usr/src/cmd/sendmail/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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  16
  17 #include <sm/gen.h>
  18 SM_RCSID("@(#)$Id: makebuf.c,v 1.26 2001/10/31 16:04:08 ca Exp $")
  19 #include <stdlib.h>
  20 #include <unistd.h>
  21 #include <sys/types.h>
  22 #include <sys/stat.h>
  23 #include <sm/io.h>
  24 #include <sm/heap.h>
  25 #include <sm/conf.h>
  26 #include "local.h"
  27
  28 /*
  29 **  SM_MAKEBUF -- make a buffer for the file
  30 **
  31 **      Parameters:
  32 **              fp -- the file to be buffered
  33 **
  34 **      Returns:
  35 **              nothing
  36 **
  37 **      Allocate a file buffer, or switch to unbuffered I/O.
  38 **      By default tty devices default to line buffered.
  39 */
  40
  41 void
  42 sm_makebuf(fp)
  43         register SM_FILE_T *fp;
  44 {
  45         register void *p;
  46         register int flags;
  47         size_t size;
  48         int couldbetty;
  49
  50         if (fp->f_flags & SMNBF)
  51         {
  52                 fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
  53                 fp->f_bf.smb_size = 1;
  54                 return;
  55         }
  56         flags = sm_whatbuf(fp, &size, &couldbetty);
  57         if ((p = sm_malloc(size)) == NULL)
  58         {
  59                 fp->f_flags |= SMNBF;
  60                 fp->f_bf.smb_base = fp->f_p = fp->f_nbuf;
  61                 fp->f_bf.smb_size = 1;
  62                 return;
  63         }
  64         if (!Sm_IO_DidInit)
  65                 sm_init();
  66         flags |= SMMBF;
  67         fp->f_bf.smb_base = fp->f_p = p;
  68         fp->f_bf.smb_size = size;
  69         if (couldbetty && isatty(fp->f_file))
  70                 flags |= SMLBF;
  71         fp->f_flags |= flags;
  72 }
  73
  74 /*
  75 **  SM_WHATBUF -- determine proper buffer for a file (internal)
  76 **
  77 **  Plus it fills in 'bufsize' for recommended buffer size and
  78 **  fills in flag to indicate if 'fp' could be a tty (nothing
  79 **  to do with "betty" :-) ).
  80 **
  81 **      Parameters:
  82 **              fp -- file pointer to be buffered
  83 **              bufsize -- new buffer size (a return)
  84 **              couldbetty -- could be a tty (returns)
  85 **
  86 **      Returns:
  87 **              Success:
  88 **              on error:
  89 **                      SMNPT -- not seek opimized
  90 **                      SMOPT -- seek opimized
  91 */
  92
  93 int
  94 sm_whatbuf(fp, bufsize, couldbetty)
  95         register SM_FILE_T *fp;
  96         size_t *bufsize;
  97         int *couldbetty;
  98 {
  99         struct stat st;
 100
 101         if (fp->f_file < 0 || fstat(fp->f_file, &st) < 0)
 102         {
 103                 *couldbetty = 0;
 104                 *bufsize = SM_IO_BUFSIZ;
 105                 return SMNPT;
 106         }
 107
 108         /* could be a tty iff it is a character device */
 109         *couldbetty = S_ISCHR(st.st_mode);
 110         if (st.st_blksize == 0)
 111         {
 112                 *bufsize = SM_IO_BUFSIZ;
 113                 return SMNPT;
 114         }
 115
 116 #if SM_IO_MAX_BUF_FILE > 0
 117         if (S_ISREG(st.st_mode) && st.st_blksize > SM_IO_MAX_BUF_FILE)
 118                 st.st_blksize = SM_IO_MAX_BUF_FILE;
 119 #endif /* SM_IO_MAX_BUF_FILE > 0 */
 120
 121 #if SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0
 122         if (!S_ISREG(st.st_mode))
 123         {
 124 # if SM_IO_MAX_BUF > 0
 125                 if (st.st_blksize > SM_IO_MAX_BUF)
 126                         st.st_blksize = SM_IO_MAX_BUF;
 127 #  if SM_IO_MIN_BUF > 0
 128                 else
 129 #  endif /* SM_IO_MIN_BUF > 0 */
 130 # endif /* SM_IO_MAX_BUF > 0 */
 131 # if SM_IO_MIN_BUF > 0
 132                 if (st.st_blksize < SM_IO_MIN_BUF)
 133                         st.st_blksize = SM_IO_MIN_BUF;
 134 # endif /* SM_IO_MIN_BUF > 0 */
 135         }
 136 #endif /* SM_IO_MAX_BUF > 0 || SM_IO_MIN_BUF > 0 */
 137
 138         /*
 139         **  Optimise fseek() only if it is a regular file.  (The test for
 140         **  sm_std_seek is mainly paranoia.)  It is safe to set _blksize
 141         **  unconditionally; it will only be used if SMOPT is also set.
 142         */
 143
 144         if ((fp->f_flags & SMSTR) == 0)
 145         {
 146                 *bufsize = st.st_blksize;
 147                 fp->f_blksize = st.st_blksize;
 148         }
 149         else
 150                 *bufsize = SM_IO_BUFSIZ;
 151         if ((st.st_mode & S_IFMT) == S_IFREG &&
 152             fp->f_seek == sm_stdseek)
 153                 return SMOPT;
 154         else
 155                 return SMNPT;
 156 }