X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/dd3c57bc8cac59e0d657ee665ce462988d27d714..18c831dcd0ae4d660c70ccac69d27ed2a97851be:/sel/sel.c

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+/* -*-c-*-
+ *
+ * I/O multiplexing support
+ *
+ * (c) 1999 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of the mLib utilities library.
+ *
+ * mLib is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * mLib 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 Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with mLib; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sys/types.h>
+#include <sys/time.h>
+#include <unistd.h>
+
+#include "sel.h"
+#include "sub.h"
+#include "tv.h"
+
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct sel_pendfile {
+  struct sel_pendfile *next;
+  sel_file *f;
+} pfile;
+
+typedef struct sel_pendtimer {
+  struct sel_pendtimer *next;
+  sel_timer *t;
+} ptimer;
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @sel_init@ --- *
+ *
+ * Arguments:	@sel_state *s@ = pointer to a state block to initialize
+ *
+ * Returns:	---
+ *
+ * Use:		Initializes a select state block.
+ */
+
+void sel_init(sel_state *s)
+{
+  int i;
+
+  for (i = 0; i < SEL_MODES; i++) {
+    s->files[i] = 0;
+    FD_ZERO(&s->fd[i]);
+  }
+  s->timers = 0;
+  s->hooks = 0;
+  s->args = 0;
+}
+
+/* --- @sel_initfile@ --- *
+ *
+ * Arguments:	@sel_state *s@ = select state to attach to
+ *		@sel_file *f@ = pointer to a file block to initialize
+ *		@int fd@ = the file descriptor to listen to
+ *		@unsigned mode@ = what to listen for
+ *		@void (*func)(int fd, unsigned mode, void *p)@ = handler
+ *		@void *p@ = argument to pass to handler
+ *
+ * Returns:	---
+ *
+ * Use:		Initializes a file block ready for use.  The file block
+ *		isn't added to the list of things to do until a call to
+ *		@sel_addfile@.
+ */
+
+void sel_initfile(sel_state *s, sel_file *f,
+		  int fd, unsigned mode,
+		  void (*func)(int /*fd*/, unsigned /*mode*/, void */*p*/),
+		  void *p)
+{
+  f->s = s;
+  f->fd = fd;
+  f->mode = mode;
+  f->func = func;
+  f->p = p;
+  f->pend = 0;
+}
+
+/* --- @sel_addfile@ --- *
+ *
+ * Arguments:	@sel_file *f@ = pointer to a file block
+ *
+ * Returns:	---
+ *
+ * Use:		Adds a file block into the list of things to listen to.
+ */
+
+void sel_addfile(sel_file *f)
+{
+  sel_file **ff = &f->s->files[f->mode];
+
+  /* --- This little dance looks like line-noise, but it does the job --- */
+
+  while (*ff && (*ff)->fd > f->fd)
+    ff = &(*ff)->next;
+  f->next = *ff;
+  f->prev = ff;
+  if (*ff)
+    (*ff)->prev = &f->next;
+  *ff = f;
+  FD_SET(f->fd, f->s->fd + f->mode);
+}
+
+/* --- @sel_force@ --- *
+ *
+ * Arguments:	@sel_file *f@ = pointer to file selector
+ *
+ * Returns:	---
+ *
+ * Use:		Forces a file selector to be considered ready.  This is only
+ *		useful during a call to @sel_select@.  Of particular use is
+ *		forcing a write selector when there's something interesting
+ *		ready for it.
+ */
+
+void sel_force(sel_file *f)
+{
+  if (f->s->args)
+    FD_SET(f->fd, &f->s->args->fd[f->mode]);
+}
+
+/* --- @sel_rmfile@ --- *
+ *
+ * Arguments:	@sel_file *f@ = pointer to a file block
+ *
+ * Returns:	---
+ *
+ * Use:		Removes a file block from the list of things to listen to.
+ */
+
+void sel_rmfile(sel_file *f)
+{
+  *f->prev = f->next;
+  if (f->next)
+    f->next->prev = f->prev;
+  FD_CLR(f->fd, f->s->fd + f->mode);
+  if (f->pend) {
+    f->pend->f = 0;
+    f->pend = 0;
+  }
+}
+
+/* --- @sel_addtimer@ --- *
+ *
+ * Arguments:	@sel_state *s@ = pointer to a state block
+ *		@sel_timer *t@ = pointer to a timer block
+ *		@struct timeval *tv@ = pointer to time to activate
+ *		@void (*func)(struct timeval *tv, void *p)@ = handler
+ *		@void *p@ = argument for handler function
+ *
+ * Returns:	---
+ *
+ * Use:		Registers and sets up a timer.
+ */
+
+void sel_addtimer(sel_state *s, sel_timer *t,
+		  struct timeval *tv,
+		  void (*func)(struct timeval */*tv*/, void */*p*/),
+		  void *p)
+{
+  sel_timer **tt = &s->timers;
+  { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); }
+
+  /* --- Set up the timer block --- */
+
+  t->tv = *tv;
+  t->func = func;
+  t->p = p;
+  t->pend = 0;
+
+  /* --- More line noise --- */
+
+  while (*tt && TV_CMP(&(*tt)->tv, <, tv))
+    tt = &(*tt)->next;
+  t->next = *tt;
+  t->prev = tt;
+  if (*tt)
+    (*tt)->prev = &t->next;
+  *tt = t;
+}
+
+/* --- @sel_rmtimer@ --- *
+ *
+ * Arguments:	@sel_timer *t@ = pointer to timer block
+ *
+ * Returns:	---
+ *
+ * Use:		Removes a timer from the list of timers.
+ */
+
+void sel_rmtimer(sel_timer *t)
+{
+  if (t->pend) {
+    t->pend->t = 0;
+    t->pend = 0;
+  } else {
+    *t->prev = t->next;
+    if (t->next)
+      t->next->prev = t->prev;
+  }
+}
+
+/* --- @sel_addhook@ --- *
+ *
+ * Arguments:	@sel_state *s@ = pointer to state block
+ *		@sel_hook *h@ = pointer to hook block
+ *		@sel_hookfn before, after@ = hook functions
+ *		@void *p@ = pointer argument to pass to hook functions
+ *
+ * Returns:	---
+ *
+ * Use:		Registers hook functions to be called on each select call.
+ */
+
+void sel_addhook(sel_state *s, sel_hook *h,
+		 sel_hookfn before, sel_hookfn after,
+		 void *p)
+{
+  h->before = before;
+  h->after = after;
+  h->p = p;
+  h->next = s->hooks;
+  h->prev = &s->hooks;
+  if (s->hooks)
+    s->hooks->prev = &h->next;
+  s->hooks = h;
+}
+
+/* --- @sel_rmhook@ --- *
+ *
+ * Arguments:	@sel_hook *h@ = pointer to hook block
+ *
+ * Returns:	---
+ *
+ * Use:		Removes hook functions.
+ */
+
+void sel_rmhook(sel_hook *h)
+{
+  if (h->next)
+    h->next->prev = h->prev;
+  *h->prev = h->next;
+}
+
+/* --- @sel_fdmerge@ --- *
+ *
+ * Arguments:	@fd_set *dest@ = destination FD set
+ *		@fd_set *fd@ = pointer to set to merge
+ *		@int maxfd@ = highest numbered descriptor in @fd@ + 1
+ *
+ * Returns:	Actual highest numbered descriptor.
+ *
+ * Use:		Merges file descriptor sets, and returns an accurate @maxfd@
+ *		value.
+ */
+
+int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd)
+{
+  int i, m = -1;
+
+  for (i = 0; i < maxfd; i++) {
+    if (FD_ISSET(i, fd)) {
+      FD_SET(i, dest);
+      m = i;
+    }
+  }
+
+  return (m + 1);
+}
+
+/* --- @sel_select@ --- *
+ *
+ * Arguments:	@sel_state *s@ = pointer to state block
+ *
+ * Returns:	Zero if all OK, -1 on error.
+ *
+ * Use:		Does a @select@ call (or equivalent @poll@).
+ */
+
+int sel_select(sel_state *s)
+{
+  sel_args a;
+  int err;
+
+  /* --- Initialize the argument block --- */
+
+  {
+    int i;
+    a.maxfd = 0;
+    for (i = 0; i < SEL_MODES; i++) {
+      if (s->files[i] && s->files[i]->fd >= a.maxfd)
+	a.maxfd = s->files[i]->fd + 1;
+    }
+  }
+
+  memcpy(a.fd, s->fd, sizeof(a.fd));
+  if (s->timers || s->hooks)
+    gettimeofday(&a.now, 0);
+  if (!s->timers)
+    a.tvp = 0;
+  else {
+    if (TV_CMP(&s->timers->tv, >, &a.now))
+      TV_SUB(&a.tv, &s->timers->tv, &a.now);
+    else {
+      a.tv.tv_sec = 0;
+      a.tv.tv_usec = 0;
+    }
+    a.tvp = &a.tv;
+  }
+  s->args = &a;
+
+  /* --- Grind through the pre hooks --- */
+
+  {
+    sel_hook *h = s->hooks;
+    while (h) {
+      sel_hook *hh = h;
+      h = h->next;
+      if (hh->before)
+	hh->before(s, &a, hh->p);
+    }
+  }
+
+  /* --- Run the @select@ call --- */
+
+  if ((err = select(a.maxfd,
+		    &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
+		    a.tvp)) < 0) {
+    s->args = 0;
+    return (err);
+  }
+
+  if (a.tvp)
+    gettimeofday(&a.now, 0);
+
+  /* --- Run through the hooks again --- */
+
+  {
+    sel_hook *h = s->hooks;
+    while (h) {
+      sel_hook *hh = h;
+      h = h->next;
+      if (hh->after)
+	hh->after(s, &a, hh->p);
+    }
+  }
+
+  /* --- Run through the timers --- */
+
+  if (s->timers) {
+    ptimer *pthead, *pt, **ptt = &pthead;
+    sel_timer *t;
+
+    for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) {
+      pt = CREATE(ptimer);
+      pt->t = t;
+      t->pend = pt;
+      *ptt = pt;
+      ptt = &pt->next;
+    }
+    *ptt = 0;
+    if (t) {
+      *t->prev = 0;
+      t->prev = &s->timers;
+    }
+    s->timers = t;
+    while (pthead) {
+      pt = pthead;
+      pthead = pt->next;
+      t = pt->t;
+      if (t) {
+	t->pend = 0;
+	t->next = 0;
+	t->prev = &t->next;
+	t->func(&a.now, t->p);
+      }
+      DESTROY(pt);
+    }
+  }
+
+  /* --- And finally run through the files --- *
+   *
+   * Do reads first.  It's quite possible that a read might prompt a write,
+   * but the other way around is less likely.  Fortunately, the modes are
+   * in the right order for this.
+   */
+
+  {
+    int i;
+
+    for (i = 0; i < SEL_MODES; i++) {
+      pfile *pfhead, *pf, **pff = &pfhead;
+      sel_file *f;
+
+      for (f = s->files[i]; f; f = f->next) {
+	if (!FD_ISSET(f->fd, &a.fd[i]))
+	  continue;
+	pf = CREATE(pfile);
+	pf->f = f;
+	f->pend = pf;
+	*pff = pf;
+	pff = &pf->next;
+      }
+      *pff = 0;
+      while (pfhead) {
+	pf = pfhead;
+	pfhead = pf->next;
+	f = pf->f;
+	if (f) {
+	  f->pend = 0;
+	  f->func(f->fd, i, f->p);
+	}
+	DESTROY(pf);
+      }
+    }
+  }
+
+  s->args = 0;
+  return (0);
+}
+
+/*----- That's all, folks -------------------------------------------------*/