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 got_error_from_errno("malloc");
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 const struct got_error *
130 buf_load_fd(BUF **buf, int fd)
131 {
132 	const struct got_error *err = NULL;
133 	unsigned char out[8192];
134 	ssize_t r;
135 	size_t len;
136 
137 	err = buf_alloc(buf, 8192);
138 	if (err)
139 		return err;
140 
141 	do {
142 		r = read(fd, out, sizeof(out));
143 		if (r == -1)
144 			return got_error_from_errno("read");
145 		if (r > 0) {
146 			err = buf_append(&len, *buf, out, r);
147 			if (err)
148 				return err;
149 		}
150 	} while (r > 0);
151 
152 	return NULL;
153 }
154 
155 void
156 buf_free(BUF *b)
157 {
158 	if (b == NULL)
159 		return;
160 	free(b->cb_buf);
161 	free(b);
162 }
163 
164 /*
165  * Free the buffer <b>'s structural information but do not free the contents
166  * of the buffer.  Instead, they are returned and should be freed later using
167  * free().
168  */
169 void *
170 buf_release(BUF *b)
171 {
172 	void *tmp;
173 
174 	tmp = b->cb_buf;
175 	free(b);
176 	return (tmp);
177 }
178 
179 u_char *
180 buf_get(BUF *b)
181 {
182 	return (b->cb_buf);
183 }
184 
185 /*
186  * Empty the contents of the buffer <b> and reset pointers.
187  */
188 void
189 buf_empty(BUF *b)
190 {
191 	memset(b->cb_buf, 0, b->cb_size);
192 	b->cb_len = 0;
193 }
194 
195 /* Discard the leading <n> bytes from the buffer. */
196 const struct got_error *
197 buf_discard(BUF *b, size_t n)
198 {
199 	if (n > b->cb_len)
200 		return got_error(GOT_ERR_RANGE);
201 
202 	if (n == b->cb_len)
203 		buf_empty(b);
204 	else {
205 		memmove(b->cb_buf, b->cb_buf + n, b->cb_len - n);
206 		b->cb_len -= n;
207 	}
208 
209 	return NULL;
210 }
211 
212 /*
213  * Append a single character <c> to the end of the buffer <b>.
214  */
215 const struct got_error *
216 buf_putc(BUF *b, int c)
217 {
218 	const struct got_error *err = NULL;
219 	u_char *bp;
220 
221 	if (SIZE_LEFT(b) == 0) {
222 		err = buf_grow(b, BUF_INCR);
223 		if (err)
224 			return err;
225 	}
226 	bp = b->cb_buf + b->cb_len;
227 	*bp = (u_char)c;
228 	b->cb_len++;
229 	return NULL;
230 }
231 
232 /*
233  * Append a string <s> to the end of buffer <b>.
234  */
235 const struct got_error *
236 buf_puts(size_t *newlen, BUF *b, const char *str)
237 {
238 	return buf_append(newlen, b, str, strlen(str));
239 }
240 
241 /*
242  * Return u_char at buffer position <pos>.
243  */
244 u_char
245 buf_getc(BUF *b, size_t pos)
246 {
247 	return (b->cb_buf[pos]);
248 }
249 
250 /*
251  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
252  * buffer is too small to accept all data, it will get resized to an
253  * appropriate size to accept all data.
254  * Returns the number of bytes successfully appended to the buffer.
255  */
256 const struct got_error *
257 buf_append(size_t *newlen, BUF *b, const void *data, size_t len)
258 {
259 	const struct got_error *err = NULL;
260 	size_t left, rlen;
261 	u_char *bp;
262 
263 	left = SIZE_LEFT(b);
264 	rlen = len;
265 
266 	if (left < len) {
267 		err = buf_grow(b, len - left);
268 		if (err)
269 			return err;
270 	}
271 	bp = b->cb_buf + b->cb_len;
272 	memcpy(bp, data, rlen);
273 	b->cb_len += rlen;
274 
275 	*newlen = rlen;
276 	return NULL;
277 }
278 
279 /*
280  * Returns the size of the buffer that is being used.
281  */
282 size_t
283 buf_len(BUF *b)
284 {
285 	return (b->cb_len);
286 }
287 
288 /*
289  * Write the contents of the buffer <b> to the specified <fd>
290  */
291 int
292 buf_write_fd(BUF *b, int fd)
293 {
294 	u_char *bp;
295 	size_t len;
296 	ssize_t ret;
297 
298 	len = b->cb_len;
299 	bp = b->cb_buf;
300 
301 	do {
302 		ret = write(fd, bp, len);
303 		if (ret == -1) {
304 			if (errno == EINTR || errno == EAGAIN)
305 				continue;
306 			return (-1);
307 		}
308 
309 		len -= (size_t)ret;
310 		bp += (size_t)ret;
311 	} while (len > 0);
312 
313 	return (0);
314 }
315 
316 /*
317  * Write the contents of the buffer <b> to the file whose path is given in
318  * <path>.  If the file does not exist, it is created with mode <mode>.
319  */
320 const struct got_error *
321 buf_write(BUF *b, const char *path, mode_t mode)
322 {
323 	const struct got_error *err = NULL;
324 	int fd;
325  open:
326 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, mode)) == -1) {
327 		err = got_error_from_errno2("open", path);
328 		if (errno == EACCES && unlink(path) != -1)
329 			goto open;
330 		else
331 			return err;
332 	}
333 
334 	if (buf_write_fd(b, fd) == -1) {
335 		err = got_error_from_errno("buf_write_fd");
336 		(void)unlink(path);
337 		return err;
338 	}
339 
340 	if (fchmod(fd, mode) < 0)
341 		err = got_error_from_errno2("fchmod", path);
342 
343 	if (close(fd) == -1 && err == NULL)
344 		err = got_error_from_errno2("close", path);
345 
346 	return err;
347 }
348 
349 /*
350  * Write the contents of the buffer <b> to a temporary file whose path is
351  * specified using <template> (see mkstemp.3).
352  * NB. This function will modify <template>, as per mkstemp
353  */
354 const struct got_error *
355 buf_write_stmp(BUF *b, char *template)
356 {
357 	const struct got_error *err = NULL;
358 	int fd;
359 
360 	if ((fd = mkstemp(template)) == -1)
361 		return got_error_from_errno("mkstemp");
362 
363 	if (buf_write_fd(b, fd) == -1) {
364 		err = got_error_from_errno("buf_write_fd");
365 		(void)unlink(template);
366 	}
367 
368 	if (close(fd) == -1 && err == NULL)
369 		err = got_error_from_errno("close");
370 
371 	return err;
372 }
373 
374 /*
375  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
376  * operation regardless of the result.
377  */
378 static const struct got_error *
379 buf_grow(BUF *b, size_t len)
380 {
381 	u_char *buf;
382 	buf = reallocarray(b->cb_buf, 1, b->cb_size + len);
383 	if (buf == NULL)
384 		return got_error_from_errno("reallocarray");
385 	b->cb_buf = buf;
386 	b->cb_size += len;
387 	return NULL;
388 }