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 NULL;
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 void
129 buf_free(BUF *b)
130 {
131 	if (b == NULL)
132 		return;
133 	free(b->cb_buf);
134 	free(b);
135 }
136 
137 /*
138  * Free the buffer <b>'s structural information but do not free the contents
139  * of the buffer.  Instead, they are returned and should be freed later using
140  * free().
141  */
142 void *
143 buf_release(BUF *b)
144 {
145 	void *tmp;
146 
147 	tmp = b->cb_buf;
148 	free(b);
149 	return (tmp);
150 }
151 
152 u_char *
153 buf_get(BUF *b)
154 {
155 	return (b->cb_buf);
156 }
157 
158 /*
159  * Empty the contents of the buffer <b> and reset pointers.
160  */
161 void
162 buf_empty(BUF *b)
163 {
164 	memset(b->cb_buf, 0, b->cb_size);
165 	b->cb_len = 0;
166 }
167 
168 /*
169  * Append a single character <c> to the end of the buffer <b>.
170  */
171 const struct got_error *
172 buf_putc(BUF *b, int c)
173 {
174 	const struct got_error *err = NULL;
175 	u_char *bp;
176 
177 	if (SIZE_LEFT(b) == 0) {
178 		err = buf_grow(b, BUF_INCR);
179 		if (err)
180 			return err;
181 	}
182 	bp = b->cb_buf + b->cb_len;
183 	*bp = (u_char)c;
184 	b->cb_len++;
185 	return NULL;
186 }
187 
188 /*
189  * Append a string <s> to the end of buffer <b>.
190  */
191 const struct got_error *
192 buf_puts(size_t *newlen, BUF *b, const char *str)
193 {
194 	return buf_append(newlen, b, str, strlen(str));
195 }
196 
197 /*
198  * Return u_char at buffer position <pos>.
199  */
200 u_char
201 buf_getc(BUF *b, size_t pos)
202 {
203 	return (b->cb_buf[pos]);
204 }
205 
206 /*
207  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
208  * buffer is too small to accept all data, it will get resized to an
209  * appropriate size to accept all data.
210  * Returns the number of bytes successfully appended to the buffer.
211  */
212 const struct got_error *
213 buf_append(size_t *newlen, BUF *b, const void *data, size_t len)
214 {
215 	const struct got_error *err = NULL;
216 	size_t left, rlen;
217 	u_char *bp;
218 
219 	left = SIZE_LEFT(b);
220 	rlen = len;
221 
222 	if (left < len) {
223 		err = buf_grow(b, len - left);
224 		if (err)
225 			return err;
226 	}
227 	bp = b->cb_buf + b->cb_len;
228 	memcpy(bp, data, rlen);
229 	b->cb_len += rlen;
230 
231 	*newlen = rlen;
232 	return NULL;
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 const struct got_error *
277 buf_write(BUF *b, const char *path, mode_t mode)
278 {
279 	const struct got_error *err = NULL;
280 	int fd;
281  open:
282 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)) == -1) {
283 		err = got_error_from_errno2("open", path);
284 		if (errno == EACCES && unlink(path) != -1)
285 			goto open;
286 		else
287 			return err;
288 	}
289 
290 	if (buf_write_fd(b, fd) == -1) {
291 		err = got_error_from_errno("buf_write_fd");
292 		(void)unlink(path);
293 		return err;
294 	}
295 
296 	if (fchmod(fd, mode) < 0)
297 		err = got_error_from_errno2("fchmod", path);
298 
299 	if (close(fd) == -1 && err == NULL)
300 		err = got_error_from_errno2("close", path);
301 
302 	return err;
303 }
304 
305 /*
306  * Write the contents of the buffer <b> to a temporary file whose path is
307  * specified using <template> (see mkstemp.3).
308  * NB. This function will modify <template>, as per mkstemp
309  */
310 const struct got_error *
311 buf_write_stmp(BUF *b, char *template)
312 {
313 	const struct got_error *err = NULL;
314 	int fd;
315 
316 	if ((fd = mkstemp(template)) == -1)
317 		return got_error_from_errno("mkstemp");
318 
319 	if (buf_write_fd(b, fd) == -1) {
320 		err = got_error_from_errno("buf_write_fd");
321 		(void)unlink(template);
322 	}
323 
324 	if (close(fd) == -1 && err == NULL)
325 		err = got_error_from_errno("close");
326 
327 	return err;
328 }
329 
330 /*
331  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
332  * operation regardless of the result.
333  */
334 static const struct got_error *
335 buf_grow(BUF *b, size_t len)
336 {
337 	u_char *buf;
338 	buf = reallocarray(b->cb_buf, 1, b->cb_size + len);
339 	if (buf == NULL)
340 		return got_error_from_errno("reallocarray");
341 	b->cb_buf = buf;
342 	b->cb_size += len;
343 	return NULL;
344 }