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