summaryrefslogtreecommitdiff
path: root/internal/syscallcompat/sys_darwin.go
blob: 39a225f66b6c562fd8644b5867ef0c3225f56cb4 (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
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
package syscallcompat

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

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

// Sorry, fallocate is not available on OSX at all and
// fcntl F_PREALLOCATE is not accessible from Go.
// See https://github.com/rfjakob/gocryptfs/issues/18 if you want to help.
func EnospcPrealloc(fd int, off int64, len int64) error {
	return nil
}

// See above.
func Fallocate(fd int, mode uint32, off int64, len int64) error {
	return syscall.EOPNOTSUPP
}

var chdirMutex sync.Mutex

// Poor man's Openat
func Openat(dirfd int, path string, flags int, mode uint32) (int, error) {
	chdirMutex.Lock()
	defer chdirMutex.Unlock()
	if !filepath.IsAbs(path) {
		// Save the old working directory
		oldWd, err := os.Getwd()
		if err != nil {
			return -1, err
		}
		// Chdir to target directory
		err = syscall.Fchdir(dirfd)
		if err != nil {
			return -1, err
		}
		// Chdir back at the end
		defer os.Chdir(oldWd)
	}
	return syscall.Open(path, flags, mode)
}

// Poor man's Renameat
func Renameat(olddirfd int, oldpath string, newdirfd int, newpath string) error {
	chdirMutex.Lock()
	defer chdirMutex.Unlock()
	// Unless both paths are absolute we have to save the old working dir and
	// Chdir(oldWd) back to it in the end. If we error out before the first
	// chdir, Chdir(oldWd) is unneccassary but does no harm.
	if !filepath.IsAbs(oldpath) || !filepath.IsAbs(newpath) {
		oldWd, err := os.Getwd()
		if err != nil {
			return err
		}
		defer os.Chdir(oldWd)
	}
	// Make oldpath absolute
	oldpath, err := dirfdAbs(olddirfd, oldpath)
	if err != nil {
		return err
	}
	// Make newpath absolute
	newpath, err = dirfdAbs(newdirfd, newpath)
	if err != nil {
		return err
	}
	return syscall.Rename(oldpath, newpath)
}

// Poor man's Unlinkat
func Unlinkat(dirfd int, path string, flags int) (err error) {
	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)
	if (flags & unix.AT_REMOVEDIR) != 0 {
		return syscall.Rmdir(path)
	} else {
		return syscall.Unlink(path)
	}
}

// Poor man's Mknodat
func Mknodat(dirfd int, path string, mode uint32, dev int) error {
	chdirMutex.Lock()
	defer chdirMutex.Unlock()
	if !filepath.IsAbs(path) {
		oldWd, err := os.Getwd()
		if err != nil {
			return err
		}
		defer os.Chdir(oldWd)
	}
	path, err := dirfdAbs(dirfd, path)
	if err != nil {
		return err
	}
	return syscall.Mknod(path, mode, dev)
}

// dirfdAbs transforms the dirfd-relative "path" to an absolute one. If the
// path is not already absolute, this function will change the working
// directory. The caller has to chdir back.
func dirfdAbs(dirfd int, path string) (string, error) {
	if filepath.IsAbs(path) {
		return path, nil
	}
	err := syscall.Fchdir(dirfd)
	if err != nil {
		return "", err
	}
	wd, err := os.Getwd()
	if err != nil {
		return "", err
	}
	return filepath.Join(wd, path), nil
}

// Dup3 is not available on Darwin, so we use Dup2 instead.
func Dup3(oldfd int, newfd int, flags int) (err error) {
	if flags != 0 {
		log.Panic("darwin does not support dup3 flags")
	}
	return syscall.Dup2(oldfd, newfd)
}

// Poor man's Fchmodat.
func Fchmodat(dirfd int, path string, mode uint32, flags int) (err error) {
	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.Chmod(path, mode)
}

// Poor man's Fchownat.
func Fchownat(dirfd int, path string, uid int, gid int, flags int) (err error) {
	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)
}

// Poor man's Symlinkat.
func Symlinkat(oldpath string, newdirfd int, newpath string) (err error) {
	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)
}

// Poor man's Mkdirat.
func Mkdirat(dirfd int, path string, mode uint32) (err error) {
	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)
}