projects/linux·blob v5.10-rc5 · refs

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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * seq_buf.c
4 *
5 * Copyright (C) 2014 Red Hat Inc, Steven Rostedt <[email protected]>
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(m, 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(s->buffer + s->len, 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, ap);
90 va_end(ap);
91
92 return ret;
93}
94EXPORT_SYMBOL_GPL(seq_buf_printf);
95
96#ifdef CONFIG_BINARY_PRINTF
97/**
98 * seq_buf_bprintf - Write the printf string from binary arguments
99 * @s: seq_buf descriptor
100 * @fmt: The format string for the @binary arguments
101 * @binary: The binary arguments for @fmt.
102 *
103 * When recording in a fast path, a printf may be recorded with just
104 * saving the format and the arguments as they were passed to the
105 * function, instead of wasting cycles converting the arguments into
106 * ASCII characters. Instead, the arguments are saved in a 32 bit
107 * word array that is defined by the format string constraints.
108 *
109 * This function will take the format and the binary array and finish
110 * the conversion into the ASCII string within the buffer.
111 *
112 * Returns zero on success, -1 on overflow.
113 */
114int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
115{
116 unsigned int len = seq_buf_buffer_left(s);
117 int ret;
118
119 WARN_ON(s->size == 0);
120
121 if (s->len < s->size) {
122 ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
123 if (s->len + ret < s->size) {
124 s->len += ret;
125 return 0;
126 }
127 }
128 seq_buf_set_overflow(s);
129 return -1;
130}
131#endif /* CONFIG_BINARY_PRINTF */
132
133/**
134 * seq_buf_puts - sequence printing of simple string
135 * @s: seq_buf descriptor
136 * @str: simple string to record
137 *
138 * Copy a simple string into the sequence buffer.
139 *
140 * Returns zero on success, -1 on overflow
141 */
142int seq_buf_puts(struct seq_buf *s, const char *str)
143{
144 size_t len = strlen(str);
145
146 WARN_ON(s->size == 0);
147
148 /* Add 1 to len for the trailing null byte which must be there */
149 len += 1;
150
151 if (seq_buf_can_fit(s, len)) {
152 memcpy(s->buffer + s->len, str, len);
153 /* Don't count the trailing null byte against the capacity */
154 s->len += len - 1;
155 return 0;
156 }
157 seq_buf_set_overflow(s);
158 return -1;
159}
160
161/**
162 * seq_buf_putc - sequence printing of simple character
163 * @s: seq_buf descriptor
164 * @c: simple character to record
165 *
166 * Copy a single character into the sequence buffer.
167 *
168 * Returns zero on success, -1 on overflow
169 */
170int seq_buf_putc(struct seq_buf *s, unsigned char c)
171{
172 WARN_ON(s->size == 0);
173
174 if (seq_buf_can_fit(s, 1)) {
175 s->buffer[s->len++] = c;
176 return 0;
177 }
178 seq_buf_set_overflow(s);
179 return -1;
180}
181
182/**
183 * seq_buf_putmem - write raw data into the sequenc buffer
184 * @s: seq_buf descriptor
185 * @mem: The raw memory to copy into the buffer
186 * @len: The length of the raw memory to copy (in bytes)
187 *
188 * There may be cases where raw memory needs to be written into the
189 * buffer and a strcpy() would not work. Using this function allows
190 * for such cases.
191 *
192 * Returns zero on success, -1 on overflow
193 */
194int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
195{
196 WARN_ON(s->size == 0);
197
198 if (seq_buf_can_fit(s, len)) {
199 memcpy(s->buffer + s->len, mem, len);
200 s->len += len;
201 return 0;
202 }
203 seq_buf_set_overflow(s);
204 return -1;
205}
206
207#define MAX_MEMHEX_BYTES 8U
208#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
209
210/**
211 * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
212 * @s: seq_buf descriptor
213 * @mem: The raw memory to write its hex ASCII representation of
214 * @len: The length of the raw memory to copy (in bytes)
215 *
216 * This is similar to seq_buf_putmem() except instead of just copying the
217 * raw memory into the buffer it writes its ASCII representation of it
218 * in hex characters.
219 *
220 * Returns zero on success, -1 on overflow
221 */
222int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
223 unsigned int len)
224{
225 unsigned char hex[HEX_CHARS];
226 const unsigned char *data = mem;
227 unsigned int start_len;
228 int i, j;
229
230 WARN_ON(s->size == 0);
231
232 while (len) {
233 start_len = min(len, HEX_CHARS - 1);
234#ifdef __BIG_ENDIAN
235 for (i = 0, j = 0; i < start_len; i++) {
236#else
237 for (i = start_len-1, j = 0; i >= 0; i--) {
238#endif
239 hex[j++] = hex_asc_hi(data[i]);
240 hex[j++] = hex_asc_lo(data[i]);
241 }
242 if (WARN_ON_ONCE(j == 0 || j/2 > len))
243 break;
244
245 /* j increments twice per loop */
246 len -= j / 2;
247 hex[j++] = ' ';
248
249 seq_buf_putmem(s, hex, j);
250 if (seq_buf_has_overflowed(s))
251 return -1;
252 }
253 return 0;
254}
255
256/**
257 * seq_buf_path - copy a path into the sequence buffer
258 * @s: seq_buf descriptor
259 * @path: path to write into the sequence buffer.
260 * @esc: set of characters to escape in the output
261 *
262 * Write a path name into the sequence buffer.
263 *
264 * Returns the number of written bytes on success, -1 on overflow
265 */
266int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
267{
268 char *buf;
269 size_t size = seq_buf_get_buf(s, &buf);
270 int res = -1;
271
272 WARN_ON(s->size == 0);
273
274 if (size) {
275 char *p = d_path(path, buf, size);
276 if (!IS_ERR(p)) {
277 char *end = mangle_path(buf, p, esc);
278 if (end)
279 res = end - buf;
280 }
281 }
282 seq_buf_commit(s, res);
283
284 return res;
285}
286
287/**
288 * seq_buf_to_user - copy the squence buffer to user space
289 * @s: seq_buf descriptor
290 * @ubuf: The userspace memory location to copy to
291 * @cnt: The amount to copy
292 *
293 * Copies the sequence buffer into the userspace memory pointed to
294 * by @ubuf. It starts from the last read position (@s->readpos)
295 * and writes up to @cnt characters or till it reaches the end of
296 * the content in the buffer (@s->len), which ever comes first.
297 *
298 * On success, it returns a positive number of the number of bytes
299 * it copied.
300 *
301 * On failure it returns -EBUSY if all of the content in the
302 * sequence has been already read, which includes nothing in the
303 * sequence (@s->len == @s->readpos).
304 *
305 * Returns -EFAULT if the copy to userspace fails.
306 */
307int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
308{
309 int len;
310 int ret;
311
312 if (!cnt)
313 return 0;
314
315 len = seq_buf_used(s);
316
317 if (len <= s->readpos)
318 return -EBUSY;
319
320 len -= s->readpos;
321 if (cnt > len)
322 cnt = len;
323 ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
324 if (ret == cnt)
325 return -EFAULT;
326
327 cnt -= ret;
328
329 s->readpos += cnt;
330 return cnt;
331}
332
333/**
334 * seq_buf_hex_dump - print formatted hex dump into the sequence buffer
335 * @s: seq_buf descriptor
336 * @prefix_str: string to prefix each line with;
337 * caller supplies trailing spaces for alignment if desired
338 * @prefix_type: controls whether prefix of an offset, address, or none
339 * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
340 * @rowsize: number of bytes to print per line; must be 16 or 32
341 * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
342 * @buf: data blob to dump
343 * @len: number of bytes in the @buf
344 * @ascii: include ASCII after the hex output
345 *
346 * Function is an analogue of print_hex_dump() and thus has similar interface.
347 *
348 * linebuf size is maximal length for one line.
349 * 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
350 * separating space
351 * 2 - spaces separating hex dump and ascii representation
352 * 32 - ascii representation
353 * 1 - terminating '\0'
354 *
355 * Returns zero on success, -1 on overflow
356 */
357int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str, int prefix_type,
358 int rowsize, int groupsize,
359 const void *buf, size_t len, bool ascii)
360{
361 const u8 *ptr = buf;
362 int i, linelen, remaining = len;
363 unsigned char linebuf[32 * 3 + 2 + 32 + 1];
364 int ret;
365
366 if (rowsize != 16 && rowsize != 32)
367 rowsize = 16;
368
369 for (i = 0; i < len; i += rowsize) {
370 linelen = min(remaining, rowsize);
371 remaining -= rowsize;
372
373 hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
374 linebuf, sizeof(linebuf), ascii);
375
376 switch (prefix_type) {
377 case DUMP_PREFIX_ADDRESS:
378 ret = seq_buf_printf(s, "%s%p: %s\n",
379 prefix_str, ptr + i, linebuf);
380 break;
381 case DUMP_PREFIX_OFFSET:
382 ret = seq_buf_printf(s, "%s%.8x: %s\n",
383 prefix_str, i, linebuf);
384 break;
385 default:
386 ret = seq_buf_printf(s, "%s%s\n", prefix_str, linebuf);
387 break;
388 }
389 if (ret)
390 return ret;
391 }
392 return 0;
393}