exec.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  package os
     6  
     7  import (
     8  	"errors"
     9  	"internal/testlog"
    10  	"runtime"
    11  	"sync"
    12  	"sync/atomic"
    13  	"syscall"
    14  	"time"
    15  )
    16  
    17  // ErrProcessDone indicates a Process has finished.
    18  var ErrProcessDone = errors.New("os: process already finished")
    19  
    20  // Process stores the information about a process created by StartProcess.
    21  type Process struct {
    22  	Pid    int
    23  	handle uintptr      // handle is accessed atomically on Windows
    24  	isdone uint32       // process has been successfully waited on, non zero if true
    25  	sigMu  sync.RWMutex // avoid race between wait and signal
    26  }
    27  
    28  func newProcess(pid int, handle uintptr) *Process {
    29  	p := &Process{Pid: pid, handle: handle}
    30  	runtime.SetFinalizer(p, (*Process).Release)
    31  	return p
    32  }
    33  
    34  func (p *Process) setDone() {
    35  	atomic.StoreUint32(&p.isdone, 1)
    36  }
    37  
    38  func (p *Process) done() bool {
    39  	return atomic.LoadUint32(&p.isdone) > 0
    40  }
    41  
    42  // ProcAttr holds the attributes that will be applied to a new process
    43  // started by StartProcess.
    44  type ProcAttr struct {
    45  	// If Dir is non-empty, the child changes into the directory before
    46  	// creating the process.
    47  	Dir string
    48  	// If Env is non-nil, it gives the environment variables for the
    49  	// new process in the form returned by Environ.
    50  	// If it is nil, the result of Environ will be used.
    51  	Env []string
    52  	// Files specifies the open files inherited by the new process. The
    53  	// first three entries correspond to standard input, standard output, and
    54  	// standard error. An implementation may support additional entries,
    55  	// depending on the underlying operating system. A nil entry corresponds
    56  	// to that file being closed when the process starts.
    57  	// On Unix systems, StartProcess will change these File values
    58  	// to blocking mode, which means that SetDeadline will stop working
    59  	// and calling Close will not interrupt a Read or Write.
    60  	Files []*File
    61  
    62  	// Operating system-specific process creation attributes.
    63  	// Note that setting this field means that your program
    64  	// may not execute properly or even compile on some
    65  	// operating systems.
    66  	Sys *syscall.SysProcAttr
    67  }
    68  
    69  // A Signal represents an operating system signal.
    70  // The usual underlying implementation is operating system-dependent:
    71  // on Unix it is syscall.Signal.
    72  type Signal interface {
    73  	String() string
    74  	Signal() // to distinguish from other Stringers
    75  }
    76  
    77  // Getpid returns the process id of the caller.
    78  func Getpid() int { return syscall.Getpid() }
    79  
    80  // Getppid returns the process id of the caller's parent.
    81  func Getppid() int { return syscall.Getppid() }
    82  
    83  // FindProcess looks for a running process by its pid.
    84  //
    85  // The Process it returns can be used to obtain information
    86  // about the underlying operating system process.
    87  //
    88  // On Unix systems, FindProcess always succeeds and returns a Process
    89  // for the given pid, regardless of whether the process exists.
    90  func FindProcess(pid int) (*Process, error) {
    91  	return findProcess(pid)
    92  }
    93  
    94  // StartProcess starts a new process with the program, arguments and attributes
    95  // specified by name, argv and attr. The argv slice will become os.Args in the
    96  // new process, so it normally starts with the program name.
    97  //
    98  // If the calling goroutine has locked the operating system thread
    99  // with runtime.LockOSThread and modified any inheritable OS-level
   100  // thread state (for example, Linux or Plan 9 name spaces), the new
   101  // process will inherit the caller's thread state.
   102  //
   103  // StartProcess is a low-level interface. The os/exec package provides
   104  // higher-level interfaces.
   105  //
   106  // If there is an error, it will be of type *PathError.
   107  func StartProcess(name string, argv []string, attr *ProcAttr) (*Process, error) {
   108  	testlog.Open(name)
   109  	return startProcess(name, argv, attr)
   110  }
   111  
   112  // Release releases any resources associated with the Process p,
   113  // rendering it unusable in the future.
   114  // Release only needs to be called if Wait is not.
   115  func (p *Process) Release() error {
   116  	return p.release()
   117  }
   118  
   119  // Kill causes the Process to exit immediately. Kill does not wait until
   120  // the Process has actually exited. This only kills the Process itself,
   121  // not any other processes it may have started.
   122  func (p *Process) Kill() error {
   123  	return p.kill()
   124  }
   125  
   126  // Wait waits for the Process to exit, and then returns a
   127  // ProcessState describing its status and an error, if any.
   128  // Wait releases any resources associated with the Process.
   129  // On most operating systems, the Process must be a child
   130  // of the current process or an error will be returned.
   131  func (p *Process) Wait() (*ProcessState, error) {
   132  	return p.wait()
   133  }
   134  
   135  // Signal sends a signal to the Process.
   136  // Sending Interrupt on Windows is not implemented.
   137  func (p *Process) Signal(sig Signal) error {
   138  	return p.signal(sig)
   139  }
   140  
   141  // UserTime returns the user CPU time of the exited process and its children.
   142  func (p *ProcessState) UserTime() time.Duration {
   143  	return p.userTime()
   144  }
   145  
   146  // SystemTime returns the system CPU time of the exited process and its children.
   147  func (p *ProcessState) SystemTime() time.Duration {
   148  	return p.systemTime()
   149  }
   150  
   151  // Exited reports whether the program has exited.
   152  // On Unix systems this reports true if the program exited due to calling exit,
   153  // but false if the program terminated due to a signal.
   154  func (p *ProcessState) Exited() bool {
   155  	return p.exited()
   156  }
   157  
   158  // Success reports whether the program exited successfully,
   159  // such as with exit status 0 on Unix.
   160  func (p *ProcessState) Success() bool {
   161  	return p.success()
   162  }
   163  
   164  // Sys returns system-dependent exit information about
   165  // the process. Convert it to the appropriate underlying
   166  // type, such as syscall.WaitStatus on Unix, to access its contents.
   167  func (p *ProcessState) Sys() any {
   168  	return p.sys()
   169  }
   170  
   171  // SysUsage returns system-dependent resource usage information about
   172  // the exited process. Convert it to the appropriate underlying
   173  // type, such as *syscall.Rusage on Unix, to access its contents.
   174  // (On Unix, *syscall.Rusage matches struct rusage as defined in the
   175  // getrusage(2) manual page.)
   176  func (p *ProcessState) SysUsage() any {
   177  	return p.sysUsage()
   178  }
   179
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