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/stat.h>
28 
29 #include <errno.h>
30 #include <fcntl.h>
31 #include <stdint.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36 
37 #include "buf.h"
38 
39 #include "got_error.h"
40 
41 #define BUF_INCR	128
42 
43 #define SIZE_LEFT(b)	((b)->cb_size - (b)->cb_len)
44 
45 static const struct got_error *buf_grow(BUF *, size_t);
46 
47 /*
48  * Create a new buffer structure and return a pointer to it.  This structure
49  * uses dynamically-allocated memory and must be freed with buf_free(), once
50  * the buffer is no longer needed.
51  */
52 const struct got_error *
53 buf_alloc(BUF **b, size_t len)
54 {
55 	const struct got_error *err = NULL;
56 
57 	*b = malloc(sizeof(**b));
58 	if (*b == NULL)
59 		return got_error_from_errno("malloc");
60 	/* Postpone creation of zero-sized buffers */
61 	if (len > 0) {
62 		(*b)->cb_buf = calloc(1, len);
63 		if ((*b)->cb_buf == NULL) {
64 			err = got_error_from_errno("calloc");
65 			free(*b);
66 			*b = NULL;
67 			return err;
68 		}
69 	} else
70 		(*b)->cb_buf = NULL;
71 
72 	(*b)->cb_size = len;
73 	(*b)->cb_len = 0;
74 
75 	return NULL;
76 }
77 
78 /*
79  * Open the file specified by <path> and load all of its contents into a
80  * buffer.
81  * Returns the loaded buffer on success or NULL on failure.
82  * Sets errno on error.
83  */
84 const struct got_error *
85 buf_load(BUF **buf, FILE *f)
86 {
87 	const struct got_error *err = NULL;
88 	size_t ret;
89 	size_t len;
90 	u_char *bp;
91 	struct stat st;
92 
93 	*buf = NULL;
94 
95 	if (fstat(fileno(f), &st) == -1) {
96 		err = got_error_from_errno("fstat");
97 		goto out;
98 	}
99 
100 	if ((uintmax_t)st.st_size > SIZE_MAX) {
101 		err = got_error_set_errno(EFBIG,
102 		    "cannot fit file into memory buffer");
103 		goto out;
104 	}
105 	err = buf_alloc(buf, st.st_size);
106 	if (err)
107 		goto out;
108 	for (bp = (*buf)->cb_buf; ; bp += ret) {
109 		len = SIZE_LEFT(*buf);
110 		ret = fread(bp, 1, len, f);
111 		if (ret == 0 && ferror(f)) {
112 			err = got_ferror(f, GOT_ERR_IO);
113 			goto out;
114 		} else if (ret == 0)
115 			break;
116 
117 		(*buf)->cb_len += (size_t)ret;
118 	}
119 
120 out:
121 	if (err) {
122 		buf_free(*buf);
123 		*buf = NULL;
124 	}
125 	return err;
126 }
127 
128 const struct got_error *
129 buf_load_fd(BUF **buf, int fd)
130 {
131 	const struct got_error *err = NULL;
132 	unsigned char out[8192];
133 	ssize_t r;
134 	size_t len;
135 
136 	err = buf_alloc(buf, 8192);
137 	if (err)
138 		return err;
139 
140 	do {
141 		r = read(fd, out, sizeof(out));
142 		if (r == -1)
143 			return got_error_from_errno("read");
144 		if (r > 0) {
145 			err = buf_append(&len, *buf, out, r);
146 			if (err)
147 				return err;
148 		}
149 	} while (r > 0);
150 
151 	return NULL;
152 }
153 
154 void
155 buf_free(BUF *b)
156 {
157 	if (b == NULL)
158 		return;
159 	free(b->cb_buf);
160 	free(b);
161 }
162 
163 /*
164  * Free the buffer <b>'s structural information but do not free the contents
165  * of the buffer.  Instead, they are returned and should be freed later using
166  * free().
167  */
168 void *
169 buf_release(BUF *b)
170 {
171 	void *tmp;
172 
173 	tmp = b->cb_buf;
174 	free(b);
175 	return (tmp);
176 }
177 
178 u_char *
179 buf_get(BUF *b)
180 {
181 	return (b->cb_buf);
182 }
183 
184 /*
185  * Empty the contents of the buffer <b> and reset pointers.
186  */
187 void
188 buf_empty(BUF *b)
189 {
190 	memset(b->cb_buf, 0, b->cb_size);
191 	b->cb_len = 0;
192 }
193 
194 /*
195  * Append a single character <c> to the end of the buffer <b>.
196  */
197 const struct got_error *
198 buf_putc(BUF *b, int c)
199 {
200 	const struct got_error *err = NULL;
201 	u_char *bp;
202 
203 	if (SIZE_LEFT(b) == 0) {
204 		err = buf_grow(b, BUF_INCR);
205 		if (err)
206 			return err;
207 	}
208 	bp = b->cb_buf + b->cb_len;
209 	*bp = (u_char)c;
210 	b->cb_len++;
211 	return NULL;
212 }
213 
214 /*
215  * Append a string <s> to the end of buffer <b>.
216  */
217 const struct got_error *
218 buf_puts(size_t *newlen, BUF *b, const char *str)
219 {
220 	return buf_append(newlen, b, str, strlen(str));
221 }
222 
223 /*
224  * Return u_char at buffer position <pos>.
225  */
226 u_char
227 buf_getc(BUF *b, size_t pos)
228 {
229 	return (b->cb_buf[pos]);
230 }
231 
232 /*
233  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
234  * buffer is too small to accept all data, it will get resized to an
235  * appropriate size to accept all data.
236  * Returns the number of bytes successfully appended to the buffer.
237  */
238 const struct got_error *
239 buf_append(size_t *newlen, BUF *b, const void *data, size_t len)
240 {
241 	const struct got_error *err = NULL;
242 	size_t left, rlen;
243 	u_char *bp;
244 
245 	left = SIZE_LEFT(b);
246 	rlen = len;
247 
248 	if (left < len) {
249 		err = buf_grow(b, len - left);
250 		if (err)
251 			return err;
252 	}
253 	bp = b->cb_buf + b->cb_len;
254 	memcpy(bp, data, rlen);
255 	b->cb_len += rlen;
256 
257 	*newlen = rlen;
258 	return NULL;
259 }
260 
261 /*
262  * Returns the size of the buffer that is being used.
263  */
264 size_t
265 buf_len(BUF *b)
266 {
267 	return (b->cb_len);
268 }
269 
270 /*
271  * Write the contents of the buffer <b> to the specified <fd>
272  */
273 int
274 buf_write_fd(BUF *b, int fd)
275 {
276 	u_char *bp;
277 	size_t len;
278 	ssize_t ret;
279 
280 	len = b->cb_len;
281 	bp = b->cb_buf;
282 
283 	do {
284 		ret = write(fd, bp, len);
285 		if (ret == -1) {
286 			if (errno == EINTR || errno == EAGAIN)
287 				continue;
288 			return (-1);
289 		}
290 
291 		len -= (size_t)ret;
292 		bp += (size_t)ret;
293 	} while (len > 0);
294 
295 	return (0);
296 }
297 
298 /*
299  * Write the contents of the buffer <b> to the file whose path is given in
300  * <path>.  If the file does not exist, it is created with mode <mode>.
301  */
302 const struct got_error *
303 buf_write(BUF *b, const char *path, mode_t mode)
304 {
305 	const struct got_error *err = NULL;
306 	int fd;
307  open:
308 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, mode)) == -1) {
309 		err = got_error_from_errno2("open", path);
310 		if (errno == EACCES && unlink(path) != -1)
311 			goto open;
312 		else
313 			return err;
314 	}
315 
316 	if (buf_write_fd(b, fd) == -1) {
317 		err = got_error_from_errno("buf_write_fd");
318 		(void)unlink(path);
319 		return err;
320 	}
321 
322 	if (fchmod(fd, mode) < 0)
323 		err = got_error_from_errno2("fchmod", path);
324 
325 	if (close(fd) == -1 && err == NULL)
326 		err = got_error_from_errno2("close", path);
327 
328 	return err;
329 }
330 
331 /*
332  * Write the contents of the buffer <b> to a temporary file whose path is
333  * specified using <template> (see mkstemp.3).
334  * NB. This function will modify <template>, as per mkstemp
335  */
336 const struct got_error *
337 buf_write_stmp(BUF *b, char *template)
338 {
339 	const struct got_error *err = NULL;
340 	int fd;
341 
342 	if ((fd = mkstemp(template)) == -1)
343 		return got_error_from_errno("mkstemp");
344 
345 	if (buf_write_fd(b, fd) == -1) {
346 		err = got_error_from_errno("buf_write_fd");
347 		(void)unlink(template);
348 	}
349 
350 	if (close(fd) == -1 && err == NULL)
351 		err = got_error_from_errno("close");
352 
353 	return err;
354 }
355 
356 /*
357  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
358  * operation regardless of the result.
359  */
360 static const struct got_error *
361 buf_grow(BUF *b, size_t len)
362 {
363 	u_char *buf;
364 	buf = reallocarray(b->cb_buf, 1, b->cb_size + len);
365 	if (buf == NULL)
366 		return got_error_from_errno("reallocarray");
367 	b->cb_buf = buf;
368 	b->cb_size += len;
369 	return NULL;
370 }