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| | // SPDX-License-Identifier: GPL-2.0-or-later
/* PASST - Plug A Simple Socket Transport
* for qemu/UNIX domain socket mode
*
* PASTA - Pack A Subtle Tap Abstraction
* for network namespace/tap device mode
*
* parse.c - Composable parsing helpers
*
* Copyright Red Hat
* Author: David Gibson <david@gibson.dropbear.id.au>
*/
#include <errno.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include "common.h"
#include "parse.h"
/**
* DOC: Theory of Operation
*
* These are a number of primitives which can be combined into parsers for
* moderately complex input. For simpler composability, they have common
* conventions.
*
* - Functions return a bool indicating whether they successfully parsed.
* - Any specific output from the parse is as output parameters
* - First argument is always @cursor, a const char **.
* - On entry, *@cursor has the point to start parsing.
* - On successful exit, *@cursor is updated to the next character after the
parsed portion of the input
* - On failure, *@cursor and any output arguments are not modified
*
* For brevity the common parameters and return information are omitted from the
* individual function documentation comments.
*/
/**
* parse_literal() - Parse a specified literal string
* @lit: Keyword to accept
*/
bool parse_literal(const char **cursor, const char *lit)
{
size_t len = strlen(lit);
if (strlen(*cursor) < len || memcmp(*cursor, lit, len))
return false;
*cursor += len;
return true;
}
/**
* parse_eoi() - Parse end of input
* @cursor: Current parse pointer
*
* Return: true if @p is at End of Input (\0), false otherwise
*/
bool parse_eoi(const char *cursor)
{
return !(*cursor);
}
/*
* parse_unsigned() - Parse an unsigned integer
* @base: Numeric base for string as strtoul(3)
* @valp: On success, updated with parsed value
*/
bool parse_unsigned(const char **cursor, int base, unsigned long *valp)
{
const char *p = *cursor;
unsigned long val;
errno = 0;
val = strtoul(p, (char **)&p, base);
if (errno || p == *cursor)
return false;
*valp = val;
*cursor = p;
return true;
}
/**
* parse_port_range() - Parse a range of port numbers '<first>[-<last>]'
* @range: Update with the parsed values on success
*/
bool parse_port_range(const char **cursor, struct port_range *range)
{
unsigned long first, last;
const char *p = *cursor;
if (!parse_unsigned(&p, 10, &first))
return false;
last = first;
if (parse_literal(&p, "-"))
if (!parse_unsigned(&p, 10, &last))
return false;
if ((last < first) || (last >= NUM_PORTS))
return false;
range->first = first;
range->last = last;
*cursor = p;
return true;
}
|