Documentation
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Index ¶
- Constants
- Variables
- func AtomicWrite(filename string, reader io.Reader, perm os.FileMode, flags AtomicWriteFlags) (err error)
- func AtomicWriteChown(filename string, reader io.Reader, perm os.FileMode, flags AtomicWriteFlags, ...) (err error)
- func AtomicWriteFile(filename string, data []byte, perm os.FileMode, flags AtomicWriteFlags) (err error)
- func AtomicWriteFileChown(filename string, data []byte, perm os.FileMode, flags AtomicWriteFlags, ...) (err error)
- func BootID() (string, error)
- func CanStat(path string) bool
- func Environ() map[string]string
- func Escape(path string) string
- func ExistsIsDir(fn string) (exists bool, isDir bool, err error)
- func ExitCode(runErr error) (e int, err error)
- func IsCurrent(uid, gid int) (bool, error)
- func IsDevice(mode os.FileMode) bool
- func IsDir(path string) bool
- func IsDirNotExist(err error) bool
- func IsExec(path string) bool
- func IsExecInPath(name string) bool
- func IsMounted(baseDir string) (bool, error)
- func IsSymlink(path string) bool
- func IsWritable(path string) bool
- func KillProcessGroup(cmd *exec.Cmd) error
- func LookPathDefault(name string, defaultPath string) string
- func MkdirAllChown(path string, perm os.FileMode, uid sys.UserID, gid sys.GroupID) error
- func MkdirChown(path string, perm os.FileMode, uid sys.UserID, gid sys.GroupID) error
- func MountOptsToCommonFlags(opts []string) (flags int, unparsed []string)
- func MountOptsToFlags(opts []string) (flags int, err error)
- func NormalizeUidGid(uid, gid *int, username, group string) (*int, *int, error)
- func OutputErr(output []byte, err error) error
- func RealUser() (*user.User, error)
- func RunAndWait(argv []string, env []string, timeout time.Duration, tomb *tomb.Tomb) ([]byte, error)
- func StreamCommand(name string, args ...string) (io.ReadCloser, error)
- func UidGid(u *user.User) (sys.UserID, sys.GroupID, error)
- func Unescape(path string) string
- type AtomicFile
- type AtomicWriteFlags
- type MountEntry
- type MountInfoEntry
Constants ¶
const NoChown = sys.FlagID
Variables ¶
var ErrCannotCancel = errors.New("cannot cancel: file has already been renamed")
ErrCannotCancel means the Commit operation failed at the last step, and your luck has run out.
Functions ¶
func AtomicWrite ¶
func AtomicWrite(filename string, reader io.Reader, perm os.FileMode, flags AtomicWriteFlags) (err error)
The AtomicWrite* family of functions work like os.WriteFile(), but the file created is an AtomicWriter, which is Committed before returning.
AtomicWriteChown and AtomicWriteFileChown take an uid and a gid that can be used to specify the ownership of the created file. A special value of 0xffffffff (math.MaxUint32, or NoChown for convenience) can be used to request no change to that attribute.
AtomicWriteFile and AtomicWriteFileChown take the content to be written as a []byte, and so work exactly like io.WriteFile(); AtomicWrite and AtomicWriteChown take an io.Reader which is copied into the file instead, and so are more amenable to streaming.
func AtomicWriteChown ¶
func AtomicWriteFile ¶
func AtomicWriteFileChown ¶
func CanStat ¶
CanStat returns true if stat succeeds on the given path. It may return false on permission issues.
func Environ ¶
Environ returns a map representing the environment. It converts the slice from os.Environ() into a map.
func ExistsIsDir ¶
ExistIsDir checks whether a given path exists, and if so whether it is a directory.
func ExitCode ¶
ExitCode extract the exit code from the error of a failed cmd.Run() or the original error if its not a exec.ExitError
func IsCurrent ¶
IsCurrent reports whether the given user ID and group ID are those of the current user.
func IsDir ¶
IsDir returns true if the given path is a directory. It may return false on permission issues.
func IsDirNotExist ¶
IsDirNotExist tells you whether the given error is due to a directory not existing.
func IsExecInPath ¶
IsExecInPath returns true if name is an executable in $PATH.
func IsWritable ¶
IsWritable checks if the given file/directory can be written by the current user
func KillProcessGroup ¶
KillProcessGroup kills the process group associated with the given command.
If the command hasn't had Setpgid set in its SysProcAttr, you'll probably end up killing yourself.
func LookPathDefault ¶
LookPathDefault searches for a given command name in all directories listed in the environment variable PATH and returns the found path or the provided default path.
func MkdirAllChown ¶
MkdirAllChown is like os.MkdirAll but it calls os.Chown on any directories it creates.
func MkdirChown ¶
MkdirChown is like os.Mkdir but it also calls os.Chown on the directory it creates.
func MountOptsToCommonFlags ¶
MountOptsToCommonFlags converts mount options strings to a mount flag, returning unparsed flags. The unparsed flags will not contain any snapd- specific mount option, those starting with the string "x-snapd."
func MountOptsToFlags ¶
MountOptsToFlags converts mount options strings to a mount flag.
func NormalizeUidGid ¶
NormalizeUidGid returns the "normalized" UID and GID for the given IDs and names. If both uid and username are specified, the username's UID must match the given uid (similar for gid and group), otherwise an error is returned.
func OutputErr ¶
OutputErr formats an error based on output if its length is not zero, or returns err otherwise.
func RealUser ¶
RealUser finds the user behind a sudo invocation when root, if applicable and possible.
Don't check SUDO_USER when not root and simply return the current uid to properly support sudo'ing from root to a non-root user
func RunAndWait ¶
func RunAndWait(argv []string, env []string, timeout time.Duration, tomb *tomb.Tomb) ([]byte, error)
RunAndWait runs a command for the given argv with the given environ added to os.Environ, killing it if it reaches timeout, or if the tomb is dying.
func StreamCommand ¶
func StreamCommand(name string, args ...string) (io.ReadCloser, error)
StreamCommand runs a the named program with the given arguments, streaming its standard output over the returned io.ReadCloser.
The program will run until EOF is reached (at which point the ReadCloser is closed), or until the ReadCloser is explicitly closed.
Types ¶
type AtomicFile ¶
An AtomicFile is similar to an os.File but it has an additional Commit() method that does whatever needs to be done so the modification is "atomic": an AtomicFile will do its best to leave either the previous content or the new content in permanent storage. It also has a Cancel() method to abort and clean up.
func NewAtomicFile ¶
func NewAtomicFile(filename string, perm os.FileMode, flags AtomicWriteFlags, uid sys.UserID, gid sys.GroupID) (aw *AtomicFile, err error)
NewAtomicFile builds an AtomicFile backed by an *os.File that will have the given filename, permissions and uid/gid when Committed.
It _might_ be implemented using O_TMPFILE (see open(2)).
Note that it won't follow symlinks and will replace existing symlinks with the real file, unless the AtomicWriteFollow flag is specified.
It is the caller's responsibility to clean up on error, by calling Cancel().
It is also the caller's responsibility to coordinate access to this, if it is used from different goroutines.
Also note that there are a number of scenarios where Commit fails and then Cancel also fails. In all these scenarios your filesystem was probably in a rather poor state. Good luck.
func (*AtomicFile) Cancel ¶
func (aw *AtomicFile) Cancel() error
Cancel closes the AtomicWriter, and cleans up any artifacts. Cancel can fail if Commit() was (even partially) successful, but calling Cancel after a successful Commit does nothing beyond returning error--so it's always safe to defer a Cancel().
func (*AtomicFile) Close ¶
func (aw *AtomicFile) Close() error
func (*AtomicFile) Commit ¶
func (aw *AtomicFile) Commit() error
Commit the modification; make it permanent.
If Commit succeeds, the writer is closed and further attempts to write will fail. If Commit fails, the writer _might_ be closed; Cancel() needs to be called to clean up.
type AtomicWriteFlags ¶
type AtomicWriteFlags uint
AtomicWriteFlags are a bitfield of flags for AtomicWriteFile
const ( // AtomicWriteFollow makes AtomicWriteFile follow symlinks AtomicWriteFollow AtomicWriteFlags = 1 << iota // AtomicWriteChmod performs an explicit chmod to file permissions after // creation for e.g. overcoming any umask modifications. AtomicWriteChmod )
type MountEntry ¶
type MountEntry struct {
Name string
Dir string
Type string
Options []string
DumpFrequency int
CheckPassNumber int
}
MountEntry describes an /etc/fstab-like mount entry.
Fields are named after names in struct returned by getmntent(3).
struct mntent {
char *mnt_fsname; /* name of mounted filesystem */
char *mnt_dir; /* filesystem path prefix */
char *mnt_type; /* mount type (see Mntent.h) */
char *mnt_opts; /* mount options (see Mntent.h) */
int mnt_freq; /* dump frequency in days */
int mnt_passno; /* pass number on parallel fsck */
};
func ParseMountEntry ¶
func ParseMountEntry(s string) (MountEntry, error)
ParseMountEntry parses a fstab-like entry.
func (*MountEntry) Equal ¶
func (e *MountEntry) Equal(o *MountEntry) bool
Equal checks if one entry is equal to another
func (*MountEntry) OptBool ¶
func (e *MountEntry) OptBool(name string) bool
OptBool returns true if a given mount option is present.
func (*MountEntry) OptStr ¶
func (e *MountEntry) OptStr(name string) (string, bool)
OptStr returns the value part of a key=value mount option. The name of the option must not contain the trailing "=" character.
func (MountEntry) String ¶
func (e MountEntry) String() string
type MountInfoEntry ¶
type MountInfoEntry struct {
MountID int
ParentID int
DevMajor int
DevMinor int
Root string
MountDir string
MountOptions map[string]string
OptionalFields []string
FsType string
MountSource string
SuperOptions map[string]string
}
MountInfoEntry contains data from /proc/$PID/mountinfo
For details please refer to mountinfo documentation at https://www.kernel.org/doc/Documentation/filesystems/proc.txt
func LoadMountInfo ¶
func LoadMountInfo(fname string) ([]*MountInfoEntry, error)
LoadMountInfo loads list of mounted entries from a given file.
The file is typically ProcSelfMountInfo but any other process mount table can be read the same way.
func ParseMountInfoEntry ¶
func ParseMountInfoEntry(s string) (*MountInfoEntry, error)
ParseMountInfoEntry parses a single line of /proc/$PID/mountinfo file.
func ReadMountInfo ¶
func ReadMountInfo(reader io.Reader) ([]*MountInfoEntry, error)
ReadMountInfo reads and parses a mountinfo file.
func (*MountInfoEntry) String ¶
func (mi *MountInfoEntry) String() string
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