/* SPDX-License-Identifier: GPL-2.0 */

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
#include <assert.h>
#include <limits.h>
#include <errno.h>
#include <pwd.h>
#include <sys/types.h>
#include <unistd.h>


#include "gcc-compat.h"
#include "log.h"
#include "err.h"
#include "str.h"

/*
 * A wrapper for realloc(3) which exits on errors so that there is no need to
 * check the return value in the caller.
 */
__must_check __malloc void *dss_realloc(void *p, size_t size)
{
	/*
	 * No need to check for NULL pointers: If p is NULL, the  call
	 * to realloc is equivalent to malloc(size).
	 */
	assert(size);
	if (!(p = realloc(p, size))) {
		DSS_EMERG_LOG("realloc failed (size = %zu), aborting\n",
			size);
		exit(EXIT_FAILURE);
	}
	return p;
}

/* A wrapper for malloc(3) which exits on errors. */
__must_check __malloc void *dss_malloc(size_t size)
{
	void *p;
	assert(size);
	p = malloc(size);

	if (!p) {
		DSS_EMERG_LOG("malloc failed (size = %zu),  aborting\n",
			size);
		exit(EXIT_FAILURE);
	}
	return p;
}

/* Allocate zeroed-out memory. */
__must_check __malloc void *dss_calloc(size_t size)
{
	void *ret = dss_malloc(size);

	memset(ret, 0, size);
	return ret;
}

/*
 * A wrapper for strdup(3) which exits on errors. If NULL is passed as the
 * string to duplicate, a pointer to an empty string is returned.
 */
__must_check __malloc char *dss_strdup(const char *s)
{
	char *ret;

	if ((ret = strdup(s? s: "")))
		return ret;
	DSS_EMERG_LOG("strdup failed, aborting\n");
	exit(EXIT_FAILURE);
}

/*
 * Allocate a sufficiently large string and print into it. No artificial bound
 * on the length of the resulting string is imposed. Either returns a pointer
 * to a string which must be freed by the caller, or aborts without returning.
 */
__must_check __printf_1_2 __malloc char *make_message(const char *fmt, ...)
{
	char *msg;
	size_t size = 100;

	msg = dss_malloc(size);
	while (1) {
		int n;
		va_list ap;

		/* Try to print in the allocated space. */
		va_start(ap, fmt);
		n = vsnprintf(msg, size, fmt, ap);
		va_end(ap);
		/* If that worked, return the string. */
		if (n < size)
			return msg;
		/* Else try again with more space. */
		size = n + 1; /* precisely what is needed */
		msg = dss_realloc(msg, size);
	}
}

/*
 * Get the home directory of the current user.
 *
 * Returns a dynamically allocated string that must be freed by the caller. If
 * the HOME environment variable is unset or empty, the function aborts.
 */
__must_check __malloc char *get_homedir(void)
{
	const char *home = getenv("HOME");
	if (home && *home)
		return dss_strdup(home);
	DSS_EMERG_LOG("fatal: HOME is unset or empty\n");
	exit(EXIT_FAILURE);
}

/* Convert a string to a 64-bit signed integer value. */
int dss_atoi64(const char *str, int64_t *value)
{
	char *endptr;
	long long tmp;

	errno = 0; /* To distinguish success/failure after call */
	tmp = strtoll(str, &endptr, 10);
	if (errno == ERANGE && (tmp == LLONG_MAX || tmp == LLONG_MIN))
		return -E_ATOI_OVERFLOW;
	if (errno != 0 && tmp == 0) /* other error */
		return -E_STRTOLL;
	if (endptr == str)
		return -E_ATOI_NO_DIGITS;
	if (*endptr != '\0') /* Further characters after number */
		return -E_ATOI_JUNK_AT_END;
	*value = tmp;
	return 1;
}

/*
 * Get the logname of the current user.
 *
 * Returns a dynamically allocated string that must be freed by the caller. On
 * errors, the string "unknown" is returned. This function never returns NULL.
 */
__must_check __malloc char *dss_logname(void)
{
	const char *logname = getenv("LOGNAME");
	if (!logname && !*logname)
		logname = "unknown";
	return dss_strdup(logname);
}

/*
 * Split a string and return pointers to its parts.
 *
 * This function modifies the string given by the first argument by replacing
 * all occurrences of space and '\t' characters by '\0'. A NULL-terminated
 * array of pointers to char * is allocated dynamically, and these pointers are
 * initialized to point to the broken-up substrings. A pointer to this array
 * is returned via the last argument.
 *
 * Returns the number of substrings found.
 */
unsigned split_args(char *args, char *** const argv_ptr)
{
	char *p;
	char **argv;
	size_t n = 0, i, j;
	const char delim[] = " \t";

	p = args + strspn(args, delim);
	for (;;) {
		i = strcspn(p, delim);
		if (!i)
			break;
		p += i;
		n++;
		p += strspn(p, delim);
	}
	*argv_ptr = dss_malloc((n + 1) * sizeof(char *));
	argv = *argv_ptr;
	i = 0;
	p = args + strspn(args, delim);
	while (p) {
		argv[i] = p;
		j = strcspn(p, delim);
		if (!j)
			break;
		p += strcspn(p, delim);
		if (*p) {
			*p = '\0';
			p++;
			p += strspn(p, delim);
		}
		i++;
	}
	argv[n] = NULL;
	return n;
}