libgo: Update to weekly.2012-01-15.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@183539 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 251 insertions, 0 deletions

diff --git a/libgo/go/syscall/exec_linux.go b/libgo/go/syscall/exec_linux.go
new file mode 100644
index 00000000000..98dbeb27750
--- /dev/null
+++ b/libgo/go/syscall/exec_linux.go
@@ -0,0 +1,251 @@
+// 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 {
+		_, err2 := Dup2(pipe, nextfd)
+		if err2 != nil {
+			err1 = err2.(Errno)
+			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) {
+			_, err2 := Dup2(fd[i], nextfd)
+			if err2 != nil {
+				err1 = err2.(Errno)
+				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.
+		_, err2 := Dup2(fd[i], i);
+		if err2 != nil {
+			err1 = err2.(Errno)
+			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")
+}