ustream.h

   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 #ifndef __USTREAM_H
  20 #define __USTREAM_H
  21
  22 #include <stdarg.h>
  23 #include "uloop.h"
  24
  25 struct ustream;
  26 struct ustream_buf;
  27
  28 enum read_blocked_reason {
  29         READ_BLOCKED_USER = (1 << 0),
  30         READ_BLOCKED_FULL = (1 << 1),
  31 };
  32
  33 struct ustream_buf_list {
  34         struct ustream_buf *head;
  35         struct ustream_buf *data_tail;
  36         struct ustream_buf *tail;
  37
  38         int (*alloc)(struct ustream *s, struct ustream_buf_list *l);
  39
  40         int data_bytes;
  41
  42         int min_buffers;
  43         int max_buffers;
  44         int buffer_len;
  45
  46         int buffers;
  47 };
  48
  49 struct ustream {
  50         struct ustream_buf_list r, w;
  51         struct uloop_timeout state_change;
  52
  53         /*
  54          * notify_read:
  55          * called by the ustream core to notify that new data is available
  56          * for reading.
  57          * must not free the ustream from this callback
  58          */
  59         void (*notify_read)(struct ustream *s, int bytes_new);
  60
  61         /*
  62          * notify_write: (optional)
  63          * called by the ustream core to notify that some buffered data has
  64          * been written to the stream.
  65          * must not free the ustream from this callback
  66          */
  67         void (*notify_write)(struct ustream *s, int bytes);
  68
  69         /*
  70          * notify_state:
  71          * called by the ustream implementation to notify that the read
  72          * side of the stream is closed (eof is set) or there was a write
  73          * error (write_error is set).
  74          * will be called again after the write buffer has been emptied when
  75          * the read side has hit EOF.
  76          */
  77         void (*notify_state)(struct ustream *s);
  78
  79         /*
  80          * write:
  81          * must be defined by ustream implementation, accepts new write data.
  82          * 'more' is used to indicate that a subsequent call will provide more
  83          * data (useful for aggregating writes)
  84          * returns the number of bytes accepted, or -1 if no more writes can
  85          * be accepted (link error)
  86          */
  87         int (*write)(struct ustream *s, const char *buf, int len, bool more);
  88
  89         /*
  90          * free: (optional)
  91          * defined by ustream implementation, tears down the ustream and frees data
  92          */
  93         void (*free)(struct ustream *s);
  94
  95         /*
  96          * set_read_blocked: (optional)
  97          * defined by ustream implementation, called when the read_blocked flag
  98          * changes
  99          */
 100         void (*set_read_blocked)(struct ustream *s);
 101
 102         /*
 103          * ustream user should set this if the input stream is expected
 104          * to contain string data. the core will keep all data 0-terminated.
 105          */
 106         bool string_data;
 107         bool write_error;
 108         bool eof, eof_write_done;
 109
 110         enum read_blocked_reason read_blocked;
 111 };
 112
 113 struct ustream_fd {
 114         struct ustream stream;
 115         struct uloop_fd fd;
 116 };
 117
 118 struct ustream_buf {
 119         struct ustream_buf *next;
 120
 121         char *data;
 122         char *tail;
 123         char *end;
 124
 125         char head[];
 126 };
 127
 128 /* ustream_fd_init: create a file descriptor ustream (uses uloop) */
 129 void ustream_fd_init(struct ustream_fd *s, int fd);
 130
 131 /* ustream_free: free all buffers and data associated with a ustream */
 132 void ustream_free(struct ustream *s);
 133
 134 /* ustream_consume: remove data from the head of the read buffer */
 135 void ustream_consume(struct ustream *s, int len);
 136
 137 /* ustream_write: add data to the write buffer */
 138 int ustream_write(struct ustream *s, const char *buf, int len, bool more);
 139 int ustream_printf(struct ustream *s, const char *format, ...);
 140 int ustream_vprintf(struct ustream *s, const char *format, va_list arg);
 141
 142 /* ustream_get_read_buf: get a pointer to the next read buffer data */
 143 char *ustream_get_read_buf(struct ustream *s, int *buflen);
 144
 145 /*
 146  * ustream_set_read_blocked: set read blocked state
 147  *
 148  * if set, the ustream will no longer fetch pending data.
 149  */
 150 void ustream_set_read_blocked(struct ustream *s, bool set);
 151
 152 static inline bool ustream_read_blocked(struct ustream *s)
 153 {
 154         return !!(s->read_blocked & READ_BLOCKED_USER);
 155 }
 156
 157 /*** --- functions only used by ustream implementations --- ***/
 158
 159 /* ustream_init_defaults: fill default callbacks and options */
 160 void ustream_init_defaults(struct ustream *s);
 161
 162 /*
 163  * ustream_reserve: allocate rx buffer space
 164  *
 165  * len: hint for how much space is needed (not guaranteed to be met)
 166  * maxlen: pointer to where the actual buffer size is going to be stored
 167  */
 168 char *ustream_reserve(struct ustream *s, int len, int *maxlen);
 169
 170 /* ustream_fill_read: mark rx buffer space as filled */
 171 void ustream_fill_read(struct ustream *s, int len);
 172
 173 /*
 174  * ustream_write_pending: attempt to write more data from write buffers
 175  * returns true if all write buffers have been emptied.
 176  */
 177 bool ustream_write_pending(struct ustream *s);
 178
 179 static inline void ustream_state_change(struct ustream *s)
 180 {
 181         uloop_timeout_set(&s->state_change, 0);
 182 }
 183
 184 #endif