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Aram Hăvărneanu committed 413a973

hg diaf

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  • Parent commits 1c75d65

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File src/pkg/syscall/exec_solaris.go

+// 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.
+
+package syscall
+
+import (
+	"unsafe"
+)
+
+type SysProcAttr struct {
+	Chroot     string      // Chroot.
+	Credential *Credential // Credential.
+	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
+}
+
+// Implemented in runtime package.
+func runtime_BeforeFork()
+func runtime_AfterFork()
+
+func chdir(path uintptr) (err Errno)
+func chroot1(path uintptr) (err Errno)
+func close(fd uintptr) (err Errno)
+func execve(path uintptr, argv uintptr, envp uintptr) (err Errno)
+func exit(code uintptr)
+func fcntl1(fd uintptr, cmd uintptr, arg uintptr) (val uintptr, err Errno)
+func forkx(flags uintptr) (pid uintptr, err Errno)
+func ioctl(fd uintptr, req uintptr, arg uintptr) (err Errno)
+func setgid(gid uintptr) (err Errno)
+func setgroups1(ngid uintptr, gid uintptr) (err Errno)
+func setsid() (pid uintptr, err Errno)
+func setuid(uid uintptr) (err Errno)
+func setpgid(pid uintptr, pgid uintptr) (err Errno)
+func write1(fd uintptr, buf uintptr, nbyte uintptr) (n uintptr, err Errno)
+
+// 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.
+//
+// We call hand-crafted syscalls, implemented in
+// ../runtime/syscall_solaris.goc, rather than generated libc wrappers
+// because we need to avoid lazy-loading the functions (might malloc,
+// split the stack, or acquire mutexes). We can't call RawSyscall
+// because it's not safe even for BSD-subsystem calls.
+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     uintptr
+		err1   Errno
+		nextfd int
+		i      int
+	)
+
+	// guard against side effects of shuffling fds below.
+	// Make sure that nextfd is beyond any currently open files so
+	// that we can't run the risk of overwriting any of them.
+	fd := make([]int, len(attr.Files))
+	nextfd = len(attr.Files)
+	for i, ufd := range attr.Files {
+		if nextfd < int(ufd) {
+			nextfd = int(ufd)
+		}
+		fd[i] = int(ufd)
+	}
+	nextfd++
+
+	// About to call fork.
+	// No more allocation or calls of non-assembly functions.
+	runtime_BeforeFork()
+	r1, err1 = forkx(0x1) // FORK_NOSIGCHLD
+	if err1 != 0 {
+		runtime_AfterFork()
+		return 0, err1
+	}
+
+	if r1 != 0 {
+		// parent; return PID
+		runtime_AfterFork()
+		return int(r1), 0
+	}
+
+	// Fork succeeded, now in child.
+
+	// Session ID
+	if sys.Setsid {
+		_, err1 = setsid()
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
+	// Set process group
+	if sys.Setpgid {
+		err1 = setpgid(0, 0)
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
+	// Chroot
+	if chroot != nil {
+		err1 = chroot1(uintptr(unsafe.Pointer(chroot)))
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
+	// User and groups
+	if cred := sys.Credential; cred != nil {
+		ngroups := uintptr(len(cred.Groups))
+		groups := uintptr(0)
+		if ngroups > 0 {
+			groups = uintptr(unsafe.Pointer(&cred.Groups[0]))
+		}
+		err1 = setgroups1(ngroups, groups)
+		if err1 != 0 {
+			goto childerror
+		}
+		err1 = setgid(uintptr(cred.Gid))
+		if err1 != 0 {
+			goto childerror
+		}
+		err1 = setuid(uintptr(cred.Uid))
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
+	// Chdir
+	if dir != nil {
+		err1 = chdir(uintptr(unsafe.Pointer(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.
+	if pipe < nextfd {
+		_, err1 = fcntl1(uintptr(pipe), F_DUP2FD, uintptr(nextfd))
+		if err1 != 0 {
+			goto childerror
+		}
+		fcntl1(uintptr(nextfd), F_SETFD, FD_CLOEXEC)
+		pipe = nextfd
+		nextfd++
+	}
+	for i = 0; i < len(fd); i++ {
+		if fd[i] >= 0 && fd[i] < int(i) {
+			_, err1 = fcntl1(uintptr(fd[i]), F_DUP2FD, uintptr(nextfd))
+			if err1 != 0 {
+				goto childerror
+			}
+			fcntl1(uintptr(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 {
+			close(uintptr(i))
+			continue
+		}
+		if fd[i] == int(i) {
+			// dup2(i, i) won't clear close-on-exec flag on Linux,
+			// probably not elsewhere either.
+			_, err1 = fcntl1(uintptr(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 = fcntl1(uintptr(fd[i]), F_DUP2FD, uintptr(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++ {
+		close(uintptr(i))
+	}
+
+	// Detach fd 0 from tty
+	if sys.Noctty {
+		err1 = ioctl(0, uintptr(TIOCNOTTY), 0)
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
+	// Make fd 0 the tty
+	if sys.Setctty {
+		err1 = ioctl(0, uintptr(TIOCSCTTY), 0)
+		if err1 != 0 {
+			goto childerror
+		}
+	}
+
+	// Time to exec.
+	err1 = execve(
+		uintptr(unsafe.Pointer(argv0)),
+		uintptr(unsafe.Pointer(&argv[0])),
+		uintptr(unsafe.Pointer(&envv[0])))
+
+childerror:
+	// send error code on pipe
+	write1(uintptr(pipe), uintptr(unsafe.Pointer(&err1)), unsafe.Sizeof(err1))
+	for {
+		exit(253)
+	}
+}
+
+// Try to open a pipe with O_CLOEXEC set on both file descriptors.
+func forkExecPipe(p []int) error {
+	err := Pipe(p)
+	if err != nil {
+		return err
+	}
+	_, err = fcntl(p[0], F_SETFD, FD_CLOEXEC)
+	if err != nil {
+		return err
+	}
+	_, err = fcntl(p[1], F_SETFD, FD_CLOEXEC)
+	return err
+}