char **
env_init(void) {
	char **p = (char **) malloc(sizeof(char **));

	if (p != NULL)
		p[0] = NULL;
	return (p);
}

void
env_free(char **envp) {
	char **p;

	for (p = envp; *p != NULL; p++)
		free(*p);
	free(envp);
}

char **
env_copy(char **envp) {
	int count, i, save_errno;
	char **p;

	for (count = 0; envp[count] != NULL; count++)
		NULL;
	p = (char **) malloc((count+1) * sizeof(char *));  /* 1 for the NULL */
	if (p != NULL) {
		for (i = 0; i < count; i++)
			if ((p[i] = strdup(envp[i])) == NULL) {
				save_errno = errno;
				while (--i >= 0)
					free(p[i]);
				free(p);
				errno = save_errno;
				return (NULL);
			}
		p[count] = NULL;
	}
	return (p);
}

char **
env_set(char **envp, char *envstr) {
	int count, found;
	char **p, *envtmp;

	/*
	 * count the number of elements, including the null pointer;
	 * also set 'found' to -1 or index of entry if already in here.
	 */
	found = -1;
	for (count = 0; envp[count] != NULL; count++) {
		if (!strcmp_until(envp[count], envstr, '='))
			found = count;
	}
	count++;	/* for the NULL */

	if (found != -1) {
		/*
		 * it exists already, so just free the existing setting,
		 * save our new one there, and return the existing array.
		 */
		if ((envtmp = strdup(envstr)) == NULL)
			return (NULL);
		free(envp[found]);
		envp[found] = envtmp;
		return (envp);
	}

	/*
	 * it doesn't exist yet, so resize the array, move null pointer over
	 * one, save our string over the old null pointer, and return resized
	 * array.
	 */
	if ((envtmp = strdup(envstr)) == NULL)
		return (NULL);
	p = (char **) realloc((void *) envp,
			      (size_t) ((count+1) * sizeof(char **)));
	if (p == NULL) {
		free(envtmp);
		return (NULL);
	}
	p[count] = p[count-1];
	p[count-1] = envtmp;
	return (p);
}

/* The following states are used by load_env(), traversed in order: */
enum env_state {
	NAMEI,		/* First char of NAME, may be quote */
	NAME,		/* Subsequent chars of NAME */
	EQ1,		/* After end of name, looking for '=' sign */
	EQ2,		/* After '=', skipping whitespace */
	VALUEI,		/* First char of VALUE, may be quote */
	VALUE,		/* Subsequent chars of VALUE */
	FINI,		/* All done, skipping trailing whitespace */
	ERROR,		/* Error */
};

/* return	ERR = end of file
 *		FALSE = not an env setting (file was repositioned)
 *		TRUE = was an env setting
 */
int
load_env(char *envstr, FILE *f) {
	long filepos;
	int fileline;
	enum env_state state;
	char name[MAX_ENVSTR], val[MAX_ENVSTR];
	char quotechar, *c, *str;

	filepos = ftell(f);
	fileline = LineNumber;
	skip_comments(f);
	if (EOF == get_string(envstr, MAX_ENVSTR, f, "\n"))
		return (ERR);

	Debug(DPARS, ("load_env, read <%s>\n", envstr))

	bzero(name, sizeof name);
	bzero(val, sizeof val);
	str = name;
	state = NAMEI;
	quotechar = '\0';
	c = envstr;
	while (state != ERROR && *c) {
		switch (state) {
		case NAMEI:
		case VALUEI:
			if (*c == '\'' || *c == '"')
				quotechar = *c++;
			state++;
			/* FALLTHROUGH */
		case NAME:
		case VALUE:
			if (quotechar) {
				if (*c == quotechar) {
					state++;
					c++;
					break;
				}
				if (state == NAME && *c == '=') {
					state = ERROR;
					break;
				}
			} else {
				if (state == NAME) {
					if (isspace((unsigned char)*c)) {
						c++;
						state++;
						break;
					}
					if (*c == '=') {
						state++;
						break;
					}
				}
			}
			*str++ = *c++;
			break;

		case EQ1:
			if (*c == '=') {
				state++;
				str = val;
				quotechar = '\0';
			} else {
				if (!isspace((unsigned char)*c))
					state = ERROR;
			}
			c++;
			break;

		case EQ2:
		case FINI:
			if (isspace((unsigned char)*c))
				c++;
			else
				state++;
			break;

		default:
			abort();
		}
	}
	if (state != FINI && !(state == VALUE && !quotechar)) {
		Debug(DPARS, ("load_env, not an env var, state = %d\n", state))
		fseek(f, filepos, 0);
		Set_LineNum(fileline);
		return (FALSE);
	}
	if (state == VALUE) {
		/* End of unquoted value: trim trailing whitespace */
		c = val + strlen(val);
		while (c > val && isspace((unsigned char)c[-1]))
			*(--c) = '\0';
	}

	/* 2 fields from parser; looks like an env setting */

	/*
	 * This can't overflow because get_string() limited the size of the
	 * name and val fields.  Still, it doesn't hurt to be careful...
	 */
	if (!glue_strings(envstr, MAX_ENVSTR, name, val, '='))
		return (FALSE);
	Debug(DPARS, ("load_env, <%s> <%s> -> <%s>\n", name, val, envstr))
	return (TRUE);
}

char *
env_get(char *name, char **envp) {
	int len = strlen(name);
	char *p, *q;

	while ((p = *envp++) != NULL) {
		if (!(q = strchr(p, '=')))
			continue;
		if ((q - p) == len && !strncmp(p, name, len))
			return (q+1);
	}
	return (NULL);
}
