xref: /illumos-gate/usr/src/cmd/sendmail/libsm/fget.c (revision 7c478bd95313f5f23a4c958a745db2134aa03244)
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 }
113