github.com/u-root/u-root@v7.0.1-0.20200915234505-ad7babab0a8e+incompatible/pkg/libinit/proc_linux.go (about)

     1  // Copyright 2014-2019 the u-root 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 libinit
     6  
     7  import (
     8  	"log"
     9  	"os"
    10  	"os/exec"
    11  	"syscall"
    12  )
    13  
    14  // WaitOrphans waits for all remaining processes on the system to exit.
    15  func WaitOrphans() uint {
    16  	var numReaped uint
    17  	for {
    18  		var (
    19  			s syscall.WaitStatus
    20  			r syscall.Rusage
    21  		)
    22  		p, err := syscall.Wait4(-1, &s, 0, &r)
    23  		if p == -1 {
    24  			break
    25  		}
    26  		log.Printf("%v: exited with %v, status %v, rusage %v", p, err, s, r)
    27  		numReaped++
    28  	}
    29  	return numReaped
    30  }
    31  
    32  // WithTTYControl turns on controlling the TTY on this command.
    33  func WithTTYControl(ctty bool) CommandModifier {
    34  	return func(c *exec.Cmd) {
    35  		if c.SysProcAttr == nil {
    36  			c.SysProcAttr = &syscall.SysProcAttr{}
    37  		}
    38  		c.SysProcAttr.Setctty = ctty
    39  		c.SysProcAttr.Setsid = ctty
    40  	}
    41  }
    42  
    43  // WithCloneFlags adds clone(2) flags to the *exec.Cmd.
    44  func WithCloneFlags(flags uintptr) CommandModifier {
    45  	return func(c *exec.Cmd) {
    46  		if c.SysProcAttr == nil {
    47  			c.SysProcAttr = &syscall.SysProcAttr{}
    48  		}
    49  		c.SysProcAttr.Cloneflags = flags
    50  	}
    51  }
    52  
    53  func init() {
    54  	osDefault = linuxDefault
    55  }
    56  
    57  func linuxDefault(c *exec.Cmd) {
    58  	c.SysProcAttr = &syscall.SysProcAttr{
    59  		Setctty: true,
    60  		Setsid:  true,
    61  	}
    62  }
    63  
    64  // FIX ME: make it not linux-specific
    65  // RunCommands runs commands in sequence.
    66  //
    67  // RunCommands returns how many commands existed and were attempted to run.
    68  //
    69  // commands must refer to absolute paths at the moment.
    70  func RunCommands(debug func(string, ...interface{}), commands ...*exec.Cmd) int {
    71  	var cmdCount int
    72  	for _, cmd := range commands {
    73  		if _, err := os.Stat(cmd.Path); os.IsNotExist(err) {
    74  			debug("%v", err)
    75  			continue
    76  		}
    77  
    78  		cmdCount++
    79  		debug("Trying to run %v", cmd)
    80  		if err := cmd.Start(); err != nil {
    81  			log.Printf("Error starting %v: %v", cmd, err)
    82  			continue
    83  		}
    84  
    85  		for {
    86  			var s syscall.WaitStatus
    87  			var r syscall.Rusage
    88  			if p, err := syscall.Wait4(-1, &s, 0, &r); p == cmd.Process.Pid {
    89  				debug("Shell exited, exit status %d", s.ExitStatus())
    90  				break
    91  			} else if p != -1 {
    92  				debug("Reaped PID %d, exit status %d", p, s.ExitStatus())
    93  			} else {
    94  				debug("Error from Wait4 for orphaned child: %v", err)
    95  				break
    96  			}
    97  		}
    98  		if err := cmd.Process.Release(); err != nil {
    99  			log.Printf("Error releasing process %v: %v", cmd, err)
   100  		}
   101  	}
   102  	return cmdCount
   103  }