summaryrefslogtreecommitdiff
path: root/internal/syscallcompat/emulate.go
blob: 8a538fbd53b458afc51ef3373e72bf93668edcf3 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
package syscallcompat

import (
	"path/filepath"
	"sync"
	"syscall"

	"golang.org/x/sys/unix"
)

var chdirMutex sync.Mutex

// emulateMknodat emulates the syscall for platforms that don't have it
// in the kernel (darwin).
func emulateMknodat(dirfd int, path string, mode uint32, dev int) error {
	if !filepath.IsAbs(path) {
		chdirMutex.Lock()
		defer chdirMutex.Unlock()
		cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
		if err != nil {
			return err
		}
		defer syscall.Close(cwd)
		err = syscall.Fchdir(dirfd)
		if err != nil {
			return err
		}
		defer syscall.Fchdir(cwd)
	}
	return syscall.Mknod(path, mode, dev)
}

// emulateFchownat emulates the syscall for platforms that don't have it
// in the kernel (darwin).
func emulateFchownat(dirfd int, path string, uid int, gid int, flags int) (err error) {
	if !filepath.IsAbs(path) {
		chdirMutex.Lock()
		defer chdirMutex.Unlock()
		cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
		if err != nil {
			return err
		}
		defer syscall.Close(cwd)
		err = syscall.Fchdir(dirfd)
		if err != nil {
			return err
		}
		defer syscall.Fchdir(cwd)
	}
	return syscall.Lchown(path, uid, gid)
}

// emulateSymlinkat emulates the syscall for platforms that don't have it
// in the kernel (darwin).
func emulateSymlinkat(oldpath string, newdirfd int, newpath string) (err error) {
	if !filepath.IsAbs(newpath) {
		chdirMutex.Lock()
		defer chdirMutex.Unlock()
		cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
		if err != nil {
			return err
		}
		defer syscall.Close(cwd)
		err = syscall.Fchdir(newdirfd)
		if err != nil {
			return err
		}
		defer syscall.Fchdir(cwd)
	}
	return syscall.Symlink(oldpath, newpath)
}

// emulateMkdirat emulates the syscall for platforms that don't have it
// in the kernel (darwin).
func emulateMkdirat(dirfd int, path string, mode uint32) (err error) {
	if !filepath.IsAbs(path) {
		chdirMutex.Lock()
		defer chdirMutex.Unlock()
		cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
		if err != nil {
			return err
		}
		defer syscall.Close(cwd)
		err = syscall.Fchdir(dirfd)
		if err != nil {
			return err
		}
		defer syscall.Fchdir(cwd)
	}
	return syscall.Mkdir(path, mode)
}

// emulateFstatat emulates the syscall for platforms that don't have it
// in the kernel (darwin).
func emulateFstatat(dirfd int, path string, stat *unix.Stat_t, flags int) (err error) {
	if !filepath.IsAbs(path) {
		chdirMutex.Lock()
		defer chdirMutex.Unlock()
		cwd, err := syscall.Open(".", syscall.O_RDONLY, 0)
		if err != nil {
			return err
		}
		defer syscall.Close(cwd)
		err = syscall.Fchdir(dirfd)
		if err != nil {
			return err
		}
		defer syscall.Fchdir(cwd)
	}
	return unix.Lstat(path, stat)
}