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 #include "worklist.h"
40 
41 #include "got_error.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 const struct got_error *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 const struct got_error *
62 buf_alloc(BUF **b, size_t len)
63 {
64 	const struct got_error *err = NULL;
65 
66 	*b = malloc(sizeof(**b));
67 	if (*b == NULL)
68 		return NULL;
69 	/* Postpone creation of zero-sized buffers */
70 	if (len > 0) {
71 		(*b)->cb_buf = calloc(1, len);
72 		if ((*b)->cb_buf == NULL) {
73 			err = got_error_from_errno("calloc");
74 			free(*b);
75 			*b = NULL;
76 			return err;
77 		}
78 	} else
79 		(*b)->cb_buf = NULL;
80 
81 	(*b)->cb_size = len;
82 	(*b)->cb_len = 0;
83 
84 	return NULL;
85 }
86 
87 /*
88  * Open the file specified by <path> and load all of its contents into a
89  * buffer.
90  * Returns the loaded buffer on success or NULL on failure.
91  * Sets errno on error.
92  */
93 const struct got_error *
94 buf_load(BUF **buf, const char *path)
95 {
96 	const struct got_error *err = NULL;
97 	int fd;
98 	ssize_t ret;
99 	size_t len;
100 	u_char *bp;
101 	struct stat st;
102 
103 	*buf = NULL;
104 
105 	fd = open(path, O_RDONLY, 0600);
106 	if (fd == -1)
107 		return got_error_from_errno2("open", path);
108 
109 	if (fstat(fd, &st) == -1) {
110 		err = got_error_from_errno2("fstat", path);
111 		goto out;
112 	}
113 
114 	if ((uintmax_t)st.st_size > SIZE_MAX) {
115 		err = got_error_set_errno(EFBIG, path);
116 		goto out;
117 	}
118 	err = buf_alloc(buf, st.st_size);
119 	if (err)
120 		goto out;
121 	for (bp = (*buf)->cb_buf; ; bp += (size_t)ret) {
122 		len = SIZE_LEFT(*buf);
123 		ret = read(fd, bp, len);
124 		if (ret == -1) {
125 			err = got_error_from_errno2("read", path);
126 			goto out;
127 		} else if (ret == 0)
128 			break;
129 
130 		(*buf)->cb_len += (size_t)ret;
131 	}
132 
133 out:
134 	if (close(fd) == -1 && err == NULL)
135 		err = got_error_from_errno2("close", path);
136 	if (err) {
137 		buf_free(*buf);
138 		*buf = NULL;
139 	}
140 	return err;
141 }
142 
143 void
144 buf_free(BUF *b)
145 {
146 	if (b == NULL)
147 		return;
148 	free(b->cb_buf);
149 	free(b);
150 }
151 
152 /*
153  * Free the buffer <b>'s structural information but do not free the contents
154  * of the buffer.  Instead, they are returned and should be freed later using
155  * free().
156  */
157 void *
158 buf_release(BUF *b)
159 {
160 	void *tmp;
161 
162 	tmp = b->cb_buf;
163 	free(b);
164 	return (tmp);
165 }
166 
167 u_char *
168 buf_get(BUF *b)
169 {
170 	return (b->cb_buf);
171 }
172 
173 /*
174  * Empty the contents of the buffer <b> and reset pointers.
175  */
176 void
177 buf_empty(BUF *b)
178 {
179 	memset(b->cb_buf, 0, b->cb_size);
180 	b->cb_len = 0;
181 }
182 
183 /*
184  * Append a single character <c> to the end of the buffer <b>.
185  */
186 const struct got_error *
187 buf_putc(BUF *b, int c)
188 {
189 	const struct got_error *err = NULL;
190 	u_char *bp;
191 
192 	if (SIZE_LEFT(b) == 0) {
193 		err = buf_grow(b, BUF_INCR);
194 		if (err)
195 			return err;
196 	}
197 	bp = b->cb_buf + b->cb_len;
198 	*bp = (u_char)c;
199 	b->cb_len++;
200 	return NULL;
201 }
202 
203 /*
204  * Append a string <s> to the end of buffer <b>.
205  */
206 const struct got_error *
207 buf_puts(size_t *newlen, BUF *b, const char *str)
208 {
209 	return buf_append(newlen, b, str, strlen(str));
210 }
211 
212 /*
213  * Return u_char at buffer position <pos>.
214  */
215 u_char
216 buf_getc(BUF *b, size_t pos)
217 {
218 	return (b->cb_buf[pos]);
219 }
220 
221 /*
222  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
223  * buffer is too small to accept all data, it will get resized to an
224  * appropriate size to accept all data.
225  * Returns the number of bytes successfully appended to the buffer.
226  */
227 const struct got_error *
228 buf_append(size_t *newlen, BUF *b, const void *data, size_t len)
229 {
230 	const struct got_error *err = NULL;
231 	size_t left, rlen;
232 	u_char *bp;
233 
234 	left = SIZE_LEFT(b);
235 	rlen = len;
236 
237 	if (left < len) {
238 		err = buf_grow(b, len - left);
239 		if (err)
240 			return err;
241 	}
242 	bp = b->cb_buf + b->cb_len;
243 	memcpy(bp, data, rlen);
244 	b->cb_len += rlen;
245 
246 	*newlen = rlen;
247 	return NULL;
248 }
249 
250 /*
251  * Returns the size of the buffer that is being used.
252  */
253 size_t
254 buf_len(BUF *b)
255 {
256 	return (b->cb_len);
257 }
258 
259 /*
260  * Write the contents of the buffer <b> to the specified <fd>
261  */
262 int
263 buf_write_fd(BUF *b, int fd)
264 {
265 	u_char *bp;
266 	size_t len;
267 	ssize_t ret;
268 
269 	len = b->cb_len;
270 	bp = b->cb_buf;
271 
272 	do {
273 		ret = write(fd, bp, len);
274 		if (ret == -1) {
275 			if (errno == EINTR || errno == EAGAIN)
276 				continue;
277 			return (-1);
278 		}
279 
280 		len -= (size_t)ret;
281 		bp += (size_t)ret;
282 	} while (len > 0);
283 
284 	return (0);
285 }
286 
287 /*
288  * Write the contents of the buffer <b> to the file whose path is given in
289  * <path>.  If the file does not exist, it is created with mode <mode>.
290  */
291 const struct got_error *
292 buf_write(BUF *b, const char *path, mode_t mode)
293 {
294 	const struct got_error *err = NULL;
295 	int fd;
296  open:
297 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)) == -1) {
298 		err = got_error_from_errno2("open", path);
299 		if (errno == EACCES && unlink(path) != -1)
300 			goto open;
301 		else
302 			return err;
303 	}
304 
305 	if (buf_write_fd(b, fd) == -1) {
306 		err = got_error_from_errno("buf_write_fd");
307 		(void)unlink(path);
308 		return err;
309 	}
310 
311 	if (fchmod(fd, mode) < 0)
312 		err = got_error_from_errno2("fchmod", path);
313 
314 	if (close(fd) != 0 && err == NULL)
315 		err = got_error_from_errno2("close", path);
316 
317 	return err;
318 }
319 
320 /*
321  * Write the contents of the buffer <b> to a temporary file whose path is
322  * specified using <template> (see mkstemp.3).
323  * NB. This function will modify <template>, as per mkstemp
324  */
325 const struct got_error *
326 buf_write_stmp(BUF *b, char *template, struct wklhead *temp_files)
327 {
328 	const struct got_error *err = NULL;
329 	int fd;
330 
331 	if ((fd = mkstemp(template)) == -1)
332 		return got_error_from_errno("mkstemp");
333 
334 	worklist_add(template, temp_files);
335 
336 	if (buf_write_fd(b, fd) == -1) {
337 		err = got_error_from_errno("buf_write_fd");
338 		(void)unlink(template);
339 	}
340 
341 	if (close(fd) != 0 && err == NULL)
342 		err = got_error_from_errno("close");
343 
344 	return err;
345 }
346 
347 /*
348  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
349  * operation regardless of the result.
350  */
351 static const struct got_error *
352 buf_grow(BUF *b, size_t len)
353 {
354 	u_char *buf;
355 	buf = reallocarray(b->cb_buf, 1, b->cb_size + len);
356 	if (buf == NULL)
357 		return got_error_from_errno("reallocarray");
358 	b->cb_buf = buf;
359 	b->cb_size += len;
360 	return NULL;
361 }