1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * seq_buf.c
4 *
5 * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
6 *
7 * The seq_buf is a handy tool that allows you to pass a descriptor around
8 * to a buffer that other functions can write to. It is similar to the
9 * seq_file functionality but has some differences.
10 *
11 * To use it, the seq_buf must be initialized with seq_buf_init().
12 * This will set up the counters within the descriptor. You can call
13 * seq_buf_init() more than once to reset the seq_buf to start
14 * from scratch.
15 */
16
17 #include <linux/bug.h>
18 #include <linux/err.h>
19 #include <linux/export.h>
20 #include <linux/hex.h>
21 #include <linux/minmax.h>
22 #include <linux/printk.h>
23 #include <linux/seq_buf.h>
24 #include <linux/seq_file.h>
25 #include <linux/sprintf.h>
26 #include <linux/string.h>
27 #include <linux/types.h>
28 #include <linux/uaccess.h>
29
30 /**
31 * seq_buf_can_fit - can the new data fit in the current buffer?
32 * @s: the seq_buf descriptor
33 * @len: The length to see if it can fit in the current buffer
34 *
35 * Returns: true if there's enough unused space in the seq_buf buffer
36 * to fit the amount of new data according to @len.
37 */
38 static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
39 {
40 return s->len + len <= s->size;
41 }
42
43 /**
44 * seq_buf_print_seq - move the contents of seq_buf into a seq_file
45 * @m: the seq_file descriptor that is the destination
46 * @s: the seq_buf descriptor that is the source.
47 *
48 * Returns: zero on success, non-zero otherwise.
49 */
50 int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
51 {
52 unsigned int len = seq_buf_used(s);
53
54 return seq_write(m, s->buffer, len);
55 }
56
57 /**
58 * seq_buf_vprintf - sequence printing of information.
59 * @s: seq_buf descriptor
60 * @fmt: printf format string
61 * @args: va_list of arguments from a printf() type function
62 *
63 * Writes a vnprintf() format into the sequence buffer.
64 *
65 * Returns: zero on success, -1 on overflow.
66 */
67 int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
68 {
69 int len;
70
71 WARN_ON(s->size == 0);
72
73 if (s->len < s->size) {
74 len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
75 if (s->len + len < s->size) {
76 s->len += len;
77 return 0;
78 }
79 }
80 seq_buf_set_overflow(s);
81 return -1;
82 }
83
84 /**
85 * seq_buf_printf - sequence printing of information
86 * @s: seq_buf descriptor
87 * @fmt: printf format string
88 *
89 * Writes a printf() format into the sequence buffer.
90 *
91 * Returns: zero on success, -1 on overflow.
92 */
93 int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
94 {
95 va_list ap;
96 int ret;
97
98 va_start(ap, fmt);
99 ret = seq_buf_vprintf(s, fmt, ap);
100 va_end(ap);
101
102 return ret;
103 }
104 EXPORT_SYMBOL_GPL(seq_buf_printf);
105
106 /**
107 * seq_buf_do_printk - printk() seq_buf line by line
108 * @s: seq_buf descriptor
109 * @lvl: printk level
110 *
111 * printk()-s a multi-line sequential buffer line by line. The function
112 * makes sure that the buffer in @s is NUL-terminated and safe to read
113 * as a string.
114 */
115 void seq_buf_do_printk(struct seq_buf *s, const char *lvl)
116 {
117 const char *start, *lf;
118
119 if (s->size == 0 || s->len == 0)
120 return;
121
122 start = seq_buf_str(s);
123 while ((lf = strchr(start, '\n'))) {
124 int len = lf - start + 1;
125
126 printk("%s%.*s", lvl, len, start);
127 start = ++lf;
128 }
129
130 /* No trailing LF */
131 if (start < s->buffer + s->len)
132 printk("%s%s\n", lvl, start);
133 }
134 EXPORT_SYMBOL_GPL(seq_buf_do_printk);
135
136 #ifdef CONFIG_BINARY_PRINTF
137 /**
138 * seq_buf_bprintf - Write the printf string from binary arguments
139 * @s: seq_buf descriptor
140 * @fmt: The format string for the @binary arguments
141 * @binary: The binary arguments for @fmt.
142 *
143 * When recording in a fast path, a printf may be recorded with just
144 * saving the format and the arguments as they were passed to the
145 * function, instead of wasting cycles converting the arguments into
146 * ASCII characters. Instead, the arguments are saved in a 32 bit
147 * word array that is defined by the format string constraints.
148 *
149 * This function will take the format and the binary array and finish
150 * the conversion into the ASCII string within the buffer.
151 *
152 * Returns: zero on success, -1 on overflow.
153 */
154 int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
155 {
156 unsigned int len = seq_buf_buffer_left(s);
157 int ret;
158
159 WARN_ON(s->size == 0);
160
161 if (s->len < s->size) {
162 ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
163 if (s->len + ret < s->size) {
164 s->len += ret;
165 return 0;
166 }
167 }
168 seq_buf_set_overflow(s);
169 return -1;
170 }
171 #endif /* CONFIG_BINARY_PRINTF */
172
173 /**
174 * seq_buf_puts - sequence printing of simple string
175 * @s: seq_buf descriptor
176 * @str: simple string to record
177 *
178 * Copy a simple string into the sequence buffer.
179 *
180 * Returns: zero on success, -1 on overflow.
181 */
182 int seq_buf_puts(struct seq_buf *s, const char *str)
183 {
184 size_t len = strlen(str);
185
186 WARN_ON(s->size == 0);
187
188 /* Add 1 to len for the trailing null byte which must be there */
189 len += 1;
190
191 if (seq_buf_can_fit(s, len)) {
192 memcpy(s->buffer + s->len, str, len);
193 /* Don't count the trailing null byte against the capacity */
194 s->len += len - 1;
195 return 0;
196 }
197 seq_buf_set_overflow(s);
198 return -1;
199 }
200 EXPORT_SYMBOL_GPL(seq_buf_puts);
201
202 /**
203 * seq_buf_putc - sequence printing of simple character
204 * @s: seq_buf descriptor
205 * @c: simple character to record
206 *
207 * Copy a single character into the sequence buffer.
208 *
209 * Returns: zero on success, -1 on overflow.
210 */
211 int seq_buf_putc(struct seq_buf *s, unsigned char c)
212 {
213 WARN_ON(s->size == 0);
214
215 if (seq_buf_can_fit(s, 1)) {
216 s->buffer[s->len++] = c;
217 return 0;
218 }
219 seq_buf_set_overflow(s);
220 return -1;
221 }
222 EXPORT_SYMBOL_GPL(seq_buf_putc);
223
224 /**
225 * seq_buf_putmem - write raw data into the sequence buffer
226 * @s: seq_buf descriptor
227 * @mem: The raw memory to copy into the buffer
228 * @len: The length of the raw memory to copy (in bytes)
229 *
230 * There may be cases where raw memory needs to be written into the
231 * buffer and a strcpy() would not work. Using this function allows
232 * for such cases.
233 *
234 * Returns: zero on success, -1 on overflow.
235 */
236 int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
237 {
238 WARN_ON(s->size == 0);
239
240 if (seq_buf_can_fit(s, len)) {
241 memcpy(s->buffer + s->len, mem, len);
242 s->len += len;
243 return 0;
244 }
245 seq_buf_set_overflow(s);
246 return -1;
247 }
248
249 #define MAX_MEMHEX_BYTES 8U
250 #define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
251
252 /**
253 * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
254 * @s: seq_buf descriptor
255 * @mem: The raw memory to write its hex ASCII representation of
256 * @len: The length of the raw memory to copy (in bytes)
257 *
258 * This is similar to seq_buf_putmem() except instead of just copying the
259 * raw memory into the buffer it writes its ASCII representation of it
260 * in hex characters.
261 *
262 * Returns: zero on success, -1 on overflow.
263 */
264 int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
265 unsigned int len)
266 {
267 unsigned char hex[HEX_CHARS];
268 const unsigned char *data = mem;
269 unsigned int start_len;
270 int i, j;
271
272 WARN_ON(s->size == 0);
273
274 BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);
275
276 while (len) {
277 start_len = min(len, MAX_MEMHEX_BYTES);
278 #ifdef __BIG_ENDIAN
279 for (i = 0, j = 0; i < start_len; i++) {
280 #else
281 for (i = start_len-1, j = 0; i >= 0; i--) {
282 #endif
283 hex[j++] = hex_asc_hi(data[i]);
284 hex[j++] = hex_asc_lo(data[i]);
285 }
286 if (WARN_ON_ONCE(j == 0 || j/2 > len))
287 break;
288
289 /* j increments twice per loop */
290 hex[j++] = ' ';
291
292 seq_buf_putmem(s, hex, j);
293 if (seq_buf_has_overflowed(s))
294 return -1;
295
296 len -= start_len;
297 data += start_len;
298 }
299 return 0;
300 }
301
302 /**
303 * seq_buf_path - copy a path into the sequence buffer
304 * @s: seq_buf descriptor
305 * @path: path to write into the sequence buffer.
306 * @esc: set of characters to escape in the output
307 *
308 * Write a path name into the sequence buffer.
309 *
310 * Returns: the number of written bytes on success, -1 on overflow.
311 */
312 int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
313 {
314 char *buf;
315 size_t size = seq_buf_get_buf(s, &buf);
316 int res = -1;
317
318 WARN_ON(s->size == 0);
319
320 if (size) {
321 char *p = d_path(path, buf, size);
322 if (!IS_ERR(p)) {
323 char *end = mangle_path(buf, p, esc);
324 if (end)
325 res = end - buf;
326 }
327 }
328 seq_buf_commit(s, res);
329
330 return res;
331 }
332
333 /**
334 * seq_buf_to_user - copy the sequence buffer to user space
335 * @s: seq_buf descriptor
336 * @ubuf: The userspace memory location to copy to
337 * @start: The first byte in the buffer to copy
338 * @cnt: The amount to copy
339 *
340 * Copies the sequence buffer into the userspace memory pointed to
341 * by @ubuf. It starts from @start and writes up to @cnt characters
342 * or until it reaches the end of the content in the buffer (@s->len),
343 * whichever comes first.
344 *
345 * Returns:
346 * On success, it returns a positive number of the number of bytes
347 * it copied.
348 *
349 * On failure it returns -EBUSY if all of the content in the
350 * sequence has been already read, which includes nothing in the
351 * sequence (@s->len == @start).
352 *
353 * Returns -EFAULT if the copy to userspace fails.
354 */
355 int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
356 {
357 int len;
358 int ret;
359
360 if (!cnt)
361 return 0;
362
363 len = seq_buf_used(s);
364
365 if (len <= start)
366 return -EBUSY;
367
368 len -= start;
369 if (cnt > len)
370 cnt = len;
371 ret = copy_to_user(ubuf, s->buffer + start, cnt);
372 if (ret == cnt)
373 return -EFAULT;
374
375 return cnt - ret;
376 }
377
378 /**
379 * seq_buf_hex_dump - print formatted hex dump into the sequence buffer
380 * @s: seq_buf descriptor
381 * @prefix_str: string to prefix each line with;
382 * caller supplies trailing spaces for alignment if desired
383 * @prefix_type: controls whether prefix of an offset, address, or none
384 * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
385 * @rowsize: number of bytes to print per line; must be 16 or 32
386 * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
387 * @buf: data blob to dump
388 * @len: number of bytes in the @buf
389 * @ascii: include ASCII after the hex output
390 *
391 * Function is an analogue of print_hex_dump() and thus has similar interface.
392 *
393 * linebuf size is maximal length for one line.
394 * 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
395 * separating space
396 * 2 - spaces separating hex dump and ASCII representation
397 * 32 - ASCII representation
398 * 1 - terminating '\0'
399 *
400 * Returns: zero on success, -1 on overflow.
401 */
402 int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str, int prefix_type,
403 int rowsize, int groupsize,
404 const void *buf, size_t len, bool ascii)
405 {
406 const u8 *ptr = buf;
407 int i, linelen, remaining = len;
408 unsigned char linebuf[32 * 3 + 2 + 32 + 1];
409 int ret;
410
411 if (rowsize != 16 && rowsize != 32)
412 rowsize = 16;
413
414 for (i = 0; i < len; i += rowsize) {
415 linelen = min(remaining, rowsize);
416 remaining -= rowsize;
417
418 hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
419 linebuf, sizeof(linebuf), ascii);
420
421 switch (prefix_type) {
422 case DUMP_PREFIX_ADDRESS:
423 ret = seq_buf_printf(s, "%s%p: %s\n",
424 prefix_str, ptr + i, linebuf);
425 break;
426 case DUMP_PREFIX_OFFSET:
427 ret = seq_buf_printf(s, "%s%.8x: %s\n",
428 prefix_str, i, linebuf);
429 break;
430 default:
431 ret = seq_buf_printf(s, "%s%s\n", prefix_str, linebuf);
432 break;
433 }
434 if (ret)
435 return ret;
436 }
437 return 0;
438 }
439
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