contrib/sendmail-8.14/libsm/makebuf.c

   1 /*
   2  * Copyright (c) 2000-2001 Sendmail, Inc. and its suppliers.
   3  *      All rights reserved.
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * By using this file, you agree to the terms and conditions set
  11  * forth in the LICENSE file which can be found at the top level of
  12  * the sendmail distribution.
  13  */
  14
  15 #include <sm/gen.h>
  16 SM_RCSID("@(#)$Id: makebuf.c,v 1.26 2001/10/31 16:04:08 ca Exp $")
  17 #include <stdlib.h>
  18 #include <unistd.h>
  19 #include <sys/types.h>
  20 #include <sys/stat.h>
  21 #include <sm/io.h>
  22 #include <sm/heap.h>
  23 #include <sm/conf.h>
  24 #include "local.h"
  25
  26 /*
  27 **  SM_MAKEBUF -- make a buffer for the file
  28 **
  29 **      Parameters:
  30 **              fp -- the file to be buffered
  31 **
  32 **      Returns:
  33 **              nothing
  34 **
  35 **      Allocate a file buffer, or switch to unbuffered I/O.
  36 **      By default tty devices default to line buffered.
  37 */
  38
  39 void
  40 sm_makebuf(fp)
  41         register SM_FILE_T *fp;
  42 {
  43         register void *p;
  44         register int flags;
  45         size_t size;
  46         int couldbetty;
  47
  48         if (fp->f_flags & SMNBF)
  49         {
  50                 fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
  51                 fp->f_bf.smb_size = 1;
  52                 return;
  53         }
  54         flags = sm_whatbuf(fp, &size, &couldbetty);
  55         if ((p = sm_malloc(size)) == NULL)
  56         {
  57                 fp->f_flags |= SMNBF;
  58                 fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
  59                 fp->f_bf.smb_size = 1;
  60                 return;
  61         }
  62         if (!Sm_IO_DidInit)
  63                 sm_init();
  64         flags |= SMMBF;
  65         fp->f_bf.smb_base = fp->f_p = p;
  66         fp->f_bf.smb_size = size;
  67         if (couldbetty && isatty(fp->f_file))
  68                 flags |= SMLBF;
  69         fp->f_flags |= flags;
  70 }
  71
  72 /*
  73 **  SM_WHATBUF -- determine proper buffer for a file (internal)
  74 **
  75 **  Plus it fills in 'bufsize' for recommended buffer size and
  76 **  fills in flag to indicate if 'fp' could be a tty (nothing
  77 **  to do with "betty" :-) ).
  78 **
  79 **      Parameters:
  80 **              fp -- file pointer to be buffered
  81 **              bufsize -- new buffer size (a return)
  82 **              couldbetty -- could be a tty (returns)
  83 **
  84 **      Returns:
  85 **              Success:
  86 **              on error:
  87 **                      SMNPT -- not seek opimized
  88 **                      SMOPT -- seek opimized
  89 */
  90
  91 int
  92 sm_whatbuf(fp, bufsize, couldbetty)
  93         register SM_FILE_T *fp;
  94         size_t *bufsize;
  95         int *couldbetty;
  96 {
  97         struct stat st;
  98
  99         if (fp->f_file < 0 || fstat(fp->f_file, &st) < 0)
 100         {
 101                 *couldbetty = 0;
 102                 *bufsize = SM_IO_BUFSIZ;
 103                 return SMNPT;
 104         }
 105
 106         /* could be a tty iff it is a character device */
 107         *couldbetty = S_ISCHR(st.st_mode);
 108         if (st.st_blksize == 0)
 109         {
 110                 *bufsize = SM_IO_BUFSIZ;
 111                 return SMNPT;
 112         }
 113
 114 #if SM_IO_MAX_BUF_FILE > 0
 115         if (S_ISREG(st.st_mode) && st.st_blksize > SM_IO_MAX_BUF_FILE)
 116                 st.st_blksize = SM_IO_MAX_BUF_FILE;
 117 #endif /* SM_IO_MAX_BUF_FILE > 0 */
 118
 119 #if SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0
 120         if (!S_ISREG(st.st_mode))
 121         {
 122 # if SM_IO_MAX_BUF > 0
 123                 if (st.st_blksize > SM_IO_MAX_BUF)
 124                         st.st_blksize = SM_IO_MAX_BUF;
 125 #  if SM_IO_MIN_BUF > 0
 126                 else
 127 #  endif /* SM_IO_MIN_BUF > 0 */
 128 # endif /* SM_IO_MAX_BUF > 0 */
 129 # if SM_IO_MIN_BUF > 0
 130                 if (st.st_blksize < SM_IO_MIN_BUF)
 131                         st.st_blksize = SM_IO_MIN_BUF;
 132 # endif /* SM_IO_MIN_BUF > 0 */
 133         }
 134 #endif /* SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0 */
 135
 136         /*
 137         **  Optimise fseek() only if it is a regular file.  (The test for
 138         **  sm_std_seek is mainly paranoia.)  It is safe to set _blksize
 139         **  unconditionally; it will only be used if SMOPT is also set.
 140         */
 141
 142         if ((fp->f_flags & SMSTR) == 0)
 143         {
 144                 *bufsize = st.st_blksize;
 145                 fp->f_blksize = st.st_blksize;
 146         }
 147         else
 148                 *bufsize = SM_IO_BUFSIZ;
 149         if ((st.st_mode & S_IFMT) == S_IFREG &&
 150             fp->f_seek == sm_stdseek)
 151                 return SMOPT;
 152         else
 153                 return SMNPT;
 154 }