c%2B%2B/socket%2B%2B-1.10/Fork.C

// Fork.C -*- C++ -*- socket library
// Copyright (C) 1992,1993,1994 Gnanasekaran Swaminathan <gs4t@virginia.edu>
// 
// Permission is granted to use at your own risk and distribute this software
// in source and binary forms provided the above copyright
// notice and this paragraph are preserved on all copies.
// This software is provided "as is" with no express or implied warranty.
//
// Version: 17Oct95 1.10

#include <config.h>

#include <iostream.h>
#include <stdio.h> // perror in solaris2.3 is declared here
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <sys/wait.h>

#include <Fork.h>

Fork::ForkProcess* Fork::ForkProcess::list = 0;
Fork::KillForks Fork::killall;

Fork::~Fork ()
{
  if (process->pid <= 0)
    delete process;
}

Fork::KillForks::~KillForks ()
     // First, kill all children whose kill_child flag is set.
     // Second, wait for other children to die.
{
  for (ForkProcess* cur = Fork::ForkProcess::list; cur; cur = cur->next)
    if (cur->kill_child)
      delete cur;

  while (Fork::ForkProcess::list && wait (0) > 0);
}

Fork::ForkProcess::ForkProcess (int kill, int give_reason)
     : kill_child (kill), reason (give_reason), next (0)
{
  if (list == 0) {
    struct sigaction sa;
    sa.sa_handler = funcptr (&Fork::ForkProcess::reaper_nohang);
    sigemptyset (&sa.sa_mask);
    sa.sa_flags = SA_RESTART;
    sigaction (SIGCHLD, &sa, 0);
  }

  pid = fork ();

  if (pid > 0) {
    next = list;
    list = this;
  } else if (pid == 0) {
    // child process. clear list
    ForkProcess* p = list;
    while (p) {
      ForkProcess* nxt = p->next;
      p->pid = 0;
      delete p;
      p = nxt;
    }
    list = 0;

    if (kill_child) {
      struct sigaction sa;
      sa.sa_handler = funcptr (&Fork::ForkProcess::commit_suicide);
      sigemptyset (&sa.sa_mask);
      sa.sa_flags = SA_RESTART;
      sigaction (SIGTERM, &sa, 0);
    }
  }
}

Fork::ForkProcess::~ForkProcess ()
{
  if (pid > 0) {
    if (kill_child)
      kill (pid, SIGTERM);
    reap_child ();

    // I remove myself from list
    if (list == this)
      list = list->next;
    else {
      for (ForkProcess* p = list; p; p = p->next)
        if (p->next == this) {
          p->next = next;
          break;
        }
    }
  }
}

void Fork::ForkProcess::kill_process () const
{
  if (pid > 0) {
    kill (pid, SIGKILL);
    reap_child ();
  }
}

void Fork::ForkProcess::reap_child () const
{
  int status;
  if (pid > 0 && waitpid (pid, &status, 0) == pid && reason)
    infanticide_reason (pid, status);
}

void Fork::ForkProcess::infanticide_reason (pid_t pid, int status)
{
  if (pid <= 0)
    return;

  if (WIFSTOPPED (status))
    cerr << "process " << pid << " gets "
      << SYS_SIGLIST [WSTOPSIG (status)] << endl;
  else if (WIFEXITED (status))
    cerr << "process " << pid << " exited with status "
      << WEXITSTATUS (status) << endl;
  else if (WIFSIGNALED (status))
    cerr << "process " << pid << " got "
      << SYS_SIGLIST [WTERMSIG (status)] << endl;
}

void Fork::ForkProcess::reaper_nohang (int signo)
{
  if (signo != SIGCHLD)
    return;

  int status;
  pid_t wpid;
  if ((wpid = waitpid (-1, &status, WNOHANG)) > 0) {
    ForkProcess* prev = 0;
    ForkProcess* cur  = list;
    while (cur) {
      if (cur->pid == wpid) {
        cur->pid = -1;
        if (prev)
          prev->next = cur->next;
        else
          list = list->next;
        
        if (cur->reason)
          infanticide_reason (wpid, status);

        delete cur;
        break;
      }
      prev = cur;
      cur  = cur->next;
    }
  }
}

void Fork::ForkProcess::commit_suicide (int)
{
  // if this process has any children we kill them.

  ForkProcess* p = list;
  while (p) {
    ForkProcess* next = p->next;
    if (!p->kill_child) // otherwise ForkProcess::~ForkProcess will take care
      kill (p->pid, SIGKILL);
    delete p; // ForkProcess::~ForkProcess will call reap_child ().
    p = next;
  }

  exit (0x0f); 
}

void Fork::suicide_signal (int signo)
     // commit suicide at the signal signo
{
  struct sigaction sa;
  sa.sa_handler = funcptr (&Fork::ForkProcess::commit_suicide);
  sigemptyset (&sa.sa_mask);
  sa.sa_flags = 0;
  if (sigaction (signo, &sa, 0) == -1)
    perror ("Fork: Cannot commit suicide with the specified signal");
}
Revision:	1.1
Committed:	Mon Feb 26 15:01:39 2001 UTC (23 years, 8 months ago) by ab11
Content type:	text/plain
Branch:	MAIN
CVS Tags:	PROJECT_COMPLETION
Log Message:	Networking class. Assumed to be bug free.
#	User	Rev	Content
1	ab11	1.1	// Fork.C -- C++ -- socket library
2			// Copyright (C) 1992,1993,1994 Gnanasekaran Swaminathan <gs4t@virginia.edu>
3			//
4			// Permission is granted to use at your own risk and distribute this software
5			// in source and binary forms provided the above copyright
6			// notice and this paragraph are preserved on all copies.
7			// This software is provided "as is" with no express or implied warranty.
8			//
9			// Version: 17Oct95 1.10
10
11			#include <config.h>
12
13			#include <iostream.h>
14			#include <stdio.h> // perror in solaris2.3 is declared here
15			#include <stdlib.h>
16			#include <unistd.h>
17			#include <errno.h>
18			#include <signal.h>
19			#include <sys/wait.h>
20
21			#include <Fork.h>
22
23			Fork::ForkProcess* Fork::ForkProcess::list = 0;
24			Fork::KillForks Fork::killall;
25
26			Fork::~Fork ()
27			{
28			if (process->pid <= 0)
29			delete process;
30			}
31
32			Fork::KillForks::~KillForks ()
33			// First, kill all children whose kill_child flag is set.
34			// Second, wait for other children to die.
35			{
36			for (ForkProcess* cur = Fork::ForkProcess::list; cur; cur = cur->next)
37			if (cur->kill_child)
38			delete cur;
39
40			while (Fork::ForkProcess::list && wait (0) > 0);
41			}
42
43			Fork::ForkProcess::ForkProcess (int kill, int give_reason)
44			: kill_child (kill), reason (give_reason), next (0)
45			{
46			if (list == 0) {
47			struct sigaction sa;
48			sa.sa_handler = funcptr (&Fork::ForkProcess::reaper_nohang);
49			sigemptyset (&sa.sa_mask);
50			sa.sa_flags = SA_RESTART;
51			sigaction (SIGCHLD, &sa, 0);
52			}
53
54			pid = fork ();
55
56			if (pid > 0) {
57			next = list;
58			list = this;
59			} else if (pid == 0) {
60			// child process. clear list
61			ForkProcess* p = list;
62			while (p) {
63			ForkProcess* nxt = p->next;
64			p->pid = 0;
65			delete p;
66			p = nxt;
67			}
68			list = 0;
69
70			if (kill_child) {
71			struct sigaction sa;
72			sa.sa_handler = funcptr (&Fork::ForkProcess::commit_suicide);
73			sigemptyset (&sa.sa_mask);
74			sa.sa_flags = SA_RESTART;
75			sigaction (SIGTERM, &sa, 0);
76			}
77			}
78			}
79
80			Fork::ForkProcess::~ForkProcess ()
81			{
82			if (pid > 0) {
83			if (kill_child)
84			kill (pid, SIGTERM);
85			reap_child ();
86
87			// I remove myself from list
88			if (list == this)
89			list = list->next;
90			else {
91			for (ForkProcess* p = list; p; p = p->next)
92			if (p->next == this) {
93			p->next = next;
94			break;
95			}
96			}
97			}
98			}
99
100			void Fork::ForkProcess::kill_process () const
101			{
102			if (pid > 0) {
103			kill (pid, SIGKILL);
104			reap_child ();
105			}
106			}
107
108			void Fork::ForkProcess::reap_child () const
109			{
110			int status;
111			if (pid > 0 && waitpid (pid, &status, 0) == pid && reason)
112			infanticide_reason (pid, status);
113			}
114
115			void Fork::ForkProcess::infanticide_reason (pid_t pid, int status)
116			{
117			if (pid <= 0)
118			return;
119
120			if (WIFSTOPPED (status))
121			cerr << "process " << pid << " gets "
122			<< SYS_SIGLIST [WSTOPSIG (status)] << endl;
123			else if (WIFEXITED (status))
124			cerr << "process " << pid << " exited with status "
125			<< WEXITSTATUS (status) << endl;
126			else if (WIFSIGNALED (status))
127			cerr << "process " << pid << " got "
128			<< SYS_SIGLIST [WTERMSIG (status)] << endl;
129			}
130
131			void Fork::ForkProcess::reaper_nohang (int signo)
132			{
133			if (signo != SIGCHLD)
134			return;
135
136			int status;
137			pid_t wpid;
138			if ((wpid = waitpid (-1, &status, WNOHANG)) > 0) {
139			ForkProcess* prev = 0;
140			ForkProcess* cur = list;
141			while (cur) {
142			if (cur->pid == wpid) {
143			cur->pid = -1;
144			if (prev)
145			prev->next = cur->next;
146			else
147			list = list->next;
148
149			if (cur->reason)
150			infanticide_reason (wpid, status);
151
152			delete cur;
153			break;
154			}
155			prev = cur;
156			cur = cur->next;
157			}
158			}
159			}
160
161			void Fork::ForkProcess::commit_suicide (int)
162			{
163			// if this process has any children we kill them.
164
165			ForkProcess* p = list;
166			while (p) {
167			ForkProcess* next = p->next;
168			if (!p->kill_child) // otherwise ForkProcess::~ForkProcess will take care
169			kill (p->pid, SIGKILL);
170			delete p; // ForkProcess::~ForkProcess will call reap_child ().
171			p = next;
172			}
173
174			exit (0x0f);
175			}
176
177			void Fork::suicide_signal (int signo)
178			// commit suicide at the signal signo
179			{
180			struct sigaction sa;
181			sa.sa_handler = funcptr (&Fork::ForkProcess::commit_suicide);
182			sigemptyset (&sa.sa_mask);
183			sa.sa_flags = 0;
184			if (sigaction (signo, &sa, 0) == -1)
185			perror ("Fork: Cannot commit suicide with the specified signal");
186			}