diff options
Diffstat (limited to 'src/lib/libast/sfio/sfpoll.c')
| -rw-r--r-- | src/lib/libast/sfio/sfpoll.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/src/lib/libast/sfio/sfpoll.c b/src/lib/libast/sfio/sfpoll.c new file mode 100644 index 0000000..09110aa --- /dev/null +++ b/src/lib/libast/sfio/sfpoll.c @@ -0,0 +1,250 @@ +/*********************************************************************** +* * +* This software is part of the ast package * +* Copyright (c) 1985-2011 AT&T Intellectual Property * +* and is licensed under the * +* Eclipse Public License, Version 1.0 * +* by AT&T Intellectual Property * +* * +* A copy of the License is available at * +* http://www.eclipse.org/org/documents/epl-v10.html * +* (with md5 checksum b35adb5213ca9657e911e9befb180842) * +* * +* Information and Software Systems Research * +* AT&T Research * +* Florham Park NJ * +* * +* Glenn Fowler <gsf@research.att.com> * +* David Korn <dgk@research.att.com> * +* Phong Vo <kpv@research.att.com> * +* * +***********************************************************************/ +#include "sfhdr.h" + +/* Poll a set of streams to see if any is available for I/O. +** Ready streams are moved to front of array but retain the +** same relative order. +** +** Written by Kiem-Phong Vo. +*/ + +#if __STD_C +int sfpoll(Sfio_t** fa, reg int n, int tm) +#else +int sfpoll(fa, n, tm) +Sfio_t** fa; /* array of streams to poll */ +reg int n; /* number of streams in array */ +int tm; /* time in millisecs for select/poll */ +#endif +{ + reg int r, c, m, np, eintr; + reg Sfio_t* f; + reg int *status, *check; + + if(n <= 0 || !fa) + return -1; + + if(!(status = (int*)malloc(2*n*sizeof(int))) ) + return -1; + check = status+n; /* streams that need polling */ + + /* a SF_READ stream is ready if there is buffered read data */ +#define RDREADY(f) (((f->mode&SF_READ) && f->next < f->endb) || \ + ((f->mode&SF_WRITE) && f->proc && f->proc->ndata > 0) ) + + /* a SF_WRITE stream is ready if there is no write data */ +#define WRREADY(f) (!(f->mode&SF_WRITE) || f->next == f->data) + +#define HASAUXFD(f) (f->proc && f->proc->file >= 0 && f->proc->file != f->file) + + for(r = c = eintr = 0; r < n; ++r) /* compute streams that must be checked */ + { f = fa[r]; + status[r] = 0; + + /* terminate poll on interrupt? */ + if(f->flags&SF_IOINTR) + eintr++; + /* check accessibility */ + m = f->mode&SF_RDWR; + if((int)f->mode != m && _sfmode(f,m,0) < 0) + continue; + + if((f->flags&SF_READ) && RDREADY(f)) + status[r] |= SF_READ; + + if((f->flags&SF_WRITE) && WRREADY(f)) + status[r] |= SF_WRITE; + + if((f->flags&SF_RDWR) == status[r]) + continue; + + /* has discipline, ask its opinion */ + if(f->disc && f->disc->exceptf) + { if((m = (*f->disc->exceptf)(f,SF_DPOLL,&tm,f->disc)) < 0) + continue; + else if(m > 0) + { status[r] = m&SF_RDWR; + continue; + } + } + + if(f->extent < 0) /* unseekable stream, must poll/select */ + check[c++] = r; + else /* seekable streams are always ready */ + { if(f->flags&SF_READ) + status[r] |= SF_READ; + if(f->flags&SF_WRITE) + status[r] |= SF_WRITE; + } + } + /* terminate poll on interrupt only if all streams marked SF_IOINTR */ + eintr = eintr == n ? -1 : EINTR; + + np = -1; +#if _lib_poll + if(c > 0) + { struct pollfd* fds; + + /* construct the poll array */ + for(m = 0, r = 0; r < c; ++r, ++m) + { f = fa[check[r]]; + if(HASAUXFD(f)) + m += 1; + } + if(!(fds = (struct pollfd*)malloc(m*sizeof(struct pollfd))) ) + return -1; + + for(m = 0, r = 0; r < c; ++r, ++m) + { f = fa[check[r]]; + + fds[m].fd = f->file; + fds[m].events = fds[m].revents = 0; + + if((f->flags&SF_WRITE) && !WRREADY(f) ) + fds[m].events |= POLLOUT; + + if((f->flags&SF_READ) && !RDREADY(f) ) + { /* a sfpopen situation with two file descriptors */ + if((f->mode&SF_WRITE) && HASAUXFD(f)) + { m += 1; + fds[m].fd = f->proc->file; + fds[m].revents = 0; + } + + fds[m].events |= POLLIN; + } + } + + while((np = SFPOLL(fds,m,tm)) < 0 ) + { if(errno == eintr || errno == EAGAIN) + errno = 0; + else break; + } + if(np > 0) /* poll succeeded */ + np = c; + + for(m = 0, r = 0; r < np; ++r, ++m) + { f = fa[check[r]]; + + if((f->flags&SF_WRITE) && !WRREADY(f) ) + { if(fds[m].revents&POLLOUT) + status[check[r]] |= SF_WRITE; + } + + if((f->flags&SF_READ) && !RDREADY(f)) + { if((f->mode&SF_WRITE) && HASAUXFD(f)) + m += 1; + if(fds[m].revents&POLLIN) + status[check[r]] |= SF_READ; + } + } + + free((Void_t*)fds); + } +#endif /*_lib_poll*/ + +#if _lib_select + if(np < 0 && c > 0) + { fd_set rd, wr; + struct timeval tmb, *tmp; + + FD_ZERO(&rd); + FD_ZERO(&wr); + m = 0; + for(r = 0; r < c; ++r) + { f = fa[check[r]]; + + if(f->file > m) + m = f->file; + + if((f->flags&SF_WRITE) && !WRREADY(f)) + FD_SET(f->file,&wr); + + if((f->flags&SF_READ) && !RDREADY(f)) + { if((f->mode&SF_WRITE) && HASAUXFD(f)) + { if(f->proc->file > m) + m = f->proc->file; + FD_SET(f->proc->file, &rd); + } + else FD_SET(f->file,&rd); + } + } + if(tm < 0) + tmp = NIL(struct timeval*); + else + { tmp = &tmb; + tmb.tv_sec = tm/SECOND; + tmb.tv_usec = (tm%SECOND)*SECOND; + } + + while((np = select(m+1,&rd,&wr,NIL(fd_set*),tmp)) < 0 ) + { if(errno == eintr) + errno = 0; + else break; + } + if(np > 0) + np = c; + + for(r = 0; r < np; ++r) + { f = fa[check[r]]; + + if((f->flags&SF_WRITE) && !WRREADY(f) ) + { if(FD_ISSET(f->file,&wr) ) + status[check[r]] |= SF_WRITE; + } + + if((f->flags&SF_READ) && !RDREADY(f) ) + { if((f->mode&SF_WRITE) && HASAUXFD(f) ) + { if(FD_ISSET(f->proc->file, &rd) ) + status[check[r]] |= SF_READ; + } + else + { if(FD_ISSET(f->file,&rd) ) + status[check[r]] |= SF_READ; + } + } + } + } +#endif /*_lib_select*/ + + for(r = c = 0; c < n; ++c) + { if(status[c] == 0) + continue; + + f = fa[c]; + f->val = (ssize_t)status[c]; + + /* announce status */ + if(f->disc && f->disc->exceptf) + (*f->disc->exceptf)(f,SF_READY,(Void_t*)(long)status[c],f->disc); + + if(c > r) /* move to front of list */ + { fa[c] = fa[r]; + fa[r] = f; + } + r += 1; + } + + free((Void_t*)status); + return r ? r : np < 0 ? -1 : 0; +} |