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Path.h

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00001 //===- llvm/System/Path.h - Path Operating System Concept -------*- C++ -*-===//
00002 // 
00003 //                     The LLVM Compiler Infrastructure
00004 //
00005 // This file was developed by Reid Spencer and is distributed under the 
00006 // University of Illinois Open Source License. See LICENSE.TXT for details.
00007 // 
00008 //===----------------------------------------------------------------------===//
00009 //
00010 // This file declares the llvm::sys::Path class.
00011 //
00012 //===----------------------------------------------------------------------===//
00013 
00014 #ifndef LLVM_SYSTEM_PATH_H
00015 #define LLVM_SYSTEM_PATH_H
00016 
00017 #include "llvm/System/TimeValue.h"
00018 #include <set>
00019 #include <string>
00020 #include <vector>
00021 
00022 namespace llvm {
00023 namespace sys {
00024 
00025   /// This class provides an abstraction for the path to a file or directory 
00026   /// in the operating system's filesystem and provides various basic operations
00027   /// on it.  Note that this class only represents the name of a path to a file
00028   /// or directory which may or may not be valid for a given machine's file 
00029   /// system. A Path ensures that the name it encapsulates is syntactical valid
00030   /// for the operating system it is running on but does not ensure correctness
00031   /// for any particular file system. A Path either references a file or a 
00032   /// directory and the distinction is consistently maintained. Most operations
00033   /// on the class have invariants that require the Path object to be either a
00034   /// file path or a directory path, but not both. Those operations will also 
00035   /// leave the object as either a file path or object path. There is exactly 
00036   /// one invalid Path which is the empty path. The class should never allow any
00037   /// other syntactically invalid non-empty path name to be assigned. Empty
00038   /// paths are required in order to indicate an error result. If the path is
00039   /// empty, the isValid operation will return false. All operations will fail
00040   /// if isValid is false. Operations that change the path will either return 
00041   /// false if it would cause a syntactically invalid path name (in which case 
00042   /// the Path object is left unchanged) or throw an std::string exception 
00043   /// indicating the error.
00044   /// @since 1.4
00045   /// @brief An abstraction for operating system paths.
00046   class Path {
00047     /// @name Types
00048     /// @{
00049     public:
00050       /// This structure provides basic file system information about a file. It
00051       /// is patterned after the stat(2) Unix operating system call but made
00052       /// platform independent and eliminates many of the unix-specific fields.
00053       /// However, to support llvm-ar, the mode, user, and group fields are
00054       /// retained. These pertain to unix security and may not have a meaningful
00055       /// value on non-Unix platforms. However, the fileSize and modTime fields
00056       /// should always be applicabe on all platforms.  The structure is 
00057       /// filled in by the getStatusInfo method.
00058       /// @brief File status structure
00059       struct StatusInfo {
00060         StatusInfo() : fileSize(0), modTime(0,0), mode(0777), user(999), 
00061                        group(999), isDir(false) { }
00062         size_t      fileSize;   ///< Size of the file in bytes
00063         TimeValue   modTime;    ///< Time of file's modification
00064         uint32_t    mode;       ///< Mode of the file, if applicable
00065         uint32_t    user;       ///< User ID of owner, if applicable
00066         uint32_t    group;      ///< Group ID of owner, if applicable
00067         bool        isDir;      ///< True if this is a directory.
00068       };
00069 
00070     /// @}
00071     /// @name Constructors
00072     /// @{
00073     public:
00074       /// Construct a path to the root directory of the file system. The root
00075       /// directory is a top level directory above which there are no more 
00076       /// directories. For example, on UNIX, the root directory is /. On Windows
00077       /// it is C:\. Other operating systems may have different notions of
00078       /// what the root directory is.
00079       /// @throws nothing
00080       static Path GetRootDirectory();
00081 
00082       /// Construct a path to a unique temporary directory that is created in
00083       /// a "standard" place for the operating system. The directory is 
00084       /// guaranteed to be created on exit from this function. If the directory 
00085       /// cannot be created, the function will throw an exception.
00086       /// @throws std::string indicating why the directory could not be created.
00087       /// @brief Constrct a path to an new, unique, existing temporary
00088       /// directory.
00089       static Path GetTemporaryDirectory();
00090 
00091       /// Determine the platform-specific location of a library by first
00092       /// searching a list of library paths, then searching a list of "well
00093       /// known" paths for the platform. T
00094       /// @returns a valid Path object if the library was found, an invalid
00095       /// one otherwise.
00096       /// @throws nothing
00097       /// @brief Locate a library in a platform specific manner.
00098       static Path GetLibraryPath(const std::string& basename, 
00099                                  const std::vector<std::string>& LibPaths);
00100       /// 
00101       /// Construct a path to the first system library directory. The
00102       /// implementation of Path on a given platform must ensure that this
00103       /// directory both exists and also contains standard system libraries
00104       /// suitable for linking into programs.
00105       /// @throws nothing
00106       /// @brief Construct a path to the first system library directory
00107       static Path GetSystemLibraryPath1();
00108 
00109       /// Construct a path to the second system library directory. The
00110       /// implementation of Path on a given platform must ensure that this
00111       /// directory both exists and also contains standard system libraries
00112       /// suitable for linking into programs. Note that the "second" system
00113       /// library directory may or may not be different from the first. 
00114       /// @throws nothing
00115       /// @brief Construct a path to the second system library directory
00116       static Path GetSystemLibraryPath2();
00117 
00118       /// Construct a path to the default LLVM configuration directory. The 
00119       /// implementation must ensure that this is a well-known (same on many
00120       /// systems) directory in which llvm configuration files exist. For 
00121       /// example, on Unix, the /etc/llvm directory has been selected.
00122       /// @throws nothing
00123       /// @brief Construct a path to the default LLVM configuration directory
00124       static Path GetLLVMDefaultConfigDir();
00125 
00126       /// Construct a path to the LLVM installed configuration directory. The
00127       /// implementation must ensure that this refers to the "etc" directory of
00128       /// the LLVM installation. This is the location where configuration files
00129       /// will be located for a particular installation of LLVM on a machine.
00130       /// @throws nothing
00131       /// @brief Construct a path to the LLVM installed configuration directory
00132       static Path GetLLVMConfigDir();
00133 
00134       /// Construct a path to the current user's home directory. The
00135       /// implementation must use an operating system specific mechanism for
00136       /// determining the user's home directory. For example, the environment 
00137       /// variable "HOME" could be used on Unix. If a given operating system 
00138       /// does not have the concept of a user's home directory, this static
00139       /// constructor must provide the same result as GetRootDirectory.
00140       /// @throws nothing
00141       /// @brief Construct a path to the current user's "home" directory
00142       static Path GetUserHomeDirectory();
00143 
00144       /// Return the suffix commonly used on file names that contain a shared
00145       /// object, shared archive, or dynamic link library. Such files are 
00146       /// linked at runtime into a process and their code images are shared 
00147       /// between processes. 
00148       /// @returns The dynamic link library suffix for the current platform.
00149       /// @brief Return the dynamic link library suffix.
00150       static std::string GetDLLSuffix();
00151 
00152       /// This is one of the very few ways in which a path can be constructed
00153       /// with a syntactically invalid name. The only *legal* invalid name is an
00154       /// empty one. Other invalid names are not permitted. Empty paths are
00155       /// provided so that they can be used to indicate null or error results in
00156       /// other lib/System functionality.
00157       /// @throws nothing
00158       /// @brief Construct an empty (and invalid) path.
00159       Path() : path() {}
00160 
00161       /// This constructor will accept a std::string as a path but if verifies
00162       /// that the path string has a legal syntax for the operating system on
00163       /// which it is running. This allows a path to be taken in from outside
00164       /// the program. However, if the path is not valid, the Path object will
00165       /// be set to an empty string and an exception will be thrown.
00166       /// @throws std::string if the path string is not legal.
00167       /// @param unverified_path The path to verify and assign.
00168       /// @brief Construct a Path from a string.
00169       explicit Path(std::string unverified_path);
00170 
00171     /// @}
00172     /// @name Operators
00173     /// @{
00174     public:
00175       /// Makes a copy of \p that to \p this.
00176       /// @returns \p this
00177       /// @throws nothing
00178       /// @brief Assignment Operator
00179       Path & operator = ( const Path & that ) {
00180         path = that.path;
00181         return *this;
00182       }
00183 
00184       /// Compares \p this Path with \p that Path for equality.
00185       /// @returns true if \p this and \p that refer to the same thing.
00186       /// @throws nothing
00187       /// @brief Equality Operator
00188       bool operator == (const Path& that) const {
00189         return 0 == path.compare(that.path) ;
00190       }
00191 
00192       /// Compares \p this Path with \p that Path for inequality.
00193       /// @returns true if \p this and \p that refer to different things.
00194       /// @throws nothing
00195       /// @brief Inequality Operator
00196       bool operator !=( const Path & that ) const {
00197         return 0 != path.compare( that.path );
00198       }
00199 
00200       /// Determines if \p this Path is less than \p that Path. This is required
00201       /// so that Path objects can be placed into ordered collections (e.g.
00202       /// std::map). The comparison is done lexicographically as defined by
00203       /// the std::string::compare method.
00204       /// @returns true if \p this path is lexicographically less than \p that.
00205       /// @throws nothing
00206       /// @brief Less Than Operator
00207       bool operator< (const Path& that) const { 
00208         return 0 > path.compare( that.path ); 
00209       }
00210 
00211     /// @}
00212     /// @name Accessors
00213     /// @{
00214     public:
00215       /// This function will use an operating system specific algorithm to
00216       /// determine if the current value of \p this is a syntactically valid
00217       /// path name for the operating system. The path name does not need to
00218       /// exist, validity is simply syntactical. Empty paths are always invalid.
00219       /// @returns true iff the path name is syntactically legal for the 
00220       /// host operating system. 
00221       /// @brief Determine if a path is syntactically valid or not.
00222       bool isValid() const;
00223 
00224       /// This function determines if the contents of the path name are
00225       /// empty. That is, the path has a zero length.
00226       /// @returns true iff the path is empty.
00227       /// @brief Determines if the path name is empty (invalid).
00228       bool isEmpty() const { return path.empty(); }
00229 
00230       /// This function determines if the path name in this object is intended
00231       /// to reference a legal file name (as opposed to a directory name). This
00232       /// function does not verify anything with the file system, it merely
00233       /// determines if the syntax of the path represents a file name or not.
00234       /// @returns true if this path name references a file.
00235       /// @brief Determines if the path name references a file.
00236       bool isFile() const;
00237 
00238       /// This function determines if the path name in this object is intended
00239       /// to reference a legal directory name (as opposed to a file name). This
00240       /// function does not verify anything with the file system, it merely
00241       /// determines if the syntax of the path represents a directory name or
00242       /// not.
00243       /// @returns true if the path name references a directory
00244       /// @brief Determines if the path name references a directory.
00245       bool isDirectory() const;
00246 
00247       /// This function determines if the path name in this object references
00248       /// the root (top level directory) of the file system. The details of what
00249       /// is considered the "root" may vary from system to system so this method
00250       /// will do the necessary checking. 
00251       /// @returns true iff the path name references the root directory.
00252       /// @brief Determines if the path references the root directory.
00253       bool isRootDirectory() const;
00254 
00255       /// This function opens the file associated with the path name provided by 
00256       /// the Path object and reads its magic number. If the magic number at the
00257       /// start of the file matches \p magic, true is returned. In all other
00258       /// cases (file not found, file not accessible, etc.) it returns false.
00259       /// @returns true if the magic number of the file matches \p magic.
00260       /// @brief Determine if file has a specific magic number
00261       bool hasMagicNumber(const std::string& magic) const;
00262 
00263       /// This function retrieves the first \p len bytes of the file associated
00264       /// with \p this. These bytes are returned as the "magic number" in the
00265       /// \p Magic parameter.
00266       /// @returns true if the Path is a file and the magic number is retrieved,
00267       /// false otherwise.
00268       /// @brief Get the file's magic number.
00269       bool getMagicNumber(std::string& Magic, unsigned len) const;
00270 
00271       /// This function determines if the path name in the object references an
00272       /// archive file by looking at its magic number.
00273       /// @returns true if the file starts with the magic number for an archive
00274       /// file.
00275       /// @brief Determine if the path references an archive file.
00276       bool isArchive() const;
00277 
00278       /// This function determines if the path name in the object references an
00279       /// LLVM Bytecode file by looking at its magic number.
00280       /// @returns true if the file starts with the magic number for LLVM 
00281       /// bytecode files.
00282       /// @brief Determine if the path references a bytecode file.
00283       bool isBytecodeFile() const;
00284 
00285       /// This function determines if the path name references an existing file
00286       /// or directory in the file system. Unlike isFile and isDirectory, this
00287       /// function actually checks for the existence of the file or directory.
00288       /// @returns true if the pathname references an existing file.
00289       /// @brief Determines if the path is a file or directory in
00290       /// the file system.
00291       bool exists() const;
00292 
00293       /// This function determines if the path name references a readable file
00294       /// or directory in the file system. Unlike isFile and isDirectory, this 
00295       /// function actually checks for the existence and readability (by the
00296       /// current program) of the file or directory.
00297       /// @returns true if the pathname references a readable file.
00298       /// @brief Determines if the path is a readable file or directory
00299       /// in the file system.
00300       bool readable() const;
00301 
00302       /// This function determines if the path name references a writable file
00303       /// or directory in the file system. Unlike isFile and isDirectory, this 
00304       /// function actually checks for the existence and writability (by the
00305       /// current program) of the file or directory.
00306       /// @returns true if the pathname references a writable file.
00307       /// @brief Determines if the path is a writable file or directory
00308       /// in the file system.
00309       bool writable() const;
00310 
00311       /// This function determines if the path name references an executable 
00312       /// file in the file system. Unlike isFile and isDirectory, this 
00313       /// function actually checks for the existence and executability (by 
00314       /// the current program) of the file.
00315       /// @returns true if the pathname references an executable file.
00316       /// @brief Determines if the path is an executable file in the file 
00317       /// system.
00318       bool executable() const;
00319 
00320       /// This function returns the current contents of the path as a
00321       /// std::string. This allows the underlying path string to be manipulated
00322       /// by other software.
00323       /// @returns std::string containing the path name.
00324       /// @brief Returns the path as a std::string.
00325       std::string get() const { return path; }
00326 
00327       /// This function returns the last component of the path name. If the
00328       /// isDirectory() function would return true then this returns the name
00329       /// of the last directory in the path. If the isFile() function would
00330       /// return true then this function returns the name of the file without
00331       /// any of the preceding directories.
00332       /// @returns std::string containing the last component of the path name.
00333       /// @brief Returns the last component of the path name.
00334       std::string getLast() const;
00335 
00336       /// This function strips off the path and suffix of the file name and
00337       /// returns just the basename.
00338       /// @returns std::string containing the basename of the path
00339       /// @throws nothing
00340       /// @brief Get the base name of the path
00341       std::string getBasename() const;
00342 
00343       /// This function builds a list of paths that are the names of the
00344       /// files and directories in a directory.
00345       /// @returns false if \p this is not a directory, true otherwise
00346       /// @throws std::string if the directory cannot be searched
00347       /// @brief Build a list of directory's contents.
00348       bool getDirectoryContents(std::set<Path>& paths) const;
00349 
00350       /// Obtain a 'C' string for the path name.
00351       /// @returns a 'C' string containing the path name.
00352       /// @brief Returns the path as a C string.
00353       const char* const c_str() const { return path.c_str(); }
00354 
00355     /// @}
00356     /// @name Mutators
00357     /// @{
00358     public:
00359       /// The path name is cleared and becomes empty. This is an invalid
00360       /// path name but is the *only* invalid path name. This is provided
00361       /// so that path objects can be used to indicate the lack of a 
00362       /// valid path being found.
00363       void clear() { path.clear(); }
00364 
00365       /// This function returns status information about the file. The type of
00366       /// path (file or directory) is updated to reflect the actual contents 
00367       /// of the file system. If the file does not exist, false is returned. 
00368       /// For other (hard I/O) errors, a std::string is throwing indicating the
00369       /// problem.
00370       /// @throws std::string if an error occurs.
00371       /// @brief Get file status.
00372       void getStatusInfo(StatusInfo& info) const;
00373 
00374       /// This method attempts to set the Path object to \p unverified_path
00375       /// and interpret the name as a directory name.  The \p unverified_path 
00376       /// is verified. If verification succeeds then \p unverified_path 
00377       /// is accepted as a directory and true is returned. Otherwise,
00378       /// the Path object remains unchanged and false is returned.
00379       /// @returns true if the path was set, false otherwise.
00380       /// @param unverified_path The path to be set in Path object.
00381       /// @throws nothing
00382       /// @brief Set a full path from a std::string
00383       bool setDirectory(const std::string& unverified_path);
00384 
00385       /// This method attempts to set the Path object to \p unverified_path
00386       /// and interpret the name as a file name.  The \p unverified_path 
00387       /// is verified. If verification succeeds then \p unverified_path 
00388       /// is accepted as a file name and true is returned. Otherwise,
00389       /// the Path object remains unchanged and false is returned.
00390       /// @returns true if the path was set, false otherwise.
00391       /// @param unverified_path The path to be set in Path object.
00392       /// @throws nothing
00393       /// @brief Set a full path from a std::string
00394       bool setFile(const std::string& unverified_path);
00395 
00396       /// The \p dirname is added to the end of the Path if it is a legal
00397       /// directory name for the operating system. The precondition for this 
00398       /// function is that the Path must reference a directory name (i.e.
00399       /// isDirectory() returns true).
00400       /// @param dirname A string providing the directory name to
00401       /// be added to the end of the path.
00402       /// @returns false if the directory name could not be added
00403       /// @throws nothing
00404       /// @brief Adds the name of a directory to a Path.
00405       bool appendDirectory( const std::string& dirname );
00406 
00407       /// One directory component is removed from the Path name. The Path must
00408       /// refer to a non-root directory name (i.e. isDirectory() returns true
00409       /// but isRootDirectory() returns false). Upon exit, the Path will 
00410       /// refer to the directory above it.
00411       /// @throws nothing
00412       /// @returns false if the directory name could not be removed.
00413       /// @brief Removes the last directory component of the Path.
00414       bool elideDirectory();
00415 
00416       /// The \p filename is added to the end of the Path if it is a legal
00417       /// directory name for the operating system. The precondition for this
00418       /// function is that the Path reference a directory name (i.e. 
00419       /// isDirectory() returns true).
00420       /// @throws nothing
00421       /// @returns false if the file name could not be added.
00422       /// @brief Appends the name of a file.
00423       bool appendFile( const std::string& filename );
00424 
00425       /// One file component is removed from the Path name. The Path must
00426       /// refer to a file (i.e. isFile() returns true). Upon exit, 
00427       /// the Path will refer to the directory above it.
00428       /// @throws nothing
00429       /// @returns false if the file name could not be removed
00430       /// @brief Removes the last file component of the path.
00431       bool elideFile();
00432 
00433       /// A period and the \p suffix are appended to the end of the pathname.
00434       /// The precondition for this function is that the Path reference a file
00435       /// name (i.e. isFile() returns true). If the Path is not a file, no 
00436       /// action is taken and the function returns false. If the path would
00437       /// become invalid for the host operating system, false is returned.
00438       /// @returns false if the suffix could not be added, true if it was.
00439       /// @throws nothing
00440       /// @brief Adds a period and the \p suffix to the end of the pathname. 
00441       bool appendSuffix(const std::string& suffix);
00442 
00443       /// The suffix of the filename is removed. The suffix begins with and
00444       /// includes the last . character in the filename after the last directory
00445       /// separator and extends until the end of the name. If no . character is
00446       /// after the last directory separator, then the file name is left
00447       /// unchanged (i.e. it was already without a suffix) but the function 
00448       /// returns false.
00449       /// @returns false if there was no suffix to remove, true otherwise.
00450       /// @throws nothing
00451       /// @brief Remove the suffix from a path name.
00452       bool elideSuffix();
00453 
00454       /// This method attempts to create a directory in the file system with the
00455       /// same name as the Path object. The \p create_parents parameter controls
00456       /// whether intermediate directories are created or not. if \p
00457       /// create_parents is true, then an attempt will be made to create all
00458       /// intermediate directories. If \p create_parents is false, then only the
00459       /// final directory component of the Path name will be created. The 
00460       /// created directory will have no entries. 
00461       /// @returns false if the Path does not reference a directory, true 
00462       /// otherwise.
00463       /// @param create_parents Determines whether non-existent directory
00464       /// components other than the last one (the "parents") are created or not.
00465       /// @throws std::string if an error occurs.
00466       /// @brief Create the directory this Path refers to.
00467       bool createDirectory( bool create_parents = false );
00468 
00469       /// This method attempts to create a file in the file system with the same 
00470       /// name as the Path object. The intermediate directories must all exist
00471       /// at the time this method is called. Use createDirectories to 
00472       /// accomplish that. The created file will be empty upon return from this
00473       /// function.
00474       /// @returns false if the Path does not reference a file, true otherwise.
00475       /// @throws std::string if an error occurs.
00476       /// @brief Create the file this Path refers to.
00477       bool createFile();
00478 
00479       /// This is like createFile except that it creates a temporary file. A 
00480       /// unique temporary file name is generated based on the contents of 
00481       /// \p this before the call. The new name is assigned to \p this and the
00482       /// file is created.  Note that this will both change the Path object
00483       /// *and* create the corresponding file. This function will ensure that
00484       /// the newly generated temporary file name is unique in the file system.
00485       /// @throws std::string if there is an error
00486       /// @brief Create a unique temporary file
00487       bool createTemporaryFile();
00488 
00489       /// This method attempts to destroy the directory named by the last in 
00490       /// the Path name.  If \p remove_contents is false, an attempt will be 
00491       /// made to remove just the directory that this Path object refers to 
00492       /// (the final Path component). If \p remove_contents is true, an attempt
00493       /// will be made to remove the entire contents of the directory, 
00494       /// recursively. 
00495       /// @param destroy_contents Indicates whether the contents of a destroyed
00496       /// directory should also be destroyed (recursively). 
00497       /// @returns false if the Path does not refer to a directory, true 
00498       /// otherwise.
00499       /// @throws std::string if there is an error.
00500       /// @brief Removes the file or directory from the filesystem.
00501       bool destroyDirectory( bool destroy_contents = false );
00502 
00503       /// This method attempts to destroy the file named by the last item in the 
00504       /// Path name. 
00505       /// @returns false if the Path does not refer to a file, true otherwise.
00506       /// @throws std::string if there is an error.
00507       /// @brief Destroy the file this Path refers to.
00508       bool destroyFile(); 
00509 
00510       /// This method renames the file referenced by \p this as \p newName. Both
00511       /// files must exist before making this call.
00512       /// @returns false if the Path does not refer to a file, true otherwise.
00513       /// @throws std::string if there is an file system error.
00514       /// @brief Rename one file as another.
00515       bool renameFile(const Path& newName);
00516 
00517       /// This method sets the access time, modification time, and permission
00518       /// mode of the file associated with \p this as given by \p si.  
00519       /// @returns false if the Path does not refer to a file, true otherwise.
00520       /// @throws std::string if the file could not be modified
00521       /// @brief Set file times and mode.
00522       bool setStatusInfo(const StatusInfo& si ) const ;
00523 
00524     /// @}
00525     /// @name Data
00526     /// @{
00527     private:
00528         mutable std::string path;   ///< Storage for the path name.
00529 
00530     /// @}
00531   };
00532 
00533   /// This enumeration delineates the kinds of files that LLVM knows about.
00534   enum LLVMFileType {
00535     UnknownFileType = 0,            ///< Unrecognized file
00536     BytecodeFileType = 1,           ///< Uncompressed bytecode file
00537     CompressedBytecodeFileType = 2, ///< Compressed bytecode file
00538     ArchiveFileType = 3,            ///< ar style archive file
00539   };
00540 
00541   /// This utility function allows any memory block to be examined in order
00542   /// to determine its file type.
00543   LLVMFileType IdentifyFileType(const char*magic, unsigned length);
00544 }
00545 
00546 }
00547 
00548 // vim: sw=2
00549 
00550 #endif