genode/repos/base/include/util/arg_string.h

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/*
* \brief Argument list string handling
* \author Norman Feske
* \date 2006-05-22
*
* Each argument has the form:
*
* ! <key>=<value>
*
* Key is an identifier that begins with a letter or underline
* and may also contain digits.
*
* A list of arguments is specified by using comma as separator,
* whereas the first argument is considered as the weakest. If
* we replace an argument value of an existing argument, the
* existing argument is removed and we append a new argument at
* the end of the string.
*/
/*
* Copyright (C) 2006-2016 Genode Labs GmbH
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*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INCLUDE__UTIL__ARG_STRING_H_
#define _INCLUDE__UTIL__ARG_STRING_H_
#include <util/token.h>
#include <util/string.h>
#include <base/snprintf.h>
namespace Genode {
class Arg_string;
class Arg;
}
class Genode::Arg
{
/**
* Define tokenizer used for argument-string parsing
*
* Argument-string tokens accept C-style identifiers.
*/
typedef ::Genode::Token<Scanner_policy_identifier_with_underline> Token;
friend class Arg_string;
private:
Token _key;
Token _value;
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/**
* Return long value of argument
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*
* \param out_value argument converted to unsigned long value
* \param out_sign 1 if positive; -1 if negative
* \return true if no syntactic anomaly occured
*
* This method handles the numberic modifiers G (2^30),
* M (2^20), and K (2^10).
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*/
bool read_ulong(unsigned long *out_value, int *out_sign) const
{
Token t = _value;
/* check for sign; default is positive */
*out_sign = 1;
if (t[0] == '+')
t = t.next();
else if (t[0] == '-') {
*out_sign = -1;
t = t.next();
}
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/* stop if token after sign is no number */
if (t.type() != Token::NUMBER)
return false;
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/* read numeric value and skip the corresponding tokens */
Number_of_bytes value;
size_t n = ascii_to(t.start(), value);
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if (n == 0)
return false;
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t = Token(t.start() + n);
*out_value = value;
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/* check for strange characters at the end of the number */
t = t.eat_whitespace();
if (t && (t[0] != ',')) return false;
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return true;
}
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public:
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/**
* Construct argument from Token(s)
*/
Arg(Token t = Token()) : _key(t), _value(0)
{
for (; t && (t[0] != ','); t = t.next().eat_whitespace())
if (t[0] == '=') {
_value = t.next().eat_whitespace();
break;
}
}
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inline bool valid() const { return _key; }
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unsigned long ulong_value(unsigned long default_value) const
{
unsigned long value = 0;
int sign = 1;
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bool valid = read_ulong(&value, &sign);
if (sign < 0)
return default_value;
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return valid ? value : default_value;
}
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long long_value(long default_value) const
{
unsigned long value = 0;
int sign = 1;
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bool valid = read_ulong(&value, &sign);
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/* FIXME we should check for overflows here! */
return valid ? sign*value : default_value;
}
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bool bool_value(bool default_value) const
{
bool result = default_value;
switch(_value.type()) {
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/* result is passed to 'ascii_to' by reference */
case Token::IDENT:;
if (ascii_to(_value.start(), result) == _value.len())
return result;
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case Token::STRING:
if (ascii_to(_value.start()+1, result) == _value.len()-2)
return result;
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default:
/* read values 0 (false) / !0 (true) */
unsigned long value;
int sign;
bool valid = read_ulong(&value, &sign);
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return valid ? value : default_value;
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}
}
void key(char *dst, size_t dst_len) const
{
_key.string(dst, dst_len);
}
void string(char *dst, size_t dst_len, const char *default_string) const
{
/* check for one-word string w/o quotes */
if (_value.type() == Token::IDENT) {
size_t len = min(dst_len - 1, _value.len());
memcpy(dst, _value.start(), len);
dst[len] = 0;
return;
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}
/* stop here if _value is not a string */
if (_value.type() != Token::STRING) {
strncpy(dst, default_string, dst_len);
return;
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}
/* unpack string to dst */
size_t num_chars = min(dst_len - 1, _value.len());
unpack_string(_value.start(), dst, num_chars);
}
/**
* Retrieve a dataspace (page) aligned size argument
*/
size_t aligned_size() const
{
unsigned long value = ulong_value(0);
return align_addr(value, 12);
}
};
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class Genode::Arg_string
{
typedef Arg::Token Token;
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private:
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static Token _next_key(Token t)
{
for (; t; t = t.next().eat_whitespace())
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/* if we find a comma, return token after comma */
if (t[0] == ',') return t.next().eat_whitespace();
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return Token();
}
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/**
* Find key token in argument string
*/
static Token _find_key(const char *args, const char *key)
{
for (Token t(args); t; t = _next_key(t))
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/* check if key matches */
if ((t.type() == Token::IDENT) && !strcmp(key, t.start(), t.len()))
return t;
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return Token();
}
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/**
* Append source string to destination string
*
* NOTE: check string length before calling this method!
*
* \return last character of result string
*/
static char *_append(char *dst, const char *src)
{
unsigned src_len = strlen(src);
while (*dst) dst++;
memcpy(dst, src, src_len + 1);
return dst + src_len;
}
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public:
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/**
* Find argument by its key
*/
static Arg find_arg(const char *args, const char *key) {
return (args && key) ? Arg(_find_key(args, key)) : Arg(); }
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static Arg first_arg(const char *args) {
return Arg(Token(args)); }
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/**
* Remove argument with the specified key
*/
static bool remove_arg(char *args, const char *key)
{
if (!args || !key) return false;
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Token beg = _find_key(args, key);
Token next = _next_key(beg);
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/* no such key to remove - we are done */
if (!beg) return true;
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/* if argument is the last one, null-terminate string right here */
if (!next) {
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/* eat all pending whitespaces at the end of the string */
char *s = max(beg.start() - 1, args);
while (s > args && (*s == ' ')) s--;
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/* write string-terminating zero */
*s = 0;
} else
memcpy(beg.start(), next.start(), strlen(next.start()) + 1);
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return true;
}
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/**
* Add new argument
*/
static bool add_arg(char *args, unsigned args_len,
const char *key, const char *value,
Token::Type type = Token::Type::IDENT)
{
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 */
if ((type == Token::Type::STRING
&& old_len + strlen(key) + strlen(value) + 4 > args_len)
|| (old_len + strlen(key) + strlen(value) + 2 > args_len))
return false;
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args += old_len;
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if (old_len)
args = _append(args, ", ");
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if (type == Token::Type::STRING)
_append(_append(_append(_append(args, key), "=\""), value), "\"");
else
_append(_append(_append(args, key), "="), value);
return true;
}
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/**
* Assign new value to argument
*/
static bool set_arg(char *args, unsigned args_len,
const char *key, const char *value)
{
return remove_arg(args, key) && add_arg(args, args_len, key, value);
}
/**
* Assign new integer argument
*/
static bool set_arg(char *args, unsigned args_len,
const char *key, int value)
{
enum { STRING_LONG_MAX = 32 };
char buf[STRING_LONG_MAX];
snprintf(buf, sizeof(buf), "%d", value);
return remove_arg(args, key) && add_arg(args, args_len, key, buf);
}
/**
* Assign new string argument
*/
static bool set_arg_string(char *args, unsigned args_len,
const char *key, const char *value)
{
return remove_arg(args, key)
&& add_arg(args, args_len, key, value, Token::Type::STRING);
}
};
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#endif /* _INCLUDE__UTIL__ARG_STRING_H_ */