URL https://opencores.org/ocsvn/openrisc/openrisc/trunk

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [syscall/] [exec_bsd.go] - Blame information for rev 867

Go to most recent revision | Details | Compare with Previous | View Log


// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
 
// +build darwin freebsd netbsd openbsd
 
package syscall
 
import (
        "unsafe"
)
 
type SysProcAttr struct {
        Chroot     string      // Chroot.
        Credential *Credential // Credential.
        Ptrace     bool        // Enable tracing.
        Setsid     bool        // Create session.
        Setpgid    bool        // Set process group ID to new pid (SYSV setpgrp)
        Setctty    bool        // Set controlling terminal to fd 0
        Noctty     bool        // Detach fd 0 from controlling terminal
}
 
// Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.
// If a dup or exec fails, write the errno error to pipe.
// (Pipe is close-on-exec so if exec succeeds, it will be closed.)
// In the child, this function must not acquire any locks, because
// they might have been locked at the time of the fork.  This means
// no rescheduling, no malloc calls, and no new stack segments.
// The calls to RawSyscall are okay because they are assembly
// functions that do not grow the stack.
func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr *ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {
        // Declare all variables at top in case any
        // declarations require heap allocation (e.g., err1).
        var (
                r1     Pid_t
                err1   Errno
                nextfd int
                i      int
        )
 
        // guard against side effects of shuffling fds below.
        fd := append([]int(nil), attr.Files...)
 
        // About to call fork.
        // No more allocation or calls of non-assembly functions.
        r1, err1 = raw_fork()
        if err1 != 0 {
                return 0, err1
        }
 
        if r1 != 0 {
                // parent; return PID
                return int(r1), 0
        }
 
        // Fork succeeded, now in child.
 
        // Enable tracing if requested.
        if sys.Ptrace {
                err1 = raw_ptrace(_PTRACE_TRACEME, 0, nil, nil)
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // Session ID
        if sys.Setsid {
                err1 = raw_setsid()
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // Set process group
        if sys.Setpgid {
                err1 = raw_setpgid(0, 0)
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // Chroot
        if chroot != nil {
                err1 = raw_chroot(chroot)
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // User and groups
        if cred := sys.Credential; cred != nil {
                ngroups := len(cred.Groups)
                if ngroups == 0 {
                        err2 := setgroups(0, nil)
                        if err2 == nil {
                                err1 = 0
                        } else {
                                err1 = err2.(Errno)
                        }
                } else {
                        groups := make([]Gid_t, ngroups)
                        for i, v := range cred.Groups {
                                groups[i] = Gid_t(v)
                        }
                        err2 := setgroups(ngroups, &groups[0])
                        if err2 == nil {
                                err1 = 0
                        } else {
                                err1 = err2.(Errno)
                        }
                }
                if err1 != 0 {
                        goto childerror
                }
                err2 := Setgid(int(cred.Gid))
                if err2 != nil {
                        err1 = err2.(Errno)
                        goto childerror
                }
                err2 = Setuid(int(cred.Uid))
                if err2 != nil {
                        err1 = err2.(Errno)
                        goto childerror
                }
        }
 
        // Chdir
        if dir != nil {
                err1 = raw_chdir(dir)
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // Pass 1: look for fd[i] < i and move those up above len(fd)
        // so that pass 2 won't stomp on an fd it needs later.
        nextfd = int(len(fd))
        if pipe < nextfd {
                err1 = raw_dup2(pipe, nextfd)
                if err1 != 0 {
                        goto childerror
                }
                raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
                pipe = nextfd
                nextfd++
        }
        for i = 0; i < len(fd); i++ {
                if fd[i] >= 0 && fd[i] < int(i) {
                        err1 = raw_dup2(fd[i], nextfd)
                        if err1 != 0 {
                                goto childerror
                        }
                        raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)
                        fd[i] = nextfd
                        nextfd++
                        if nextfd == pipe { // don't stomp on pipe
                                nextfd++
                        }
                }
        }
 
        // Pass 2: dup fd[i] down onto i.
        for i = 0; i < len(fd); i++ {
                if fd[i] == -1 {
                        raw_close(i)
                        continue
                }
                if fd[i] == int(i) {
                        // dup2(i, i) won't clear close-on-exec flag on Linux,
                        // probably not elsewhere either.
                        _, err1 = raw_fcntl(fd[i], F_SETFD, 0)
                        if err1 != 0 {
                                goto childerror
                        }
                        continue
                }
                // The new fd is created NOT close-on-exec,
                // which is exactly what we want.
                err1 = raw_dup2(fd[i], i)
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // By convention, we don't close-on-exec the fds we are
        // started with, so if len(fd) < 3, close 0, 1, 2 as needed.
        // Programs that know they inherit fds >= 3 will need
        // to set them close-on-exec.
        for i = len(fd); i < 3; i++ {
                raw_close(i)
        }
 
        // Detach fd 0 from tty
        if sys.Noctty {
                _, err1 = raw_ioctl(0, TIOCNOTTY, 0)
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // Make fd 0 the tty
        if sys.Setctty {
                _, err1 = raw_ioctl(0, TIOCSCTTY, 0)
                if err1 != 0 {
                        goto childerror
                }
        }
 
        // Time to exec.
        err1 = raw_execve(argv0, &argv[0], &envv[0])
 
childerror:
        // send error code on pipe
        raw_write(pipe, (*byte)(unsafe.Pointer(&err1)), int(unsafe.Sizeof(err1)))
        for {
                raw_exit(253)
        }
 
        // Calling panic is not actually safe,
        // but the for loop above won't break
        // and this shuts up the compiler.
        panic("unreached")
}

Browse

Tools

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [syscall/] [exec_bsd.go] - Blame information for rev 867

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2011 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`// +build darwin freebsd netbsd openbsd`
6
7			`package syscall`
8
9			`import (`
10			`"unsafe"`
11			`)`
12
13			`type SysProcAttr struct {`
14			`Chroot string // Chroot.`
15			`Credential *Credential // Credential.`
16			`Ptrace bool // Enable tracing.`
17			`Setsid bool // Create session.`
18			`Setpgid bool // Set process group ID to new pid (SYSV setpgrp)`
19			`Setctty bool // Set controlling terminal to fd 0`
20			`Noctty bool // Detach fd 0 from controlling terminal`
21			`}`
22
23			`// Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.`
24			`// If a dup or exec fails, write the errno error to pipe.`
25			`// (Pipe is close-on-exec so if exec succeeds, it will be closed.)`
26			`// In the child, this function must not acquire any locks, because`
27			`// they might have been locked at the time of the fork. This means`
28			`// no rescheduling, no malloc calls, and no new stack segments.`
29			`// The calls to RawSyscall are okay because they are assembly`
30			`// functions that do not grow the stack.`
31			`func forkAndExecInChild(argv0 byte, argv, envv []byte, chroot, dir byte, attr ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {`
32			`// Declare all variables at top in case any`
33			`// declarations require heap allocation (e.g., err1).`
34			`var (`
35			`r1 Pid_t`
36			`err1 Errno`
37			`nextfd int`
38			`i int`
39			`)`
40
41			`// guard against side effects of shuffling fds below.`
42			`fd := append([]int(nil), attr.Files...)`
43
44			`// About to call fork.`
45			`// No more allocation or calls of non-assembly functions.`
46			`r1, err1 = raw_fork()`
47			`if err1 != 0 {`
48			`return 0, err1`
49			`}`
50
51			`if r1 != 0 {`
52			`// parent; return PID`
53			`return int(r1), 0`
54			`}`
55
56			`// Fork succeeded, now in child.`
57
58			`// Enable tracing if requested.`
59			`if sys.Ptrace {`
60			`err1 = raw_ptrace(_PTRACE_TRACEME, 0, nil, nil)`
61			`if err1 != 0 {`
62			`goto childerror`
63			`}`
64			`}`
65
66			`// Session ID`
67			`if sys.Setsid {`
68			`err1 = raw_setsid()`
69			`if err1 != 0 {`
70			`goto childerror`
71			`}`
72			`}`
73
74			`// Set process group`
75			`if sys.Setpgid {`
76			`err1 = raw_setpgid(0, 0)`
77			`if err1 != 0 {`
78			`goto childerror`
79			`}`
80			`}`
81
82			`// Chroot`
83			`if chroot != nil {`
84			`err1 = raw_chroot(chroot)`
85			`if err1 != 0 {`
86			`goto childerror`
87			`}`
88			`}`
89
90			`// User and groups`
91			`if cred := sys.Credential; cred != nil {`
92			`ngroups := len(cred.Groups)`
93			`if ngroups == 0 {`
94			`err2 := setgroups(0, nil)`
95			`if err2 == nil {`
96			`err1 = 0`
97			`} else {`
98			`err1 = err2.(Errno)`
99			`}`
100			`} else {`
101			`groups := make([]Gid_t, ngroups)`
102			`for i, v := range cred.Groups {`
103			`groups[i] = Gid_t(v)`
104			`}`
105			`err2 := setgroups(ngroups, &groups[0])`
106			`if err2 == nil {`
107			`err1 = 0`
108			`} else {`
109			`err1 = err2.(Errno)`
110			`}`
111			`}`
112			`if err1 != 0 {`
113			`goto childerror`
114			`}`
115			`err2 := Setgid(int(cred.Gid))`
116			`if err2 != nil {`
117			`err1 = err2.(Errno)`
118			`goto childerror`
119			`}`
120			`err2 = Setuid(int(cred.Uid))`
121			`if err2 != nil {`
122			`err1 = err2.(Errno)`
123			`goto childerror`
124			`}`
125			`}`
126
127			`// Chdir`
128			`if dir != nil {`
129			`err1 = raw_chdir(dir)`
130			`if err1 != 0 {`
131			`goto childerror`
132			`}`
133			`}`
134
135			`// Pass 1: look for fd[i] < i and move those up above len(fd)`
136			`// so that pass 2 won't stomp on an fd it needs later.`
137			`nextfd = int(len(fd))`
138			`if pipe < nextfd {`
139			`err1 = raw_dup2(pipe, nextfd)`
140			`if err1 != 0 {`
141			`goto childerror`
142			`}`
143			`raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)`
144			`pipe = nextfd`
145			`nextfd++`
146			`}`
147			`for i = 0; i < len(fd); i++ {`
148			`if fd[i] >= 0 && fd[i] < int(i) {`
149			`err1 = raw_dup2(fd[i], nextfd)`
150			`if err1 != 0 {`
151			`goto childerror`
152			`}`
153			`raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)`
154			`fd[i] = nextfd`
155			`nextfd++`
156			`if nextfd == pipe { // don't stomp on pipe`
157			`nextfd++`
158			`}`
159			`}`
160			`}`
161
162			`// Pass 2: dup fd[i] down onto i.`
163			`for i = 0; i < len(fd); i++ {`
164			`if fd[i] == -1 {`
165			`raw_close(i)`
166			`continue`
167			`}`
168			`if fd[i] == int(i) {`
169			`// dup2(i, i) won't clear close-on-exec flag on Linux,`
170			`// probably not elsewhere either.`
171			`_, err1 = raw_fcntl(fd[i], F_SETFD, 0)`
172			`if err1 != 0 {`
173			`goto childerror`
174			`}`
175			`continue`
176			`}`
177			`// The new fd is created NOT close-on-exec,`
178			`// which is exactly what we want.`
179			`err1 = raw_dup2(fd[i], i)`
180			`if err1 != 0 {`
181			`goto childerror`
182			`}`
183			`}`
184
185			`// By convention, we don't close-on-exec the fds we are`
186			`// started with, so if len(fd) < 3, close 0, 1, 2 as needed.`
187			`// Programs that know they inherit fds >= 3 will need`
188			`// to set them close-on-exec.`
189			`for i = len(fd); i < 3; i++ {`
190			`raw_close(i)`
191			`}`
192
193			`// Detach fd 0 from tty`
194			`if sys.Noctty {`
195			`_, err1 = raw_ioctl(0, TIOCNOTTY, 0)`
196			`if err1 != 0 {`
197			`goto childerror`
198			`}`
199			`}`
200
201			`// Make fd 0 the tty`
202			`if sys.Setctty {`
203			`_, err1 = raw_ioctl(0, TIOCSCTTY, 0)`
204			`if err1 != 0 {`
205			`goto childerror`
206			`}`
207			`}`
208
209			`// Time to exec.`
210			`err1 = raw_execve(argv0, &argv[0], &envv[0])`
211
212			`childerror:`
213			`// send error code on pipe`
214			`raw_write(pipe, (*byte)(unsafe.Pointer(&err1)), int(unsafe.Sizeof(err1)))`
215			`for {`
216			`raw_exit(253)`
217			`}`
218
219			`// Calling panic is not actually safe,`
220			`// but the for loop above won't break`
221			`// and this shuts up the compiler.`
222			`panic("unreached")`
223			`}`