Documentation
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Overview ¶
Package syscallcompat wraps Linux-specific syscalls.
Index ¶
- Constants
- func Dup3(oldfd int, newfd int, flags int) (err error)
- func EnospcPrealloc(fd int, off int64, len int64) (err error)
- func Faccessat(dirfd int, path string, mode uint32) error
- func Fallocate(fd int, mode uint32, off int64, len int64) (err error)
- func FchmodatNofollow(dirfd int, path string, mode uint32) (err error)
- func Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error)
- func Fgetxattr(fd int, attr string) (val []byte, err error)
- func Flistxattr(fd int) (attrs []string, err error)
- func Flush(fd int) error
- func Fstatat(dirfd int, path string, stat *unix.Stat_t, flags int) (err error)
- func Fstatat2(dirfd int, path string, flags int) (*syscall.Stat_t, error)
- func FutimesNano(fd int, a *time.Time, m *time.Time) (err error)
- func Getdents(fd int) ([]fuse.DirEntry, error)
- func GetdentsSpecial(fd int) (entries []fuse.DirEntry, entriesSpecial []fuse.DirEntry, err error)
- func IsENOSPC(err error) bool
- func Lgetxattr(path string, attr string) (val []byte, err error)
- func Linkat(olddirfd int, oldpath string, newdirfd int, newpath string, flags int) (err error)
- func Llistxattr(path string) (attrs []string, err error)
- func Mkdirat(dirfd int, path string, mode uint32) (err error)
- func MkdiratUser(dirfd int, path string, mode uint32, context *fuse.Context) (err error)
- func Mknodat(dirfd int, path string, mode uint32, dev int) (err error)
- func MknodatUser(dirfd int, path string, mode uint32, dev int, context *fuse.Context) (err error)
- func Open(path string, mode int, perm uint32) (fd int, err error)
- func OpenDirNofollow(baseDir string, relPath string) (fd int, err error)
- func Openat(dirfd int, path string, flags int, mode uint32) (fd int, err error)
- func OpenatUser(dirfd int, path string, flags int, mode uint32, context *fuse.Context) (fd int, err error)
- func Readlinkat(dirfd int, path string) (string, error)
- func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)
- func Renameat2(olddirfd int, oldpath string, newdirfd int, newpath string, flags uint) (err error)
- func Symlinkat(oldpath string, newdirfd int, newpath string) (err error)
- func SymlinkatUser(oldpath string, newdirfd int, newpath string, context *fuse.Context) (err error)
- func Unix2syscall(u unix.Stat_t) syscall.Stat_t
- func Unlinkat(dirfd int, path string, flags int) (err error)
- func UtimesNanoAtNofollow(dirfd int, path string, a *time.Time, m *time.Time) (err error)
Constants ¶
const ( // O_DIRECT means oncached I/O on Linux. No direct equivalent on MacOS and defined // to zero there. O_DIRECT = syscall.O_DIRECT // O_PATH is only defined on Linux O_PATH = unix.O_PATH // RENAME_NOREPLACE is only defined on Linux RENAME_NOREPLACE = unix.RENAME_NOREPLACE )
const PATH_MAX = 4096
PATH_MAX is the maximum allowed path length on Linux. It is not defined on Darwin, so we use the Linux value.
const XATTR_BUFSZ = XATTR_SIZE_MAX + 1024
Make the buffer 1kB bigger so we can detect overflows. Unfortunately, slices larger than 64kB are always allocated on the heap.
const XATTR_BUFSZ_SMALL = 500
We try with a small buffer first - this one can be allocated on the stack.
const XATTR_SIZE_MAX = 65536
Variables ¶
This section is empty.
Functions ¶
func Dup3 ¶
Dup3 wraps the Dup3 syscall. We want to use Dup3 rather than Dup2 because Dup2 is not implemented on arm64.
func EnospcPrealloc ¶
EnospcPrealloc preallocates ciphertext space without changing the file size. This guarantees that we don't run out of space while writing a ciphertext block (that would corrupt the block).
func Faccessat ¶
Faccessat exists both in Linux and in MacOS 10.10+, but the Linux version DOES NOT support any flags. Emulate AT_SYMLINK_NOFOLLOW like glibc does.
func FchmodatNofollow ¶
FchmodatNofollow is like Fchmodat but never follows symlinks.
This should be handled by the AT_SYMLINK_NOFOLLOW flag, but Linux does not implement it, so we have to perform an elaborate dance with O_PATH and /proc/self/fd.
See also: Qemu implemented the same logic as fchmodat_nofollow(): https://git.qemu.org/?p=qemu.git;a=blob;f=hw/9pfs/9p-local.c#l335
func Flistxattr ¶
Flistxattr is a wrapper for unix.Flistxattr that handles buffer sizing and parsing the returned blob to a string slice.
func Fstatat2 ¶
Fstatat2 is a more convenient version of Fstatat. It allocates a Stat_t for you and also handles the Unix2syscall conversion. Retries on EINTR.
func FutimesNano ¶
FutimesNano syscall.
func GetdentsSpecial ¶
GetdentsSpecial calls the Getdents syscall, with normal entries and "." / ".." split into two slices.
func Llistxattr ¶
Llistxattr is a wrapper for unix.Llistxattr that handles buffer sizing and parsing the returned blob to a string slice.
func MkdiratUser ¶
MkdiratUser runs the Mkdirat syscall in the context of a different user.
See OpenatUser() for how this works.
func MknodatUser ¶
MknodatUser runs the Mknodat syscall in the context of a different user.
See OpenatUser() for how this works.
func OpenDirNofollow ¶
OpenDirNofollow opens the dir at "relPath" in a way that is secure against symlink attacks. Symlinks that are part of "relPath" are never followed. This function is implemented by walking the directory tree, starting at "baseDir", using the Openat syscall with the O_NOFOLLOW flag. Symlinks that are part of the "baseDir" path are followed. Retries on EINTR.
func OpenatUser ¶
func OpenatUser(dirfd int, path string, flags int, mode uint32, context *fuse.Context) (fd int, err error)
OpenatUser runs the Openat syscall in the context of a different user.
It switches the current thread to the new user, performs the syscall, and switches back.
func Readlinkat ¶
Readlinkat is a convenience wrapper around unix.Readlinkat() that takes care of buffer sizing. Implemented like os.Readlink().
func SymlinkatUser ¶
SymlinkatUser runs the Symlinkat syscall in the context of a different user.
See OpenatUser() for how this works.
func Unix2syscall ¶
Unix2syscall converts a unix.Stat_t struct to a syscall.Stat_t struct. A direct cast does not work because the padding is named differently in unix.Stat_t for some reason ("X__unused" in syscall, "_" in unix).
Types ¶
This section is empty.
Source Files