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/*
* Copyright (c) 2021, Xavier Defrang <xavier.defrang@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Assertions.h>
#include <AK/CharacterTypes.h>
#include <AK/StringUtils.h>
#include <LibCore/FilePermissionsMask.h>
namespace Core {
enum State {
Classes,
Mode
};
enum ClassFlag {
Other = 1,
Group = 2,
User = 4,
All = 7
};
enum Operation {
Add,
Remove,
Assign,
};
ErrorOr<FilePermissionsMask> FilePermissionsMask::parse(StringView string)
{
return (!string.is_empty() && is_ascii_digit(string[0]))
? from_numeric_notation(string)
: from_symbolic_notation(string);
}
ErrorOr<FilePermissionsMask> FilePermissionsMask::from_numeric_notation(StringView string)
{
mode_t mode = AK::StringUtils::convert_to_uint_from_octal<u16>(string).value_or(01000);
if (mode > 0777)
return Error::from_string_literal("invalid octal representation"sv);
return FilePermissionsMask().assign_permissions(mode);
}
ErrorOr<FilePermissionsMask> FilePermissionsMask::from_symbolic_notation(StringView string)
{
auto mask = FilePermissionsMask();
u8 state = State::Classes;
u8 classes = 0;
u8 operation = 0;
for (auto ch : string) {
switch (state) {
case State::Classes: {
// zero or more [ugoa] terminated by one operator [+-=]
if (ch == 'u')
classes |= ClassFlag::User;
else if (ch == 'g')
classes |= ClassFlag::Group;
else if (ch == 'o')
classes |= ClassFlag::Other;
else if (ch == 'a')
classes = ClassFlag::All;
else {
if (ch == '+')
operation = Operation::Add;
else if (ch == '-')
operation = Operation::Remove;
else if (ch == '=')
operation = Operation::Assign;
else if (classes == 0)
return Error::from_string_literal("invalid class: expected 'u', 'g', 'o' or 'a'"sv);
else
return Error::from_string_literal("invalid operation: expected '+', '-' or '='"sv);
// if an operation was specified without a class, assume all
if (classes == 0)
classes = ClassFlag::All;
state = State::Mode;
}
break;
}
case State::Mode: {
// one or more [rwx] terminated by a comma
// End of mode part, expect class next
if (ch == ',') {
state = State::Classes;
classes = operation = 0;
continue;
}
mode_t write_bits = 0;
if (ch == 'r')
write_bits = 4;
else if (ch == 'w')
write_bits = 2;
else if (ch == 'x')
write_bits = 1;
else
return Error::from_string_literal("invalid symbolic permission: expected 'r', 'w' or 'x'"sv);
mode_t clear_bits = operation == Operation::Assign ? 7 : write_bits;
// Update masks one class at a time in other, group, user order
for (auto cls = classes; cls != 0; cls >>= 1) {
if (cls & 1) {
if (operation == Operation::Add || operation == Operation::Assign)
mask.add_permissions(write_bits);
if (operation == Operation::Remove || operation == Operation::Assign)
mask.remove_permissions(clear_bits);
}
write_bits <<= 3;
clear_bits <<= 3;
}
break;
}
default:
VERIFY_NOT_REACHED();
}
}
return mask;
}
FilePermissionsMask& FilePermissionsMask::assign_permissions(mode_t mode)
{
m_write_mask = mode;
m_clear_mask = 0777;
return *this;
}
FilePermissionsMask& FilePermissionsMask::add_permissions(mode_t mode)
{
m_write_mask |= mode;
return *this;
}
FilePermissionsMask& FilePermissionsMask::remove_permissions(mode_t mode)
{
m_clear_mask |= mode;
return *this;
}
}
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