mango/kernel/arg.c

#include <kernel/arg.h>
#include <kernel/libc/string.h>
#include <kernel/libc/ctype.h>

static char g_cmdline[CMDLINE_MAX + 1] = {0};

static kern_status_t remove_quotes(char *s, size_t max)
{
	size_t i = 0;
	while (i < max) {
		if (s[i] != '"') {
			i++;
			continue;
		}

		size_t start = i;
		size_t end = i + 1;
		while (s[end] != '"' && end < max) {
			end++;
		}

		if (s[end] != '"') {
			return KERN_INVALID_ARGUMENT;
		}

		/* length of quoted string (excluding quotes) */
		size_t len = end - start - 1;

		/* remove trailing quote */
		s[end] = 0;

		/* add 1 to len to include the null terminator */
		memmove(s + start, s + start + 1, len + 1);

		i = end + 1;
	}

	return KERN_OK;
}

kern_status_t parse_cmdline(const char *cmdline)
{
	strncpy(g_cmdline, cmdline, sizeof g_cmdline - 1);
	g_cmdline[sizeof g_cmdline - 1] = 0;

	bool in_string = false;

	for (size_t i = 0; g_cmdline[i]; i++) {
		char c = g_cmdline[i];

		if (c == '"') {
			in_string = !in_string;
			continue;
		}

		if (isspace(c) && !in_string) {
			g_cmdline[i] = 0;
		}
	}

	if (in_string) {
		/* unterminated string on command line */
		return KERN_INVALID_ARGUMENT;
	}

	remove_quotes(g_cmdline, sizeof g_cmdline);

	return KERN_OK;
}

static char *advance_to_next_arg(char *s, char *max)
{
	while (*s && s < max) {
		s++;
	}

	while (!*s && s < max) {
		s++;
	}

	return s;
}


const char *arg_value(const char *arg_name)
{
	char *s = g_cmdline;
	char *end = s + sizeof g_cmdline;

	while (s < end) {
		size_t len = strlen(s);
		size_t name_len = strcspn(s, "=");

		if (!strncmp(s, arg_name, name_len)) {
			if (len == name_len) {
				/* arg has no value */
				return NULL;
			}

			return s + name_len + 1;
		}

		s = advance_to_next_arg(s, end);
	}

	return NULL;
}

bool arg_is_set(const char *arg_name)
{
	char *s = g_cmdline;
	char *end = s + sizeof g_cmdline;

	while (s < end) {
		size_t name_len = strcspn(s, "=");

		if (!strncmp(s, arg_name, name_len)) {
			return true;
		}

		s = advance_to_next_arg(s, end);
	}

	return false;
}