contrib/sendmail-8.14/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 #include <sm/gen.h>
  16 SM_RCSID("@(#)$Id: fget.c,v 1.24 2001/09/11 04:04:48 gshapiro Exp $")
  17 #include <stdlib.h>
  18 #include <string.h>
  19 #include <sm/io.h>
  20 #include <sm/assert.h>
  21 #include "local.h"
  22
  23 /*
  24 **  SM_IO_FGETS -- get a string from a file
  25 **
  26 **  Read at most n-1 characters from the given file.
  27 **  Stop when a newline has been read, or the count ('n') runs out.
  28 **
  29 **      Parameters:
  30 **              fp -- the file to read from
  31 **              timeout -- time to complete reading the string in milliseconds
  32 **              buf -- buffer to place read string in
  33 **              n -- size of 'buf'
  34 **
  35 **      Returns:
  36 **              success: returns value of 'buf'
  37 **              failure: NULL (no characters were read)
  38 **              timeout: NULL and errno set to EAGAIN
  39 **
  40 **      Side Effects:
  41 **              may move the file pointer
  42 */
  43
  44 char *
  45 sm_io_fgets(fp, timeout, buf, n)
  46         register SM_FILE_T *fp;
  47         int timeout;
  48         char *buf;
  49         register int n;
  50 {
  51         register int len;
  52         register char *s;
  53         register unsigned char *p, *t;
  54
  55         SM_REQUIRE_ISA(fp, SmFileMagic);
  56         if (n <= 0)             /* sanity check */
  57                 return NULL;
  58
  59         s = buf;
  60         n--;                    /* leave space for NUL */
  61         while (n > 0)
  62         {
  63                 /* If the buffer is empty, refill it. */
  64                 if ((len = fp->f_r) <= 0)
  65                 {
  66
  67                         /*
  68                         **  Timeout is only passed if we can't get the data
  69                         **  from the buffer (which is counted as immediately).
  70                         */
  71
  72                         if (sm_refill(fp, timeout) != 0)
  73                         {
  74                                 /* EOF/error: stop with partial or no line */
  75                                 if (s == buf)
  76                                         return NULL;
  77                                 break;
  78                         }
  79                         len = fp->f_r;
  80                 }
  81                 p = fp->f_p;
  82
  83                 /*
  84                 **  Scan through at most n bytes of the current buffer,
  85                 **  looking for '\n'.  If found, copy up to and including
  86                 **  newline, and stop.  Otherwise, copy entire chunk
  87                 **  and loop.
  88                 */
  89
  90                 if (len > n)
  91                         len = n;
  92                 t = (unsigned char *) memchr((void *) p, '\n', len);
  93                 if (t != NULL)
  94                 {
  95                         len = ++t - p;
  96                         fp->f_r -= len;
  97                         fp->f_p = t;
  98                         (void) memcpy((void *) s, (void *) p, len);
  99                         s[len] = 0;
 100                         return buf;
 101                 }
 102                 fp->f_r -= len;
 103                 fp->f_p += len;
 104                 (void) memcpy((void *) s, (void *) p, len);
 105                 s += len;
 106                 n -= len;
 107         }
 108         *s = 0;
 109         return buf;
 110 }