lib/libstdbuf/stdbuf.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
   3  *
   4  * Copyright (c) 2012 Jeremie Le Hen <jlh@FreeBSD.org>
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  26  * SUCH DAMAGE.
  27  *
  28  * $FreeBSD$
  29  */
  30
  31 #include <err.h>
  32 #include <errno.h>
  33 #include <limits.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37
  38 static const char *
  39 stream_name(FILE *s)
  40 {
  41
  42         if (s == stdin)
  43                 return "stdin";
  44         if (s == stdout)
  45                 return "stdout";
  46         if (s == stderr)
  47                 return "stderr";
  48         /* This should not happen. */
  49         abort();
  50 }
  51
  52 static void
  53 change_buf(FILE *s, const char *bufmode)
  54 {
  55         char *unit;
  56         size_t bufsize;
  57         int mode;
  58
  59         bufsize = 0;
  60         if (bufmode[0] == '0' && bufmode[1] == '\0')
  61                 mode = _IONBF;
  62         else if (bufmode[0] == 'L' && bufmode[1] == '\0')
  63                 mode = _IOLBF;
  64         else if (bufmode[0] == 'B' && bufmode[1] == '\0') {
  65                 mode = _IOFBF;
  66                 bufsize = 0;
  67         } else {
  68                 /*
  69                  * This library being preloaded, depending on libutil
  70                  * would lead to excessive namespace pollution.
  71                  * Thus we do not use expand_number().
  72                  */
  73                 errno = 0;
  74                 bufsize = strtol(bufmode, &unit, 0);
  75                 if (errno == EINVAL || errno == ERANGE || unit == bufmode)
  76                         warn("Wrong buffer mode '%s' for %s", bufmode,
  77                             stream_name(s));
  78                 switch (*unit) {
  79                 case 'G':
  80                         bufsize *= 1024 * 1024 * 1024;
  81                         break;
  82                 case 'M':
  83                         bufsize *= 1024 * 1024;
  84                         break;
  85                 case 'k':
  86                         bufsize *= 1024;
  87                         break;
  88                 case '\0':
  89                         break;
  90                 default:
  91                         warnx("Unknown suffix '%c' for %s", *unit,
  92                             stream_name(s));
  93                         return;
  94                 }
  95                 mode = _IOFBF;
  96         }
  97         if (setvbuf(s, NULL, mode, bufsize) != 0)
  98                 warn("Cannot set buffer mode '%s' for %s", bufmode,
  99                     stream_name(s));
 100 }
 101
 102 __attribute__ ((constructor)) static void
 103 stdbuf(void)
 104 {
 105         char *i_mode, *o_mode, *e_mode;
 106
 107         i_mode = getenv("_STDBUF_I");
 108         o_mode = getenv("_STDBUF_O");
 109         e_mode = getenv("_STDBUF_E");
 110
 111         if (e_mode != NULL)
 112                 change_buf(stderr, e_mode);
 113         if (i_mode != NULL)
 114                 change_buf(stdin, i_mode);
 115         if (o_mode != NULL)
 116                 change_buf(stdout, o_mode);
 117 }