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 #include "worklist.h"
40 
41 #include "got_error.h"
42 
43 #define BUF_INCR	128
44 
45 struct buf {
46 	/* buffer handle, buffer size, and data length */
47 	u_char	*cb_buf;
48 	size_t	 cb_size;
49 	size_t	 cb_len;
50 };
51 
52 #define SIZE_LEFT(b)	(b->cb_size - b->cb_len)
53 
54 static const struct got_error *buf_grow(BUF *, size_t);
55 
56 /*
57  * Create a new buffer structure and return a pointer to it.  This structure
58  * uses dynamically-allocated memory and must be freed with buf_free(), once
59  * the buffer is no longer needed.
60  */
61 BUF *
62 buf_alloc(size_t len)
63 {
64 	BUF *b;
65 
66 	b = malloc(sizeof(*b));
67 	if (b == NULL)
68 		return NULL;
69 	/* Postpone creation of zero-sized buffers */
70 	if (len > 0) {
71 		b->cb_buf = calloc(1, len);
72 		if (b->cb_buf == NULL) {
73 			free(b);
74 			return NULL;
75 		}
76 	} else
77 		b->cb_buf = NULL;
78 
79 	b->cb_size = len;
80 	b->cb_len = 0;
81 
82 	return (b);
83 }
84 
85 /*
86  * Open the file specified by <path> and load all of its contents into a
87  * buffer.
88  * Returns the loaded buffer on success or NULL on failure.
89  * Sets errno on error.
90  */
91 BUF *
92 buf_load(const char *path)
93 {
94 	int fd;
95 	ssize_t ret;
96 	size_t len;
97 	u_char *bp;
98 	struct stat st;
99 	BUF *buf;
100 
101 	buf = NULL;
102 
103 	if ((fd = open(path, O_RDONLY, 0600)) == -1)
104 		goto out;
105 
106 	if (fstat(fd, &st) == -1)
107 		goto out;
108 
109 	if ((uintmax_t)st.st_size > SIZE_MAX) {
110 		errno = EFBIG;
111 		goto out;
112 	}
113 	buf = buf_alloc(st.st_size);
114 	for (bp = buf->cb_buf; ; bp += (size_t)ret) {
115 		len = SIZE_LEFT(buf);
116 		ret = read(fd, bp, len);
117 		if (ret == -1) {
118 			int saved_errno;
119 
120 			saved_errno = errno;
121 			buf_free(buf);
122 			buf = NULL;
123 			errno = saved_errno;
124 			goto out;
125 		} else if (ret == 0)
126 			break;
127 
128 		buf->cb_len += (size_t)ret;
129 	}
130 
131 out:
132 	if (fd != -1) {
133 		int saved_errno;
134 
135 		/* We may want to preserve errno here. */
136 		saved_errno = errno;
137 		(void)close(fd);
138 		errno = saved_errno;
139 	}
140 
141 	return (buf);
142 }
143 
144 void
145 buf_free(BUF *b)
146 {
147 	if (b == NULL)
148 		return;
149 	free(b->cb_buf);
150 	free(b);
151 }
152 
153 /*
154  * Free the buffer <b>'s structural information but do not free the contents
155  * of the buffer.  Instead, they are returned and should be freed later using
156  * free().
157  */
158 void *
159 buf_release(BUF *b)
160 {
161 	void *tmp;
162 
163 	tmp = b->cb_buf;
164 	free(b);
165 	return (tmp);
166 }
167 
168 u_char *
169 buf_get(BUF *b)
170 {
171 	return (b->cb_buf);
172 }
173 
174 /*
175  * Empty the contents of the buffer <b> and reset pointers.
176  */
177 void
178 buf_empty(BUF *b)
179 {
180 	memset(b->cb_buf, 0, b->cb_size);
181 	b->cb_len = 0;
182 }
183 
184 /*
185  * Append a single character <c> to the end of the buffer <b>.
186  */
187 const struct got_error *
188 buf_putc(BUF *b, int c)
189 {
190 	const struct got_error *err = NULL;
191 	u_char *bp;
192 
193 	if (SIZE_LEFT(b) == 0) {
194 		err = buf_grow(b, BUF_INCR);
195 		if (err)
196 			return err;
197 	}
198 	bp = b->cb_buf + b->cb_len;
199 	*bp = (u_char)c;
200 	b->cb_len++;
201 	return NULL;
202 }
203 
204 /*
205  * Append a string <s> to the end of buffer <b>.
206  */
207 const struct got_error *
208 buf_puts(size_t *newlen, BUF *b, const char *str)
209 {
210 	return buf_append(newlen, b, str, strlen(str));
211 }
212 
213 /*
214  * Return u_char at buffer position <pos>.
215  */
216 u_char
217 buf_getc(BUF *b, size_t pos)
218 {
219 	return (b->cb_buf[pos]);
220 }
221 
222 /*
223  * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
224  * buffer is too small to accept all data, it will get resized to an
225  * appropriate size to accept all data.
226  * Returns the number of bytes successfully appended to the buffer.
227  */
228 const struct got_error *
229 buf_append(size_t *newlen, BUF *b, const void *data, size_t len)
230 {
231 	const struct got_error *err = NULL;
232 	size_t left, rlen;
233 	u_char *bp;
234 
235 	left = SIZE_LEFT(b);
236 	rlen = len;
237 
238 	if (left < len) {
239 		err = buf_grow(b, len - left);
240 		if (err)
241 			return err;
242 	}
243 	bp = b->cb_buf + b->cb_len;
244 	memcpy(bp, data, rlen);
245 	b->cb_len += rlen;
246 
247 	*newlen = rlen;
248 	return NULL;
249 }
250 
251 /*
252  * Returns the size of the buffer that is being used.
253  */
254 size_t
255 buf_len(BUF *b)
256 {
257 	return (b->cb_len);
258 }
259 
260 /*
261  * Write the contents of the buffer <b> to the specified <fd>
262  */
263 int
264 buf_write_fd(BUF *b, int fd)
265 {
266 	u_char *bp;
267 	size_t len;
268 	ssize_t ret;
269 
270 	len = b->cb_len;
271 	bp = b->cb_buf;
272 
273 	do {
274 		ret = write(fd, bp, len);
275 		if (ret == -1) {
276 			if (errno == EINTR || errno == EAGAIN)
277 				continue;
278 			return (-1);
279 		}
280 
281 		len -= (size_t)ret;
282 		bp += (size_t)ret;
283 	} while (len > 0);
284 
285 	return (0);
286 }
287 
288 /*
289  * Write the contents of the buffer <b> to the file whose path is given in
290  * <path>.  If the file does not exist, it is created with mode <mode>.
291  */
292 const struct got_error *
293 buf_write(BUF *b, const char *path, mode_t mode)
294 {
295 	const struct got_error *err = NULL;
296 	int fd;
297  open:
298 	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)) == -1) {
299 		err = got_error_from_errno2("open", path);
300 		if (errno == EACCES && unlink(path) != -1)
301 			goto open;
302 		else
303 			return err;
304 	}
305 
306 	if (buf_write_fd(b, fd) == -1) {
307 		err = got_error_from_errno("buf_write_fd");
308 		(void)unlink(path);
309 		return err;
310 	}
311 
312 	if (fchmod(fd, mode) < 0)
313 		err = got_error_from_errno2("fchmod", path);
314 
315 	if (close(fd) != 0 && err == NULL)
316 		err = got_error_from_errno2("close", path);
317 
318 	return err;
319 }
320 
321 /*
322  * Write the contents of the buffer <b> to a temporary file whose path is
323  * specified using <template> (see mkstemp.3).
324  * NB. This function will modify <template>, as per mkstemp
325  */
326 const struct got_error *
327 buf_write_stmp(BUF *b, char *template, struct wklhead *temp_files)
328 {
329 	const struct got_error *err = NULL;
330 	int fd;
331 
332 	if ((fd = mkstemp(template)) == -1)
333 		return got_error_from_errno("mkstemp");
334 
335 	worklist_add(template, temp_files);
336 
337 	if (buf_write_fd(b, fd) == -1) {
338 		err = got_error_from_errno("buf_write_fd");
339 		(void)unlink(template);
340 	}
341 
342 	if (close(fd) != 0 && err == NULL)
343 		err = got_error_from_errno("close");
344 
345 	return err;
346 }
347 
348 /*
349  * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
350  * operation regardless of the result.
351  */
352 static const struct got_error *
353 buf_grow(BUF *b, size_t len)
354 {
355 	u_char *buf;
356 	buf = reallocarray(b->cb_buf, 1, b->cb_size + len);
357 	if (buf == NULL)
358 		return got_error_from_errno("reallocarray");
359 	b->cb_buf = buf;
360 	b->cb_size += len;
361 	return NULL;
362 }