Directories and links v0.1.0

The working directory, directory entries, removal, renaming and links.

`RemoveDirectory`

pub const RemoveDirectory: int32 = 0x0800;

AT_REMOVEDIR: make UnlinkAt remove a directory rather than a file.

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`Getcwd`

pub func Getcwd(buffer: *var char8, size: uint) -> int64

Writes the current working directory's absolute path into buffer, NUL-terminated. Returns zero, or a negative error number — unlike Linux's, which returns the length. ERANGE where the buffer is too small for the answer. buffer must be writable for size bytes.

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Parameters

Name	Type	Description
`buffer`	`*var char8`	receives the working directory as a null-terminated path
`size`	`uint`	how many bytes `buffer` holds

Returns: the bytes written including the terminator, or a negative error number

`Chdir`

pub func Chdir(path: *char8) -> int64

Makes path the process's working directory. Returns zero, or a negative error number. The change is process-wide and immediately visible to every thread.

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Parameters

Name	Type	Description
`path`	`*char8`	the directory to move to

Returns: zero, or a negative error number

`ReadlinkAt`

pub func ReadlinkAt(
    directoryFd: FileDescriptor,
    path: *char8,
    buffer: *var char8,
    size: uint
) -> int64

Reads the text a symbolic link holds into buffer. directoryFd is AtFdCwd for an ordinary path. Returns the number of bytes written, or a negative error number. The text is not NUL-terminated, and is silently truncated where it does not fit.

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Parameters

Name	Type	Description
`directoryFd`	`FileDescriptor`	the directory `path` is relative to, or `AtFdCwd` for an ordinary path
`path`	`*char8`	the symbolic link to read
`buffer`	`*var char8`	receives the link's text, without a terminator
`size`	`uint`	how many bytes `buffer` holds

Returns: the bytes written, which equals size when the text was truncated, or a negative error number

`SymlinkNoFollow`

pub const SymlinkNoFollow: int32 = 0x0200;

AT_SYMLINK_NOFOLLOW: act on a symbolic link itself rather than on what it points at.

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`LinkAt`

pub func LinkAt(
    oldDirectoryFd: FileDescriptor,
    oldPath: *char8,
    newDirectoryFd: FileDescriptor,
    newPath: *char8,
    flags: int32
) -> int64

Creates a hard link: newPath becomes a second name for the file oldPath names. Returns zero, or a negative error number. flags is zero to leave a symbolic link at oldPath unfollowed, or FollowSymlinks to link what it points at.

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Parameters

Name	Type	Description
`oldDirectoryFd`	`FileDescriptor`	the directory `oldPath` is relative to
`oldPath`	`*char8`	the existing name
`newDirectoryFd`	`FileDescriptor`	the directory `newPath` is relative to
`newPath`	`*char8`	the new name for the same file
`flags`	`int32`	zero, or `FollowSymlinks` to link what a final link points at

Returns: zero, or a negative error number

`FollowSymlinks`

pub const FollowSymlinks: int32 = 0x0400;

AT_SYMLINK_FOLLOW: make LinkAt link a symbolic link's target rather than the link.

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`SymlinkAt`

pub func SymlinkAt(
    target: *char8,
    newDirectoryFd: FileDescriptor,
    linkPath: *char8
) -> int64

Creates a symbolic link at linkPath holding target as its text. Returns zero, or a negative error number. The target is stored, not checked: a dangling link is created as readily as a good one, which is a property callers rely on.

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Parameters

Name	Type	Description
`target`	`*char8`	the text the link will hold, which need not exist
`newDirectoryFd`	`FileDescriptor`	the directory `linkPath` is relative to
`linkPath`	`*char8`	the link to create

Returns: zero, or a negative error number

`Getdirentries`

pub func Getdirentries(
    fd: FileDescriptor,
    buffer: *var opaque,
    count: uint,
    position: *var int64
) -> int64

Reads directory entries from fd into buffer. The buffer holds packed dirent records: the file number at offset 0 (8 bytes), a seek cookie at 8 (8 bytes), the record's length at 16 (2 bytes), the entry type at 18 (1 byte), padding at 19, the name's length at 20 (2 bytes), padding at 22, and the name from 24. The kernel writes as many whole records as fit. The fourth parameter is named as macOS names Getdirentries64's, which is the same output. buffer must be writable for count bytes, and position must be null or writable for an int64.

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Parameters

Name	Type	Description
`fd`	`FileDescriptor`	an open directory descriptor
`buffer`	`*var opaque`	receives the packed records
`count`	`uint`	how many bytes `buffer` holds
`position`	`*var int64`	receives the position of the block read, and may be null

Returns: the bytes filled, zero at the end of the directory, or a negative error number

`UnlinkAt`

pub func UnlinkAt(
    directoryFd: FileDescriptor,
    path: *char8,
    flags: int32
) -> int64

Removes the name path from its directory. flags is zero for a file or RemoveDirectory for an empty directory. Removing a name does not free the file: anything still holding it open keeps using it. path must be non-null and terminated.

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Parameters

Name	Type	Description
`directoryFd`	`FileDescriptor`	the directory `path` is relative to, or `AtFdCwd` for an ordinary path
`path`	`*char8`	the name to remove
`flags`	`int32`	zero for a file, or `RemoveDirectory` for a directory

Returns: zero, or a negative error number

`MkdirAt`

pub func MkdirAt(
    directoryFd: FileDescriptor,
    path: *char8,
    mode: FileMode
) -> int64

Creates a directory named path with permission bits mode. Reports EEXIST when the name is taken, which is how this is used as a lock. path must be non-null and terminated.

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Parameters

Name	Type	Description
`directoryFd`	`FileDescriptor`	the directory `path` is relative to, or `AtFdCwd` for an ordinary path
`path`	`*char8`	the directory to create
`mode`	`FileMode`	the permission bits for it

Returns: zero, or a negative error number

`RenameAt`

pub func RenameAt(
    oldDirectoryFd: FileDescriptor,
    oldPath: *char8,
    newDirectoryFd: FileDescriptor,
    newPath: *char8
) -> int64

Renames oldPath to newPath, each resolved against its own directory descriptor. Within one file system this replaces any existing newPath atomically. Across file systems it reports EXDEV rather than copying. Both paths must be non-null and terminated.

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Parameters

Name	Type	Description
`oldDirectoryFd`	`FileDescriptor`	the directory `oldPath` is relative to
`oldPath`	`*char8`	the name to move
`newDirectoryFd`	`FileDescriptor`	the directory `newPath` is relative to
`newPath`	`*char8`	the name to move it to

Returns: zero, or a negative error number

Types

FreeBSD's scalar types for process, file and user identifiers.

GetRandom

Fills up to length bytes of buffer with unpredictable bytes.

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