| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: lbuf.c,v 1.3 1999/05/22 13:38:50 mdw Exp $ |
| 4 | * |
| 5 | * Block-to-line buffering |
| 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: lbuf.c,v $ |
| 33 | * Revision 1.3 1999/05/22 13:38:50 mdw |
| 34 | * Fix bug which discarded initial portions of incomplete lines. |
| 35 | * |
| 36 | * Revision 1.2 1999/05/17 20:36:08 mdw |
| 37 | * Make the magical constants for the buffer flags uppercase. |
| 38 | * |
| 39 | * Revision 1.1 1999/05/14 21:01:14 mdw |
| 40 | * Integrated `select' handling bits from the background resolver project. |
| 41 | * |
| 42 | */ |
| 43 | |
| 44 | /*----- Header files ------------------------------------------------------*/ |
| 45 | |
| 46 | #include <stdio.h> |
| 47 | #include <stdlib.h> |
| 48 | #include <string.h> |
| 49 | |
| 50 | #include "lbuf.h" |
| 51 | |
| 52 | /*----- Main code ---------------------------------------------------------*/ |
| 53 | |
| 54 | /* --- @lbuf_flush@ --- * |
| 55 | * |
| 56 | * Arguments: @lbuf *b@ = pointer to buffer block |
| 57 | * @char *p@ = pointer to where to start searching |
| 58 | * @size_t len@ = length of new material added |
| 59 | * |
| 60 | * Returns: --- |
| 61 | * |
| 62 | * Use: Flushes any complete lines in a line buffer. New material |
| 63 | * is assumed to have been added starting at @p@. If @p@ is |
| 64 | * null, then the scan starts at the beginning of the buffer, |
| 65 | * and the size of data already in the buffer is used in place |
| 66 | * of @len@. |
| 67 | * |
| 68 | * It is assumed that the buffer is initially enabled. You |
| 69 | * shouldn't be contributing data to a disabled buffer anyway. |
| 70 | * However, the buffer handler may at some point disable itself, |
| 71 | * and @lbuf_flush@ can cope with this eventuality. Any pending |
| 72 | * data is left at the start of the buffer and can be flushed |
| 73 | * out by calling @lbuf_flush(b, 0, 0)@ if the buffer is ever |
| 74 | * re-enabled. |
| 75 | */ |
| 76 | |
| 77 | void lbuf_flush(lbuf *b, char *p, size_t len) |
| 78 | { |
| 79 | char *l; /* Limit of data in buffer */ |
| 80 | char *q; /* Roving pointer through string */ |
| 81 | char *base; /* Base address of current line */ |
| 82 | int cr; /* Carriage return state */ |
| 83 | |
| 84 | /* --- Initialize variables as necessary --- */ |
| 85 | |
| 86 | if (!p) { |
| 87 | p = b->buf; |
| 88 | cr = 0; |
| 89 | len = b->len; |
| 90 | } else |
| 91 | cr = b->f & LBUF_CR; |
| 92 | |
| 93 | l = p + len; |
| 94 | |
| 95 | /* --- Clear @base@ if I'm discarding an overlong line --- */ |
| 96 | |
| 97 | if (b->len == sizeof(b->buf)) |
| 98 | base = 0; |
| 99 | else |
| 100 | base = b->buf; |
| 101 | |
| 102 | /* --- Now I march through the string --- */ |
| 103 | |
| 104 | for (q = p; q < l; q++) { |
| 105 | |
| 106 | /* --- Quickly discard uninteresting characters --- */ |
| 107 | |
| 108 | if (*q != '\r' && *q != '\n') { |
| 109 | cr = 0; |
| 110 | continue; |
| 111 | } |
| 112 | if (*q == '\r') { |
| 113 | cr = 1; |
| 114 | continue; |
| 115 | } |
| 116 | |
| 117 | /* --- Two choices here --- * |
| 118 | * |
| 119 | * I can either be strict about CRLF line ends, or I can be shoddy |
| 120 | * and allow bare LFs. I'll do the latter, although I oughtn't, |
| 121 | * because it makes testing interactively and with Unix text files |
| 122 | * easier. |
| 123 | */ |
| 124 | |
| 125 | #ifdef STRICT_CRLF |
| 126 | if (!cr) |
| 127 | continue; |
| 128 | #endif |
| 129 | |
| 130 | /* --- I have a positive ID on a linefeed --- * |
| 131 | * |
| 132 | * If I'm interested in this string, report it to my owner. |
| 133 | */ |
| 134 | |
| 135 | if (base) { |
| 136 | if (cr) |
| 137 | q[-1] = 0; /* Exercise: why is this safe? */ |
| 138 | else |
| 139 | *q = 0; |
| 140 | b->func(base, b->p); |
| 141 | if (!(b->f & LBUF_ENABLE)) { |
| 142 | base = q + 1; |
| 143 | break; |
| 144 | } |
| 145 | } |
| 146 | base = q + 1; |
| 147 | cr = 0; |
| 148 | } |
| 149 | |
| 150 | /* --- Sift through the aftermath --- */ |
| 151 | |
| 152 | if (base) { |
| 153 | size_t len = l - base; |
| 154 | if (len == sizeof(b->buf)) { |
| 155 | b->buf[len - 1] = 0; |
| 156 | b->func(base, b->p); |
| 157 | } else if (base != b->buf) |
| 158 | memmove(b->buf, base, len); |
| 159 | b->len = len; |
| 160 | if (cr) |
| 161 | b->f |= LBUF_CR; |
| 162 | else |
| 163 | b->f &= ~LBUF_CR; |
| 164 | } |
| 165 | } |
| 166 | |
| 167 | /* --- @lbuf_close@ --- * |
| 168 | * |
| 169 | * Arguments: @lbuf *b@ = pointer to buffer block |
| 170 | * |
| 171 | * Returns: --- |
| 172 | * |
| 173 | * Use: Empties the buffer of any data currently lurking in it, and |
| 174 | * informs the client that this has happened. It's assumed that |
| 175 | * the buffer is enabled: you shouldn't be reading close events |
| 176 | * on disabled buffers. |
| 177 | */ |
| 178 | |
| 179 | void lbuf_close(lbuf *b) |
| 180 | { |
| 181 | if (b->len && b->len != sizeof(b->buf)) { |
| 182 | b->buf[b->len] = 0; |
| 183 | b->func(b->buf, b->p); |
| 184 | } |
| 185 | if (b->f & LBUF_ENABLE) |
| 186 | b->func(0, b->p); |
| 187 | } |
| 188 | |
| 189 | /* --- @lbuf_free@ --- * |
| 190 | * |
| 191 | * Arguments: @lbuf *b@ = pointer to buffer block |
| 192 | * @char **p@ = output pointer to free space |
| 193 | * |
| 194 | * Returns: Free buffer size. |
| 195 | * |
| 196 | * Use: Returns the free portion of a line buffer. Data can then be |
| 197 | * written to this portion, and split out into lines by calling |
| 198 | * @lbuf_flush@. |
| 199 | */ |
| 200 | |
| 201 | size_t lbuf_free(lbuf *b, char **p) |
| 202 | { |
| 203 | /* --- There's a special case to consider --- * |
| 204 | * |
| 205 | * If a line from the file wouldn't fit in the buffer, I truncate it and |
| 206 | * return what would fit. The rest of the line ought to be discarded. |
| 207 | * This condition is signalled by @len = sizeof(buf)@, and means that the |
| 208 | * entire buffer is OK to be trashed. In other cases, @len@ is the amount |
| 209 | * of space currently occupied in the buffer. This special case is the |
| 210 | * reason this routine exists. |
| 211 | */ |
| 212 | |
| 213 | if (b->len != 0 && b->len != sizeof(b->buf)) { |
| 214 | *p = b->buf + b->len; |
| 215 | return (sizeof(b->buf) - b->len); |
| 216 | } else { |
| 217 | *p = b->buf; |
| 218 | return (sizeof(b->buf)); |
| 219 | } |
| 220 | } |
| 221 | |
| 222 | /* --- @lbuf_snarf@ --- * |
| 223 | * |
| 224 | * Arguments: @lbuf *b@ = pointer to buffer block |
| 225 | * @const void *p@ = pointer to input data buffer |
| 226 | * @size_t sz@ = size of data in input buffer |
| 227 | * |
| 228 | * Returns: --- |
| 229 | * |
| 230 | * Use: Snarfs the data from the input buffer and spits it out as |
| 231 | * lines. This interface ignores the complexities of dealing |
| 232 | * with disablement: you should be using @lbuf_free@ to |
| 233 | * contribute data if you want to cope with that. |
| 234 | */ |
| 235 | |
| 236 | void lbuf_snarf(lbuf *b, const void *p, size_t sz) |
| 237 | { |
| 238 | const char *pp = p; |
| 239 | while (sz) { |
| 240 | size_t bsz; |
| 241 | char *bp; |
| 242 | |
| 243 | bsz = lbuf_free(b, &bp); |
| 244 | if (bsz > sz) |
| 245 | bsz = sz; |
| 246 | memcpy(bp, pp, bsz); |
| 247 | lbuf_flush(b, bp, bsz); |
| 248 | pp += bsz; |
| 249 | sz -= bsz; |
| 250 | } |
| 251 | } |
| 252 | |
| 253 | /* --- @lbuf_init@ --- * |
| 254 | * |
| 255 | * Arguments: @lbuf *b@ = pointer to buffer block |
| 256 | * @void (*func)(char *s, void *p)@ = handler function |
| 257 | * @void *p@ = argument pointer for @func@ |
| 258 | * |
| 259 | * Returns: --- |
| 260 | * |
| 261 | * Use: Initializes a line buffer block. Any recognized lines are |
| 262 | * passed to @func@ for processing. |
| 263 | */ |
| 264 | |
| 265 | void lbuf_init(lbuf *b, |
| 266 | void (*func)(char */*s*/, void */*p*/), |
| 267 | void *p) |
| 268 | { |
| 269 | b->func = func; |
| 270 | b->p = p; |
| 271 | b->len = 0; |
| 272 | b->f = LBUF_ENABLE; |
| 273 | } |
| 274 | |
| 275 | /*----- That's all, folks -------------------------------------------------*/ |