gpxe/src/core/linebuf.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 /**
  22  * @file
  23  *
  24  * Line buffering
  25  *
  26  */
  27
  28 #include <stdint.h>
  29 #include <string.h>
  30 #include <stdlib.h>
  31 #include <errno.h>
  32 #include <gpxe/linebuf.h>
  33
  34 /**
  35  * Retrieve buffered-up line
  36  *
  37  * @v linebuf           Line buffer
  38  * @ret line            Buffered line, or NULL if no line ready to read
  39  */
  40 char * buffered_line ( struct line_buffer *linebuf ) {
  41         return ( linebuf->ready ? linebuf->data : NULL );
  42 }
  43
  44 /**
  45  * Discard line buffer contents
  46  *
  47  * @v linebuf           Line buffer
  48  */
  49 void empty_line_buffer ( struct line_buffer *linebuf ) {
  50         free ( linebuf->data );
  51         linebuf->data = NULL;
  52         linebuf->len = 0;
  53         linebuf->ready = 0;
  54 }
  55
  56 /**
  57  * Buffer up received data by lines
  58  *
  59  * @v linebuf                   Line buffer
  60  * @v data                      New data to add
  61  * @v len                       Length of new data to add
  62  * @ret len                     Consumed length, or negative error number
  63  *
  64  * After calling line_buffer(), use buffered_line() to determine
  65  * whether or not a complete line is available.  Carriage returns and
  66  * newlines will have been stripped, and the line will be
  67  * NUL-terminated.  This buffered line is valid only until the next
  68  * call to line_buffer() (or to empty_line_buffer()).
  69  *
  70  * Note that line buffers use dynamically allocated storage; you
  71  * should call empty_line_buffer() before freeing a @c struct @c
  72  * line_buffer.
  73  */
  74 ssize_t line_buffer ( struct line_buffer *linebuf,
  75                       const char *data, size_t len ) {
  76         const char *eol;
  77         size_t consume;
  78         size_t new_len;
  79         char *new_data;
  80
  81         /* Free any completed line from previous iteration */
  82         if ( linebuf->ready )
  83                 empty_line_buffer ( linebuf );
  84
  85         /* Search for line terminator */
  86         if ( ( eol = memchr ( data, '\n', len ) ) ) {
  87                 consume = ( eol - data + 1 );
  88         } else {
  89                 consume = len;
  90         }
  91
  92         /* Reallocate data buffer and copy in new data */
  93         new_len = ( linebuf->len + consume );
  94         new_data = realloc ( linebuf->data, ( new_len + 1 ) );
  95         if ( ! new_data )
  96                 return -ENOMEM;
  97         memcpy ( ( new_data + linebuf->len ), data, consume );
  98         new_data[new_len] = '\0';
  99         linebuf->data = new_data;
 100         linebuf->len = new_len;
 101
 102         /* If we have reached end of line, trim the line and mark as ready */
 103         if ( eol ) {
 104                 linebuf->data[--linebuf->len] = '\0'; /* trim NL */
 105                 if ( linebuf->data[linebuf->len - 1] == '\r' )
 106                         linebuf->data[--linebuf->len] = '\0'; /* trim CR */
 107                 linebuf->ready = 1;
 108         }
 109
 110         return consume;
 111 }