usr/src/cmd/sendmail/libsm/fget.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: fget.c,v 1.22 2001/08/27 18:54:14 gshapiro Exp $")
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <sm/io.h>
  22 #include <sm/assert.h>
  23 #include "local.h"
  24
  25 /*
  26 **  SM_IO_FGETS -- get a string from a file
  27 **
  28 **  Read at most n-1 characters from the given file.
  29 **  Stop when a newline has been read, or the count ('n') runs out.
  30 **
  31 **      Parameters:
  32 **              fp -- the file to read from
  33 **              timeout -- time to complete reading the string in milliseconds
  34 **              buf -- buffer to place read string in
  35 **              n -- size of 'buf'
  36 **
  37 **      Returns:
  38 **              success: returns value of 'buf'
  39 **              failure: NULL (no characters were read)
  40 **              timeout: NULL and errno set to EAGAIN
  41 **
  42 **      Side Effects:
  43 **              may move the file pointer
  44 */
  45
  46 char *
  47 sm_io_fgets(fp, timeout, buf, n)
  48         register SM_FILE_T *fp;
  49         int timeout;
  50         char *buf;
  51         register int n;
  52 {
  53         register int len;
  54         register char *s;
  55         register unsigned char *p, *t;
  56
  57         SM_REQUIRE_ISA(fp, SmFileMagic);
  58         if (n <= 0)             /* sanity check */
  59                 return NULL;
  60
  61         s = buf;
  62         n--;                    /* leave space for NUL */
  63         while (n > 0)
  64         {
  65                 /* If the buffer is empty, refill it. */
  66                 if ((len = fp->f_r) <= 0)
  67                 {
  68
  69                         /*
  70                         **  Timeout is only passed if we can't get the data
  71                         **  from the buffer (which is counted as immediately).
  72                         */
  73
  74                         if (sm_refill(fp, timeout) != 0)
  75                         {
  76                                 /* EOF/error: stop with partial or no line */
  77                                 if (s == buf)
  78                                         return NULL;
  79                                 break;
  80                         }
  81                         len = fp->f_r;
  82                 }
  83                 p = fp->f_p;
  84
  85                 /*
  86                 **  Scan through at most n bytes of the current buffer,
  87                 **  looking for '\n'.  If found, copy up to and including
  88                 **  newline, and stop.  Otherwise, copy entire chunk
  89                 **  and loop.
  90                 */
  91
  92                 if (len > n)
  93                         len = n;
  94                 t = (unsigned char *) memchr((void *) p, '\n', len);
  95                 if (t != NULL)
  96                 {
  97                         len = ++t - p;
  98                         fp->f_r -= len;
  99                         fp->f_p = t;
 100                         (void) memcpy((void *) s, (void *) p, len);
 101                         s[len] = 0;
 102                         return buf;
 103                 }
 104                 fp->f_r -= len;
 105                 fp->f_p += len;
 106                 (void) memcpy((void *) s, (void *) p, len);
 107                 s += len;
 108                 n -= len;
 109         }
 110         *s = 0;
 111         return buf;
 112 }