1 /*	$OpenBSD: buf.c,v 1.27 2016/10/16 13:35:51 okan Exp $	*/
2 /*
3  * Copyright (c) 2003 Jean-Francois Brousseau <jfb@openbsd.org>
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  *
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. The name of the author may not be used to endorse or promote products
13  *    derived from this software without specific prior written permission.
14  *
15  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
16  * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
17  * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
18  * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
19  * EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLUDING, BUT NOT LIMITED TO,
20  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
21  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
22  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
23  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
24  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include <sys/queue.h>
28 #include <sys/stat.h>
29 
30 #include <err.h>
31 #include <errno.h>
32 #include <fcntl.h>
33 #include <stdint.h>
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <unistd.h>
38 
39 #include "buf.h"
40 #include "xmalloc.h"
41 #include "worklist.h"
42 
43 #define BUF_INCR	128
44 
45 struct buf {
46 	/* buffer handle, buffer size, and data length */
47 	u_char	*cb_buf;
48 	size_t	 cb_size;
49 	size_t	 cb_len;
50 };
51 
52 #define SIZE_LEFT(b)	(b->cb_size - b->cb_len)
53 
54 static void	buf_grow(BUF *, size_t);
55 
56 /*
57  * Create a new buffer structure and return a pointer to it.  This structure
58  * uses dynamically-allocated memory and must be freed with buf_free(), once
59  * the buffer is no longer needed.
60  */
61 BUF *
62 buf_alloc(size_t len)
63 {
64 	BUF *b;
65 
66 	b = xmalloc(sizeof(*b));
67 	/* Postpone creation of zero-sized buffers */
68 	if (len > 0)
69 		b->cb_buf = xcalloc(1, len);
70 	else
71 		b->cb_buf = NULL;
72 
73 	b->cb_size = len;
74 	b->cb_len = 0;
75 
76 	return (b);
77 }
78 
79 /*
80  * Open the file specified by <path> and load all of its contents into a
81  * buffer.
82  * Returns the loaded buffer on success or NULL on failure.
83  * Sets errno on error.
84  */
85 BUF *
86 buf_load(const char *path)
87 {
88 	int fd;
89 	ssize_t ret;
90 	size_t len;
91 	u_char *bp;
92 	struct stat st;
93 	BUF *buf;
94 
95 	buf = NULL;
96 
97 	if ((fd = open(path, O_RDONLY, 0600)) == -1)
98 		goto out;
99 
100 	if (fstat(fd, &st) == -1)
101 		goto out;
102 
103 	if ((uintmax_t)st.st_size > SIZE_MAX) {
104 		errno = EFBIG;
105 		goto out;
106 	}
107 	buf = buf_alloc(st.st_size);
108 	for (bp = buf->cb_buf; ; bp += (size_t)ret) {
109 		len = SIZE_LEFT(buf);
110 		ret = read(fd, bp, len);
111 		if (ret == -1) {
112 			int saved_errno;
113 
114 			saved_errno = errno;
115 			buf_free(buf);
116 			buf = NULL;
117 			errno = saved_errno;
118 			goto out;
119 		} else if (ret == 0)
120 			break;
121 
122 		buf->cb_len += (size_t)ret;
123 	}
124 
125 out:
126 	if (fd != -1) {
127 		int saved_errno;
128 
129 		/* We may want to preserve errno here. */
130 		saved_errno = errno;
131 		(void)close(fd);
132 		errno = saved_errno;
133 	}
134 
135 	return (buf);
136 }
137 
138 void
139 buf_free(BUF *b)
140 {
141 	if (b == NULL)
142 		return;
143 	free(b->cb_buf);
144 	free(b);
145 }
146 
147 /*
148  * Free the buffer <b>'s structural information but do not free the contents
149  * of the buffer.  Instead, they are returned and should be freed later using
150  * free().
151  */
152 void *
153 buf_release(BUF *b)
154 {
155 	void *tmp;
156 
157 	tmp = b->cb_buf;
158 	free(b);
159 	return (tmp);
160 }
161 
162 u_char *
163 buf_get(BUF *b)
164 {
165 	return (b->cb_buf);
166 }
167 
168 /*
169  * Empty the contents of the buffer <b> and reset pointers.
170  */
171 void
172 buf_empty(BUF *b)
173 {
174 	memset(b->cb_buf, 0, b->cb_size);
175 	b->cb_len = 0;
176 }
177 
178 /*
179  * Append a single character <c> to the end of the buffer <b>.
180  */
181 void
182 buf_putc(BUF *b, int c)
183 {
184 	u_char *bp;
185 
186 	if (SIZE_LEFT(b) == 0)
187 		buf_grow(b, BUF_INCR);
188 	bp = b->cb_buf + b->cb_len;
189 	*bp = (u_char)c;
190 	b->cb_len++;
191 }
192 
193 /*
194  * Append a string <s> to the end of buffer <b>.
195  */
196 void
197 buf_puts(BUF *b, const char *str)
198 {
199 	buf_append(b, str, strlen(str));
200 }
201 
202 /*
203  * Return u_char at buffer position <pos>.
204  */
205 u_char
206 buf_getc(BUF *b, size_t pos)
207 {
208 	return (b->cb_buf[pos]);
209 }
210 
211 /*
212  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
213  * buffer is too small to accept all data, it will get resized to an
214  * appropriate size to accept all data.
215  * Returns the number of bytes successfully appended to the buffer.
216  */
217 size_t
218 buf_append(BUF *b, const void *data, size_t len)
219 {
220 	size_t left, rlen;
221 	u_char *bp;
222 
223 	left = SIZE_LEFT(b);
224 	rlen = len;
225 
226 	if (left < len)
227 		buf_grow(b, len - left);
228 	bp = b->cb_buf + b->cb_len;
229 	memcpy(bp, data, rlen);
230 	b->cb_len += rlen;
231 
232 	return (rlen);
233 }
234 
235 /*
236  * Returns the size of the buffer that is being used.
237  */
238 size_t
239 buf_len(BUF *b)
240 {
241 	return (b->cb_len);
242 }
243 
244 /*
245  * Write the contents of the buffer <b> to the specified <fd>
246  */
247 int
248 buf_write_fd(BUF *b, int fd)
249 {
250 	u_char *bp;
251 	size_t len;
252 	ssize_t ret;
253 
254 	len = b->cb_len;
255 	bp = b->cb_buf;
256 
257 	do {
258 		ret = write(fd, bp, len);
259 		if (ret == -1) {
260 			if (errno == EINTR || errno == EAGAIN)
261 				continue;
262 			return (-1);
263 		}
264 
265 		len -= (size_t)ret;
266 		bp += (size_t)ret;
267 	} while (len > 0);
268 
269 	return (0);
270 }
271 
272 /*
273  * Write the contents of the buffer <b> to the file whose path is given in
274  * <path>.  If the file does not exist, it is created with mode <mode>.
275  */
276 int
277 buf_write(BUF *b, const char *path, mode_t mode)
278 {
279 	int fd;
280  open:
281 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)) == -1) {
282 		if (errno == EACCES && unlink(path) != -1)
283 			goto open;
284 		else
285 			err(1, "%s", path);
286 	}
287 
288 	if (buf_write_fd(b, fd) == -1) {
289 		(void)unlink(path);
290 		errx(1, "buf_write: buf_write_fd: `%s'", path);
291 	}
292 
293 	if (fchmod(fd, mode) < 0)
294 		warn("permissions not set on file %s", path);
295 
296 	(void)close(fd);
297 
298 	return (0);
299 }
300 
301 /*
302  * Write the contents of the buffer <b> to a temporary file whose path is
303  * specified using <template> (see mkstemp.3).
304  * NB. This function will modify <template>, as per mkstemp
305  */
306 void
307 buf_write_stmp(BUF *b, char *template)
308 {
309 	int fd;
310 
311 	if ((fd = mkstemp(template)) == -1)
312 		err(1, "%s", template);
313 
314 	worklist_add(template, &temp_files);
315 
316 	if (buf_write_fd(b, fd) == -1) {
317 		(void)unlink(template);
318 		errx(1, "buf_write_stmp: buf_write_fd: `%s'", template);
319 	}
320 
321 	(void)close(fd);
322 }
323 
324 /*
325  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
326  * operation regardless of the result.
327  */
328 static void
329 buf_grow(BUF *b, size_t len)
330 {
331 	b->cb_buf = xreallocarray(b->cb_buf, 1, b->cb_size + len);
332 	b->cb_size += len;
333 }