mdw@git.distorted.org.uk Git - mLib/blob - selbuf.c

   1 /* -*-c-*-
   2  *
   3  * $Id: selbuf.c,v 1.2 1999/05/17 20:36:50 mdw Exp $
   4  *
   5  * Line-buffering select handler
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the mLib utilities library.
  13  *
  14  * mLib is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * mLib is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with mLib; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: selbuf.c,v $
  33  * Revision 1.2  1999/05/17 20:36:50  mdw
  34  * Make the magical constants for the buffer flags uppercase.
  35  *
  36  * Revision 1.1  1999/05/14 21:01:15  mdw
  37  * Integrated `select' handling bits from the background resolver project.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include <errno.h>
  44 #include <stdio.h>
  45 #include <stdlib.h>
  46 #include <string.h>
  47
  48 #include <sys/types.h>
  49 #include <sys/time.h>
  50 #include <unistd.h>
  51
  52 #include "lbuf.h"
  53 #include "sel.h"
  54 #include "selbuf.h"
  55
  56 /*----- Main code ---------------------------------------------------------*/
  57
  58 /* --- @selbuf_enable@ --- *
  59  *
  60  * Arguments:   @selbuf *b@ = pointer to buffer block
  61  *
  62  * Returns:     ---
  63  *
  64  * Use:         Enables a buffer for reading, and emits any queued lines
  65  *              to the buffer's owner.
  66  */
  67
  68 void selbuf_enable(selbuf *b)
  69 {
  70   if (!(b->b.f & LBUF_ENABLE)) {
  71     b->b.f |= LBUF_ENABLE;
  72     sel_addfile(&b->reader);
  73     lbuf_flush(&b->b, 0, 0);
  74   }
  75 }
  76
  77 /* --- @selbuf_disable@ --- *
  78  *
  79  * Arguments:   @selbuf *b@ = pointer to a buffer block
  80  *
  81  * Returns:     ---
  82  *
  83  * Use:         Disables a buffer.  It won't be read from until it's
  84  *              enabled again.
  85  */
  86
  87 void selbuf_disable(selbuf *b)
  88 {
  89   if (b->b.f & LBUF_ENABLE) {
  90     b->b.f &= ~LBUF_ENABLE;
  91     sel_rmfile(&b->reader);
  92   }
  93 }
  94
  95 /* --- @selbuf_read@ --- *
  96  *
  97  * Arguments:   @int fd@ = file descriptor to read from
  98  *              @int mode@ = what we can do to the file
  99  *              @void *vp@ = pointer to buffer context
 100  *
 101  * Returns:     ---
 102  *
 103  * Use:         Acts on the result of a @select@ call.
 104  */
 105
 106 static void selbuf_read(int fd, unsigned mode, void *vp)
 107 {
 108   selbuf *b = vp;
 109   char *p;
 110   size_t sz;
 111   int n;
 112
 113   sz = lbuf_free(&b->b, &p);
 114 again:
 115   n = read(fd, p, sz);
 116   if (n <= 0) {
 117     switch (errno) {
 118       case EINTR:
 119         goto again;
 120       case EAGAIN:
 121 #if EAGAIN != EWOULDBLOCK
 122       case EWOULDBLOCK:
 123 #endif
 124         return;
 125       default:
 126         lbuf_close(&b->b);
 127     }
 128   }
 129   else
 130     lbuf_flush(&b->b, p, n);
 131 }
 132
 133 /* --- @selbuf_init@ --- *
 134  *
 135  * Arguments:   @selbuf *b@ = pointer to buffer block
 136  *              @sel_state *s@ = pointer to select state to attach to
 137  *              @int fd@ = file descriptor to listen to
 138  *              @void (*func)(char *s, void *p)@ = function to call
 139  *              @void *p@ = argument for function
 140  *
 141  * Returns:     ---
 142  *
 143  * Use:         Initializes a buffer block.
 144  */
 145
 146 void selbuf_init(selbuf *b,
 147                  sel_state *s,
 148                  int fd,
 149                  void (*func)(char */*s*/, void */*p*/),
 150                  void *p)
 151 {
 152   lbuf_init(&b->b, func, p);
 153   b->b.f &= ~LBUF_ENABLE;
 154   sel_initfile(s, &b->reader, fd, SEL_READ, selbuf_read, b);
 155   selbuf_enable(b);
 156 }
 157
 158 /*----- That's all, folks -------------------------------------------------*/