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

Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [syscall/] [exec_linux.go] - Blame information for rev 747

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 linux
 
package syscall
 
import (
        "unsafe"
)
 
//sysnb raw_prctl(option int, arg2 int, arg3 int, arg4 int, arg5 int) (ret int, err Errno)
//prctl(option int, arg2 _C_long, arg3 _C_long, arg4 _C_long, arg5 _C_long) int
 
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
        Pdeathsig  int         // Signal that the process will get when its parent dies (Linux only)
}
 
// 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.
 
        // Parent death signal
        if sys.Pdeathsig != 0 {
                _, err1 = raw_prctl(PR_SET_PDEATHSIG, sys.Pdeathsig, 0, 0, 0)
                if err1 != 0 {
                        goto childerror
                }
 
                // Signal self if parent is already dead. This might cause a
                // duplicate signal in rare cases, but it won't matter when
                // using SIGKILL.
                ppid := Getppid()
                if ppid == 1 {
                        pid = Getpid()
                        err2 := Kill(pid, sys.Pdeathsig)
                        if err2 != nil {
                                err1 = err2.(Errno)
                                goto childerror
                        }
                }
        }
 
        // 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_linux.go] - Blame information for rev 747

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 linux`
6
7			`package syscall`
8
9			`import (`
10			`"unsafe"`
11			`)`
12
13			`//sysnb raw_prctl(option int, arg2 int, arg3 int, arg4 int, arg5 int) (ret int, err Errno)`
14			`//prctl(option int, arg2 _C_long, arg3 _C_long, arg4 _C_long, arg5 _C_long) int`
15
16			`type SysProcAttr struct {`
17			`Chroot string // Chroot.`
18			`Credential *Credential // Credential.`
19			`Ptrace bool // Enable tracing.`
20			`Setsid bool // Create session.`
21			`Setpgid bool // Set process group ID to new pid (SYSV setpgrp)`
22			`Setctty bool // Set controlling terminal to fd 0`
23			`Noctty bool // Detach fd 0 from controlling terminal`
24			`Pdeathsig int // Signal that the process will get when its parent dies (Linux only)`
25			`}`
26
27			`// Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.`
28			`// If a dup or exec fails, write the errno error to pipe.`
29			`// (Pipe is close-on-exec so if exec succeeds, it will be closed.)`
30			`// In the child, this function must not acquire any locks, because`
31			`// they might have been locked at the time of the fork. This means`
32			`// no rescheduling, no malloc calls, and no new stack segments.`
33			`// The calls to RawSyscall are okay because they are assembly`
34			`// functions that do not grow the stack.`
35			`func forkAndExecInChild(argv0 byte, argv, envv []byte, chroot, dir byte, attr ProcAttr, sys *SysProcAttr, pipe int) (pid int, err Errno) {`
36			`// Declare all variables at top in case any`
37			`// declarations require heap allocation (e.g., err1).`
38			`var (`
39			`r1 Pid_t`
40			`err1 Errno`
41			`nextfd int`
42			`i int`
43			`)`
44
45			`// guard against side effects of shuffling fds below.`
46			`fd := append([]int(nil), attr.Files...)`
47
48			`// About to call fork.`
49			`// No more allocation or calls of non-assembly functions.`
50			`r1, err1 = raw_fork()`
51			`if err1 != 0 {`
52			`return 0, err1`
53			`}`
54
55			`if r1 != 0 {`
56			`// parent; return PID`
57			`return int(r1), 0`
58			`}`
59
60			`// Fork succeeded, now in child.`
61
62			`// Parent death signal`
63			`if sys.Pdeathsig != 0 {`
64			`_, err1 = raw_prctl(PR_SET_PDEATHSIG, sys.Pdeathsig, 0, 0, 0)`
65			`if err1 != 0 {`
66			`goto childerror`
67			`}`
68
69			`// Signal self if parent is already dead. This might cause a`
70			`// duplicate signal in rare cases, but it won't matter when`
71			`// using SIGKILL.`
72			`ppid := Getppid()`
73			`if ppid == 1 {`
74			`pid = Getpid()`
75			`err2 := Kill(pid, sys.Pdeathsig)`
76			`if err2 != nil {`
77			`err1 = err2.(Errno)`
78			`goto childerror`
79			`}`
80			`}`
81			`}`
82
83			`// Enable tracing if requested.`
84			`if sys.Ptrace {`
85			`err1 = raw_ptrace(_PTRACE_TRACEME, 0, nil, nil)`
86			`if err1 != 0 {`
87			`goto childerror`
88			`}`
89			`}`
90
91			`// Session ID`
92			`if sys.Setsid {`
93			`err1 = raw_setsid()`
94			`if err1 != 0 {`
95			`goto childerror`
96			`}`
97			`}`
98
99			`// Set process group`
100			`if sys.Setpgid {`
101			`err1 = raw_setpgid(0, 0)`
102			`if err1 != 0 {`
103			`goto childerror`
104			`}`
105			`}`
106
107			`// Chroot`
108			`if chroot != nil {`
109			`err1 = raw_chroot(chroot)`
110			`if err1 != 0 {`
111			`goto childerror`
112			`}`
113			`}`
114
115			`// User and groups`
116			`if cred := sys.Credential; cred != nil {`
117			`ngroups := len(cred.Groups)`
118			`if ngroups == 0 {`
119			`err2 := setgroups(0, nil)`
120			`if err2 == nil {`
121			`err1 = 0`
122			`} else {`
123			`err1 = err2.(Errno)`
124			`}`
125			`} else {`
126			`groups := make([]Gid_t, ngroups)`
127			`for i, v := range cred.Groups {`
128			`groups[i] = Gid_t(v)`
129			`}`
130			`err2 := setgroups(ngroups, &groups[0])`
131			`if err2 == nil {`
132			`err1 = 0`
133			`} else {`
134			`err1 = err2.(Errno)`
135			`}`
136			`}`
137			`if err1 != 0 {`
138			`goto childerror`
139			`}`
140			`err2 := Setgid(int(cred.Gid))`
141			`if err2 != nil {`
142			`err1 = err2.(Errno)`
143			`goto childerror`
144			`}`
145			`err2 = Setuid(int(cred.Uid))`
146			`if err2 != nil {`
147			`err1 = err2.(Errno)`
148			`goto childerror`
149			`}`
150			`}`
151
152			`// Chdir`
153			`if dir != nil {`
154			`err1 = raw_chdir(dir)`
155			`if err1 != 0 {`
156			`goto childerror`
157			`}`
158			`}`
159
160			`// Pass 1: look for fd[i] < i and move those up above len(fd)`
161			`// so that pass 2 won't stomp on an fd it needs later.`
162			`nextfd = int(len(fd))`
163			`if pipe < nextfd {`
164			`err1 = raw_dup2(pipe, nextfd)`
165			`if err1 != 0 {`
166			`goto childerror`
167			`}`
168			`raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)`
169			`pipe = nextfd`
170			`nextfd++`
171			`}`
172			`for i = 0; i < len(fd); i++ {`
173			`if fd[i] >= 0 && fd[i] < int(i) {`
174			`err1 = raw_dup2(fd[i], nextfd)`
175			`if err1 != 0 {`
176			`goto childerror`
177			`}`
178			`raw_fcntl(nextfd, F_SETFD, FD_CLOEXEC)`
179			`fd[i] = nextfd`
180			`nextfd++`
181			`if nextfd == pipe { // don't stomp on pipe`
182			`nextfd++`
183			`}`
184			`}`
185			`}`
186
187			`// Pass 2: dup fd[i] down onto i.`
188			`for i = 0; i < len(fd); i++ {`
189			`if fd[i] == -1 {`
190			`raw_close(i)`
191			`continue`
192			`}`
193			`if fd[i] == int(i) {`
194			`// dup2(i, i) won't clear close-on-exec flag on Linux,`
195			`// probably not elsewhere either.`
196			`_, err1 = raw_fcntl(fd[i], F_SETFD, 0)`
197			`if err1 != 0 {`
198			`goto childerror`
199			`}`
200			`continue`
201			`}`
202			`// The new fd is created NOT close-on-exec,`
203			`// which is exactly what we want.`
204			`err1 = raw_dup2(fd[i], i)`
205			`if err1 != 0 {`
206			`goto childerror`
207			`}`
208			`}`
209
210			`// By convention, we don't close-on-exec the fds we are`
211			`// started with, so if len(fd) < 3, close 0, 1, 2 as needed.`
212			`// Programs that know they inherit fds >= 3 will need`
213			`// to set them close-on-exec.`
214			`for i = len(fd); i < 3; i++ {`
215			`raw_close(i)`
216			`}`
217
218			`// Detach fd 0 from tty`
219			`if sys.Noctty {`
220			`_, err1 = raw_ioctl(0, TIOCNOTTY, 0)`
221			`if err1 != 0 {`
222			`goto childerror`
223			`}`
224			`}`
225
226			`// Make fd 0 the tty`
227			`if sys.Setctty {`
228			`_, err1 = raw_ioctl(0, TIOCSCTTY, 0)`
229			`if err1 != 0 {`
230			`goto childerror`
231			`}`
232			`}`
233
234			`// Time to exec.`
235			`err1 = raw_execve(argv0, &argv[0], &envv[0])`
236
237			`childerror:`
238			`// send error code on pipe`
239			`raw_write(pipe, (*byte)(unsafe.Pointer(&err1)), int(unsafe.Sizeof(err1)))`
240			`for {`
241			`raw_exit(253)`
242			`}`
243
244			`// Calling panic is not actually safe,`
245			`// but the for loop above won't break`
246			`// and this shuts up the compiler.`
247			`panic("unreached")`
248			`}`