Source file src/pkg/os/exec_posix.go

     1	// Copyright 2009 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 linux netbsd openbsd windows
     6	
     7	package os
     8	
     9	import (
    10		"syscall"
    11	)
    12	
    13	// The only signal values guaranteed to be present on all systems
    14	// are Interrupt (send the process an interrupt) and Kill (force
    15	// the process to exit).
    16	var (
    17		Interrupt Signal = syscall.SIGINT
    18		Kill      Signal = syscall.SIGKILL
    19	)
    20	
    21	func startProcess(name string, argv []string, attr *ProcAttr) (p *Process, err error) {
    22		// If there is no SysProcAttr (ie. no Chroot or changed
    23		// UID/GID), double-check existence of the directory we want
    24		// to chdir into.  We can make the error clearer this way.
    25		if attr != nil && attr.Sys == nil && attr.Dir != "" {
    26			if _, err := Stat(attr.Dir); err != nil {
    27				pe := err.(*PathError)
    28				pe.Op = "chdir"
    29				return nil, pe
    30			}
    31		}
    32	
    33		sysattr := &syscall.ProcAttr{
    34			Dir: attr.Dir,
    35			Env: attr.Env,
    36			Sys: attr.Sys,
    37		}
    38		if sysattr.Env == nil {
    39			sysattr.Env = Environ()
    40		}
    41		for _, f := range attr.Files {
    42			sysattr.Files = append(sysattr.Files, f.Fd())
    43		}
    44	
    45		pid, h, e := syscall.StartProcess(name, argv, sysattr)
    46		if e != nil {
    47			return nil, &PathError{"fork/exec", name, e}
    48		}
    49		return newProcess(pid, h), nil
    50	}
    51	
    52	func (p *Process) kill() error {
    53		return p.Signal(Kill)
    54	}
    55	
    56	// ProcessState stores information about a process, as reported by Wait.
    57	type ProcessState struct {
    58		pid    int                // The process's id.
    59		status syscall.WaitStatus // System-dependent status info.
    60		rusage *syscall.Rusage
    61	}
    62	
    63	// Pid returns the process id of the exited process.
    64	func (p *ProcessState) Pid() int {
    65		return p.pid
    66	}
    67	
    68	func (p *ProcessState) exited() bool {
    69		return p.status.Exited()
    70	}
    71	
    72	func (p *ProcessState) success() bool {
    73		return p.status.ExitStatus() == 0
    74	}
    75	
    76	func (p *ProcessState) sys() interface{} {
    77		return p.status
    78	}
    79	
    80	func (p *ProcessState) sysUsage() interface{} {
    81		return p.rusage
    82	}
    83	
    84	// Convert i to decimal string.
    85	func itod(i int) string {
    86		if i == 0 {
    87			return "0"
    88		}
    89	
    90		u := uint64(i)
    91		if i < 0 {
    92			u = -u
    93		}
    94	
    95		// Assemble decimal in reverse order.
    96		var b [32]byte
    97		bp := len(b)
    98		for ; u > 0; u /= 10 {
    99			bp--
   100			b[bp] = byte(u%10) + '0'
   101		}
   102	
   103		if i < 0 {
   104			bp--
   105			b[bp] = '-'
   106		}
   107	
   108		return string(b[bp:])
   109	}
   110	
   111	func (p *ProcessState) String() string {
   112		if p == nil {
   113			return "<nil>"
   114		}
   115		status := p.Sys().(syscall.WaitStatus)
   116		res := ""
   117		switch {
   118		case status.Exited():
   119			res = "exit status " + itod(status.ExitStatus())
   120		case status.Signaled():
   121			res = "signal: " + status.Signal().String()
   122		case status.Stopped():
   123			res = "stop signal: " + status.StopSignal().String()
   124			if status.StopSignal() == syscall.SIGTRAP && status.TrapCause() != 0 {
   125				res += " (trap " + itod(status.TrapCause()) + ")"
   126			}
   127		case status.Continued():
   128			res = "continued"
   129		}
   130		if status.CoreDump() {
   131			res += " (core dumped)"
   132		}
   133		return res
   134	}

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