)
{
	if (err == &err_no_mem)
		return;

	free(err);
}

static void initialize(void)
{
	cdecl__init_i18n();
	err_no_mem.err.str = _("failed to allocate memory");

	gl_tls_key_init(tls_key, free_err);
}

/*
 * cdecl__err(CDECL_ENOMEM);
 * cdecl__err(code, fmt, ...);
 *
 * Sets the library error to code, with a printf-style error string.
 */
void cdecl__err(unsigned code, ...)
{
	const char *fmt;
	struct err_state *state;
	int rc, try = 0;
	va_list ap;

	gl_once(tls_initialized, initialize);

	state = gl_tls_get(tls_key);
	if (!state || state == &err_no_mem) {
		void *tmp = malloc(sizeof *state + 100);

		if (!tmp) {
			state = &err_no_mem;
			return;
		}

		gl_tls_set(tls_key, (state = tmp));
		state->nstr = 100;
	}

	if (code == CDECL_ENOMEM) {
		if (state != &err_no_mem)
			state->err = err_no_mem.err;
		return;
	}
retry:
	va_start(ap, code);
	fmt = va_arg(ap, const char *);
	rc = vsnprintf(state->str, state->nstr, fmt, ap);
	va_end(ap);

	if (rc > 0 && rc >= state->nstr) {
		void *tmp;
		size_t n;

		assert(try == 0 && rc < SIZE_MAX / 4);

		n = ((size_t)rc + 1) * 2;
		tmp = realloc(state, sizeof *state + n);
		if (tmp) {
			state = tmp;
			state->nstr = n;
			try++;

			goto retry;
		}

		state->err = err_no_mem.err;
		return;
	}

	state->err.str = state->str;
	state->err.code = code;
}

const struct cdecl_error *cdecl_get_error(void)
{
	struct err_state *state;

	gl_once(tls_initialized, initialize);

	state = gl_tls_get(tls_key);
	return state ? &state->err : NULL;
}