kits/storage/Path.cpp

/*
 * Copyright 2002-2012, Haiku Inc.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *		Tyler Dauwalder
 *		Axel Dörfler, axeld@pinc-software.de
 *		Ingo Weinhold, bonefish@users.sf.net
 */


#include <Path.h>

#include <new>

#include <Directory.h>
#include <Entry.h>
#include <StorageDefs.h>
#include <String.h>

#include <syscalls.h>

#include "storage_support.h"


using namespace std;


// Creates an uninitialized BPath object.
BPath::BPath()
	:
	fName(NULL),
	fCStatus(B_NO_INIT)
{
}


// Creates a copy of the given BPath object.
BPath::BPath(const BPath& path)
	:
	fName(NULL),
	fCStatus(B_NO_INIT)
{
	*this = path;
}


// Creates a BPath object and initializes it to the filesystem entry
// specified by the passed in entry_ref struct.
BPath::BPath(const entry_ref* ref)
	:
	fName(NULL),
	fCStatus(B_NO_INIT)
{
	SetTo(ref);
}


// Creates a BPath object and initializes it to the filesystem entry
// specified by the passed in BEntry object.
BPath::BPath(const BEntry* entry)
	:
	fName(NULL),
	fCStatus(B_NO_INIT)
{
	SetTo(entry);
}


// Creates a BPath object and initializes it to the specified path or
// path and filename combination.
BPath::BPath(const char* dir, const char* leaf, bool normalize)
	:
	fName(NULL),
	fCStatus(B_NO_INIT)
{
	SetTo(dir, leaf, normalize);
}


// Creates a BPath object and initializes it to the specified directory
// and filename combination.
BPath::BPath(const BDirectory* dir, const char* leaf, bool normalize)
	:
	fName(NULL),
	fCStatus(B_NO_INIT)
{
	SetTo(dir, leaf, normalize);
}


// Destroys the BPath object and frees any of its associated resources.
BPath::~BPath()
{
	Unset();
}


// Checks whether or not the object was properly initialized.
status_t
BPath::InitCheck() const
{
	return fCStatus;
}


// Reinitializes the object to the filesystem entry specified by the
// passed in entry_ref struct.
status_t
BPath::SetTo(const entry_ref* ref)
{
	Unset();
	if (!ref)
		return fCStatus = B_BAD_VALUE;

	char path[B_PATH_NAME_LENGTH];
	fCStatus = _kern_entry_ref_to_path(ref->device, ref->directory,
		ref->name, path, sizeof(path));
	if (fCStatus != B_OK)
		return fCStatus;

	fCStatus = _SetPath(path);
		// the path is already normalized
	return fCStatus;
}


// Reinitializes the object to the specified filesystem entry.
status_t
BPath::SetTo(const BEntry* entry)
{
	Unset();
	if (entry == NULL)
		return B_BAD_VALUE;

	entry_ref ref;
	fCStatus = entry->GetRef(&ref);
	if (fCStatus == B_OK)
		fCStatus = SetTo(&ref);

	return fCStatus;
}


// Reinitializes the object to the passed in path or path and
// leaf combination.
status_t
BPath::SetTo(const char* path, const char* leaf, bool normalize)
{
	status_t error = (path ? B_OK : B_BAD_VALUE);
	if (error == B_OK && leaf && BPrivate::Storage::is_absolute_path(leaf))
		error = B_BAD_VALUE;
	char newPath[B_PATH_NAME_LENGTH];
	if (error == B_OK) {
		// we always normalize relative paths
		normalize |= !BPrivate::Storage::is_absolute_path(path);
		// build a new path from path and leaf
		// copy path first
		uint32 pathLen = strlen(path);
		if (pathLen >= sizeof(newPath))
			error = B_NAME_TOO_LONG;
		if (error == B_OK)
			strcpy(newPath, path);
		// append leaf, if supplied
		if (error == B_OK && leaf) {
			bool needsSeparator = (pathLen > 0 && path[pathLen - 1] != '/');
			uint32 wholeLen = pathLen + (needsSeparator ? 1 : 0)
							  + strlen(leaf);
			if (wholeLen >= sizeof(newPath))
				error = B_NAME_TOO_LONG;
			if (error == B_OK) {
				if (needsSeparator) {
					newPath[pathLen] = '/';
					pathLen++;
				}
				strcpy(newPath + pathLen, leaf);
			}
		}
		// check, if necessary to normalize
		if (error == B_OK && !normalize)
			normalize = _MustNormalize(newPath, &error);

		// normalize the path, if necessary, otherwise just set it
		if (error == B_OK) {
			if (normalize) {
				// create a BEntry and initialize us with this entry
				BEntry entry;
				error = entry.SetTo(newPath, false);
				if (error == B_OK)
					return SetTo(&entry);
			} else
				error = _SetPath(newPath);
		}
	}
	// cleanup, if something went wrong
	if (error != B_OK)
		Unset();
	fCStatus = error;
	return error;
}


// Reinitializes the object to the passed in dir and relative path combination.
status_t
BPath::SetTo(const BDirectory* dir, const char* path, bool normalize)
{
	status_t error = (dir && dir->InitCheck() == B_OK ? B_OK : B_BAD_VALUE);
	// get the path of the BDirectory
	BEntry entry;
	if (error == B_OK)
		error = dir->GetEntry(&entry);
	BPath dirPath;
	if (error == B_OK)
		error = dirPath.SetTo(&entry);
	// let the other version do the work
	if (error == B_OK)
		error = SetTo(dirPath.Path(), path, normalize);
	if (error != B_OK)
		Unset();
	fCStatus = error;
	return error;
}


// Returns the object to an uninitialized state.
void
BPath::Unset()
{
	_SetPath(NULL);
	fCStatus = B_NO_INIT;
}


// Appends the passed in relative path to the end of the current path.
status_t
BPath::Append(const char* path, bool normalize)
{
	status_t error = (InitCheck() == B_OK ? B_OK : B_BAD_VALUE);
	if (error == B_OK)
		error = SetTo(Path(), path, normalize);
	if (error != B_OK)
		Unset();
	fCStatus = error;
	return error;
}


// Gets the entire path of the object.
const char*
BPath::Path() const
{
	return fName;
}


// Gets the leaf portion of the path.
const char*
BPath::Leaf() const
{
	if (InitCheck() != B_OK)
		return NULL;

	const char* result = fName + strlen(fName);
	// There should be no need for the second condition, since we deal
	// with absolute paths only and those contain at least one '/'.
	// However, it doesn't harm.
	while (*result != '/' && result > fName)
		result--;
	result++;

	return result;
}


// Initializes path with the parent directory of the BPath object.
status_t
BPath::GetParent(BPath* path) const
{
	if (path == NULL)
		return B_BAD_VALUE;

	status_t error = InitCheck();
	if (error != B_OK)
		return error;

	int32 length = strlen(fName);
	if (length == 1) {
		// handle "/" (path is supposed to be absolute)
		return B_ENTRY_NOT_FOUND;
	}

	char parentPath[B_PATH_NAME_LENGTH];
	length--;
	while (fName[length] != '/' && length > 0)
		length--;
	if (length == 0) {
		// parent dir is "/"
		length++;
	}
	memcpy(parentPath, fName, length);
	parentPath[length] = '\0';

	return path->SetTo(parentPath);
}


// Gets whether or not the path is absolute or relative.
bool
BPath::IsAbsolute() const
{
	if (InitCheck() != B_OK)
		return false;

	return fName[0] == '/';
}


// Performs a simple (string-wise) comparison of paths for equality.
bool
BPath::operator==(const BPath& item) const
{
	return *this == item.Path();
}


// Performs a simple (string-wise) comparison of paths for equality.
bool
BPath::operator==(const char* path) const
{
	return (InitCheck() != B_OK && path == NULL)
		|| (fName != NULL && path != NULL && strcmp(fName, path) == 0);
}


// Performs a simple (string-wise) comparison of paths for inequality.
bool
BPath::operator!=(const BPath& item) const
{
	return !(*this == item);
}


// Performs a simple (string-wise) comparison of paths for inequality.
bool
BPath::operator!=(const char* path) const
{
	return !(*this == path);
}


// Initializes the object as a copy of item.
BPath&
BPath::operator=(const BPath& item)
{
	if (this != &item)
		*this = item.Path();
	return *this;
}


// Initializes the object with the passed in path.
BPath&
BPath::operator=(const char* path)
{
	if (path == NULL)
		Unset();
	else
		SetTo(path);
	return *this;
}


//	#pragma mark - BFlattenable functionality


// that's the layout of a flattened entry_ref
struct flattened_entry_ref {
	dev_t device;
	ino_t directory;
	char name[1];
};

// base size of a flattened entry ref
static const size_t flattened_entry_ref_size
	= sizeof(dev_t) + sizeof(ino_t);


// Overrides BFlattenable::IsFixedSize()
bool
BPath::IsFixedSize() const
{
	return false;
}


// Overrides BFlattenable::TypeCode()
type_code
BPath::TypeCode() const
{
	return B_REF_TYPE;
}


// Gets the size of the flattened entry_ref struct that represents
// the path in bytes.
ssize_t
BPath::FlattenedSize() const
{
	ssize_t size = flattened_entry_ref_size;
	BEntry entry;
	entry_ref ref;
	if (InitCheck() == B_OK
		&& entry.SetTo(Path()) == B_OK
		&& entry.GetRef(&ref) == B_OK) {
		size += strlen(ref.name) + 1;
	}
	return size;
}


// Converts the path of the object to an entry_ref and writes it into buffer.
status_t
BPath::Flatten(void* buffer, ssize_t size) const
{
	if (buffer == NULL)
		return B_BAD_VALUE;

	// ToDo: Reimplement for performance reasons: Don't call FlattenedSize().
	ssize_t flattenedSize = FlattenedSize();
	if (flattenedSize < 0)
		return flattenedSize;
	if (size < flattenedSize)
		return B_BAD_VALUE;

	// convert the path to an entry_ref
	BEntry entry;
	entry_ref ref;

	if (Path() != NULL) {
		status_t status = entry.SetTo(Path());
		if (status == B_OK)
			status = entry.GetRef(&ref);
		if (status != B_OK)
			return status;
	}

	// store the entry_ref in the buffer
	flattened_entry_ref& fref = *(flattened_entry_ref*)buffer;
	fref.device = ref.device;
	fref.directory = ref.directory;
	if (ref.name)
		strcpy(fref.name, ref.name);

	return B_OK;
}


// Checks if type code is equal to B_REF_TYPE.
bool
BPath::AllowsTypeCode(type_code code) const
{
	return code == B_REF_TYPE;
}


// Initializes the object with the flattened entry_ref data from the passed
// in buffer.
status_t
BPath::Unflatten(type_code code, const void* buffer, ssize_t size)
{
	Unset();
	status_t error = B_OK;
	// check params
	if (!(code == B_REF_TYPE && buffer != NULL
		  && size >= (ssize_t)flattened_entry_ref_size)) {
		error = B_BAD_VALUE;
	}
	if (error == B_OK) {
		if (size == (ssize_t)flattened_entry_ref_size) {
			// already Unset();
		} else {
			// reconstruct the entry_ref from the buffer
			const flattened_entry_ref& fref
				= *(const flattened_entry_ref*)buffer;
			BString name(fref.name, size - flattened_entry_ref_size);
			entry_ref ref(fref.device, fref.directory, name.String());
			error = SetTo(&ref);
		}
	}
	if (error != B_OK)
		fCStatus = error;
	return error;
}


void BPath::_WarPath1() {}
void BPath::_WarPath2() {}
void BPath::_WarPath3() {}


/*!	Sets the supplied path.

	The path is copied, if \a path is \c NULL the path of the object is set to
	\c NULL as well. The old path is deleted.

	\param path the path to be set

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_MEMORY Insufficient memory.
*/
status_t
BPath::_SetPath(const char* path)
{
	status_t error = B_OK;
	const char* oldPath = fName;
	// set the new path
	if (path) {
		fName = new(nothrow) char[strlen(path) + 1];
		if (fName)
			strcpy(fName, path);
		else
			error = B_NO_MEMORY;
	} else
		fName = NULL;

	// delete the old one
	delete[] oldPath;
	return error;
}


/*!	Checks a path to see if normalization is required.

	The following items require normalization:
	- Relative pathnames (after concatenation; e.g. "boot/ltj")
	- The presence of "." or ".." ("/boot/ltj/../ltj/./gwar")
	- Redundant slashes ("/boot//ltj")
	- A trailing slash ("/boot/ltj/")

	\param _error A pointer to an error variable that will be set if the input
		is not a valid path.

	\return \c true if \a path requires normalization, \c false otherwise.
*/
bool
BPath::_MustNormalize(const char* path, status_t* _error)
{
	// Check for useless input
	if (path == NULL || path[0] == 0) {
		if (_error != NULL)
			*_error = B_BAD_VALUE;
		return false;
	}

	int len = strlen(path);

	/* Look for anything in the string that forces us to normalize:
			+ No leading /
			+ any occurence of /./ or /../ or //, or a trailing /. or /..
			+ a trailing /
	*/;
	if (path[0] != '/')
		return true;	//	not "/*"
	else if (len == 1)
		return false;	//	"/"
	else if (len > 1 && path[len-1] == '/')
		return true;	// 	"*/"
	else {
		enum ParseState {
			NoMatch,
			InitialSlash,
			OneDot,
			TwoDots
		} state = NoMatch;

		for (int i = 0; path[i] != 0; i++) {
			switch (state) {
				case NoMatch:
					if (path[i] == '/')
						state = InitialSlash;
					break;

				case InitialSlash:
					if (path[i] == '/')
						return true;		// "*//*"

					if (path[i] == '.')
						state = OneDot;
					else
						state = NoMatch;
					break;

				case OneDot:
					if (path[i] == '/')
						return true;		// "*/./*"

					if (path[i] == '.')
						state = TwoDots;
					else
						state = NoMatch;
					break;

				case TwoDots:
					if (path[i] == '/')
						return true;		// "*/../*"

					state = NoMatch;
					break;
			}
		}

		// If we hit the end of the string while in either
		// of these two states, there was a trailing /. or /..
		if (state == OneDot || state == TwoDots)
			return true;

		return false;
	}
}