add os.ForkExec, os.Exec, os.Wait, exec.OpenCmd.
as thread-safe as possible, given the surrounding system.
add stub RWLock implementation.
R=r
DELTA=852 (834 added, 6 deleted, 12 changed)
OCL=25046
CL=25053
diff --git a/src/lib/Makefile b/src/lib/Makefile
index a6b0c47..780aa3a 100644
--- a/src/lib/Makefile
+++ b/src/lib/Makefile
@@ -7,8 +7,8 @@
GC=6g
DIRS=\
- container/array\
container\
+ container/array\
fmt\
hash\
http\
@@ -26,7 +26,9 @@
unicode\
FILES=\
+ bignum\
bufio\
+ exec\
flag\
log\
malloc\
@@ -36,15 +38,15 @@
strings\
testing\
utf8\
- bignum\
TEST=\
+ bignum\
bufio\
+ exec\
once\
sort\
strings\
utf8\
- bignum\
clean.dirs: $(addsuffix .dirclean, $(DIRS))
install.dirs: $(addsuffix .dirinstall, $(DIRS))
@@ -96,6 +98,7 @@
log.6: fmt.dirinstall io.dirinstall os.dirinstall time.dirinstall
testing.6: flag.install fmt.dirinstall
strings.6: utf8.install
+exec.6: os.dirinstall
fmt.dirinstall: io.dirinstall reflect.dirinstall strconv.dirinstall
hash.dirinstall: os.dirinstall
@@ -112,4 +115,5 @@
tabwriter.dirinstall: os.dirinstall io.dirinstall container/array.dirinstall
time.dirinstall: once.install os.dirinstall io.dirinstall
sync.dirinstall:
+syscall.dirinstall: sync.dirinstall
diff --git a/src/lib/exec.go b/src/lib/exec.go
new file mode 100644
index 0000000..ec48801
--- /dev/null
+++ b/src/lib/exec.go
@@ -0,0 +1,160 @@
+// Copyright 2009 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 exec
+
+import (
+ "os";
+ "syscall";
+)
+
+const (
+ DevNull = iota;
+ Passthru;
+ Pipe;
+ MergeWithStdout;
+)
+
+type Cmd struct {
+ Stdin *os.FD;
+ Stdout *os.FD;
+ Stderr *os.FD;
+ Pid int;
+}
+
+// Given mode (DevNull, etc), return fd for child
+// and fd to record in Cmd structure.
+func modeToFDs(mode, fd int) (*os.FD, *os.FD, *os.Error) {
+ switch mode {
+ case DevNull:
+ rw := os.O_WRONLY;
+ if fd == 0 {
+ rw = os.O_RDONLY;
+ }
+ f, err := os.Open("/dev/null", rw, 0);
+ return f, nil, err;
+ case Passthru:
+ switch fd {
+ case 0:
+ return os.Stdin, nil, nil;
+ case 1:
+ return os.Stdout, nil, nil;
+ case 2:
+ return os.Stderr, nil, nil;
+ }
+ case Pipe:
+ r, w, err := os.Pipe();
+ if err != nil {
+ return nil, nil, err;
+ }
+ if fd == 0 {
+ return r, w, nil;
+ }
+ return w, r, nil;
+ }
+ return nil, nil, os.EINVAL;
+}
+
+// Start command running with pipes possibly
+// connected to stdin, stdout, stderr.
+// TODO(rsc): Should the stdin,stdout,stderr args
+// be [3]int instead?
+func OpenCmd(argv0 string, argv, envv []string, stdin, stdout, stderr int)
+ (p *Cmd, err *os.Error)
+{
+ p = new(Cmd);
+ var fd [3]*os.FD;
+
+ if fd[0], p.Stdin, err = modeToFDs(stdin, 0); err != nil {
+ goto Error;
+ }
+ if fd[1], p.Stdout, err = modeToFDs(stdout, 1); err != nil {
+ goto Error;
+ }
+ if stderr == MergeWithStdout {
+ p.Stderr = p.Stdout;
+ } else if fd[2], p.Stderr, err = modeToFDs(stderr, 2); err != nil {
+ goto Error;
+ }
+
+ // Run command.
+ p.Pid, err = os.ForkExec(argv0, argv, envv, fd);
+ if err != nil {
+ goto Error;
+ }
+ if fd[0] != os.Stdin {
+ fd[0].Close();
+ }
+ if fd[1] != os.Stdout {
+ fd[1].Close();
+ }
+ if fd[2] != os.Stderr && fd[2] != fd[1] {
+ fd[2].Close();
+ }
+ return p, nil;
+
+Error:
+ if fd[0] != os.Stdin && fd[0] != nil {
+ fd[0].Close();
+ }
+ if fd[1] != os.Stdout && fd[1] != nil {
+ fd[1].Close();
+ }
+ if fd[2] != os.Stderr && fd[2] != nil && fd[2] != fd[1] {
+ fd[2].Close();
+ }
+ if p.Stdin != nil {
+ p.Stdin.Close();
+ }
+ if p.Stdout != nil {
+ p.Stdout.Close();
+ }
+ if p.Stderr != nil {
+ p.Stderr.Close();
+ }
+ return nil, err;
+}
+
+func (p *Cmd) Wait(options uint64) (*os.Waitmsg, *os.Error) {
+ if p.Pid < 0 {
+ return nil, os.EINVAL;
+ }
+ w, err := os.Wait(p.Pid, options);
+ if w != nil && (w.Exited() || w.Signaled()) {
+ p.Pid = -1;
+ }
+ return w, err;
+}
+
+func (p *Cmd) Close() *os.Error {
+ if p.Pid >= 0 {
+ // Loop on interrupt, but
+ // ignore other errors -- maybe
+ // caller has already waited for pid.
+ w, err := p.Wait(0);
+ for err == os.EINTR {
+ w, err = p.Wait(0);
+ }
+ }
+
+ // Close the FDs that are still open.
+ var err *os.Error;
+ if p.Stdin != nil && p.Stdin.Fd() >= 0 {
+ if err1 := p.Stdin.Close(); err1 != nil {
+ err = err1;
+ }
+ }
+ if p.Stdout != nil && p.Stdout.Fd() >= 0 {
+ if err1 := p.Stdout.Close(); err1 != nil && err != nil {
+ err = err1;
+ }
+ }
+ if p.Stderr != nil && p.Stderr != p.Stdout && p.Stderr.Fd() >= 0 {
+ if err1 := p.Stderr.Close(); err1 != nil && err != nil {
+ err = err1;
+ }
+ }
+ return err;
+}
+
diff --git a/src/lib/exec_test.go b/src/lib/exec_test.go
new file mode 100644
index 0000000..740dfa7
--- /dev/null
+++ b/src/lib/exec_test.go
@@ -0,0 +1,51 @@
+// Copyright 2009 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 exec
+
+import (
+ "exec";
+ "io";
+ "testing";
+)
+
+func TestOpenCmdCat(t *testing.T) {
+ cmd, err := exec.OpenCmd("/bin/cat", []string("cat"), nil,
+ exec.Pipe, exec.Pipe, exec.DevNull);
+ if err != nil {
+ t.Fatalf("opencmd /bin/cat: %v", err);
+ }
+ io.WriteString(cmd.Stdin, "hello, world\n");
+ cmd.Stdin.Close();
+ var buf [64]byte;
+ n, err1 := io.Readn(cmd.Stdout, buf);
+ if err1 != nil && err1 != io.ErrEOF {
+ t.Fatalf("reading from /bin/cat: %v", err1);
+ }
+ if string(buf[0:n]) != "hello, world\n" {
+ t.Fatalf("reading from /bin/cat: got %q", buf[0:n]);
+ }
+ if err1 = cmd.Close(); err1 != nil {
+ t.Fatalf("closing /bin/cat: %v", err1);
+ }
+}
+
+func TestOpenCmdEcho(t *testing.T) {
+ cmd, err := OpenCmd("/bin/echo", []string("echo", "hello", "world"), nil,
+ exec.DevNull, exec.Pipe, exec.DevNull);
+ if err != nil {
+ t.Fatalf("opencmd /bin/echo: %v", err);
+ }
+ var buf [64]byte;
+ n, err1 := io.Readn(cmd.Stdout, buf);
+ if err1 != nil && err1 != io.ErrEOF {
+ t.Fatalf("reading from /bin/echo: %v", err1);
+ }
+ if string(buf[0:n]) != "hello world\n" {
+ t.Fatalf("reading from /bin/echo: got %q", buf[0:n]);
+ }
+ if err1 = cmd.Close(); err1 != nil {
+ t.Fatalf("closing /bin/echo: %v", err1);
+ }
+}
diff --git a/src/lib/net/fd.go b/src/lib/net/fd.go
index 1ec0d8a..0c7770c 100644
--- a/src/lib/net/fd.go
+++ b/src/lib/net/fd.go
@@ -280,17 +280,26 @@
return nil, os.EINVAL
}
+ // See ../syscall/exec.go for description of ForkLock.
+ // It is okay to hold the lock across syscall.Accept
+ // because we have put fd.fd into non-blocking mode.
+ syscall.ForkLock.RLock();
var s, e int64;
for {
s, e = syscall.Accept(fd.fd, sa);
if e != syscall.EAGAIN {
break;
}
+ syscall.ForkLock.RUnlock();
pollserver.WaitRead(fd);
+ syscall.ForkLock.RLock();
}
if e != 0 {
+ syscall.ForkLock.RUnlock();
return nil, os.ErrnoToError(e)
}
+ syscall.CloseOnExec(s);
+ syscall.ForkLock.RUnlock();
raddr, err1 := sockaddrToHostPort(sa);
if err1 != nil {
diff --git a/src/lib/net/net.go b/src/lib/net/net.go
index b81e992..db70819 100644
--- a/src/lib/net/net.go
+++ b/src/lib/net/net.go
@@ -143,10 +143,15 @@
func socket(net, laddr, raddr string, f, p, t int64, la, ra *syscall.Sockaddr)
(fd *netFD, err *os.Error)
{
+ // See ../syscall/exec.go for description of ForkLock.
+ syscall.ForkLock.RLock();
s, e := syscall.Socket(f, p, t);
if e != 0 {
+ syscall.ForkLock.RUnlock();
return nil, os.ErrnoToError(e)
}
+ syscall.CloseOnExec(s);
+ syscall.ForkLock.RUnlock();
// Allow reuse of recently-used addresses.
syscall.Setsockopt_int(s, syscall.SOL_SOCKET, syscall.SO_REUSEADDR, 1);
diff --git a/src/lib/os/Makefile b/src/lib/os/Makefile
index ac0d339..413a8d1 100644
--- a/src/lib/os/Makefile
+++ b/src/lib/os/Makefile
@@ -3,8 +3,8 @@
# license that can be found in the LICENSE file.
# DO NOT EDIT. Automatically generated by gobuild.
-# gobuild -m dir_amd64_linux.go env.go error.go file.go stat_amd64_linux.go\
-# time.go types.go >Makefile
+# gobuild -m dir_${GOARCH}_${GOOS}.go env.go error.go file.go\
+# stat_${GOARCH}_${GOOS}.go time.go types.go exec.go >Makefile
O=6
GC=$(O)g
CC=$(O)c -w
@@ -46,6 +46,7 @@
O4=\
dir_$(GOARCH)_$(GOOS).$O\
+ exec.$O\
os.a: a1 a2 a3 a4
@@ -62,7 +63,7 @@
rm -f $(O3)
a4: $(O4)
- $(AR) grc os.a dir_$(GOARCH)_$(GOOS).$O
+ $(AR) grc os.a dir_$(GOARCH)_$(GOOS).$O exec.$O
rm -f $(O4)
newpkg: clean
diff --git a/src/lib/os/exec.go b/src/lib/os/exec.go
new file mode 100644
index 0000000..0ce5177
--- /dev/null
+++ b/src/lib/os/exec.go
@@ -0,0 +1,70 @@
+// Copyright 2009 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 os
+
+import (
+ "os";
+ "syscall";
+)
+
+func ForkExec(argv0 string, argv []string, envv []string, fd []*FD)
+ (pid int, err *Error)
+{
+ // Create array of integer (system) fds.
+ intfd := make([]int64, len(fd));
+ for i, f := range(fd) {
+ if f == nil {
+ intfd[i] = -1;
+ } else {
+ intfd[i] = f.Fd();
+ }
+ }
+
+ p, e := syscall.ForkExec(argv0, argv, envv, intfd);
+ return int(p), ErrnoToError(e);
+}
+
+func Exec(argv0 string, argv []string, envv []string) *Error {
+ e := syscall.Exec(argv0, argv, envv);
+ return ErrnoToError(e);
+}
+
+// TODO(rsc): Should os implement its own syscall.WaitStatus
+// wrapper with the methods, or is exposing the underlying one enough?
+//
+// TODO(rsc): Certainly need to have os.Rusage struct,
+// since syscall one might have different field types across
+// different OS.
+
+type Waitmsg struct {
+ Pid int;
+ syscall.WaitStatus;
+ Rusage *syscall.Rusage;
+}
+
+const (
+ WNOHANG = syscall.WNOHANG;
+ WSTOPPED = syscall.WSTOPPED;
+ WRUSAGE = 1<<60;
+)
+
+func Wait(pid int, options uint64) (w *Waitmsg, err *Error) {
+ var status syscall.WaitStatus;
+ var rusage *syscall.Rusage;
+ if options & WRUSAGE != 0 {
+ rusage = new(syscall.Rusage);
+ options ^= WRUSAGE;
+ }
+ pid1, e := syscall.Wait4(int64(pid), &status, int64(options), rusage);
+ if e != 0 {
+ return nil, ErrnoToError(e);
+ }
+ w = new(Waitmsg);
+ w.Pid = pid;
+ w.WaitStatus = status;
+ w.Rusage = rusage;
+ return w, nil;
+}
+
diff --git a/src/lib/os/file.go b/src/lib/os/file.go
index d472576..24aab12 100644
--- a/src/lib/os/file.go
+++ b/src/lib/os/file.go
@@ -4,8 +4,10 @@
package os
-import syscall "syscall"
-import os "os"
+import (
+ "os";
+ "syscall";
+)
// Auxiliary information if the FD describes a directory
type dirInfo struct { // TODO(r): 6g bug means this can't be private
@@ -57,7 +59,17 @@
)
func Open(name string, mode int, flags int) (fd *FD, err *Error) {
- r, e := syscall.Open(name, int64(mode), int64(flags));
+ r, e := syscall.Open(name, int64(mode), int64(flags | syscall.O_CLOEXEC));
+ if e != 0 {
+ return nil, ErrnoToError(e);
+ }
+
+ // There's a race here with fork/exec, which we are
+ // content to live with. See ../syscall/exec.go
+ if syscall.O_CLOEXEC == 0 { // O_CLOEXEC not supported
+ syscall.CloseOnExec(r);
+ }
+
return NewFD(r, name), ErrnoToError(e)
}
@@ -122,10 +134,18 @@
func Pipe() (fd1 *FD, fd2 *FD, err *Error) {
var p [2]int64;
+
+ // See ../syscall/exec.go for description of lock.
+ syscall.ForkLock.RLock();
r, e := syscall.Pipe(&p);
if e != 0 {
+ syscall.ForkLock.RUnlock();
return nil, nil, ErrnoToError(e)
}
+ syscall.CloseOnExec(p[0]);
+ syscall.CloseOnExec(p[1]);
+ syscall.ForkLock.RUnlock();
+
return NewFD(p[0], "|0"), NewFD(p[1], "|1"), nil
}
diff --git a/src/lib/sync/mutex.go b/src/lib/sync/mutex.go
index 1269027..8e05cd8 100644
--- a/src/lib/sync/mutex.go
+++ b/src/lib/sync/mutex.go
@@ -39,3 +39,20 @@
semrelease(&m.sema);
}
+// Stub implementation of r/w locks.
+// This satisfies the semantics but
+// is not terribly efficient.
+// TODO(rsc): Real r/w locks.
+
+type RWMutex struct {
+ Mutex;
+}
+
+func (m *RWMutex) RLock() {
+ m.Lock();
+}
+
+func (m *RWMutex) RUnlock() {
+ m.Unlock();
+}
+
diff --git a/src/lib/syscall/Makefile b/src/lib/syscall/Makefile
index a9975b5..194fcca 100644
--- a/src/lib/syscall/Makefile
+++ b/src/lib/syscall/Makefile
@@ -3,9 +3,10 @@
# license that can be found in the LICENSE file.
# DO NOT EDIT. Automatically generated by gobuild.
-# gobuild -m errstr_darwin.go file_darwin.go socket_darwin.go\
-# syscall_amd64_darwin.go time_amd64_darwin.go types_amd64_darwin.go\
-# asm_amd64_darwin.s syscall.go signal_amd64_darwin.go >Makefile
+# gobuild -m errstr_${GOOS}.go file_${GOOS}.go socket_${GOOS}.go\
+# syscall_${GOARCH}_${GOOS}.go time_${GOARCH}_${GOOS}.go types_${GOARCH}_${GOOS}.go\
+# asm_${GOARCH}_${GOOS}.s syscall.go signal_${GOARCH}_${GOOS}.go\
+# exec.go >Makefile
O=6
GC=$(O)g
CC=$(O)c -w
@@ -36,31 +37,46 @@
O1=\
errstr_$(GOOS).$O\
syscall_$(GOARCH)_$(GOOS).$O\
- types_$(GOARCH)_$(GOOS).$O\
asm_$(GOARCH)_$(GOOS).$O\
syscall.$O\
signal_$(GOARCH)_$(GOOS).$O\
O2=\
+ types_$(GOARCH)_$(GOOS).$O\
+
+O3=\
file_$(GOOS).$O\
socket_$(GOOS).$O\
time_$(GOARCH)_$(GOOS).$O\
-syscall.a: a1 a2
+O4=\
+ exec.$O\
+
+syscall.a: a1 a2 a3 a4
a1: $(O1)
- $(AR) grc syscall.a errstr_$(GOOS).$O syscall_$(GOARCH)_$(GOOS).$O types_$(GOARCH)_$(GOOS).$O asm_$(GOARCH)_$(GOOS).$O syscall.$O signal_$(GOARCH)_$(GOOS).$O
+ $(AR) grc syscall.a errstr_$(GOOS).$O syscall_$(GOARCH)_$(GOOS).$O asm_$(GOARCH)_$(GOOS).$O syscall.$O signal_$(GOARCH)_$(GOOS).$O
rm -f $(O1)
a2: $(O2)
- $(AR) grc syscall.a file_$(GOOS).$O socket_$(GOOS).$O time_$(GOARCH)_$(GOOS).$O
+ $(AR) grc syscall.a types_$(GOARCH)_$(GOOS).$O
rm -f $(O2)
+a3: $(O3)
+ $(AR) grc syscall.a file_$(GOOS).$O socket_$(GOOS).$O time_$(GOARCH)_$(GOOS).$O
+ rm -f $(O3)
+
+a4: $(O4)
+ $(AR) grc syscall.a exec.$O
+ rm -f $(O4)
+
newpkg: clean
$(AR) grc syscall.a
$(O1): newpkg
$(O2): a1
+$(O3): a2
+$(O4): a3
nuke: clean
rm -f $(GOROOT)/pkg/syscall.a
diff --git a/src/lib/syscall/exec.go b/src/lib/syscall/exec.go
new file mode 100644
index 0000000..809cd8c
--- /dev/null
+++ b/src/lib/syscall/exec.go
@@ -0,0 +1,291 @@
+// Copyright 2009 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.
+
+// Fork, exec, wait, etc.
+
+package syscall
+
+import (
+ "sync";
+ "syscall";
+ "unsafe";
+)
+
+// Lock synchronizing creation of new file descriptors with fork.
+//
+// We want the child in a fork/exec sequence to inherit only the
+// file descriptors we intend. To do that, we mark all file
+// descriptors close-on-exec and then, in the child, explicitly
+// unmark the ones we want the exec'ed program to keep.
+// Unix doesn't make this easy: there is, in general, no way to
+// allocate a new file descriptor close-on-exec. Instead you
+// have to allocate the descriptor and then mark it close-on-exec.
+// If a fork happens between those two events, the child's exec
+// will inherit an unwanted file descriptor.
+//
+// This lock solves that race: the create new fd/mark close-on-exec
+// operation is done holding ForkLock for reading, and the fork itself
+// is done holding ForkLock for writing. At least, that's the idea.
+// There are some complications.
+//
+// Some system calls that create new file descriptors can block
+// for arbitrarily long times: open on a hung NFS server or named
+// pipe, accept on a socket, and so on. We can't reasonably grab
+// the lock across those operations.
+//
+// It is worse to inherit some file descriptors than others.
+// If a non-malicious child accidentally inherits an open ordinary file,
+// that's not a big deal. On the other hand, if a long-lived child
+// accidentally inherits the write end of a pipe, then the reader
+// of that pipe will not see EOF until that child exits, potentially
+// causing the parent program to hang. This is a common problem
+// in threaded C programs that use popen.
+//
+// Luckily, the file descriptors that are most important not to
+// inherit are not the ones that can take an arbitrarily long time
+// to create: pipe returns instantly, and the net package uses
+// non-blocking I/O to accept on a listening socket.
+// The rules for which file descriptor-creating operations use the
+// ForkLock are as follows:
+//
+// 1) Pipe. Does not block. Use the ForkLock.
+// 2) Socket. Does not block. Use the ForkLock.
+// 3) Accept. If using non-blocking mode, use the ForkLock.
+// Otherwise, live with the race.
+// 4) Open. Can block. Use O_CLOEXEC if available (Linux).
+// Otherwise, live with the race.
+// 5) Dup. Does not block. Use the ForkLock.
+// On Linux, could use fcntl F_DUPFD_CLOEXEC
+// instead of the ForkLock, but only for dup(fd, -1).
+
+var ForkLock sync.RWMutex
+
+func CloseOnExec(fd int64) {
+ Fcntl(fd, F_SETFD, FD_CLOEXEC);
+}
+
+// Convert array of string to array
+// of NUL-terminated byte pointer.
+func StringArrayPtr(ss []string) []*byte {
+ bb := make([]*byte, len(ss)+1);
+ for i := 0; i < len(ss); i++ {
+ bb[i] = StringBytePtr(ss[i]);
+ }
+ bb[len(ss)] = nil;
+ return bb;
+}
+
+func Wait4(pid int64, wstatus *WaitStatus, options int64, rusage *Rusage)
+ (wpid, err int64)
+{
+ var s WaitStatus;
+ r1, r2, err1 := Syscall6(SYS_WAIT4,
+ pid,
+ int64(uintptr(unsafe.Pointer(&s))),
+ options,
+ int64(uintptr(unsafe.Pointer(rusage))), 0, 0);
+ if wstatus != nil {
+ *wstatus = s;
+ }
+ return r1, err1;
+}
+
+// Fork, dup fd onto 0..len(fd), and exec(argv0, argvv, envv) in child.
+// If a dup or exec fails, write the errno int64 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 []*byte, envv []*byte, fd []int64, pipe int64)
+ (pid int64, err int64)
+{
+ // Declare all variables at top in case any
+ // declarations require heap allocation (e.g., err1).
+ var r1, r2, err1 int64;
+ var nextfd int64;
+ var i int;
+
+ darwin := OS == "darwin";
+
+ // About to call fork.
+ // No more allocation or calls of non-assembly functions.
+ r1, r2, err1 = RawSyscall(SYS_FORK, 0, 0, 0);
+ if err1 != 0 {
+ return 0, err1
+ }
+
+ // On Darwin:
+ // r1 = child pid in both parent and child.
+ // r2 = 0 in parent, 1 in child.
+ // Convert to normal Unix r1 = 0 in child.
+ if darwin && r2 == 1 {
+ r1 = 0;
+ }
+
+ if r1 != 0 {
+ // parent; return PID
+ return r1, 0
+ }
+
+ // Fork succeeded, now in child.
+
+ // 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 = int64(len(fd));
+ if pipe < nextfd {
+ r1, r2, err = RawSyscall(SYS_DUP2, pipe, nextfd, 0);
+ if err != 0 {
+ goto childerror;
+ }
+ RawSyscall(SYS_FCNTL, nextfd, F_SETFD, FD_CLOEXEC);
+ pipe = nextfd;
+ nextfd++;
+ }
+ for i = 0; i < len(fd); i++ {
+ if fd[i] >= 0 && fd[i] < int64(i) {
+ r1, r2, err = RawSyscall(SYS_DUP2, fd[i], nextfd, 0);
+ if err != 0 {
+ goto childerror;
+ }
+ RawSyscall(SYS_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 {
+ RawSyscall(SYS_CLOSE, int64(i), 0, 0);
+ continue;
+ }
+ if fd[i] == int64(i) {
+ // dup2(i, i) won't clear close-on-exec flag on Linux,
+ // probably not elsewhere either.
+ r1, r2, err = RawSyscall(SYS_FCNTL, fd[i], F_SETFD, 0);
+ if err != 0 {
+ goto childerror;
+ }
+ continue;
+ }
+ // The new fd is created NOT close-on-exec,
+ // which is exactly what we want.
+ r1, r2, err = RawSyscall(SYS_DUP2, fd[i], int64(i), 0);
+ if err != 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++ {
+ RawSyscall(SYS_CLOSE, int64(i), 0, 0);
+ }
+
+ // Time to exec.
+ r1, r2, err1 = RawSyscall(SYS_EXECVE,
+ int64(uintptr(unsafe.Pointer(argv0))),
+ int64(uintptr(unsafe.Pointer(&argv[0]))),
+ int64(uintptr(unsafe.Pointer(&envv[0]))));
+
+childerror:
+ // send error code on pipe
+ RawSyscall(SYS_WRITE, pipe, int64(uintptr(unsafe.Pointer(&err1))), 8);
+ for {
+ RawSyscall(SYS_EXIT, 253, 0, 0);
+ }
+
+ // Calling panic is not actually safe,
+ // but the for loop above won't break
+ // and this shuts up the compiler.
+ panic("unreached");
+}
+
+// Combination of fork and exec, careful to be thread safe.
+func ForkExec(argv0 string, argv []string, envv []string, fd []int64)
+ (pid int64, err int64)
+{
+ var p [2]int64;
+ var r1 int64;
+ var n, err1 int64;
+ var wstatus WaitStatus;
+
+ p[0] = -1;
+ p[1] = -1;
+
+ // Convert args to C form.
+ argv0p := StringBytePtr(argv0);
+ argvp := StringArrayPtr(argv);
+ envvp := StringArrayPtr(envv);
+
+ // Acquire the fork lock so that no other threads
+ // create new fds that are not yet close-on-exec
+ // before we fork.
+ ForkLock.Lock();
+
+ // Allocate child status pipe close on exec.
+ if r1, err = Pipe(&p); err != 0 {
+ goto error;
+ }
+ if r1, err = Fcntl(p[0], F_SETFD, FD_CLOEXEC); err != 0 {
+ goto error;
+ }
+ if r1, err = Fcntl(p[1], F_SETFD, FD_CLOEXEC); err != 0 {
+ goto error;
+ }
+
+ // Kick off child.
+ pid, err = forkAndExecInChild(argv0p, argvp, envvp, fd, p[1]);
+ if err != 0 {
+ error:
+ if p[0] >= 0 {
+ Close(p[0]);
+ Close(p[1]);
+ }
+ ForkLock.Unlock();
+ return 0, err
+ }
+ ForkLock.Unlock();
+
+ // Read child error status from pipe.
+ Close(p[1]);
+ n, r1, err = Syscall(SYS_READ, p[0], int64(uintptr(unsafe.Pointer(&err1))), 8);
+ Close(p[0]);
+ if err != 0 || n != 0 {
+ if n == 8 {
+ err = err1;
+ }
+ if err == 0 {
+ err = EPIPE;
+ }
+
+ // Child failed; wait for it to exit, to make sure
+ // the zombies don't accumulate.
+ pid1, err1 := Wait4(pid, &wstatus, 0, nil);
+ for err1 == EINTR {
+ pid1, err1 = Wait4(pid, &wstatus, 0, nil);
+ }
+ return 0, err
+ }
+
+ // Read got EOF, so pipe closed on exec, so exec succeeded.
+ return pid, 0
+}
+
+// Ordinary exec.
+func Exec(argv0 string, argv []string, envv []string) (err int64) {
+ r1, r2, err1 := RawSyscall(SYS_EXECVE,
+ int64(uintptr(unsafe.Pointer(StringBytePtr(argv0)))),
+ int64(uintptr(unsafe.Pointer(&StringArrayPtr(argv)[0]))),
+ int64(uintptr(unsafe.Pointer(&StringArrayPtr(envv)[0]))));
+ return err1;
+}
+
diff --git a/src/lib/syscall/types_amd64_darwin.go b/src/lib/syscall/types_amd64_darwin.go
index 101f223..36ced7a 100644
--- a/src/lib/syscall/types_amd64_darwin.go
+++ b/src/lib/syscall/types_amd64_darwin.go
@@ -7,6 +7,9 @@
package syscall
+import "syscall"
+
+const OS = "darwin"
// Time
@@ -57,6 +60,7 @@
O_NDELAY = O_NONBLOCK;
O_SYNC = 0x80;
O_TRUNC = 0x400;
+ O_CLOEXEC = 0; // not supported
F_GETFD = 1;
F_SETFD = 2;
@@ -239,3 +243,88 @@
Udata int64;
}
+
+// Wait status.
+// See /usr/include/bits/waitstatus.h
+
+const (
+ WNOHANG = 1;
+ WUNTRACED = 2;
+ WEXITED = 4;
+ WSTOPPED = 8;
+ WCONTINUED = 0x10;
+ WNOWAIT = 0x20;
+)
+
+type WaitStatus uint32;
+
+// TODO(rsc): should be method on WaitStatus,
+// not *WaitStatus, but causes problems when
+// embedding in a *Waitmsg in package os.
+// Need to find the 6g bug.
+
+// Wait status is 7 bits at bottom, either 0 (exited),
+// 0x7F (stopped), or a signal number that caused an exit.
+// The 0x80 bit is whether there was a core dump.
+// An extra number (exit code, signal causing a stop)
+// is in the high bits.
+
+const (
+ mask = 0x7F;
+ core = 0x80;
+ shift = 8;
+
+ exited = 0;
+ stopped = 0x7F;
+)
+
+func (wp *WaitStatus) Exited() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w&mask == exited;
+}
+
+func (wp *WaitStatus) ExitStatus() int {
+ w := *wp; // TODO(rsc): no pointer
+ if w&mask != exited {
+ return -1;
+ }
+ return int(w >> shift);
+}
+
+func (wp *WaitStatus) Signaled() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w&mask != stopped && w&mask != 0;
+}
+
+func (wp *WaitStatus) Signal() int {
+ w := *wp; // TODO(rsc): no pointer
+ sig := int(w & mask);
+ if sig == stopped || sig == 0 {
+ return -1;
+ }
+ return sig;
+}
+
+func (wp *WaitStatus) CoreDump() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w.Signaled() && w&core != 0;
+}
+
+func (wp *WaitStatus) Stopped() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w&mask == stopped && w>>shift != SIGSTOP;
+}
+
+func (wp *WaitStatus) Continued() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w&mask == stopped && w>>shift == SIGSTOP;
+}
+
+func (wp *WaitStatus) StopSignal() int {
+ w := *wp; // TODO(rsc): no pointer
+ if !w.Stopped() {
+ return -1;
+ }
+ return int(w >> shift) & 0xFF;
+}
+
diff --git a/src/lib/syscall/types_amd64_linux.go b/src/lib/syscall/types_amd64_linux.go
index ebfe21c..cbb65ee 100644
--- a/src/lib/syscall/types_amd64_linux.go
+++ b/src/lib/syscall/types_amd64_linux.go
@@ -7,6 +7,9 @@
package syscall
+import "syscall"
+
+const OS = "linux"
// Time
@@ -57,6 +60,7 @@
O_NDELAY = O_NONBLOCK;
O_SYNC = 0x1000;
O_TRUNC = 0x200;
+ O_CLOEXEC = 0x80000;
F_GETFD = 1;
F_SETFD = 2;
@@ -218,3 +222,98 @@
Fd int32;
Pad int32;
}
+
+
+// Wait status.
+// See /usr/include/bits/waitstatus.h
+
+const (
+ WNOHANG = 1;
+ WUNTRACED = 2;
+ WSTOPPED = 2; // same as WUNTRACED
+ WEXITED = 4;
+ WCONTINUED = 8;
+ WNOWAIT = 0x01000000;
+ WNOTHREAD = 0x20000000;
+ WALL = 0x40000000;
+ WCLONE = 0x80000000;
+)
+
+type WaitStatus uint32;
+
+// TODO(rsc): should be method on WaitStatus,
+// not *WaitStatus, but causes problems when
+// embedding in a *Waitmsg in package os.
+// Need to find the 6g bug.
+
+// Wait status is 7 bits at bottom, either 0 (exited),
+// 0x7F (stopped), or a signal number that caused an exit.
+// The 0x80 bit is whether there was a core dump.
+// An extra number (exit code, signal causing a stop)
+// is in the high bits. At least that's the idea.
+// There are various irregularities. For example, the
+// "continued" status is 0xFFFF, distinguishing itself
+// from stopped via the core dump bit.
+
+const (
+ mask = 0x7F;
+ core = 0x80;
+ exited = 0x00;
+ stopped = 0x7F;
+ shift = 8;
+
+ // types_amd64_darwin.go refers to SIGSTOP.
+ // do the same here so the dependencies are
+ // the same on Linux as on Darwin.
+ __unused = SIGSTOP;
+)
+
+func (wp *WaitStatus) Exited() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w&mask == exited;
+}
+
+func (wp *WaitStatus) Signaled() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w&mask != stopped && w&mask != exited;
+}
+
+func (wp *WaitStatus) Stopped() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w&0xFF == stopped;
+}
+
+func (wp *WaitStatus) Continued() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w == 0xFFFF;
+}
+
+func (wp *WaitStatus) CoreDump() bool {
+ w := *wp; // TODO(rsc): no pointer
+ return w.Signaled() && w&core != 0;
+}
+
+func (wp *WaitStatus) ExitStatus() int {
+ w := *wp; // TODO(rsc): no pointer
+ if !w.Exited() {
+ return -1;
+ }
+ return int(w >> shift) & 0xFF;
+}
+
+func (wp *WaitStatus) Signal() int {
+ w := *wp; // TODO(rsc): no pointer
+ if !w.Signaled() {
+ return -1;
+ }
+ return int(w & mask);
+}
+
+func (wp *WaitStatus) StopSignal() int {
+ w := *wp; // TODO(rsc): no pointer
+ if !w.Stopped() {
+ return -1;
+ }
+ return int(w >> shift) & 0xFF;
+}
+
