clues::item::DirEntries Class Reference

A range of directory entries from getdents(). More...

#include <fs.hxx>

Inheritance diagram for clues::item::DirEntries:

Classes
struct	Entry

Public Member Functions
std::string	str () const override
	Returns a human readable string representation of the item.
const auto &	entries () const
Public Member Functions inherited from clues::item::PointerOutValue
	PointerOutValue (const std::string_view short_name, const std::string_view long_name={}, const ItemType type=ItemType::PARAM_OUT)
Public Member Functions inherited from clues::item::PointerValue
	PointerValue (const ItemType type, const std::string_view short_name, const std::string_view long_name)
Public Member Functions inherited from clues::SystemCallItem
	SystemCallItem (const ItemType type, const std::string_view short_name={}, const std::string_view long_name={})
	Constructs a new SystemCallItem.
auto	type () const
bool	isIn () const
bool	isOut () const
bool	isInOut () const
bool	isReturnValue () const
void	fill (const Tracee &proc, const Word word)
	Fills the item from the given register data.
bool	needsUpdate () const
	Returns whether the item needs to be updated after the system call is finished.
std::string_view	shortName () const
	Returns the friendly short name for this item.
std::string_view	longName () const
	Returns the friendly long name for this item, if available, else the short name.
auto	hasLongName () const
bool	isZero () const
	Returns whether the parameter is set to 0 / NULL.
Word	value () const
	Returns the currently stored raw value of the item.
template<typename OTHER>
OTHER	valueAs () const
	Helper to cast the strongly typed Word m_val to other strong enum types.
ForeignPtr	asPtr () const
Flags	flags () const
bool	deferFill () const

Protected Member Functions
void	processValue (const Tracee &) override
	Processes the value stored in m_val acc. to the actual item type.
void	updateData (const Tracee &proc) override
	Called upon exit of the system call to update possible out parameters.
template<typename DIRENT>
void	parseEntries32 (const size_t bytes)
	Parses the dirent structures from m_buffer.
void	parseEntries64 (const size_t bytes)
	Parses the dirent structures for getdents64().
Protected Member Functions inherited from clues::SystemCallItem
void	setSystemCall (const SystemCall &sc)
	Sets the system call context this item is a part of.

Protected Attributes
std::vector< Entry >	m_entries
std::unique_ptr< char[]>	m_buffer
	the raw buffer backing m_entries
Protected Attributes inherited from clues::SystemCallItem
const SystemCall *	m_call = nullptr
	The system call context this item part of.
const ItemType	m_type
	The type of item.
std::string_view	m_short_name
	A human readable short name for the item, should be one word only.
std::string_view	m_long_name
	A human readable longer name for the item.
Word	m_val
	The raw register value for the item.
Flags	m_flags
	Flags influencing the processing of the item.

Additional Inherited Members
Public Types inherited from clues::SystemCallItem
enum class	Flag { DEFER_FILL = 1 << 0 }
using	Flags = cosmos::BitMask<Flag>

Detailed Description

A range of directory entries from getdents().

Definition at line 230 of file fs.hxx.

Constructor & Destructor Documentation

DirEntries()

clues::item::DirEntries::DirEntries ( )

inlineexplicit

Definition at line 246 of file fs.hxx.

                              :
                        PointerOutValue{"dirent", "struct linux_dirent"}
        {}

Member Function Documentation

entries()

const auto & clues::item::DirEntries::entries ( ) const

inline

Definition at line 252 of file fs.hxx.

                                    {
                return m_entries;
        }

parseEntries32()

template<typename DIRENT>

void clues::item::DirEntries::parseEntries32 ( const size_t bytes )

protected

Parses the dirent structures from m_buffer.

to make up for differently sized structures when dealing with 32-bit emulation we need a template type here.

Definition at line 424 of file fs.cxx.

                                                  {
 
        DIRENT *cur = nullptr;
        size_t pos = 0;
        constexpr auto NAME_OFFSET = offsetof(DIRENT, d_name);
 
        while (pos < bytes) {
                cur = (DIRENT*)(m_buffer.get() + pos);
                auto namelen = cur->d_reclen - NAME_OFFSET - 2;
                /*
                 * the length can still include padding, thus look from the
                 * back for the first non-zero byte at the end to correct the
                 * length.
                 */
                for (char *last = cur->d_name + namelen - 1; last > cur->d_name && *last == '\0'; last--, namelen--);
 
                const auto type = *(m_buffer.get() + pos + cur->d_reclen - 1);
 
                m_entries.emplace_back(Entry{
                        cur->d_ino,
                        static_cast<int64_t>(cur->d_off),
                        // to avoid copying we only keep a string_view in
                        // Entry pointing to the raw buffer data.
                        std::string_view{cur->d_name, namelen},
                        cosmos::DirEntry::Type{static_cast<unsigned char>(type)}
                });
                pos += cur->d_reclen;
        }
}

parseEntries64()

void clues::item::DirEntries::parseEntries64 ( const size_t bytes )

protected

Parses the dirent structures for getdents64().

Definition at line 454 of file fs.cxx.

                                                  {
        struct linux_dirent64 *cur = nullptr;
        size_t pos = 0;
        constexpr auto NAME_OFFSET = offsetof(linux_dirent64, d_name);
 
        while (pos < bytes) {
                cur = (linux_dirent64*)(m_buffer.get() + pos);
                auto namelen = cur->d_reclen - NAME_OFFSET;
                /*
                 * remove padding from length
                 */
                for (char *last = cur->d_name + namelen - 1; last > cur->d_name && *last == '\0'; last--, namelen--);
 
                m_entries.emplace_back(Entry{
                        cur->d_ino,
                        cur->d_off,
                        std::string_view{cur->d_name, namelen},
                        cosmos::DirEntry::Type{static_cast<unsigned char>(cur->d_type)}
                });
 
                pos += cur->d_reclen;
        }
}

processValue()

void clues::item::DirEntries::processValue ( const Tracee & )

inlineoverrideprotectedvirtual

Processes the value stored in m_val acc. to the actual item type.

This function is called for all parameter types upon entry to a system call, and for ItemType::RETVAL upon exit from a system call.

For parameters of ItemType::PARAM_OUT this callback can be used to reset any stored data to be filled in later when updateData() is called.

Reimplemented from clues::SystemCallItem.

Definition at line 258 of file fs.hxx.

                                                   {
                m_entries.clear();
                m_buffer.reset();
        }

str()

std::string clues::item::DirEntries::str ( ) const

overridevirtual

Returns a human readable string representation of the item.

This member function should be specialized in derived classes to output the item's data in a fashion suitable for the concrete item type.

Reimplemented from clues::SystemCallItem.

Definition at line 363 of file fs.cxx.

                                {
        std::stringstream ss;
        auto result = m_call->result();
 
        if (!result) {
                ss << "undefined";
        } else if (m_entries.empty()) {
                ss << "empty";
        } else {
                ss << m_entries.size() << " entries: ";
 
                std::string comma;
 
                for (const auto &entry: m_entries) {
                        ss << comma << "{d_ino=" << entry.inode
                                << ", d_off=" << entry.offset
                                << ", d_reclen=" << offsetof(struct linux_dirent, d_name) + entry.name.length() + 2
                                << ", d_name=\"" << entry.name
                                << "\", d_type=" << entry_type_label(entry.type)
                                << "}";
 
                        if (comma.empty()) {
                                comma = ", ";
                        }
                }
        }
 
        return ss.str();
}

updateData()

void clues::item::DirEntries::updateData ( const Tracee & t )

overrideprotectedvirtual

Called upon exit of the system call to update possible out parameters.

This function is called for parameters of ItemType::PARAM_OUT and ItemType::PARAM_IN_OUT upon system call exit to update the data from the values returned from the system call.

The default implementation calls processValue() to allow to share the same data processing code for input and output for item types that support both.

This function is called regardless of system call success or error, so it can happen that there is no valid data returned by the kernel or pointers in userspace are broken. Implementations should take this into consideration when operating on the data.

Reimplemented from clues::SystemCallItem.

Definition at line 393 of file fs.cxx.

                                              {
        // the amount of data stored at the DirEntries location depends on the
        // system call result value.
        auto result = m_call->result();
        if (!result)
                // error occurred
                return;
 
        const auto bytes = result->valueAs<size_t>();
        if (bytes == 0)
                // empty
                return;
 
        /*
         * first copy over all the necessary data from the tracee
         */
        m_buffer = std::unique_ptr<char[]>(new char[bytes]);
        proc.readBlob(asPtr(), m_buffer.get(), bytes);
 
        if (m_call->callNr() == SystemCallNr::GETDENTS64) {
                parseEntries64(bytes);
        } else {
                if (m_call->is32BitEmulationABI()) {
                        parseEntries32<struct linux_dirent32>(bytes);
                } else {
                        parseEntries32<struct linux_dirent>(bytes);
                }
        }
}

Member Data Documentation

m_buffer

std::unique_ptr<char[]> clues::item::DirEntries::m_buffer

protected

the raw buffer backing m_entries

Definition at line 280 of file fs.hxx.

m_entries

std::vector<Entry> clues::item::DirEntries::m_entries

protected

Definition at line 278 of file fs.hxx.

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The documentation for this class was generated from the following files:

• include/items/fs.hxx
• src/items/fs.cxx