1 /* $OpenBSD: buf.c,v 1.29 2021/10/24 21:24:17 deraadt 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 <err.h>
31 #include <errno.h>
32 #include <fcntl.h>
33 #include <stdint.h>
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <unistd.h>
38
39 #include "buf.h"
40 #include "xmalloc.h"
41 #include "worklist.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 void 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 *
buf_alloc(size_t len)62 buf_alloc(size_t len)
63 {
64 BUF *b;
65
66 b = xmalloc(sizeof(*b));
67 /* Postpone creation of zero-sized buffers */
68 if (len > 0)
69 b->cb_buf = xcalloc(1, len);
70 else
71 b->cb_buf = NULL;
72
73 b->cb_size = len;
74 b->cb_len = 0;
75
76 return (b);
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 BUF *
buf_load(const char * path)86 buf_load(const char *path)
87 {
88 int fd;
89 ssize_t ret;
90 size_t len;
91 u_char *bp;
92 struct stat st;
93 BUF *buf;
94
95 buf = NULL;
96
97 if ((fd = open(path, O_RDONLY)) == -1)
98 goto out;
99
100 if (fstat(fd, &st) == -1)
101 goto out;
102
103 if ((uintmax_t)st.st_size > SIZE_MAX) {
104 errno = EFBIG;
105 goto out;
106 }
107 buf = buf_alloc(st.st_size);
108 for (bp = buf->cb_buf; ; bp += (size_t)ret) {
109 len = SIZE_LEFT(buf);
110 ret = read(fd, bp, len);
111 if (ret == -1) {
112 int saved_errno;
113
114 saved_errno = errno;
115 buf_free(buf);
116 buf = NULL;
117 errno = saved_errno;
118 goto out;
119 } else if (ret == 0)
120 break;
121
122 buf->cb_len += (size_t)ret;
123 }
124
125 out:
126 if (fd != -1) {
127 int saved_errno;
128
129 /* We may want to preserve errno here. */
130 saved_errno = errno;
131 (void)close(fd);
132 errno = saved_errno;
133 }
134
135 return (buf);
136 }
137
138 void
buf_free(BUF * b)139 buf_free(BUF *b)
140 {
141 if (b == NULL)
142 return;
143 free(b->cb_buf);
144 free(b);
145 }
146
147 /*
148 * Free the buffer <b>'s structural information but do not free the contents
149 * of the buffer. Instead, they are returned and should be freed later using
150 * free().
151 */
152 void *
buf_release(BUF * b)153 buf_release(BUF *b)
154 {
155 void *tmp;
156
157 tmp = b->cb_buf;
158 free(b);
159 return (tmp);
160 }
161
162 u_char *
buf_get(BUF * b)163 buf_get(BUF *b)
164 {
165 return (b->cb_buf);
166 }
167
168 /*
169 * Empty the contents of the buffer <b> and reset pointers.
170 */
171 void
buf_empty(BUF * b)172 buf_empty(BUF *b)
173 {
174 memset(b->cb_buf, 0, b->cb_size);
175 b->cb_len = 0;
176 }
177
178 /*
179 * Append a single character <c> to the end of the buffer <b>.
180 */
181 void
buf_putc(BUF * b,int c)182 buf_putc(BUF *b, int c)
183 {
184 u_char *bp;
185
186 if (SIZE_LEFT(b) == 0)
187 buf_grow(b, BUF_INCR);
188 bp = b->cb_buf + b->cb_len;
189 *bp = (u_char)c;
190 b->cb_len++;
191 }
192
193 /*
194 * Append a string <s> to the end of buffer <b>.
195 */
196 void
buf_puts(BUF * b,const char * str)197 buf_puts(BUF *b, const char *str)
198 {
199 buf_append(b, str, strlen(str));
200 }
201
202 /*
203 * Return u_char at buffer position <pos>.
204 */
205 u_char
buf_getc(BUF * b,size_t pos)206 buf_getc(BUF *b, size_t pos)
207 {
208 return (b->cb_buf[pos]);
209 }
210
211 /*
212 * Append <len> bytes of data pointed to by <data> to the buffer <b>. If the
213 * buffer is too small to accept all data, it will get resized to an
214 * appropriate size to accept all data.
215 * Returns the number of bytes successfully appended to the buffer.
216 */
217 size_t
buf_append(BUF * b,const void * data,size_t len)218 buf_append(BUF *b, const void *data, size_t len)
219 {
220 size_t left, rlen;
221 u_char *bp;
222
223 left = SIZE_LEFT(b);
224 rlen = len;
225
226 if (left < len)
227 buf_grow(b, len - left);
228 bp = b->cb_buf + b->cb_len;
229 memcpy(bp, data, rlen);
230 b->cb_len += rlen;
231
232 return (rlen);
233 }
234
235 /*
236 * Returns the size of the buffer that is being used.
237 */
238 size_t
buf_len(BUF * b)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
buf_write_fd(BUF * b,int fd)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 int
buf_write(BUF * b,const char * path,mode_t mode)277 buf_write(BUF *b, const char *path, mode_t mode)
278 {
279 int fd;
280 open:
281 if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)) == -1) {
282 if (errno == EACCES && unlink(path) != -1)
283 goto open;
284 else
285 err(1, "%s", path);
286 }
287
288 if (buf_write_fd(b, fd) == -1) {
289 (void)unlink(path);
290 errx(1, "buf_write: buf_write_fd: `%s'", path);
291 }
292
293 if (fchmod(fd, mode) == -1)
294 warn("permissions not set on file %s", path);
295
296 (void)close(fd);
297
298 return (0);
299 }
300
301 /*
302 * Write the contents of the buffer <b> to a temporary file whose path is
303 * specified using <template> (see mkstemp.3).
304 * NB. This function will modify <template>, as per mkstemp
305 */
306 void
buf_write_stmp(BUF * b,char * template)307 buf_write_stmp(BUF *b, char *template)
308 {
309 int fd;
310
311 if ((fd = mkstemp(template)) == -1)
312 err(1, "%s", template);
313
314 worklist_add(template, &temp_files);
315
316 if (buf_write_fd(b, fd) == -1) {
317 (void)unlink(template);
318 errx(1, "buf_write_stmp: buf_write_fd: `%s'", template);
319 }
320
321 (void)close(fd);
322 }
323
324 /*
325 * Grow the buffer <b> by <len> bytes. The contents are unchanged by this
326 * operation regardless of the result.
327 */
328 static void
buf_grow(BUF * b,size_t len)329 buf_grow(BUF *b, size_t len)
330 {
331 b->cb_buf = xreallocarray(b->cb_buf, 1, b->cb_size + len);
332 b->cb_size += len;
333 }
334