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

source code of linux/lib/seq_buf.c