cheat/vendor/github.com/go-git/go-billy/v5/fs.go
Christopher Allen Lane 80c91cbdee feat(installer): use go-git to clone
Integrate `go-git` into the application, and use it to `git clone`
cheatsheets when the installer runs.

Previously, the installer required that `git` be installed on the system
`PATH`, so this change has to big advantages:

1. It removes that system dependency on `git`
2. It paves the way for implementing the `--update` command

Additionally, `cheat` now performs a `--depth=1` clone when installing
cheatsheets, which should at least somewhat improve installation times
(especially on slow network connections).
2022-08-27 21:00:46 -04:00

203 lines
7.9 KiB
Go

package billy
import (
"errors"
"io"
"os"
"time"
)
var (
ErrReadOnly = errors.New("read-only filesystem")
ErrNotSupported = errors.New("feature not supported")
ErrCrossedBoundary = errors.New("chroot boundary crossed")
)
// Capability holds the supported features of a billy filesystem. This does
// not mean that the capability has to be supported by the underlying storage.
// For example, a billy filesystem may support WriteCapability but the
// storage be mounted in read only mode.
type Capability uint64
const (
// WriteCapability means that the fs is writable.
WriteCapability Capability = 1 << iota
// ReadCapability means that the fs is readable.
ReadCapability
// ReadAndWriteCapability is the ability to open a file in read and write mode.
ReadAndWriteCapability
// SeekCapability means it is able to move position inside the file.
SeekCapability
// TruncateCapability means that a file can be truncated.
TruncateCapability
// LockCapability is the ability to lock a file.
LockCapability
// DefaultCapabilities lists all capable features supported by filesystems
// without Capability interface. This list should not be changed until a
// major version is released.
DefaultCapabilities Capability = WriteCapability | ReadCapability |
ReadAndWriteCapability | SeekCapability | TruncateCapability |
LockCapability
// AllCapabilities lists all capable features.
AllCapabilities Capability = WriteCapability | ReadCapability |
ReadAndWriteCapability | SeekCapability | TruncateCapability |
LockCapability
)
// Filesystem abstract the operations in a storage-agnostic interface.
// Each method implementation mimics the behavior of the equivalent functions
// at the os package from the standard library.
type Filesystem interface {
Basic
TempFile
Dir
Symlink
Chroot
}
// Basic abstract the basic operations in a storage-agnostic interface as
// an extension to the Basic interface.
type Basic interface {
// Create creates the named file with mode 0666 (before umask), truncating
// it if it already exists. If successful, methods on the returned File can
// be used for I/O; the associated file descriptor has mode O_RDWR.
Create(filename string) (File, error)
// Open opens the named file for reading. If successful, methods on the
// returned file can be used for reading; the associated file descriptor has
// mode O_RDONLY.
Open(filename string) (File, error)
// OpenFile is the generalized open call; most users will use Open or Create
// instead. It opens the named file with specified flag (O_RDONLY etc.) and
// perm, (0666 etc.) if applicable. If successful, methods on the returned
// File can be used for I/O.
OpenFile(filename string, flag int, perm os.FileMode) (File, error)
// Stat returns a FileInfo describing the named file.
Stat(filename string) (os.FileInfo, error)
// Rename renames (moves) oldpath to newpath. If newpath already exists and
// is not a directory, Rename replaces it. OS-specific restrictions may
// apply when oldpath and newpath are in different directories.
Rename(oldpath, newpath string) error
// Remove removes the named file or directory.
Remove(filename string) error
// Join joins any number of path elements into a single path, adding a
// Separator if necessary. Join calls filepath.Clean on the result; in
// particular, all empty strings are ignored. On Windows, the result is a
// UNC path if and only if the first path element is a UNC path.
Join(elem ...string) string
}
type TempFile interface {
// TempFile creates a new temporary file in the directory dir with a name
// beginning with prefix, opens the file for reading and writing, and
// returns the resulting *os.File. If dir is the empty string, TempFile
// uses the default directory for temporary files (see os.TempDir).
// Multiple programs calling TempFile simultaneously will not choose the
// same file. The caller can use f.Name() to find the pathname of the file.
// It is the caller's responsibility to remove the file when no longer
// needed.
TempFile(dir, prefix string) (File, error)
}
// Dir abstract the dir related operations in a storage-agnostic interface as
// an extension to the Basic interface.
type Dir interface {
// ReadDir reads the directory named by dirname and returns a list of
// directory entries sorted by filename.
ReadDir(path string) ([]os.FileInfo, error)
// MkdirAll creates a directory named path, along with any necessary
// parents, and returns nil, or else returns an error. The permission bits
// perm are used for all directories that MkdirAll creates. If path is/
// already a directory, MkdirAll does nothing and returns nil.
MkdirAll(filename string, perm os.FileMode) error
}
// Symlink abstract the symlink related operations in a storage-agnostic
// interface as an extension to the Basic interface.
type Symlink interface {
// Lstat returns a FileInfo describing the named file. If the file is a
// symbolic link, the returned FileInfo describes the symbolic link. Lstat
// makes no attempt to follow the link.
Lstat(filename string) (os.FileInfo, error)
// Symlink creates a symbolic-link from link to target. target may be an
// absolute or relative path, and need not refer to an existing node.
// Parent directories of link are created as necessary.
Symlink(target, link string) error
// Readlink returns the target path of link.
Readlink(link string) (string, error)
}
// Change abstract the FileInfo change related operations in a storage-agnostic
// interface as an extension to the Basic interface
type Change interface {
// Chmod changes the mode of the named file to mode. If the file is a
// symbolic link, it changes the mode of the link's target.
Chmod(name string, mode os.FileMode) error
// Lchown changes the numeric uid and gid of the named file. If the file is
// a symbolic link, it changes the uid and gid of the link itself.
Lchown(name string, uid, gid int) error
// Chown changes the numeric uid and gid of the named file. If the file is a
// symbolic link, it changes the uid and gid of the link's target.
Chown(name string, uid, gid int) error
// Chtimes changes the access and modification times of the named file,
// similar to the Unix utime() or utimes() functions.
//
// The underlying filesystem may truncate or round the values to a less
// precise time unit.
Chtimes(name string, atime time.Time, mtime time.Time) error
}
// Chroot abstract the chroot related operations in a storage-agnostic interface
// as an extension to the Basic interface.
type Chroot interface {
// Chroot returns a new filesystem from the same type where the new root is
// the given path. Files outside of the designated directory tree cannot be
// accessed.
Chroot(path string) (Filesystem, error)
// Root returns the root path of the filesystem.
Root() string
}
// File represent a file, being a subset of the os.File
type File interface {
// Name returns the name of the file as presented to Open.
Name() string
io.Writer
io.Reader
io.ReaderAt
io.Seeker
io.Closer
// Lock locks the file like e.g. flock. It protects against access from
// other processes.
Lock() error
// Unlock unlocks the file.
Unlock() error
// Truncate the file.
Truncate(size int64) error
}
// Capable interface can return the available features of a filesystem.
type Capable interface {
// Capabilities returns the capabilities of a filesystem in bit flags.
Capabilities() Capability
}
// Capabilities returns the features supported by a filesystem. If the FS
// does not implement Capable interface it returns all features.
func Capabilities(fs Basic) Capability {
capable, ok := fs.(Capable)
if !ok {
return DefaultCapabilities
}
return capable.Capabilities()
}
// CapabilityCheck tests the filesystem for the provided capabilities and
// returns true in case it supports all of them.
func CapabilityCheck(fs Basic, capabilities Capability) bool {
fsCaps := Capabilities(fs)
return fsCaps&capabilities == capabilities
}