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 /**
  20  * @file
  21  *
  22  * Line buffering
  23  *
  24  */
  25
  26 #include <stdint.h>
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <errno.h>
  30 #include <gpxe/linebuf.h>
  31
  32 /**
  33  * Retrieve buffered-up line
  34  *
  35  * @v linebuf           Line buffer
  36  * @ret line            Buffered line, or NULL if no line ready to read
  37  */
  38 char * buffered_line ( struct line_buffer *linebuf ) {
  39         return ( linebuf->ready ? linebuf->data : NULL );
  40 }
  41
  42 /**
  43  * Discard line buffer contents
  44  *
  45  * @v linebuf           Line buffer
  46  */
  47 void empty_line_buffer ( struct line_buffer *linebuf ) {
  48         free ( linebuf->data );
  49         linebuf->data = NULL;
  50         linebuf->len = 0;
  51         linebuf->ready = 0;
  52 }
  53
  54 /**
  55  * Buffer up received data by lines
  56  *
  57  * @v linebuf                   Line buffer
  58  * @v data                      New data to add
  59  * @v len                       Length of new data to add
  60  * @ret len                     Consumed length, or negative error number
  61  *
  62  * After calling line_buffer(), use buffered_line() to determine
  63  * whether or not a complete line is available.  Carriage returns and
  64  * newlines will have been stripped, and the line will be
  65  * NUL-terminated.  This buffered line is valid only until the next
  66  * call to line_buffer() (or to empty_line_buffer()).
  67  *
  68  * Note that line buffers use dynamically allocated storage; you
  69  * should call empty_line_buffer() before freeing a @c struct @c
  70  * line_buffer.
  71  */
  72 ssize_t line_buffer ( struct line_buffer *linebuf,
  73                       const char *data, size_t len ) {
  74         const char *eol;
  75         size_t consume;
  76         size_t new_len;
  77         char *new_data;
  78
  79         /* Free any completed line from previous iteration */
  80         if ( linebuf->ready )
  81                 empty_line_buffer ( linebuf );
  82
  83         /* Search for line terminator */
  84         if ( ( eol = memchr ( data, '\n', len ) ) ) {
  85                 consume = ( eol - data + 1 );
  86         } else {
  87                 consume = len;
  88         }
  89
  90         /* Reallocate data buffer and copy in new data */
  91         new_len = ( linebuf->len + consume );
  92         new_data = realloc ( linebuf->data, ( new_len + 1 ) );
  93         if ( ! new_data )
  94                 return -ENOMEM;
  95         memcpy ( ( new_data + linebuf->len ), data, consume );
  96         new_data[new_len] = '\0';
  97         linebuf->data = new_data;
  98         linebuf->len = new_len;
  99
 100         /* If we have reached end of line, trim the line and mark as ready */
 101         if ( eol ) {
 102                 linebuf->data[--linebuf->len] = '\0'; /* trim NL */
 103                 if ( linebuf->data[linebuf->len - 1] == '\r' )
 104                         linebuf->data[--linebuf->len] = '\0'; /* trim CR */
 105                 linebuf->ready = 1;
 106         }
 107
 108         return consume;
 109 }