/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1982-2009 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Roland Mainz <roland.mainz@nrubsig.org> *
* *
***********************************************************************/
#pragma prototyped
#include <shell.h>
#include <stdio.h>
#include <stdbool.h>
#include <option.h>
#include <stk.h>
#include <tm.h>
#include "name.h"
#undef nv_isnull
#ifndef SH_DICT
# define SH_DICT "libshell"
#endif
#include <poll.h>
#ifdef __GNUC__
#include <alloca.h>
#endif /* __GNUC__ */
#define sh_contexttoshb(context) ((Shbltin_t*)(context))
#define sh_contexttoshell(context) ((context)?(sh_contexttoshb(context)->shp):(NULL))
static const char sh_optpoll[] =
"[-?\n@(#)$Id: poll (AT&T Labs Research) 2009-05-14 $\n]"
"[-author?Roland Mainz <roland.mainz@nrubsig.org]"
"[-license?http://www.opensource.org/licenses/cpl1.0.txt]"
"[+NAME? poll - input/output multiplexing]"
"[+DESCRIPTION?The poll command provides applications with a mechanism "
"for multiplexing input/output over a set of file descriptors. "
"For each member of the array variable \bvar\b, "
"poll examines the given file descriptor in the subscript \b.fd\b "
"for the event(s) specified in the subscript \b.events\b."
"The poll command identifies those file descriptors on which an "
"application can read or write data, or on which certain events have "
"occurred.]"
"[+?The \bvar\b argument specifies the file descriptors to be examined "
"and the events of interest for each file descriptor. "
"It is a array of structured variables with one member for each open "
"file descriptor of interest. The array's members contain the following "
"subscripts:]{"
"[+?\b.fd\b # file descriptor]"
"[+?\b.events\b # requested events]"
"[+?\b.revents\b # returned event]"
"}"
"[+?The \bfd\b variable specifies an open file descriptor and the "
"\bevents\b and \brevents\b members are strings constructed from "
"a concatenation of the following event flags, separated by '|':]"
"{ "
"[+POLLIN?Data other than high priority data may be "
"read without blocking. For STREAMS, this "
"flag is set in revents even if the message "
"is of zero length.]"
"[+POLLRDNORM?Normal data (priority band equals 0) may be "
"read without blocking. For STREAMS, this "
"flag is set in revents even if the message "
"is of zero length.]"
"[+POLLRDBAND?Data from a non-zero priority band may be "
"read without blocking. For STREAMS, this "
"flag is set in revents even if the message "
"is of zero length.]"
"[+POLLPRI?High priority data may be received without "
"blocking. For STREAMS, this flag is set in "
"revents even if the message is of zero "
"length.]"
"[+POLLOUT?Normal data (priority band equals 0) may be "
"written without blocking.]"
"[+POLLWRNORM?The same as POLLOUT.]"
"[+POLLWRBAND?Priority data (priority band > 0) may be "
"written. This event only examines bands "
"that have been written to at least once.]"
"[+POLLERR?An error has occurred on the device or "
"stream. This flag is only valid in the "
"revents bitmask; it is not used in the "
"events member.]"
"[+POLLHUP?A hangup has occurred on the stream. This "
"event and POLLOUT are mutually exclusive; a "
"stream can never be writable if a hangup has "
"occurred. However, this event and POLLIN, "
", POLLRDBAND, or POLLPRI are not "
"mutually exclusive. This flag is only valid "
"in the revents bitmask; it is not used in "
"the events member.]"
"[+POLLNVAL?The specified fd value does not belong to an "
"open file. This flag is only valid in the "
"revents member; it is not used in the events "
"member.]"
"}"
"]"
"[+?If the value fd is less than 0, events is ignored and "
"revents is set to 0 in that entry on return from poll.]"
"[+?The results of the poll query are stored in the revents "
"member in the \bvar\b structure. POLL*-strings are set in the \brevents\b "
"variable to indicate which of the requested events are true. "
"If none are true, the \brevents\b will be an empty string when "
"the poll command returns. The event flags "
"POLLHUP, POLLERR, and POLLNVAL are always set in \brevents\b "
"if the conditions they indicate are true; this occurs even "
"though these flags were not present in events.]"
"[+?If none of the defined events have occurred on any selected "
"file descriptor, poll waits at least timeout milliseconds "
"for an event to occur on any of the selected file descriptors. "
"On a computer where millisecond timing accuracy is not "
"available, timeout is rounded up to the nearest legal value "
"available on that system. If the value timeout is 0, poll "
"returns immediately. If the value of timeout is -1, poll "
"blocks until a requested event occurs or until the call is "
"interrupted.]"
"[+?The poll function supports regular files, terminal and "
"pseudo-terminal devices, STREAMS-based files, FIFOs and "
"pipes. The behavior of poll on elements of fds that refer "
"to other types of file is unspecified.]"
"[+?The poll function supports sockets.]"
"[+?A file descriptor for a socket that is listening for connections "
"will indicate that it is ready for reading, once connections "
"are available. A file descriptor for a socket that "
"is connecting asynchronously will indicate that it is ready "
"for writing, once a connection has been established.]"
"[+?Regular files always poll TRUE for reading and writing.]"
"[e:eventarray]:[fdcount?Upon successful completion, an indexed array "
"of strings is returned which contains a list of array subscripts "
"in the poll array which received events.]"
"[t:timeout]:[seconds?Timeout in seconds. If the value timeout is 0, "
"poll returns immediately. If the value of timeout is -1, poll "
"blocks until a requested event occurs or until the call is "
"interrupted.]"
"[T:mtimeout]:[milliseconds?Timeout in milliseconds. If the value timeout is 0, "
"poll returns immediately. If the value of timeout is -1, poll "
"blocks until a requested event occurs or until the call is "
"interrupted.]"
"\n"
"\nvar\n"
"\n"
"[+EXIT STATUS?]{"
"[+0?Success.]"
"[+>0?An error occurred.]"
"}"
"[+SEE ALSO?\bopen\b(1),\btmpfile\b(1),\bdup\b(1),\bclose\b(1),\bpoll\b(2)]"
;
/*
* |mystpcpy| - like |strcpy()| but returns the end of the buffer
*
* Copy string s2 to s1. s1 must be large enough.
* return s1-1 (position of string terminator ('\0') in destnation buffer).
*/
static
char *mystpcpy(char *s1, const char *s2)
{
while (*s1++ = *s2++)
;
return (s1-1);
}
static
Namval_t *nv_open_fmt(Dt_t *dict, int flags, const char *namefmt, ...)
{
char varnamebuff[PATH_MAX];
va_list ap;
va_start(ap, namefmt);
vsnprintf(varnamebuff, sizeof(varnamebuff), namefmt, ap);
va_end(ap);
return nv_open(varnamebuff, dict, flags);
}
static
int poll_strtoevents(const char *str)
{
int events = 0;
if (strstr(str, "POLLIN")) events |= POLLIN;
if (strstr(str, "POLLRDNORM")) events |= POLLRDNORM;
if (strstr(str, "POLLRDBAND")) events |= POLLRDBAND;
if (strstr(str, "POLLPRI")) events |= POLLPRI;
if (strstr(str, "POLLOUT")) events |= POLLOUT;
if (strstr(str, "POLLWRNORM")) events |= POLLWRNORM;
if (strstr(str, "POLLWRBAND")) events |= POLLWRBAND;
if (strstr(str, "POLLERR")) events |= POLLERR;
if (strstr(str, "POLLHUP")) events |= POLLHUP;
if (strstr(str, "POLLNVAL")) events |= POLLNVAL;
return events;
}
static
void poll_eventstostr(char *s, int events)
{
*s='\0';
if (!events)
return;
if (events & POLLIN) s=mystpcpy(s, "POLLIN|");
if (events & POLLRDNORM) s=mystpcpy(s, "POLLRDNORM|");
if (events & POLLRDBAND) s=mystpcpy(s, "POLLRDBAND|");
if (events & POLLPRI) s=mystpcpy(s, "POLLPRI|");
if (events & POLLOUT) s=mystpcpy(s, "POLLOUT|");
if (events & POLLWRNORM) s=mystpcpy(s, "POLLWRNORM|");
if (events & POLLWRBAND) s=mystpcpy(s, "POLLWRBAND|");
if (events & POLLERR) s=mystpcpy(s, "POLLERR|");
if (events & POLLHUP) s=mystpcpy(s, "POLLHUP|");
if (events & POLLNVAL) s=mystpcpy(s, "POLLNVAL|");
/* Remove trailling '|' */
s--;
if(*s=='|')
*s='\0';
}
#undef getconf
#define getconf(x) strtol(astconf(x,NiL,NiL),NiL,0)
extern int b_poll(int argc, char *argv[], void *extra)
{
Namval_t *np;
Shell_t *shp = sh_contexttoshell(extra);
char *varname;
int n;
int fd;
nfds_t numpollfd = 0;
int i;
char *s;
double timeout = -1.;
char buff[PATH_MAX*2+1]; /* enough to hold two variable names */
char *eventarrayname = NULL;
while (n = optget(argv, sh_optpoll)) switch (n)
{
case 't':
case 'T':
errno = 0;
timeout = strtod(opt_info.arg, (char **)NULL);
if (errno != 0)
errormsg(SH_DICT, ERROR_system(1), "%s: invalid timeout", opt_info.arg);
/* -t uses seconds, -T milliseconds */
if (n == 't')
timeout *= 1000.;
break;
case 'e':
eventarrayname = opt_info.arg;
break;
case ':':
errormsg(SH_DICT, 2, "%s", opt_info.arg);
break;
case '?':
errormsg(SH_DICT, ERROR_usage(2), "%s", opt_info.arg);
break;
}
argc -= opt_info.index;
argv += opt_info.index;
if(argc!=1)
errormsg(SH_DICT, ERROR_usage(2), optusage((char*)0));
varname = argv[0];
Namval_t *array_np, *array_np_sub;
const char *subname;
array_np = nv_open(varname, shp->var_tree, NV_NOFAIL|NV_NOADD);
if (!array_np)
errormsg(SH_DICT, ERROR_system(1), "cannot find array variable %s", varname);
if(!nv_isattr(array_np, NV_ARRAY))
errormsg(SH_DICT, ERROR_system(1), "variable %s is not an array", varname);
/* Count number of array elememts. We need to do it "manually" to
* handle sparse indexed and associative arrays */
nv_putsub(array_np, NULL, ARRAY_SCAN);
array_np_sub = array_np;
do
{
if (!(subname=nv_getsub(array_np_sub)))
break;
numpollfd++;
} while( array_np_sub && nv_nextsub(array_np_sub) );
#ifdef __GNUC__
/*
* Allocate stack space via |alloca()| for gcc builds since ctfconvert
* is unable to handle VLAs from gcc. We need this until CR #6379193
* is fixed.
*/
struct pollfd *pollfd = alloca(sizeof(struct pollfd)*(numpollfd+1));
#else
/* We must allocate one more entry with VLA with zero elements do not work with all compilers */
struct pollfd pollfd[numpollfd+1];
#endif /* __GNUC__ */
nv_putsub(array_np, NULL, ARRAY_SCAN);
array_np_sub = array_np;
i = 0;
do
{
if (!(subname=nv_getsub(array_np_sub)))
break;
np = nv_open_fmt(shp->var_tree, NV_NOFAIL|NV_NOADD, "%s[%s].fd", varname, subname);
if (!np)
errormsg(SH_DICT, ERROR_system(1), "missing pollfd %s[%s].fd", varname, subname);
fd = (int)nv_getnum(np);
if (fd < 0 || fd > OPEN_MAX)
errormsg(SH_DICT, ERROR_system(1), "invalid pollfd fd %d", fd);
nv_close(np);
pollfd[i].fd = fd;
np = nv_open_fmt(shp->var_tree, NV_NOFAIL|NV_NOADD, "%s[%s].events", varname, subname);
if (!np)
errormsg(SH_DICT, ERROR_system(1), "missing pollfd %s[%s].events", varname, subname);
s = nv_getval(np);
if (!s)
errormsg(SH_DICT, ERROR_system(1), "missing pollfd events value");
pollfd[i].events = poll_strtoevents(s);
nv_close(np);
pollfd[i].revents = 0;
i++;
} while( array_np_sub && nv_nextsub(array_np_sub) );
n = poll(pollfd, numpollfd, timeout);
/* FixMe: EGAIN and EINTR may require extra handling */
if (n < 0)
errormsg(SH_DICT, ERROR_system(1), "failure");
if (eventarrayname)
{
np = nv_open_fmt(shp->var_tree, NV_VARNAME|NV_ARRAY|NV_NOFAIL, "%s", eventarrayname);
if (!np)
errormsg(SH_DICT, ERROR_system(1), "couldn't create poll count variable %s", eventarrayname);
nv_close(np);
}
nv_putsub(array_np, NULL, ARRAY_SCAN);
array_np_sub = array_np;
i = 0;
do
{
if (!(subname=nv_getsub(array_np_sub)))
break;
np = nv_open_fmt(shp->var_tree, NV_NOFAIL, "%s[%s].revents", varname, subname);
if (!np)
errormsg(SH_DICT, ERROR_system(1), "couldn't create pollfd %s[%s].revents", varname, subname);
poll_eventstostr(buff, pollfd[i].revents);
nv_putval(np, buff, 0);
nv_close(np);
if (eventarrayname && pollfd[i].revents)
{
sprintf(buff, "%s+=( '%s' )", eventarrayname, subname);
sh_trap(buff, 0);
}
i++;
} while( array_np_sub && nv_nextsub(array_np_sub) );
nv_close(array_np);
return(0);
}