338 lines
7.7 KiB
C++
338 lines
7.7 KiB
C++
/*
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* \brief Argument list string handling
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* \author Norman Feske
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* \date 2006-05-22
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*
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* Each argument has the form:
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*
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* ! <key>=<value>
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*
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* Key is an identifier that begins with a letter or underline
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* and may also contain digits.
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*
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* A list of arguments is specified by using comma as separator,
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* whereas the first argument is considered as the weakest. If
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* we replace an argument value of an existing argument, the
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* existing argument is removed and we append a new argument at
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* the end of the string.
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*/
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/*
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* Copyright (C) 2006-2013 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__UTIL__ARG_STRING_H_
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#define _INCLUDE__UTIL__ARG_STRING_H_
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#include <util/token.h>
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#include <util/string.h>
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#include <base/snprintf.h>
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namespace Genode {
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class Arg_string;
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class Arg;
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}
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class Genode::Arg
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{
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/**
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* Define tokenizer used for argument-string parsing
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*
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* Argument-string tokens accept C-style identifiers.
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*/
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typedef ::Genode::Token<Scanner_policy_identifier_with_underline> Token;
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friend class Arg_string;
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private:
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Token _key;
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Token _value;
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/**
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* Return long value of argument
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*
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* \param out_value argument converted to unsigned long value
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* \param out_sign 1 if positive; -1 if negative
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* \return true if no syntactic anomaly occured
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*
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* This method handles the numberic modifiers G (2^30),
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* M (2^20), and K (2^10).
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*/
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bool read_ulong(unsigned long *out_value, int *out_sign) const
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{
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Token t = _value;
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/* check for sign; default is positive */
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*out_sign = 1;
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if (t[0] == '+')
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t = t.next();
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else if (t[0] == '-') {
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*out_sign = -1;
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t = t.next();
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}
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/* stop if token after sign is no number */
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if (t.type() != Token::NUMBER)
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return false;
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/* read numeric value and skip the corresponding tokens */
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Number_of_bytes value;
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size_t n = ascii_to(t.start(), value);
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if (n == 0)
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return false;
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t = Token(t.start() + n);
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*out_value = value;
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/* check for strange characters at the end of the number */
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t = t.eat_whitespace();
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if (t && (t[0] != ',')) return false;
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return true;
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}
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public:
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/**
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* Construct argument from Token(s)
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*/
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Arg(Token t = Token()) : _key(t), _value(0)
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{
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for (; t && (t[0] != ','); t = t.next().eat_whitespace())
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if (t[0] == '=') {
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_value = t.next().eat_whitespace();
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break;
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}
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}
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inline bool valid() const { return _key; }
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unsigned long ulong_value(unsigned long default_value) const
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{
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unsigned long value = 0;
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int sign = 1;
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bool valid = read_ulong(&value, &sign);
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if (sign < 0)
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return default_value;
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return valid ? value : default_value;
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}
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long long_value(long default_value) const
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{
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unsigned long value = 0;
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int sign = 1;
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bool valid = read_ulong(&value, &sign);
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/* FIXME we should check for overflows here! */
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return valid ? sign*value : default_value;
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}
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bool bool_value(bool default_value) const
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{
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bool result = default_value;
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switch(_value.type()) {
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/* result is passed to 'ascii_to' by reference */
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case Token::IDENT:;
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if (ascii_to(_value.start(), result) == _value.len())
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return result;
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case Token::STRING:
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if (ascii_to(_value.start()+1, result) == _value.len()-2)
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return result;
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default:
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/* read values 0 (false) / !0 (true) */
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unsigned long value;
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int sign;
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bool valid = read_ulong(&value, &sign);
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return valid ? value : default_value;
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}
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}
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void key(char *dst, size_t dst_len) const
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{
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_key.string(dst, dst_len);
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}
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void string(char *dst, size_t dst_len, const char *default_string) const
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{
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/* check for one-word string w/o quotes */
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if (_value.type() == Token::IDENT) {
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size_t len = min(dst_len - 1, _value.len());
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memcpy(dst, _value.start(), len);
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dst[len] = 0;
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return;
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}
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/* stop here if _value is not a string */
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if (_value.type() != Token::STRING) {
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strncpy(dst, default_string, dst_len);
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return;
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}
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/* unpack string to dst */
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size_t num_chars = min(dst_len - 1, _value.len());
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unpack_string(_value.start(), dst, num_chars);
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}
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};
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class Genode::Arg_string
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{
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typedef Arg::Token Token;
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private:
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static Token _next_key(Token t)
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{
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for (; t; t = t.next().eat_whitespace())
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/* if we find a comma, return token after comma */
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if (t[0] == ',') return t.next().eat_whitespace();
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return Token();
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}
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/**
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* Find key token in argument string
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*/
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static Token _find_key(const char *args, const char *key)
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{
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for (Token t(args); t; t = _next_key(t))
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/* check if key matches */
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if ((t.type() == Token::IDENT) && !strcmp(key, t.start(), t.len()))
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return t;
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return Token();
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}
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/**
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* Append source string to destination string
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*
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* NOTE: check string length before calling this method!
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*
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* \return last character of result string
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*/
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static char *_append(char *dst, const char *src)
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{
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unsigned src_len = strlen(src);
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while (*dst) dst++;
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memcpy(dst, src, src_len + 1);
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return dst + src_len;
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}
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public:
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/**
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* Find argument by its key
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*/
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static Arg find_arg(const char *args, const char *key) {
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return (args && key) ? Arg(_find_key(args, key)) : Arg(); }
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static Arg first_arg(const char *args) {
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return Arg(Token(args)); }
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/**
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* Remove argument with the specified key
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*/
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static bool remove_arg(char *args, const char *key)
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{
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if (!args || !key) return false;
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Token beg = _find_key(args, key);
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Token next = _next_key(beg);
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/* no such key to remove - we are done */
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if (!beg) return true;
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/* if argument is the last one, null-terminate string right here */
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if (!next) {
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/* eat all pending whitespaces at the end of the string */
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char *s = max(beg.start() - 1, args);
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while (s > args && (*s == ' ')) s--;
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/* write string-terminating zero */
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*s = 0;
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} else
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memcpy(beg.start(), next.start(), strlen(next.start()) + 1);
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return true;
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}
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/**
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* Add new argument
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*/
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static bool add_arg(char *args, unsigned args_len,
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const char *key, const char *value,
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Token::Type type = Token::Type::IDENT)
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{
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if (!args || !key || !value) return false;
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unsigned old_len = strlen(args);
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/* check if args string has enough capacity */
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if ((type == Token::Type::STRING
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&& old_len + strlen(key) + strlen(value) + 4 > args_len)
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|| (old_len + strlen(key) + strlen(value) + 2 > args_len))
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return false;
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args += old_len;
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if (old_len)
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args = _append(args, ", ");
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if (type == Token::Type::STRING)
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_append(_append(_append(_append(args, key), "=\""), value), "\"");
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else
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_append(_append(_append(args, key), "="), value);
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return true;
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}
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/**
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* Assign new value to argument
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*/
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static bool set_arg(char *args, unsigned args_len,
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const char *key, const char *value)
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{
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return remove_arg(args, key) && add_arg(args, args_len, key, value);
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}
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/**
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* Assign new integer argument
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*/
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static bool set_arg(char *args, unsigned args_len,
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const char *key, int value)
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{
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enum { STRING_LONG_MAX = 32 };
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char buf[STRING_LONG_MAX];
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snprintf(buf, sizeof(buf), "%d", value);
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return remove_arg(args, key) && add_arg(args, args_len, key, buf);
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}
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/**
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* Assign new string argument
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*/
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static bool set_arg_string(char *args, unsigned args_len,
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const char *key, const char *value)
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{
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return remove_arg(args, key)
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&& add_arg(args, args_len, key, value, Token::Type::STRING);
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}
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};
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#endif /* _INCLUDE__UTIL__ARG_STRING_H_ */
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