ustream-fd.c

   1 /*
   2  * ustream - library for stream buffer management
   3  *
   4  * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18
  19 #include <unistd.h>
  20 #include <errno.h>
  21 #include <stdio.h>
  22 #include "ustream.h"
  23
  24 static void ustream_fd_set_uloop(struct ustream *s, bool write)
  25 {
  26         struct ustream_fd *sf = container_of(s, struct ustream_fd, stream);
  27         struct ustream_buf *buf;
  28         unsigned int flags = ULOOP_EDGE_TRIGGER;
  29
  30         if (!s->read_blocked && !s->eof)
  31                 flags |= ULOOP_READ;
  32
  33         buf = s->w.head;
  34         if (write || (buf && s->w.data_bytes && !s->write_error))
  35                 flags |= ULOOP_WRITE;
  36
  37         uloop_fd_add(&sf->fd, flags);
  38
  39         if (flags & ULOOP_READ)
  40                 sf->fd.cb(&sf->fd, ULOOP_READ);
  41 }
  42
  43 static void ustream_fd_set_read_blocked(struct ustream *s)
  44 {
  45         ustream_fd_set_uloop(s, false);
  46 }
  47
  48 static void ustream_fd_read_pending(struct ustream_fd *sf, bool *more)
  49 {
  50         struct ustream *s = &sf->stream;
  51         int buflen = 0;
  52         ssize_t len;
  53         char *buf;
  54
  55         do {
  56                 buf = ustream_reserve(s, 1, &buflen);
  57                 if (!buf)
  58                         break;
  59
  60                 len = read(sf->fd.fd, buf, buflen);
  61                 if (len < 0) {
  62                         if (errno == EINTR)
  63                                 continue;
  64
  65                         if (errno == EAGAIN)
  66                                 return;
  67
  68                         len = 0;
  69                 }
  70
  71                 if (!len) {
  72                         sf->fd.eof = true;
  73                         return;
  74                 }
  75
  76                 ustream_fill_read(s, len);
  77                 *more = true;
  78         } while (1);
  79 }
  80
  81 static int ustream_fd_write(struct ustream *s, const char *buf, int buflen, bool more)
  82 {
  83         struct ustream_fd *sf = container_of(s, struct ustream_fd, stream);
  84         ssize_t len;
  85
  86         if (!buflen)
  87                 return 0;
  88
  89 retry:
  90         len = write(sf->fd.fd, buf, buflen);
  91         if (!len)
  92                 goto retry;
  93
  94         if (len < 0) {
  95                 if (errno == EINTR)
  96                         goto retry;
  97
  98                 if (errno == EAGAIN || errno == EWOULDBLOCK)
  99                         len = 0;
 100         }
 101
 102         if (len >= 0 && len < buflen)
 103                 ustream_fd_set_uloop(s, true);
 104
 105         return len;
 106 }
 107
 108 static bool __ustream_fd_poll(struct ustream_fd *sf, unsigned int events)
 109 {
 110         struct ustream *s = &sf->stream;
 111         struct uloop_fd *fd = &sf->fd;
 112         bool more = false;
 113
 114         if (events & ULOOP_READ)
 115                 ustream_fd_read_pending(sf, &more);
 116
 117         if (events & ULOOP_WRITE) {
 118                 if (!ustream_write_pending(s))
 119                         ustream_fd_set_uloop(s, false);
 120         }
 121
 122         if (!s->eof && fd->eof) {
 123                 s->eof = true;
 124                 ustream_fd_set_uloop(s, false);
 125                 ustream_state_change(s);
 126         }
 127
 128         return more;
 129 }
 130
 131 static bool ustream_fd_poll(struct ustream *s)
 132 {
 133         struct ustream_fd *sf = container_of(s, struct ustream_fd, stream);
 134
 135         return __ustream_fd_poll(sf, ULOOP_READ | ULOOP_WRITE);
 136 }
 137
 138 static void ustream_uloop_cb(struct uloop_fd *fd, unsigned int events)
 139 {
 140         struct ustream_fd *sf = container_of(fd, struct ustream_fd, fd);
 141
 142         __ustream_fd_poll(sf, events);
 143 }
 144
 145 static void ustream_fd_free(struct ustream *s)
 146 {
 147         struct ustream_fd *sf = container_of(s, struct ustream_fd, stream);
 148
 149         uloop_fd_delete(&sf->fd);
 150 }
 151
 152 void ustream_fd_init(struct ustream_fd *sf, int fd)
 153 {
 154         struct ustream *s = &sf->stream;
 155
 156         ustream_init_defaults(s);
 157
 158         sf->fd.fd = fd;
 159         sf->fd.cb = ustream_uloop_cb;
 160         s->set_read_blocked = ustream_fd_set_read_blocked;
 161         s->write = ustream_fd_write;
 162         s->free = ustream_fd_free;
 163         s->poll = ustream_fd_poll;
 164         ustream_fd_set_uloop(s, false);
 165 }