refill.c revision 261363 
1/*
2 * Copyright (c) 2000-2001, 2005-2006 Proofpoint, 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>
16SM_RCSID("@(#)$Id: refill.c,v 1.54 2013/11/22 20:51:43 ca Exp $")
17#include <stdlib.h>
18#include <unistd.h>
19#include <errno.h>
20#include <setjmp.h>
21#include <signal.h>
22#include <sm/time.h>
23#include <fcntl.h>
24#include <string.h>
25#include <sm/io.h>
26#include <sm/conf.h>
27#include <sm/assert.h>
28#include "local.h"
29
30static int sm_lflush __P((SM_FILE_T *, int *));
31
32/*
33**  SM_IO_RD_TIMEOUT -- measured timeout for reads
34**
35**  This #define uses a select() to wait for the 'fd' to become readable.
36**  The select() can be active for up to 'To' time. The select() may not
37**  use all of the the 'To' time. Hence, the amount of "wall-clock" time is
38**  measured to decide how much to subtract from 'To' to update it. On some
39**  BSD-based/like systems the timeout for a select() is updated for the
40**  amount of time used. On many/most systems this does not happen. Therefore
41**  the updating of 'To' must be done ourselves; a copy of 'To' is passed
42**  since a BSD-like system will have updated it and we don't want to
43**  double the time used!
44**  Note: if a valid 'fd' doesn't exist yet, don't use this (e.g. the
45**  sendmail buffered file type in sendmail/bf.c; see use below).
46**
47**	Parameters
48**		fp -- the file pointer for the active file
49**		fd -- raw file descriptor (from 'fp') to use for select()
50**		to -- struct timeval of the timeout
51**		timeout -- the original timeout value
52**		sel_ret -- the return value from the select()
53**
54**	Returns:
55**		nothing, flow through code
56*/
57
58#define SM_IO_RD_TIMEOUT(fp, fd, to, timeout, sel_ret)			\
59{									\
60	struct timeval sm_io_to_before, sm_io_to_after, sm_io_to_diff;	\
61	fd_set sm_io_to_mask, sm_io_x_mask;				\
62	errno = 0;							\
63	if (timeout == SM_TIME_IMMEDIATE)				\
64	{								\
65		errno = EAGAIN;						\
66		return SM_IO_EOF;					\
67	}								\
68	if (FD_SETSIZE > 0 && (fd) >= FD_SETSIZE)			\
69	{								\
70		errno = EINVAL;						\
71		return SM_IO_EOF;					\
72	}								\
73	FD_ZERO(&sm_io_to_mask);					\
74	FD_SET((fd), &sm_io_to_mask);					\
75	FD_ZERO(&sm_io_x_mask);						\
76	FD_SET((fd), &sm_io_x_mask);					\
77	if (gettimeofday(&sm_io_to_before, NULL) < 0)			\
78		return SM_IO_EOF;					\
79	do								\
80	{								\
81		(sel_ret) = select((fd) + 1, &sm_io_to_mask, NULL,	\
82			   	&sm_io_x_mask, (to));			\
83	} while ((sel_ret) < 0 && errno == EINTR);			\
84	if ((sel_ret) < 0)						\
85	{								\
86		/* something went wrong, errno set */			\
87		fp->f_r = 0;						\
88		fp->f_flags |= SMERR;					\
89		return SM_IO_EOF;					\
90	}								\
91	else if ((sel_ret) == 0)					\
92	{								\
93		/* timeout */						\
94		errno = EAGAIN;						\
95		return SM_IO_EOF;					\
96	}								\
97	/* calulate wall-clock time used */				\
98	if (gettimeofday(&sm_io_to_after, NULL) < 0)			\
99		return SM_IO_EOF;					\
100	timersub(&sm_io_to_after, &sm_io_to_before, &sm_io_to_diff);	\
101	timersub((to), &sm_io_to_diff, (to));				\
102}
103
104/*
105**  SM_LFLUSH -- flush a file if it is line buffered and writable
106**
107**	Parameters:
108**		fp -- file pointer to flush
109**		timeout -- original timeout value (in milliseconds)
110**
111**	Returns:
112**		Failure: returns SM_IO_EOF and sets errno
113**		Success: returns 0
114*/
115
116static int
117sm_lflush(fp, timeout)
118	SM_FILE_T *fp;
119	int *timeout;
120{
121
122	if ((fp->f_flags & (SMLBF|SMWR)) == (SMLBF|SMWR))
123		return sm_flush(fp, timeout);
124	return 0;
125}
126
127/*
128**  SM_REFILL -- refill a buffer
129**
130**	Parameters:
131**		fp -- file pointer for buffer refill
132**		timeout -- time to complete filling the buffer in milliseconds
133**
134**	Returns:
135**		Success: returns 0
136**		Failure: returns SM_IO_EOF
137*/
138
139int
140sm_refill(fp, timeout)
141	register SM_FILE_T *fp;
142	int timeout;
143{
144	int ret, r;
145	struct timeval to;
146	int fd;
147
148	if (timeout == SM_TIME_DEFAULT)
149		timeout = fp->f_timeout;
150	if (timeout == SM_TIME_IMMEDIATE)
151	{
152		/*
153		**  Filling the buffer will take time and we are wanted to
154		**  return immediately. And we're not EOF or ERR really.
155		**  So... the failure is we couldn't do it in time.
156		*/
157
158		errno = EAGAIN;
159		fp->f_r = 0; /* just to be sure */
160		return 0;
161	}
162
163	/* make sure stdio is set up */
164	if (!Sm_IO_DidInit)
165		sm_init();
166
167	fp->f_r = 0;		/* largely a convenience for callers */
168
169	if (fp->f_flags & SMFEOF)
170		return SM_IO_EOF;
171
172	SM_CONVERT_TIME(fp, fd, timeout, &to);
173
174	/* if not already reading, have to be reading and writing */
175	if ((fp->f_flags & SMRD) == 0)
176	{
177		if ((fp->f_flags & SMRW) == 0)
178		{
179			errno = EBADF;
180			fp->f_flags |= SMERR;
181			return SM_IO_EOF;
182		}
183
184		/* switch to reading */
185		if (fp->f_flags & SMWR)
186		{
187			if (sm_flush(fp, &timeout))
188				return SM_IO_EOF;
189			fp->f_flags &= ~SMWR;
190			fp->f_w = 0;
191			fp->f_lbfsize = 0;
192		}
193		fp->f_flags |= SMRD;
194	}
195	else
196	{
197		/*
198		**  We were reading.  If there is an ungetc buffer,
199		**  we must have been reading from that.  Drop it,
200		**  restoring the previous buffer (if any).  If there
201		**  is anything in that buffer, return.
202		*/
203
204		if (HASUB(fp))
205		{
206			FREEUB(fp);
207			if ((fp->f_r = fp->f_ur) != 0)
208			{
209				fp->f_p = fp->f_up;
210
211				/* revert blocking state */
212				return 0;
213			}
214		}
215	}
216
217	if (fp->f_bf.smb_base == NULL)
218		sm_makebuf(fp);
219
220	/*
221	**  Before reading from a line buffered or unbuffered file,
222	**  flush all line buffered output files, per the ANSI C standard.
223	*/
224
225	if (fp->f_flags & (SMLBF|SMNBF))
226		(void) sm_fwalk(sm_lflush, &timeout);
227
228	/*
229	**  If this file is linked to another, and we are going to hang
230	**  on the read, flush the linked file before continuing.
231	*/
232
233	if (fp->f_flushfp != NULL &&
234	    (*fp->f_getinfo)(fp, SM_IO_IS_READABLE, NULL) <= 0)
235		sm_flush(fp->f_flushfp, &timeout);
236
237	fp->f_p = fp->f_bf.smb_base;
238
239	/*
240	**  The do-while loop stops trying to read when something is read
241	**  or it appears that the timeout has expired before finding
242	**  something available to be read (via select()).
243	*/
244
245	ret = 0;
246	do
247	{
248		errno = 0; /* needed to ensure EOF correctly found */
249		r = (*fp->f_read)(fp, (char *)fp->f_p, fp->f_bf.smb_size);
250		if (r <= 0)
251		{
252			if (r == 0 && errno == 0)
253				break; /* EOF found */
254			if (IS_IO_ERROR(fd, r, timeout))
255				goto err; /* errno set */
256
257			/* read would block */
258			SM_IO_RD_TIMEOUT(fp, fd, &to, timeout, ret);
259		}
260	} while (r <= 0 && ret > 0);
261
262err:
263	if (r <= 0)
264	{
265		if (r == 0)
266			fp->f_flags |= SMFEOF;
267		else
268			fp->f_flags |= SMERR;
269		fp->f_r = 0;
270		return SM_IO_EOF;
271	}
272	fp->f_r = r;
273	return 0;
274}
275
276/*
277**  SM_RGET -- refills buffer and returns first character
278**
279**  Handle sm_getc() when the buffer ran out:
280**  Refill, then return the first character in the newly-filled buffer.
281**
282**	Parameters:
283**		fp -- file pointer to work on
284**		timeout -- time to complete refill
285**
286**	Returns:
287**		Success: first character in refilled buffer as an int
288**		Failure: SM_IO_EOF
289*/
290
291int
292sm_rget(fp, timeout)
293	register SM_FILE_T *fp;
294	int timeout;
295{
296	if (sm_refill(fp, timeout) == 0)
297	{
298		fp->f_r--;
299		return *fp->f_p++;
300	}
301	return SM_IO_EOF;
302}
303