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 "got_compat.h"
28 
29 #include <sys/queue.h>
30 #include <sys/stat.h>
31 
32 #include <errno.h>
33 #include <fcntl.h>
34 #include <stdint.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <unistd.h>
39 
40 #include "buf.h"
41 
42 #include "got_error.h"
43 
44 #define BUF_INCR	128
45 
46 #define SIZE_LEFT(b)	((b)->cb_size - (b)->cb_len)
47 
48 static const struct got_error *buf_grow(BUF *, size_t);
49 
50 /*
51  * Create a new buffer structure and return a pointer to it.  This structure
52  * uses dynamically-allocated memory and must be freed with buf_free(), once
53  * the buffer is no longer needed.
54  */
55 const struct got_error *
56 buf_alloc(BUF **b, size_t len)
57 {
58 	const struct got_error *err = NULL;
59 
60 	*b = malloc(sizeof(**b));
61 	if (*b == NULL)
62 		return got_error_from_errno("malloc");
63 	/* Postpone creation of zero-sized buffers */
64 	if (len > 0) {
65 		(*b)->cb_buf = calloc(1, len);
66 		if ((*b)->cb_buf == NULL) {
67 			err = got_error_from_errno("calloc");
68 			free(*b);
69 			*b = NULL;
70 			return err;
71 		}
72 	} else
73 		(*b)->cb_buf = NULL;
74 
75 	(*b)->cb_size = len;
76 	(*b)->cb_len = 0;
77 
78 	return NULL;
79 }
80 
81 /*
82  * Open the file specified by <path> and load all of its contents into a
83  * buffer.
84  * Returns the loaded buffer on success or NULL on failure.
85  * Sets errno on error.
86  */
87 const struct got_error *
88 buf_load(BUF **buf, FILE *f)
89 {
90 	const struct got_error *err = NULL;
91 	size_t ret;
92 	size_t len;
93 	u_char *bp;
94 	struct stat st;
95 
96 	*buf = NULL;
97 
98 	if (fstat(fileno(f), &st) == -1) {
99 		err = got_error_from_errno("fstat");
100 		goto out;
101 	}
102 
103 	if ((uintmax_t)st.st_size > SIZE_MAX) {
104 		err = got_error_set_errno(EFBIG,
105 		    "cannot fit file into memory buffer");
106 		goto out;
107 	}
108 	err = buf_alloc(buf, st.st_size);
109 	if (err)
110 		goto out;
111 	for (bp = (*buf)->cb_buf; ; bp += ret) {
112 		len = SIZE_LEFT(*buf);
113 		ret = fread(bp, 1, len, f);
114 		if (ret == 0 && ferror(f)) {
115 			err = got_ferror(f, GOT_ERR_IO);
116 			goto out;
117 		} else if (ret == 0)
118 			break;
119 
120 		(*buf)->cb_len += (size_t)ret;
121 	}
122 
123 out:
124 	if (err) {
125 		buf_free(*buf);
126 		*buf = NULL;
127 	}
128 	return err;
129 }
130 
131 const struct got_error *
132 buf_load_fd(BUF **buf, int fd)
133 {
134 	const struct got_error *err = NULL;
135 	unsigned char out[8192];
136 	ssize_t r;
137 	size_t len;
138 
139 	err = buf_alloc(buf, 8192);
140 	if (err)
141 		return err;
142 
143 	do {
144 		r = read(fd, out, sizeof(out));
145 		if (r == -1)
146 			return got_error_from_errno("read");
147 		if (r > 0) {
148 			err = buf_append(&len, *buf, out, r);
149 			if (err)
150 				return err;
151 		}
152 	} while (r > 0);
153 
154 	return NULL;
155 }
156 
157 void
158 buf_free(BUF *b)
159 {
160 	if (b == NULL)
161 		return;
162 	free(b->cb_buf);
163 	free(b);
164 }
165 
166 /*
167  * Free the buffer <b>'s structural information but do not free the contents
168  * of the buffer.  Instead, they are returned and should be freed later using
169  * free().
170  */
171 void *
172 buf_release(BUF *b)
173 {
174 	void *tmp;
175 
176 	tmp = b->cb_buf;
177 	free(b);
178 	return (tmp);
179 }
180 
181 u_char *
182 buf_get(BUF *b)
183 {
184 	return (b->cb_buf);
185 }
186 
187 /*
188  * Empty the contents of the buffer <b> and reset pointers.
189  */
190 void
191 buf_empty(BUF *b)
192 {
193 	memset(b->cb_buf, 0, b->cb_size);
194 	b->cb_len = 0;
195 }
196 
197 /* Discard the leading <n> bytes from the buffer. */
198 const struct got_error *
199 buf_discard(BUF *b, size_t n)
200 {
201 	if (n > b->cb_len)
202 		return got_error(GOT_ERR_RANGE);
203 
204 	if (n == b->cb_len)
205 		buf_empty(b);
206 	else {
207 		memmove(b->cb_buf, b->cb_buf + n, b->cb_len - n);
208 		b->cb_len -= n;
209 	}
210 
211 	return NULL;
212 }
213 
214 /*
215  * Append a single character <c> to the end of the buffer <b>.
216  */
217 const struct got_error *
218 buf_putc(BUF *b, int c)
219 {
220 	const struct got_error *err = NULL;
221 	u_char *bp;
222 
223 	if (SIZE_LEFT(b) == 0) {
224 		err = buf_grow(b, BUF_INCR);
225 		if (err)
226 			return err;
227 	}
228 	bp = b->cb_buf + b->cb_len;
229 	*bp = (u_char)c;
230 	b->cb_len++;
231 	return NULL;
232 }
233 
234 /*
235  * Append a string <s> to the end of buffer <b>.
236  */
237 const struct got_error *
238 buf_puts(size_t *newlen, BUF *b, const char *str)
239 {
240 	return buf_append(newlen, b, str, strlen(str));
241 }
242 
243 /*
244  * Return u_char at buffer position <pos>.
245  */
246 u_char
247 buf_getc(BUF *b, size_t pos)
248 {
249 	return (b->cb_buf[pos]);
250 }
251 
252 /*
253  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
254  * buffer is too small to accept all data, it will get resized to an
255  * appropriate size to accept all data.
256  * Returns the number of bytes successfully appended to the buffer.
257  */
258 const struct got_error *
259 buf_append(size_t *newlen, BUF *b, const void *data, size_t len)
260 {
261 	const struct got_error *err = NULL;
262 	size_t left, rlen;
263 	u_char *bp;
264 
265 	left = SIZE_LEFT(b);
266 	rlen = len;
267 
268 	if (left < len) {
269 		err = buf_grow(b, len - left);
270 		if (err)
271 			return err;
272 	}
273 	bp = b->cb_buf + b->cb_len;
274 	memcpy(bp, data, rlen);
275 	b->cb_len += rlen;
276 
277 	*newlen = rlen;
278 	return NULL;
279 }
280 
281 /*
282  * Returns the size of the buffer that is being used.
283  */
284 size_t
285 buf_len(BUF *b)
286 {
287 	return (b->cb_len);
288 }
289 
290 /*
291  * Write the contents of the buffer <b> to the specified <fd>
292  */
293 int
294 buf_write_fd(BUF *b, int fd)
295 {
296 	u_char *bp;
297 	size_t len;
298 	ssize_t ret;
299 
300 	len = b->cb_len;
301 	bp = b->cb_buf;
302 
303 	do {
304 		ret = write(fd, bp, len);
305 		if (ret == -1) {
306 			if (errno == EINTR || errno == EAGAIN)
307 				continue;
308 			return (-1);
309 		}
310 
311 		len -= (size_t)ret;
312 		bp += (size_t)ret;
313 	} while (len > 0);
314 
315 	return (0);
316 }
317 
318 /*
319  * Write the contents of the buffer <b> to the file whose path is given in
320  * <path>.  If the file does not exist, it is created with mode <mode>.
321  */
322 const struct got_error *
323 buf_write(BUF *b, const char *path, mode_t mode)
324 {
325 	const struct got_error *err = NULL;
326 	int fd;
327  open:
328 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, mode)) == -1) {
329 		err = got_error_from_errno2("open", path);
330 		if (errno == EACCES && unlink(path) != -1)
331 			goto open;
332 		else
333 			return err;
334 	}
335 
336 	if (buf_write_fd(b, fd) == -1) {
337 		err = got_error_from_errno("buf_write_fd");
338 		(void)unlink(path);
339 		return err;
340 	}
341 
342 	if (fchmod(fd, mode) < 0)
343 		err = got_error_from_errno2("fchmod", path);
344 
345 	if (close(fd) == -1 && err == NULL)
346 		err = got_error_from_errno2("close", path);
347 
348 	return err;
349 }
350 
351 /*
352  * Write the contents of the buffer <b> to a temporary file whose path is
353  * specified using <template> (see mkstemp.3).
354  * NB. This function will modify <template>, as per mkstemp
355  */
356 const struct got_error *
357 buf_write_stmp(BUF *b, char *template)
358 {
359 	const struct got_error *err = NULL;
360 	int fd;
361 
362 	if ((fd = mkstemp(template)) == -1)
363 		return got_error_from_errno("mkstemp");
364 
365 	if (buf_write_fd(b, fd) == -1) {
366 		err = got_error_from_errno("buf_write_fd");
367 		(void)unlink(template);
368 	}
369 
370 	if (close(fd) == -1 && err == NULL)
371 		err = got_error_from_errno("close");
372 
373 	return err;
374 }
375 
376 /*
377  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
378  * operation regardless of the result.
379  */
380 static const struct got_error *
381 buf_grow(BUF *b, size_t len)
382 {
383 	u_char *buf;
384 	buf = reallocarray(b->cb_buf, 1, b->cb_size + len);
385 	if (buf == NULL)
386 		return got_error_from_errno("reallocarray");
387 	b->cb_buf = buf;
388 	b->cb_size += len;
389 	return NULL;
390 }