path: root/include/llvm/System/Path.h

//===- llvm/System/Path.h - Path Operating System Concept -------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by Reid Spencer and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file declares the llvm::sys::Path class.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SYSTEM_PATH_H
#define LLVM_SYSTEM_PATH_H

#include "llvm/System/TimeValue.h"
#include "llvm/System/IncludeFile.h"
#include <set>
#include <string>
#include <vector>
#include <iosfwd>

namespace llvm {
namespace sys {

  /// This structure provides basic file system information about a file. It
  /// is patterned after the stat(2) Unix operating system call but made
  /// platform independent and eliminates many of the unix-specific fields.
  /// However, to support llvm-ar, the mode, user, and group fields are
  /// retained. These pertain to unix security and may not have a meaningful
  /// value on non-Unix platforms. However, the fileSize and modTime fields
  /// should always be applicable on all platforms.  The structure is
  /// filled in by the Path::getFileStatus method.
  /// @brief File status structure
  class FileStatus {
  public:
    uint64_t    fileSize;   ///< Size of the file in bytes
    TimeValue   modTime;    ///< Time of file's modification
    uint32_t    mode;       ///< Mode of the file, if applicable
    uint32_t    user;       ///< User ID of owner, if applicable
    uint32_t    group;      ///< Group ID of owner, if applicable
    bool        isDir  : 1; ///< True if this is a directory.
    bool        isFile : 1; ///< True if this is a file.

    FileStatus() : fileSize(0), modTime(0,0), mode(0777), user(999),
                   group(999), isDir(false) { }
    
    TimeValue getTimestamp() const { return modTime; }
    uint64_t getSize() const { return fileSize; }
    uint32_t getMode() const { return mode; }
    uint32_t getUser() const { return user; }
    uint32_t getGroup() const { return group; }
  };

  /// This class provides an abstraction for the path to a file or directory
  /// in the operating system's filesystem and provides various basic operations
  /// on it.  Note that this class only represents the name of a path to a file
  /// or directory which may or may not be valid for a given machine's file
  /// system. The class is patterned after the java.io.File class with various
  /// extensions and several omissions (not relevant to LLVM).  A Path object
  /// ensures that the path it encapsulates is syntactically valid for the
  /// operating system it is running on but does not ensure correctness for
  /// any particular file system. That is, a syntactically valid path might
  /// specify path components that do not exist in the file system and using
  /// such a Path to act on the file system could produce errors. There is one
  /// invalid Path value which is permitted: the empty path.  The class should
  /// never allow a syntactically invalid non-empty path name to be assigned.
  /// Empty paths are required in order to indicate an error result in some
  /// situations. If the path is empty, the isValid operation will return
  /// false. All operations will fail if isValid is false. Operations that
  /// change the path will either return false if it would cause a syntactically
  /// invalid path name (in which case the Path object is left unchanged) or
  /// throw an std::string exception indicating the error. The methods are
  /// grouped into four basic categories: Path Accessors (provide information
  /// about the path without accessing disk), Disk Accessors (provide
  /// information about the underlying file or directory), Path Mutators
  /// (change the path information, not the disk), and Disk Mutators (change
  /// the disk file/directory referenced by the path). The Disk Mutator methods
  /// all have the word "disk" embedded in their method name to reinforce the
  /// notion that the operation modifies the file system.
  /// @since 1.4
  /// @brief An abstraction for operating system paths.
  class Path {
    /// @name Constructors
    /// @{
    public:
      /// Construct a path to the root directory of the file system. The root
      /// directory is a top level directory above which there are no more
      /// directories. For example, on UNIX, the root directory is /. On Windows
      /// it is C:\. Other operating systems may have different notions of
      /// what the root directory is or none at all. In that case, a consistent
      /// default root directory will be used.
      static Path GetRootDirectory();

      /// Construct a path to a unique temporary directory that is created in
      /// a "standard" place for the operating system. The directory is
      /// guaranteed to be created on exit from this function. If the directory
      /// cannot be created, the function will throw an exception.
      /// @returns an invalid path (empty) on error
      /// @param ErrMsg Optional place for an error message if an error occurs
      /// @brief Constrct a path to an new, unique, existing temporary
      /// directory.
      static Path GetTemporaryDirectory(std::string* ErrMsg = 0);

      /// Construct a vector of sys::Path that contains the "standard" system
      /// library paths suitable for linking into programs. This function *must*
      /// return the value of LLVM_LIB_SEARCH_PATH as the first item in \p Paths
      /// if that environment variable is set and it references a directory.
      /// @brief Construct a path to the system library directory
      static void GetSystemLibraryPaths(std::vector<sys::Path>& Paths);

      /// Construct a vector of sys::Path that contains the "standard" bytecode
      /// library paths suitable for linking into an llvm program. This function
      /// *must* return the value of LLVM_LIB_SEARCH_PATH as well as the value
      /// of LLVM_LIBDIR. It also must provide the System library paths as
      /// returned by GetSystemLibraryPaths.
      /// @see GetSystemLibraryPaths
      /// @brief Construct a list of directories in which bytecode could be
      /// found.
      static void GetBytecodeLibraryPaths(std::vector<sys::Path>& Paths);

      /// Find the path to a library using its short name. Use the system
      /// dependent library paths to locate the library.
      /// @brief Find a library.
      static Path  FindLibrary(std::string& short_name);

      /// Construct a path to the default LLVM configuration directory. The
      /// implementation must ensure that this is a well-known (same on many
      /// systems) directory in which llvm configuration files exist. For
      /// example, on Unix, the /etc/llvm directory has been selected.
      /// @brief Construct a path to the default LLVM configuration directory
      static Path GetLLVMDefaultConfigDir();

      /// Construct a path to the LLVM installed configuration directory. The
      /// implementation must ensure that this refers to the "etc" directory of
      /// the LLVM installation. This is the location where configuration files
      /// will be located for a particular installation of LLVM on a machine.
      /// @brief Construct a path to the LLVM installed configuration directory
      static Path GetLLVMConfigDir();

      /// Construct a path to the current user's home directory. The
      /// implementation must use an operating system specific mechanism for
      /// determining the user's home directory. For example, the environment
      /// variable "HOME" could be used on Unix. If a given operating system
      /// does not have the concept of a user's home directory, this static
      /// constructor must provide the same result as GetRootDirectory.
      /// @brief Construct a path to the current user's "home" directory
      static Path GetUserHomeDirectory();

      /// Return the suffix commonly used on file names that contain a shared
      /// object, shared archive, or dynamic link library. Such files are
      /// linked at runtime into a process and their code images are shared
      /// between processes.
      /// @returns The dynamic link library suffix for the current platform.
      /// @brief Return the dynamic link library suffix.
      static std::string GetDLLSuffix();

      /// This is one of the very few ways in which a path can be constructed
      /// with a syntactically invalid name. The only *legal* invalid name is an
      /// empty one. Other invalid names are not permitted. Empty paths are
      /// provided so that they can be used to indicate null or error results in
      /// other lib/System functionality.
      /// @brief Construct an empty (and invalid) path.
      Path() : path() {}

      /// This constructor will accept a std::string as a path. No checking is
      /// done on this path to determine if it is valid. To determine validity
      /// of the path, use the isValid method. 
      /// @param p The path to assign.
      /// @brief Construct a Path from a string.
      explicit Path(const std::string& p) : path(p) {}

    /// @}
    /// @name Operators
    /// @{
    public:
      /// Makes a copy of \p that to \p this.
      /// @returns \p this
      /// @brief Assignment Operator
      Path &operator=(const Path &that) {
        path = that.path;
        return *this;
      }

      /// Compares \p this Path with \p that Path for equality.
      /// @returns true if \p this and \p that refer to the same thing.
      /// @brief Equality Operator
      bool operator==(const Path &that) const {
        return 0 == path.compare(that.path);
      }

      /// Compares \p this Path with \p that Path for inequality.
      /// @returns true if \p this and \p that refer to different things.
      /// @brief Inequality Operator
      bool operator!=(const Path &that) const {
        return 0 != path.compare(that.path);
      }

      /// Determines if \p this Path is less than \p that Path. This is required
      /// so that Path objects can be placed into ordered collections (e.g.
      /// std::map). The comparison is done lexicographically as defined by
      /// the std::string::compare method.
      /// @returns true if \p this path is lexicographically less than \p that.
      /// @brief Less Than Operator
      bool operator<(const Path& that) const {
        return 0 > path.compare(that.path);
      }

    /// @}
    /// @name Path Accessors
    /// @{
    public:
      /// This function will use an operating system specific algorithm to
      /// determine if the current value of \p this is a syntactically valid
      /// path name for the operating system. The path name does not need to
      /// exist, validity is simply syntactical. Empty paths are always invalid.
      /// @returns true iff the path name is syntactically legal for the
      /// host operating system.
      /// @brief Determine if a path is syntactically valid or not.
      bool isValid() const;

      /// This function determines if the contents of the path name are
      /// empty. That is, the path has a zero length. This does NOT determine if
      /// if the file is empty. Use the getSize method for that.
      /// @returns true iff the path is empty.
      /// @brief Determines if the path name is empty (invalid).
      bool isEmpty() const { return path.empty(); }

      /// This function returns the current contents of the path as a
      /// std::string. This allows the underlying path string to be manipulated.
      /// @returns std::string containing the path name.
      /// @brief Returns the path as a std::string.
      const std::string &toString() const { return path; }

      /// This function returns the last component of the path name. The last
      /// component is the file or directory name occuring after the last
      /// directory separator. If no directory separator is present, the entire
      /// path name is returned (i.e. same as toString).
      /// @returns std::string containing the last component of the path name.
      /// @brief Returns the last component of the path name.
      std::string getLast() const;

      /// This function strips off the path and suffix of the file or directory
      /// name and returns just the basename. For example /a/foo.bar would cause
      /// this function to return "foo".
      /// @returns std::string containing the basename of the path
      /// @brief Get the base name of the path
      std::string getBasename() const;

      /// Obtain a 'C' string for the path name.
      /// @returns a 'C' string containing the path name.
      /// @brief Returns the path as a C string.
      const char *const c_str() const { return path.c_str(); }

    /// @}
    /// @name Disk Accessors
    /// @{
    public:
      /// This function determines if the path name in this object references
      /// the root (top level directory) of the file system. The details of what
      /// is considered the "root" may vary from system to system so this method
      /// will do the necessary checking.
      /// @returns true iff the path name references the root directory.
      /// @brief Determines if the path references the root directory.
      bool isRootDirectory() const;

      /// This function opens the file associated with the path name provided by
      /// the Path object and reads its magic number. If the magic number at the
      /// start of the file matches \p magic, true is returned. In all other
      /// cases (file not found, file not accessible, etc.) it returns false.
      /// @returns true if the magic number of the file matches \p magic.
      /// @brief Determine if file has a specific magic number
      bool hasMagicNumber(const std::string& magic) const;

      /// This function retrieves the first \p len bytes of the file associated
      /// with \p this. These bytes are returned as the "magic number" in the
      /// \p Magic parameter.
      /// @returns true if the Path is a file and the magic number is retrieved,
      /// false otherwise.
      /// @brief Get the file's magic number.
      bool getMagicNumber(std::string& Magic, unsigned len) const;

      /// This function determines if the path name in the object references an
      /// archive file by looking at its magic number.
      /// @returns true if the file starts with the magic number for an archive
      /// file.