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 <errno.h>
31 #include <fcntl.h>
32 #include <stdint.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <unistd.h>
37 
38 #include "buf.h"
39 
40 #include "got_error.h"
41 
42 #define BUF_INCR	128
43 
44 #define SIZE_LEFT(b)	((b)->cb_size - (b)->cb_len)
45 
46 static const struct got_error *buf_grow(BUF *, size_t);
47 
48 /*
49  * Create a new buffer structure and return a pointer to it.  This structure
50  * uses dynamically-allocated memory and must be freed with buf_free(), once
51  * the buffer is no longer needed.
52  */
53 const struct got_error *
54 buf_alloc(BUF **b, size_t len)
55 {
56 	const struct got_error *err = NULL;
57 
58 	*b = malloc(sizeof(**b));
59 	if (*b == NULL)
60 		return NULL;
61 	/* Postpone creation of zero-sized buffers */
62 	if (len > 0) {
63 		(*b)->cb_buf = calloc(1, len);
64 		if ((*b)->cb_buf == NULL) {
65 			err = got_error_from_errno("calloc");
66 			free(*b);
67 			*b = NULL;
68 			return err;
69 		}
70 	} else
71 		(*b)->cb_buf = NULL;
72 
73 	(*b)->cb_size = len;
74 	(*b)->cb_len = 0;
75 
76 	return NULL;
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 const struct got_error *
86 buf_load(BUF **buf, const char *path)
87 {
88 	const struct got_error *err = NULL;
89 	int fd;
90 	ssize_t ret;
91 	size_t len;
92 	u_char *bp;
93 	struct stat st;
94 
95 	*buf = NULL;
96 
97 	fd = open(path, O_RDONLY, 0600);
98 	if (fd == -1)
99 		return got_error_from_errno2("open", path);
100 
101 	if (fstat(fd, &st) == -1) {
102 		err = got_error_from_errno2("fstat", path);
103 		goto out;
104 	}
105 
106 	if ((uintmax_t)st.st_size > SIZE_MAX) {
107 		err = got_error_set_errno(EFBIG, path);
108 		goto out;
109 	}
110 	err = buf_alloc(buf, st.st_size);
111 	if (err)
112 		goto out;
113 	for (bp = (*buf)->cb_buf; ; bp += (size_t)ret) {
114 		len = SIZE_LEFT(*buf);
115 		ret = read(fd, bp, len);
116 		if (ret == -1) {
117 			err = got_error_from_errno2("read", path);
118 			goto out;
119 		} else if (ret == 0)
120 			break;
121 
122 		(*buf)->cb_len += (size_t)ret;
123 	}
124 
125 out:
126 	if (close(fd) == -1 && err == NULL)
127 		err = got_error_from_errno2("close", path);
128 	if (err) {
129 		buf_free(*buf);
130 		*buf = NULL;
131 	}
132 	return err;
133 }
134 
135 void
136 buf_free(BUF *b)
137 {
138 	if (b == NULL)
139 		return;
140 	free(b->cb_buf);
141 	free(b);
142 }
143 
144 /*
145  * Free the buffer <b>'s structural information but do not free the contents
146  * of the buffer.  Instead, they are returned and should be freed later using
147  * free().
148  */
149 void *
150 buf_release(BUF *b)
151 {
152 	void *tmp;
153 
154 	tmp = b->cb_buf;
155 	free(b);
156 	return (tmp);
157 }
158 
159 u_char *
160 buf_get(BUF *b)
161 {
162 	return (b->cb_buf);
163 }
164 
165 /*
166  * Empty the contents of the buffer <b> and reset pointers.
167  */
168 void
169 buf_empty(BUF *b)
170 {
171 	memset(b->cb_buf, 0, b->cb_size);
172 	b->cb_len = 0;
173 }
174 
175 /*
176  * Append a single character <c> to the end of the buffer <b>.
177  */
178 const struct got_error *
179 buf_putc(BUF *b, int c)
180 {
181 	const struct got_error *err = NULL;
182 	u_char *bp;
183 
184 	if (SIZE_LEFT(b) == 0) {
185 		err = buf_grow(b, BUF_INCR);
186 		if (err)
187 			return err;
188 	}
189 	bp = b->cb_buf + b->cb_len;
190 	*bp = (u_char)c;
191 	b->cb_len++;
192 	return NULL;
193 }
194 
195 /*
196  * Append a string <s> to the end of buffer <b>.
197  */
198 const struct got_error *
199 buf_puts(size_t *newlen, BUF *b, const char *str)
200 {
201 	return buf_append(newlen, b, str, strlen(str));
202 }
203 
204 /*
205  * Return u_char at buffer position <pos>.
206  */
207 u_char
208 buf_getc(BUF *b, size_t pos)
209 {
210 	return (b->cb_buf[pos]);
211 }
212 
213 /*
214  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
215  * buffer is too small to accept all data, it will get resized to an
216  * appropriate size to accept all data.
217  * Returns the number of bytes successfully appended to the buffer.
218  */
219 const struct got_error *
220 buf_append(size_t *newlen, BUF *b, const void *data, size_t len)
221 {
222 	const struct got_error *err = NULL;
223 	size_t left, rlen;
224 	u_char *bp;
225 
226 	left = SIZE_LEFT(b);
227 	rlen = len;
228 
229 	if (left < len) {
230 		err = buf_grow(b, len - left);
231 		if (err)
232 			return err;
233 	}
234 	bp = b->cb_buf + b->cb_len;
235 	memcpy(bp, data, rlen);
236 	b->cb_len += rlen;
237 
238 	*newlen = rlen;
239 	return NULL;
240 }
241 
242 /*
243  * Returns the size of the buffer that is being used.
244  */
245 size_t
246 buf_len(BUF *b)
247 {
248 	return (b->cb_len);
249 }
250 
251 /*
252  * Write the contents of the buffer <b> to the specified <fd>
253  */
254 int
255 buf_write_fd(BUF *b, int fd)
256 {
257 	u_char *bp;
258 	size_t len;
259 	ssize_t ret;
260 
261 	len = b->cb_len;
262 	bp = b->cb_buf;
263 
264 	do {
265 		ret = write(fd, bp, len);
266 		if (ret == -1) {
267 			if (errno == EINTR || errno == EAGAIN)
268 				continue;
269 			return (-1);
270 		}
271 
272 		len -= (size_t)ret;
273 		bp += (size_t)ret;
274 	} while (len > 0);
275 
276 	return (0);
277 }
278 
279 /*
280  * Write the contents of the buffer <b> to the file whose path is given in
281  * <path>.  If the file does not exist, it is created with mode <mode>.
282  */
283 const struct got_error *
284 buf_write(BUF *b, const char *path, mode_t mode)
285 {
286 	const struct got_error *err = NULL;
287 	int fd;
288  open:
289 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)) == -1) {
290 		err = got_error_from_errno2("open", path);
291 		if (errno == EACCES && unlink(path) != -1)
292 			goto open;
293 		else
294 			return err;
295 	}
296 
297 	if (buf_write_fd(b, fd) == -1) {
298 		err = got_error_from_errno("buf_write_fd");
299 		(void)unlink(path);
300 		return err;
301 	}
302 
303 	if (fchmod(fd, mode) < 0)
304 		err = got_error_from_errno2("fchmod", path);
305 
306 	if (close(fd) != 0 && err == NULL)
307 		err = got_error_from_errno2("close", path);
308 
309 	return err;
310 }
311 
312 /*
313  * Write the contents of the buffer <b> to a temporary file whose path is
314  * specified using <template> (see mkstemp.3).
315  * NB. This function will modify <template>, as per mkstemp
316  */
317 const struct got_error *
318 buf_write_stmp(BUF *b, char *template)
319 {
320 	const struct got_error *err = NULL;
321 	int fd;
322 
323 	if ((fd = mkstemp(template)) == -1)
324 		return got_error_from_errno("mkstemp");
325 
326 	if (buf_write_fd(b, fd) == -1) {
327 		err = got_error_from_errno("buf_write_fd");
328 		(void)unlink(template);
329 	}
330 
331 	if (close(fd) != 0 && err == NULL)
332 		err = got_error_from_errno("close");
333 
334 	return err;
335 }
336 
337 /*
338  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
339  * operation regardless of the result.
340  */
341 static const struct got_error *
342 buf_grow(BUF *b, size_t len)
343 {
344 	u_char *buf;
345 	buf = reallocarray(b->cb_buf, 1, b->cb_size + len);
346 	if (buf == NULL)
347 		return got_error_from_errno("reallocarray");
348 	b->cb_buf = buf;
349 	b->cb_size += len;
350 	return NULL;
351 }