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Diffstat (limited to 'manual/signal.texi')
| -rw-r--r-- | manual/signal.texi | 87 |
1 files changed, 44 insertions, 43 deletions
diff --git a/manual/signal.texi b/manual/signal.texi index bca02c528b..088c35d02f 100644 --- a/manual/signal.texi +++ b/manual/signal.texi @@ -34,7 +34,7 @@ and synchronize. * Generating Signals:: How to send a signal to a process. * Blocking Signals:: Making the system hold signals temporarily. * Waiting for a Signal:: Suspending your program until a signal - arrives. + arrives. * Signal Stack:: Using a Separate Signal Stack. * BSD Signal Handling:: Additional functions for backward compatibility with BSD. @@ -51,11 +51,11 @@ signals. * Kinds of Signals:: Some examples of what can cause a signal. * Signal Generation:: Concepts of why and how signals occur. * Delivery of Signal:: Concepts of what a signal does to the - process. + process. @end menu @node Kinds of Signals -@subsection Some Kinds of Signals +@subsection Some Kinds of Signals A signal reports the occurrence of an exceptional event. These are some of the events that can cause (or @dfn{generate}, or @dfn{raise}) a @@ -229,7 +229,7 @@ defined. Since the signal numbers are allocated consecutively, @menu * Program Error Signals:: Used to report serious program errors. * Termination Signals:: Used to interrupt and/or terminate the - program. + program. * Alarm Signals:: Used to indicate expiration of timers. * Asynchronous I/O Signals:: Used to indicate input is available. * Job Control Signals:: Signals used to support job control. @@ -279,7 +279,7 @@ files is so that you can examine them with a debugger to investigate what caused the error. @comment signal.h -@comment ANSI +@comment ISO @deftypevr Macro int SIGFPE The @code{SIGFPE} signal reports a fatal arithmetic error. Although the name is derived from ``floating-point exception'', this signal actually @@ -294,7 +294,8 @@ floating-point number. Actual floating-point exceptions are a complicated subject because there are many types of exceptions with subtly different meanings, and the @code{SIGFPE} signal doesn't distinguish between them. The @cite{IEEE -Standard for Binary Floating-Point Arithmetic (ANSI/IEEE Std 754-1985)} +Standard for Binary Floating-Point Arithmetic (ANSI/IEEE Std 754-1985 +and ANSI/IEEE Std 854-1987)} defines various floating-point exceptions and requires conforming computer systems to report their occurrences. However, this standard does not specify how the exceptions are reported, or what kinds of @@ -368,7 +369,7 @@ Floating underflow fault. @end table @comment signal.h -@comment ANSI +@comment ISO @deftypevr Macro int SIGILL The name of this signal is derived from ``illegal instruction''; it usually means your program is trying to execute garbage or a privileged @@ -387,7 +388,7 @@ the system has trouble running the handler for a signal. @cindex illegal instruction @comment signal.h -@comment ANSI +@comment ISO @deftypevr Macro int SIGSEGV @cindex segmentation violation This signal is generated when a program tries to read or write outside @@ -421,7 +422,7 @@ The name of this signal is an abbreviation for ``bus error''. @cindex bus error @comment signal.h -@comment ANSI +@comment ISO @deftypevr Macro int SIGABRT @cindex abort signal This signal indicates an error detected by the program itself and @@ -480,7 +481,7 @@ The (obvious) default action for all of these signals is to cause the process to terminate. @comment signal.h -@comment ANSI +@comment ISO @deftypevr Macro int SIGTERM @cindex termination signal The @code{SIGTERM} signal is a generic signal used to cause program @@ -493,7 +494,7 @@ The shell command @code{kill} generates @code{SIGTERM} by default. @end deftypevr @comment signal.h -@comment ANSI +@comment ISO @deftypevr Macro int SIGINT @cindex interrupt signal The @code{SIGINT} (``program interrupt'') signal is sent when the user @@ -595,7 +596,7 @@ time used by the current process. The name is an abbreviation for @comment BSD @deftypevr Macro int SIGPROF This signal is typically indicates expiration of a timer that measures -both CPU time used by the current process, and CPU time expended on +both CPU time used by the current process, and CPU time expended on behalf of the process by the system. Such a timer is used to implement code profiling facilities, hence the name of this signal. @end deftypevr @@ -623,7 +624,7 @@ On most operating systems, terminals and sockets are the only kinds of files that can generate @code{SIGIO}; other kinds, including ordinary files, never generate @code{SIGIO} even if you ask them to. -In the GNU system @code{SIGIO} will always be generated properly +In the GNU system @code{SIGIO} will always be generated properly if you successfully set asynchronous mode with @code{fcntl}. @end deftypevr @@ -703,7 +704,7 @@ ignored, or blocked. @comment POSIX.1 @deftypevr Macro int SIGTSTP The @code{SIGTSTP} signal is an interactive stop signal. Unlike -@code{SIGSTOP}, this signal can be handled and ignored. +@code{SIGSTOP}, this signal can be handled and ignored. Your program should handle this signal if you have a special need to leave files or system tables in a secure state when a process is @@ -719,7 +720,7 @@ support, see @ref{Special Characters}. @comment signal.h @comment POSIX.1 @deftypevr Macro int SIGTTIN -A process cannot read from the the user's terminal while it is running +A process cannot read from the the user's terminal while it is running as a background job. When any process in a background job tries to read from the terminal, all of the processes in the job are sent a @code{SIGTTIN} signal. The default action for this signal is to @@ -906,11 +907,11 @@ This function prints a message describing the signal @var{signum} to the standard error output stream @code{stderr}; see @ref{Standard Streams}. If you call @code{psignal} with a @var{message} that is either a null -pointer or an empty string, @code{psignal} just prints the message +pointer or an empty string, @code{psignal} just prints the message corresponding to @var{signum}, adding a trailing newline. If you supply a non-null @var{message} argument, then @code{psignal} -prefixes its output with this string. It adds a colon and a space +prefixes its output with this string. It adds a colon and a space character to separate the @var{message} from the string corresponding to @var{signum}. @@ -969,7 +970,7 @@ The name @code{sighandler_t} for this data type is a GNU extension. @end deftp @comment signal.h -@comment ANSI +@comment ISO @deftypefun sighandler_t signal (int @var{signum}, sighandler_t @var{action}) The @code{signal} function establishes @var{action} as the action for the signal @var{signum}. @@ -1086,7 +1087,7 @@ provided only for compatibility with SVID. @end deftypefun @comment signal.h -@comment ANSI +@comment ISO @deftypevr Macro sighandler_t SIG_ERR The value of this macro is used as the return value from @code{signal} to indicate an error. @@ -1139,7 +1140,7 @@ handler is started; this is true regardless of the value in handler, you must write code in the handler to unblock it. @item int sa_flags -This specifies various flags which can affect the behavior of +This specifies various flags which can affect the behavior of the signal. These are described in more detail in @ref{Flags for Sigaction}. @end table @end deftp @@ -1201,10 +1202,10 @@ you can rely on using it as an argument to @code{sigaction}. This problem never happens on the GNU system. So, you're better off using one or the other of the mechanisms -consistently within a single program. +consistently within a single program. @strong{Portability Note:} The basic @code{signal} function is a feature -of ANSI C, while @code{sigaction} is part of the POSIX.1 standard. If +of @w{ISO C}, while @code{sigaction} is part of the POSIX.1 standard. If you are concerned about portability to non-POSIX systems, then you should use the @code{signal} function instead. @@ -1267,7 +1268,7 @@ action for @code{SIGINT} without changing that action. struct sigaction query_action; if (sigaction (SIGINT, NULL, &query_action) < 0) - /* @r{@code{sigaction} returns -1 in case of error.} */ + /* @r{@code{sigaction} returns -1 in case of error.} */ else if (query_action.sa_handler == SIG_DFL) /* @r{@code{SIGINT} is handled in the default, fatal manner.} */ else if (query_action.sa_handler == SIG_IGN) @@ -1412,7 +1413,7 @@ describes what your handler should do, and what you should avoid. @menu * Handler Returns:: Handlers that return normally, and what - this means. + this means. * Termination in Handler:: How handler functions terminate a program. * Longjmp in Handler:: Nonlocal transfer of control out of a signal handler. @@ -1421,9 +1422,9 @@ describes what your handler should do, and what you should avoid. * Merged Signals:: When a second signal arrives before the first is handled. * Nonreentrancy:: Do not call any functions unless you know they - are reentrant with respect to signals. + are reentrant with respect to signals. * Atomic Data Access:: A single handler can run in the middle of - reading or writing a single object. + reading or writing a single object. @end menu @node Handler Returns @@ -1567,7 +1568,7 @@ read_data () waiting_for_input = 1; @dots{} waiting_for_input = 0; - @} else @{ + @} else @{ @dots{} @} @} @@ -1679,7 +1680,7 @@ sigchld_handler (int signo) struct process *p; /* @r{Keep asking for a status until we get a definitive result.} */ - do + do @{ errno = 0; pid = waitpid (WAIT_ANY, &w, WNOHANG | WUNTRACED); @@ -1777,7 +1778,7 @@ sig_atomic_t last_process_status_change; @end smallexample @node Nonreentrancy -@subsection Signal Handling and Nonreentrant Functions +@subsection Signal Handling and Nonreentrant Functions @cindex restrictions on signal handler functions Handler functions usually don't do very much. The best practice is to @@ -1994,7 +1995,7 @@ one it is, and how many bits it contains, may vary from machine to machine. @comment signal.h -@comment ANSI +@comment ISO @deftp {Data Type} sig_atomic_t This is an integer data type. Objects of this type are always accessed atomically. @@ -2134,7 +2135,7 @@ function is declared in @file{signal.h}. @pindex signal.h @comment signal.h -@comment ANSI +@comment ISO @deftypefun int raise (int @var{signum}) The @code{raise} function sends the signal @var{signum} to the calling process. It returns zero if successful and a nonzero value if it fails. @@ -2201,7 +2202,7 @@ main (void) @end group @end smallexample -@strong{Portability note:} @code{raise} was invented by the ANSI C +@strong{Portability note:} @code{raise} was invented by the @w{ISO C} committee. Older systems may not support it, so using @code{kill} may be more portable. @xref{Signaling Another Process}. @@ -2369,7 +2370,7 @@ them from interrupting sensitive operations. For instance: @itemize @bullet @item You can use the @code{sigprocmask} function to block signals while you -modify global variables that are also modified by the handlers for these +modify global variables that are also modified by the handlers for these signals. @item @@ -2381,18 +2382,18 @@ signal handler can run without being interrupted itself by signals. @menu * Why Block:: The purpose of blocking signals. * Signal Sets:: How to specify which signals to - block. + block. * Process Signal Mask:: Blocking delivery of signals to your process during normal execution. * Testing for Delivery:: Blocking to Test for Delivery of - a Signal. + a Signal. * Blocking for Handler:: Blocking additional signals while a handler is being run. * Checking for Pending Signals:: Checking for Pending Signals * Remembering a Signal:: How you can get almost the same effect as blocking a signal, by handling it and setting a flag - to be tested later. + to be tested later. @end menu @node Why Block @@ -2743,7 +2744,7 @@ sigaddset (&base_mask, SIGINT); sigaddset (&base_mask, SIGTSTP); /* @r{Block user interrupts while doing other processing.} */ -sigprocmask (SIG_SETMASK, &base_mask, NULL); +sigprocmask (SIG_SETMASK, &base_mask, NULL); @dots{} /* @r{After a while, check to see whether any signals are pending.} */ @@ -2980,7 +2981,7 @@ returns. The mask remains @var{set} only as long as @code{sigsuspend} is waiting. The function @code{sigsuspend} always restores the previous signal mask -when it returns. +when it returns. The return value and error conditions are the same as for @code{pause}. @end deftypefun @@ -2993,8 +2994,8 @@ sigset_t mask, oldmask; @dots{} -/* @r{Set up the mask of signals to temporarily block.} */ -sigemptyset (&mask); +/* @r{Set up the mask of signals to temporarily block.} */ +sigemptyset (&mask); sigaddset (&mask, SIGUSR1); @dots{} @@ -3121,7 +3122,7 @@ The return value is @code{0} on success and @code{-1} on failure. If You tried to disable a stack that was in fact currently in use. @item ENOMEM -The size of the alternate stack was too small. +The size of the alternate stack was too small. It must be greater than @code{MINSIGSTKSZ}. @end table @end deftypefun @@ -3193,7 +3194,7 @@ The BSD facilities are declared in @file{signal.h}. @menu * BSD Handler:: BSD Function to Establish a Handler. -* Blocking in BSD:: BSD Functions for Blocking Signals. +* Blocking in BSD:: BSD Functions for Blocking Signals. @end menu @node BSD Handler @@ -3270,7 +3271,7 @@ code @code{EINTR}. @xref{Interrupted Primitives}. @end deftypefun @node Blocking in BSD -@subsection BSD Functions for Blocking Signals +@subsection BSD Functions for Blocking Signals @comment signal.h @comment BSD |