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scanf.cpp
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/*
* Copyright (c) 2021, the SerenityOS developers.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/Format.h>
#include <AK/GenericLexer.h>
#include <AK/StdLibExtras.h>
#include <ctype.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
enum class LengthModifier {
None,
Default,
Char,
Short,
Long,
LongLong,
IntMax,
Size,
PtrDiff,
LongDouble,
};
enum class ConversionSpecifier {
Unspecified,
Decimal,
Integer,
Octal,
Unsigned,
Hex,
Floating,
String,
UseScanList,
Character,
Pointer,
OutputNumberOfBytes,
Invalid,
};
enum class ReadKind {
Normal,
Octal,
Hex,
Infer,
};
template<typename T, typename ApT, ReadKind kind = ReadKind::Normal>
struct ReadElementConcrete {
bool operator()(GenericLexer&, va_list)
{
return false;
}
};
template<typename ApT, ReadKind kind>
struct ReadElementConcrete<int, ApT, kind> {
bool operator()(GenericLexer& lexer, va_list* ap, bool suppress_assignment)
{
lexer.ignore_while(isspace);
long value = 0;
char* endptr = nullptr;
auto nptr = lexer.remaining().characters_without_null_termination();
if constexpr (kind == ReadKind::Normal)
value = strtol(nptr, &endptr, 10);
if constexpr (kind == ReadKind::Octal)
value = strtol(nptr, &endptr, 8);
if constexpr (kind == ReadKind::Hex)
value = strtol(nptr, &endptr, 16);
if constexpr (kind == ReadKind::Infer)
value = strtol(nptr, &endptr, 0);
if (!endptr)
return false;
if (endptr == nptr)
return false;
auto diff = endptr - nptr;
VERIFY(diff > 0);
lexer.ignore((size_t)diff);
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, ApT*);
*ptr = value;
}
return true;
}
};
template<typename ApT, ReadKind kind>
struct ReadElementConcrete<char, ApT, kind> {
bool operator()(GenericLexer& lexer, va_list* ap, bool suppress_assignment)
{
static_assert(kind == ReadKind::Normal, "Can't read a non-normal character");
if (lexer.is_eof())
return false;
auto ch = lexer.consume();
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, ApT*);
*ptr = ch;
}
return true;
}
};
template<typename ApT, ReadKind kind>
struct ReadElementConcrete<unsigned, ApT, kind> {
bool operator()(GenericLexer& lexer, va_list* ap, bool suppress_assignment)
{
lexer.ignore_while(isspace);
unsigned long value = 0;
char* endptr = nullptr;
auto nptr = lexer.remaining().characters_without_null_termination();
if constexpr (kind == ReadKind::Normal)
value = strtoul(nptr, &endptr, 10);
if constexpr (kind == ReadKind::Octal)
value = strtoul(nptr, &endptr, 8);
if constexpr (kind == ReadKind::Hex)
value = strtoul(nptr, &endptr, 16);
if constexpr (kind == ReadKind::Infer)
value = strtoul(nptr, &endptr, 0);
if (!endptr)
return false;
if (endptr == nptr)
return false;
auto diff = endptr - nptr;
VERIFY(diff > 0);
lexer.ignore((size_t)diff);
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, ApT*);
*ptr = value;
}
return true;
}
};
template<typename ApT, ReadKind kind>
struct ReadElementConcrete<long long, ApT, kind> {
bool operator()(GenericLexer& lexer, va_list* ap, bool suppress_assignment)
{
lexer.ignore_while(isspace);
long long value = 0;
char* endptr = nullptr;
auto nptr = lexer.remaining().characters_without_null_termination();
if constexpr (kind == ReadKind::Normal)
value = strtoll(nptr, &endptr, 10);
if constexpr (kind == ReadKind::Octal)
value = strtoll(nptr, &endptr, 8);
if constexpr (kind == ReadKind::Hex)
value = strtoll(nptr, &endptr, 16);
if constexpr (kind == ReadKind::Infer)
value = strtoll(nptr, &endptr, 0);
if (!endptr)
return false;
if (endptr == nptr)
return false;
auto diff = endptr - nptr;
VERIFY(diff > 0);
lexer.ignore((size_t)diff);
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, ApT*);
*ptr = value;
}
return true;
}
};
template<typename ApT, ReadKind kind>
struct ReadElementConcrete<unsigned long long, ApT, kind> {
bool operator()(GenericLexer& lexer, va_list* ap, bool suppress_assignment)
{
lexer.ignore_while(isspace);
unsigned long long value = 0;
char* endptr = nullptr;
auto nptr = lexer.remaining().characters_without_null_termination();
if constexpr (kind == ReadKind::Normal)
value = strtoull(nptr, &endptr, 10);
if constexpr (kind == ReadKind::Octal)
value = strtoull(nptr, &endptr, 8);
if constexpr (kind == ReadKind::Hex)
value = strtoull(nptr, &endptr, 16);
if constexpr (kind == ReadKind::Infer)
value = strtoull(nptr, &endptr, 0);
if (!endptr)
return false;
if (endptr == nptr)
return false;
auto diff = endptr - nptr;
VERIFY(diff > 0);
lexer.ignore((size_t)diff);
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, ApT*);
*ptr = value;
}
return true;
}
};
template<typename ApT, ReadKind kind>
struct ReadElementConcrete<float, ApT, kind> {
bool operator()(GenericLexer& lexer, va_list* ap, bool suppress_assignment)
{
lexer.ignore_while(isspace);
double value = 0;
char* endptr = nullptr;
auto nptr = lexer.remaining().characters_without_null_termination();
if constexpr (kind == ReadKind::Normal)
value = strtod(nptr, &endptr);
else
return false;
if (!endptr)
return false;
if (endptr == nptr)
return false;
auto diff = endptr - nptr;
VERIFY(diff > 0);
lexer.ignore((size_t)diff);
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, ApT*);
*ptr = value;
}
return true;
}
};
template<typename T, ReadKind kind>
struct ReadElement {
bool operator()(LengthModifier length_modifier, GenericLexer& input_lexer, va_list* ap, bool suppress_assignment)
{
switch (length_modifier) {
default:
case LengthModifier::None:
VERIFY_NOT_REACHED();
case LengthModifier::Default:
return ReadElementConcrete<T, T, kind> {}(input_lexer, ap, suppress_assignment);
case LengthModifier::Char:
return ReadElementConcrete<T, char, kind> {}(input_lexer, ap, suppress_assignment);
case LengthModifier::Short:
return ReadElementConcrete<T, short, kind> {}(input_lexer, ap, suppress_assignment);
case LengthModifier::Long:
if constexpr (IsSame<T, int>)
return ReadElementConcrete<T, long, kind> {}(input_lexer, ap, suppress_assignment);
if constexpr (IsSame<T, unsigned>)
return ReadElementConcrete<T, unsigned long, kind> {}(input_lexer, ap, suppress_assignment);
if constexpr (IsSame<T, float>)
return ReadElementConcrete<int, double, kind> {}(input_lexer, ap, suppress_assignment);
return false;
case LengthModifier::LongLong:
if constexpr (IsSame<T, int>)
return ReadElementConcrete<long long, long long, kind> {}(input_lexer, ap, suppress_assignment);
if constexpr (IsSame<T, unsigned>)
return ReadElementConcrete<unsigned long long, unsigned long long, kind> {}(input_lexer, ap, suppress_assignment);
if constexpr (IsSame<T, float>)
return ReadElementConcrete<long long, double, kind> {}(input_lexer, ap, suppress_assignment);
return false;
case LengthModifier::IntMax:
return ReadElementConcrete<T, intmax_t, kind> {}(input_lexer, ap, suppress_assignment);
case LengthModifier::Size:
return ReadElementConcrete<T, size_t, kind> {}(input_lexer, ap, suppress_assignment);
case LengthModifier::PtrDiff:
return ReadElementConcrete<T, ptrdiff_t, kind> {}(input_lexer, ap, suppress_assignment);
case LengthModifier::LongDouble:
return ReadElementConcrete<T, long double, kind> {}(input_lexer, ap, suppress_assignment);
}
}
};
template<>
struct ReadElement<char*, ReadKind::Normal> {
ReadElement(StringView scan_set = {}, bool invert = false)
: scan_set(scan_set.is_null() ? " \t\n\f\r"sv : scan_set)
, invert(scan_set.is_null() ? true : invert)
, was_null(scan_set.is_null())
{
}
bool operator()(LengthModifier length_modifier, GenericLexer& input_lexer, va_list* ap, bool suppress_assignment)
{
// FIXME: Implement wide strings and such.
if (length_modifier != LengthModifier::Default)
return false;
if (was_null)
input_lexer.ignore_while(isspace);
auto str = input_lexer.consume_while([this](auto c) { return this->matches(c); });
if (str.is_empty())
return false;
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, char*);
memcpy(ptr, str.characters_without_null_termination(), str.length());
ptr[str.length()] = 0;
}
return true;
}
private:
bool matches(char c) const
{
return invert ^ scan_set.contains(c);
}
const StringView scan_set;
bool invert { false };
bool was_null { false };
};
template<>
struct ReadElement<void*, ReadKind::Normal> {
bool operator()(LengthModifier length_modifier, GenericLexer& input_lexer, va_list* ap, bool suppress_assignment)
{
if (length_modifier != LengthModifier::Default)
return false;
input_lexer.ignore_while(isspace);
auto str = input_lexer.consume_while([this](auto c) { return this->should_consume(c); });
if (count != 8) {
fail:;
for (size_t i = 0; i < count; ++i)
input_lexer.retreat();
return false;
}
char buf[9] { 0 };
memcpy(buf, str.characters_without_null_termination(), 8);
buf[8] = 0;
char* endptr = nullptr;
auto value = strtoull(buf, &endptr, 16);
if (endptr != &buf[8])
goto fail;
if (!suppress_assignment) {
auto* ptr = va_arg(*ap, void**);
memcpy(ptr, &value, sizeof(value));
}
return true;
}
private:
bool should_consume(char c)
{
if (count == 8)
return false;
if (!isxdigit(c))
return false;
++count;
return true;
}
size_t count { 0 };
};
extern "C" int vsscanf(char const* input, char const* format, va_list ap)
{
GenericLexer format_lexer { { format, strlen(format) } };
GenericLexer input_lexer { { input, strlen(input) } };
int elements_matched = 0;
va_list copy;
__builtin_va_copy(copy, ap);
while (!format_lexer.is_eof()) {
format_lexer.ignore_while(isspace);
if (!format_lexer.next_is('%')) {
read_one_literal:;
input_lexer.ignore_while(isspace);
if (format_lexer.is_eof())
break;
auto next_char = format_lexer.consume();
if (!input_lexer.consume_specific(next_char))
return elements_matched;
continue;
}
if (format_lexer.next_is("%%")) {
format_lexer.ignore();
goto read_one_literal;
}
format_lexer.ignore(); // '%'
bool suppress_assignment = false;
if (format_lexer.next_is('*')) {
suppress_assignment = true;
format_lexer.ignore();
}
// Parse width specification
[[maybe_unused]] int width_specifier = 0;
if (format_lexer.next_is(isdigit)) {
auto width_digits = format_lexer.consume_while([](char c) { return isdigit(c); });
width_specifier = width_digits.to_int().value();
// FIXME: Actually use width specifier
}
bool invert_scanlist = false;
StringView scanlist;
LengthModifier length_modifier { LengthModifier::None };
ConversionSpecifier conversion_specifier { ConversionSpecifier::Unspecified };
reread_lookahead:;
auto format_lookahead = format_lexer.peek();
if (length_modifier == LengthModifier::None) {
switch (format_lookahead) {
case 'h':
if (format_lexer.peek(1) == 'h') {
format_lexer.consume(2);
length_modifier = LengthModifier::Char;
} else {
format_lexer.consume(1);
length_modifier = LengthModifier::Short;
}
break;
case 'l':
if (format_lexer.peek(1) == 'l') {
format_lexer.consume(2);
length_modifier = LengthModifier::LongLong;
} else {
format_lexer.consume(1);
length_modifier = LengthModifier::Long;
}
break;
case 'j':
format_lexer.consume();
length_modifier = LengthModifier::IntMax;
break;
case 'z':
format_lexer.consume();
length_modifier = LengthModifier::Size;
break;
case 't':
format_lexer.consume();
length_modifier = LengthModifier::PtrDiff;
break;
case 'L':
format_lexer.consume();
length_modifier = LengthModifier::LongDouble;
break;
default:
length_modifier = LengthModifier::Default;
break;
}
goto reread_lookahead;
}
if (conversion_specifier == ConversionSpecifier::Unspecified) {
switch (format_lookahead) {
case 'd':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Decimal;
break;
case 'i':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Integer;
break;
case 'o':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Octal;
break;
case 'u':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Unsigned;
break;
case 'x':
case 'X':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Hex;
break;
case 'a':
case 'e':
case 'f':
case 'g':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Floating;
break;
case 's':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::String;
break;
case '[':
format_lexer.consume();
scanlist = format_lexer.consume_until(']');
format_lexer.ignore();
if (scanlist.starts_with('^')) {
scanlist = scanlist.substring_view(1);
invert_scanlist = true;
}
conversion_specifier = ConversionSpecifier::UseScanList;
break;
case 'c':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Character;
break;
case 'p':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Pointer;
break;
case 'n':
format_lexer.consume();
conversion_specifier = ConversionSpecifier::OutputNumberOfBytes;
break;
case 'C':
format_lexer.consume();
length_modifier = LengthModifier::Long;
conversion_specifier = ConversionSpecifier::Character;
break;
case 'S':
format_lexer.consume();
length_modifier = LengthModifier::Long;
conversion_specifier = ConversionSpecifier::String;
break;
default:
format_lexer.consume();
conversion_specifier = ConversionSpecifier::Invalid;
break;
}
}
// Now try to read.
switch (conversion_specifier) {
case ConversionSpecifier::Invalid:
case ConversionSpecifier::Unspecified:
default:
// "undefined behavior", let's be nice and crash.
dbgln("Invalid conversion specifier {} in scanf!", (int)conversion_specifier);
VERIFY_NOT_REACHED();
case ConversionSpecifier::Decimal:
if (!ReadElement<int, ReadKind::Normal> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::Integer:
if (!ReadElement<int, ReadKind::Infer> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::Octal:
if (!ReadElement<unsigned, ReadKind::Octal> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::Unsigned:
if (!ReadElement<unsigned, ReadKind::Normal> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::Hex:
if (!ReadElement<unsigned, ReadKind::Hex> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::Floating:
if (!ReadElement<float, ReadKind::Normal> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::String:
if (!ReadElement<char*, ReadKind::Normal> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::UseScanList:
if (!ReadElement<char*, ReadKind::Normal> { scanlist, invert_scanlist }(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::Character:
if (!ReadElement<char, ReadKind::Normal> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::Pointer:
if (!ReadElement<void*, ReadKind::Normal> {}(length_modifier, input_lexer, ©, suppress_assignment))
format_lexer.consume_all();
else if (!suppress_assignment)
++elements_matched;
break;
case ConversionSpecifier::OutputNumberOfBytes: {
input_lexer.ignore_while(isspace);
if (!suppress_assignment) {
auto* ptr = va_arg(copy, int*);
*ptr = input_lexer.tell();
}
break;
}
}
}
va_end(copy);
return elements_matched;
}