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signal2.h File Reference

Signal handling. More...

#include <stdbool.h>
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Typedefs

typedef void(* sig_handler_t) (int sig)
 

Functions

void mutt_sig_allow_interrupt (bool allow)
 Allow/disallow Ctrl-C (SIGINT) More...
 
void mutt_sig_block (void)
 Block signals during critical operations. More...
 
void mutt_sig_block_system (void)
 Block signals before calling exec() More...
 
void mutt_sig_empty_handler (int sig)
 Dummy signal handler. More...
 
void mutt_sig_exit_handler (int sig)
 Notify the user and shutdown gracefully. More...
 
void mutt_sig_init (sig_handler_t sig_fn, sig_handler_t exit_fn, sig_handler_t segv_fn)
 Initialise the signal handling. More...
 
void mutt_sig_unblock (void)
 Restore previously blocked signals. More...
 
void mutt_sig_unblock_system (bool restore)
 Restore previously blocked signals. More...
 

Detailed Description

Signal handling.

Authors
  • Richard Russon

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Definition in file signal2.h.

Typedef Documentation

◆ sig_handler_t

typedef void(* sig_handler_t) (int sig)

Definition at line 35 of file signal2.h.

Function Documentation

◆ mutt_sig_allow_interrupt()

void mutt_sig_allow_interrupt ( bool  allow)

Allow/disallow Ctrl-C (SIGINT)

Parameters
allowTrue to allow Ctrl-C to interrupt signals

Allow the user to interrupt some long operations.

Definition at line 238 of file signal.c.

239{
240 struct sigaction sa;
241
242 memset(&sa, 0, sizeof(sa));
243 sa.sa_handler = sig_handler;
244#ifdef SA_RESTART
245 if (!allow)
246 sa.sa_flags |= SA_RESTART;
247#endif
248 sigaction(SIGINT, &sa, NULL);
249}
static sig_handler_t sig_handler
Definition: signal.c:46
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◆ mutt_sig_block()

void mutt_sig_block ( void  )

Block signals during critical operations.

It's important that certain signals don't interfere with critical operations. Call mutt_sig_unblock() to restore the signals' behaviour.

Definition at line 150 of file signal.c.

151{
152 if (SignalsBlocked)
153 return;
154
155 sigemptyset(&Sigset);
156 sigaddset(&Sigset, SIGTERM);
157 sigaddset(&Sigset, SIGHUP);
158 sigaddset(&Sigset, SIGTSTP);
159 sigaddset(&Sigset, SIGINT);
160 sigaddset(&Sigset, SIGWINCH);
161 sigprocmask(SIG_BLOCK, &Sigset, 0);
162 SignalsBlocked = true;
163}
static sigset_t Sigset
Definition: signal.c:39
static bool SignalsBlocked
Definition: signal.c:43
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◆ mutt_sig_block_system()

void mutt_sig_block_system ( void  )

Block signals before calling exec()

It's important that certain signals don't interfere with the child process. Call mutt_sig_unblock_system() to restore the signals' behaviour.

Definition at line 183 of file signal.c.

184{
186 return;
187
188 struct sigaction sa;
189
190 /* POSIX: ignore SIGINT and SIGQUIT & block SIGCHLD before exec */
191 sa.sa_handler = SIG_IGN;
192 sa.sa_flags = 0;
193 sigemptyset(&sa.sa_mask);
194 sigaction(SIGINT, &sa, &SysOldInt);
195 sigaction(SIGQUIT, &sa, &SysOldQuit);
196
197 sigemptyset(&SigsetSys);
198 sigaddset(&SigsetSys, SIGCHLD);
199 sigprocmask(SIG_BLOCK, &SigsetSys, 0);
200 SysSignalsBlocked = true;
201}
static bool SysSignalsBlocked
Definition: signal.c:44
static struct sigaction SysOldQuit
Definition: signal.c:42
static sigset_t SigsetSys
Definition: signal.c:40
static struct sigaction SysOldInt
Definition: signal.c:41
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◆ mutt_sig_empty_handler()

void mutt_sig_empty_handler ( int  sig)

Dummy signal handler.

Parameters
sigSignal number, e.g. SIGINT

Useful for signals that we can't ignore, or don't want to do anything with.

Definition at line 57 of file signal.c.

58{
59}
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◆ mutt_sig_exit_handler()

void mutt_sig_exit_handler ( int  sig)

Notify the user and shutdown gracefully.

Parameters
sigSignal number, e.g. SIGINT

Definition at line 65 of file signal.c.

66{
67#ifdef HAVE_DECL_SYS_SIGLIST
68 printf(_("Caught signal %d (%s) ... Exiting\n"), sig, sys_siglist[sig]);
69#elif (defined(__sun__) && defined(__svr4__))
70 printf(_("Caught signal %d (%s) ... Exiting\n"), sig, _sys_siglist[sig]);
71#elif (defined(__alpha) && defined(__osf__))
72 printf(_("Caught signal %d (%s) ... Exiting\n"), sig, __sys_siglist[sig]);
73#else
74 printf(_("Caught signal %d ... Exiting\n"), sig);
75#endif
76 exit(0);
77}
#define _(a)
Definition: message.h:28
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◆ mutt_sig_init()

void mutt_sig_init ( sig_handler_t  sig_fn,
sig_handler_t  exit_fn,
sig_handler_t  segv_fn 
)

Initialise the signal handling.

Parameters
sig_fnFunction to handle signals
exit_fnFunction to call on uncaught signals
segv_fnFunction to call on a segfault (Segmentation Violation)

Set up handlers to ignore or catch signals of interest. We use three handlers for the signals we want to catch, ignore, or exit.

Definition at line 88 of file signal.c.

89{
90 if (sig_fn)
91 sig_handler = sig_fn;
92
93 if (exit_fn)
94 exit_handler = exit_fn;
95
96 if (segv_fn)
97 segv_handler = segv_fn;
98
99 struct sigaction act;
100
101 sigemptyset(&act.sa_mask);
102 act.sa_flags = 0;
103 act.sa_handler = SIG_IGN;
104 sigaction(SIGPIPE, &act, NULL);
105
106 act.sa_handler = segv_handler;
107 sigaction(SIGSEGV, &act, NULL);
108
109 act.sa_handler = exit_handler;
110 sigaction(SIGTERM, &act, NULL);
111 sigaction(SIGHUP, &act, NULL);
112 sigaction(SIGQUIT, &act, NULL);
113
114 /* we want to avoid race conditions */
115 sigaddset(&act.sa_mask, SIGTSTP);
116
117 act.sa_handler = sig_handler;
118
119 /* we want SIGALRM to abort the current syscall, so we do this before
120 * setting the SA_RESTART flag below. currently this is only used to
121 * timeout on a connect() call in a reasonable amount of time. */
122 sigaction(SIGALRM, &act, NULL);
123
124/* we also don't want to mess with interrupted system calls */
125#ifdef SA_RESTART
126 act.sa_flags = SA_RESTART;
127#endif
128
129 sigaction(SIGCONT, &act, NULL);
130 sigaction(SIGTSTP, &act, NULL);
131 sigaction(SIGINT, &act, NULL);
132 sigaction(SIGWINCH, &act, NULL);
133
134 /* POSIX doesn't allow us to ignore SIGCHLD,
135 * so we just install a dummy handler for it */
136 act.sa_handler = mutt_sig_empty_handler;
137 /* don't need to block any other signals here */
138 sigemptyset(&act.sa_mask);
139 /* we don't want to mess with stopped children */
140 act.sa_flags |= SA_NOCLDSTOP;
141 sigaction(SIGCHLD, &act, NULL);
142}
void mutt_sig_empty_handler(int sig)
Dummy signal handler.
Definition: signal.c:57
static sig_handler_t exit_handler
Definition: signal.c:47
static sig_handler_t segv_handler
Definition: signal.c:48
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◆ mutt_sig_unblock()

void mutt_sig_unblock ( void  )

Restore previously blocked signals.

Definition at line 168 of file signal.c.

169{
170 if (!SignalsBlocked)
171 return;
172
173 sigprocmask(SIG_UNBLOCK, &Sigset, 0);
174 SignalsBlocked = false;
175}
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◆ mutt_sig_unblock_system()

void mutt_sig_unblock_system ( bool  restore)

Restore previously blocked signals.

Parameters
restoreIf true, restore previous SIGINT, SIGQUIT behaviour

Definition at line 207 of file signal.c.

208{
210 return;
211
212 sigprocmask(SIG_UNBLOCK, &SigsetSys, NULL);
213 if (restore)
214 {
215 sigaction(SIGQUIT, &SysOldQuit, NULL);
216 sigaction(SIGINT, &SysOldInt, NULL);
217 }
218 else
219 {
220 struct sigaction sa;
221
222 sa.sa_handler = SIG_DFL;
223 sigemptyset(&sa.sa_mask);
224 sa.sa_flags = 0;
225 sigaction(SIGQUIT, &sa, NULL);
226 sigaction(SIGINT, &sa, NULL);
227 }
228
229 SysSignalsBlocked = false;
230}
static struct Email * restore(const unsigned char *d)
Restore an Email from data retrieved from the cache.
Definition: hcache.c:143
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