release/src/router/udpxy/prbuf.c

   1 /* @(#) formatted printing into a buffer
   2  *
   3  * Copyright 2008-2011 Pavel V. Cherenkov (pcherenkov@gmail.com)
   4  *
   5  *  This file is part of udpxy.
   6  *
   7  *  udpxy is free software: you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation, either version 3 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  udpxy is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with udpxy.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <sys/types.h>
  22 #include <stdarg.h>
  23 #include <stdio.h>
  24 #include <assert.h>
  25 #include <string.h>
  26 #include <stdlib.h>
  27 #include <errno.h>
  28
  29 #include "prbuf.h"
  30
  31 struct printbuf
  32 {
  33     char*   buf;
  34     size_t  len,
  35             pos;
  36 };
  37
  38
  39 int
  40 prbuf_open( prbuf_t* pb, void* buf, size_t n )
  41 {
  42     prbuf_t p = NULL;
  43
  44     assert( pb && buf && (n > (size_t)0) );
  45
  46     p = malloc( sizeof(struct printbuf) );
  47     if( NULL == p ) return -1;
  48
  49     *pb = p;
  50
  51     p->buf = (char*)buf;
  52     p->len = n;
  53     p->pos = 0;
  54
  55     return 0;
  56 }
  57
  58
  59 void
  60 prbuf_rewind( prbuf_t pb )
  61 {
  62     assert( pb );
  63
  64     pb->pos = 0;
  65     pb->buf[0] = '\0';
  66 }
  67
  68
  69
  70 int
  71 prbuf_close( prbuf_t pb )
  72 {
  73     assert( pb );
  74
  75     free( pb );
  76     return 0;
  77 }
  78
  79 size_t
  80 prbuf_len( prbuf_t pb )
  81 {
  82     assert( pb );
  83     return pb->pos;
  84 }
  85
  86 int
  87 prbuf_printf( prbuf_t pb, const char* format, ... )
  88 {
  89     va_list ap;
  90     char* p = NULL;
  91     int n = -1;
  92     size_t left;
  93
  94     assert( pb && format );
  95
  96     if( pb->pos >= pb->len ) return 0;
  97
  98     left = pb->len - pb->pos - 1;
  99     p = pb->buf + pb->pos;
 100
 101     va_start( ap, format );
 102     errno = 0;
 103     n = vsnprintf( p, left, format, ap );
 104     va_end( ap );
 105
 106     if( n < 0 ) return -1;
 107
 108     if( (size_t)n >= left ) {
 109         n = left;
 110     }
 111
 112     p[ n ] = '\0';
 113     pb->pos += (size_t)n;
 114     return n;
 115 }
 116
 117
 118 /* __EOF__ */
 119