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| /* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */ |
| /* An implementation of select() |
| |
| Copyright 1995 by Morten Welinder |
| This file maybe freely distributed and modified as long as the |
| copyright notice remains. |
| |
| Notes: In a single process system as Dos this really boils down to |
| something that can check whether a character from standard input |
| is ready. However, the code is organised in a way to make it easy |
| to extend to multi process systems like WinNT and OS/2. */ |
| |
| #include <libc/stubs.h> |
| #include <sys/types.h> |
| #include <time.h> |
| #include <errno.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <libc/file.h> |
| #include <libc/local.h> |
| #include <libc/dosio.h> |
| #include <sys/fsext.h> |
| |
| inline static int fp_output_ready(FILE *fp) |
| { |
| return !ferror(fp); |
| } |
| |
| /* This is as close as we get, I think. For a file connected to a printer |
| we could of course go ask the BIOS, but this should be enough. */ |
| |
| inline static int fp_except_ready(FILE *fp) |
| { |
| return ferror (fp); |
| } |
| |
| inline static int fp_input_ready (FILE *fp) |
| { |
| /* I think if there is something in the buffer, we should return |
| ``ready'', even if some error was encountered. Let him consume |
| the buffered characters, *then* return ``not ready''. */ |
| if (fp->_cnt) |
| return 1; |
| |
| /* The `feof' part is only correct in a single-tasked environment. */ |
| if (ferror (fp) || feof (fp)) |
| return 0; |
| |
| /* There is nothing in the buffer (perhaps because we read unbuffered). |
| We don't know if we are ready. Return ``ready'' anyway and let |
| read() or write() tell the truth. */ |
| return 1; |
| } |
| |
| /* The Dos call 4407 always returns TRUE for disk files. So the |
| following really is meaningful for character devices only... */ |
| |
| inline static int fd_output_ready(int fd) |
| { |
| return 0; |
| } |
| |
| inline static int fd_input_ready(int fd) |
| { |
| return 0; |
| } |
| |
| int select(int nfds,fd_set *readfds,fd_set *writefds,fd_set *exceptfds, |
| struct timeval *timeout) |
| { |
| int ready; |
| fd_set oread, owrite, oexcept; |
| struct timeval now, then; |
| |
| if (nfds > FD_SETSIZE) |
| { |
| errno = EINVAL; |
| return -1; |
| } |
| |
| FD_ZERO (&oread); |
| FD_ZERO (&owrite); |
| FD_ZERO (&oexcept); |
| ready = 0; |
| |
| if (timeout) |
| { |
| if (timeout->tv_usec < 0) |
| { |
| errno = EINVAL; |
| return -1; |
| } |
| gettimeofday (&now, 0); |
| then.tv_usec = timeout->tv_usec + now.tv_usec; |
| then.tv_sec = timeout->tv_sec + now.tv_sec + then.tv_usec / 1000000; |
| then.tv_usec %= 1000000; |
| } |
| |
| do { |
| int i; |
| int fd0 = 0; |
| __file_rec *fr = __file_rec_list; |
| FILE *fp; |
| |
| /* First, check the file handles with low-level DOS calls. */ |
| for (i = 0; i < nfds; i++) |
| { |
| register int ioctl_result; |
| __FSEXT_Function *func = __FSEXT_get_function(i); |
| int fsext_ready = -1; |
| |
| if (func) |
| func(__FSEXT_ready, &fsext_ready, &i); |
| |
| if (readfds && FD_ISSET (i, readfds)) |
| { |
| if (fsext_ready != -1) |
| { |
| if (fsext_ready & __FSEXT_ready_read) |
| ready++, FD_SET(i, &oread); |
| } |
| else if ((ioctl_result = fd_input_ready (i)) == -1) |
| return -1; |
| else if (ioctl_result) |
| ready++, FD_SET (i, &oread); |
| } |
| if (writefds && FD_ISSET (i, writefds)) |
| { |
| if (fsext_ready != -1) |
| { |
| if (fsext_ready & __FSEXT_ready_write) |
| ready++, FD_SET(i, &owrite); |
| } |
| else if ((ioctl_result = fd_output_ready (i)) == -1) |
| return -1; |
| else if (ioctl_result) |
| ready++, FD_SET (i, &owrite); |
| } |
| if (exceptfds && FD_ISSET (i, exceptfds)) |
| { |
| if (fsext_ready != -1) |
| { |
| if (fsext_ready & __FSEXT_ready_error) |
| ready++, FD_SET(i, &oexcept); |
| } |
| } |
| } |
| |
| /* Now look at the table of FILE ptrs and reset the bits for file |
| descriptors which we *thought* are ready, but for which the flags |
| say they're NOT ready. */ |
| for (i = 0; fr; i++) |
| { |
| if (i >= fd0 + fr->count) /* done with this subtable, go to next */ |
| { |
| fd0 += fr->count; |
| fr = fr->next; |
| } |
| if (fr) |
| { |
| fp = fr->files[i - fd0]; |
| if (fp->_flag) |
| { |
| int this_fd = fileno(fp); |
| |
| if (this_fd < nfds) |
| { |
| if (readfds && FD_ISSET (this_fd, readfds) && |
| FD_ISSET (this_fd, &oread) && !fp_input_ready (fp)) |
| ready--, FD_CLR (this_fd, &oread); |
| if (writefds && FD_ISSET (this_fd, writefds) && |
| FD_ISSET (this_fd, &owrite) && !fp_output_ready (fp)) |
| ready--, FD_CLR (this_fd, &owrite); |
| |
| /* For exceptional conditions, ferror() is the only one |
| which can tell us an exception is pending. */ |
| if (exceptfds && FD_ISSET (this_fd, exceptfds) && |
| fp_except_ready (fp)) |
| ready++, FD_SET (this_fd, &oexcept); |
| } |
| } |
| } |
| } |
| |
| /* Exit if we found what we were waiting for. */ |
| if (ready > 0) |
| { |
| if (readfds) |
| *readfds = oread; |
| if (writefds) |
| *writefds = owrite; |
| if (exceptfds) |
| *exceptfds = oexcept; |
| return ready; |
| } |
| |
| /* Exit if we hit the time limit. */ |
| if (timeout) |
| { |
| gettimeofday (&now, 0); |
| if (now.tv_sec > then.tv_sec |
| || (now.tv_sec = then.tv_sec && now.tv_usec >= then.tv_usec)) |
| return 0; |
| } |
| } while (1); |
| } |