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v5.14.15
  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(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	BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);
233
234	while (len) {
235		start_len = min(len, MAX_MEMHEX_BYTES);
236#ifdef __BIG_ENDIAN
237		for (i = 0, j = 0; i < start_len; i++) {
238#else
239		for (i = start_len-1, j = 0; i >= 0; i--) {
240#endif
241			hex[j++] = hex_asc_hi(data[i]);
242			hex[j++] = hex_asc_lo(data[i]);
243		}
244		if (WARN_ON_ONCE(j == 0 || j/2 > len))
245			break;
246
247		/* j increments twice per loop */
248		hex[j++] = ' ';
249
250		seq_buf_putmem(s, hex, j);
251		if (seq_buf_has_overflowed(s))
252			return -1;
253
254		len -= start_len;
255		data += start_len;
256	}
257	return 0;
258}
259
260/**
261 * seq_buf_path - copy a path into the sequence buffer
262 * @s: seq_buf descriptor
263 * @path: path to write into the sequence buffer.
264 * @esc: set of characters to escape in the output
265 *
266 * Write a path name into the sequence buffer.
267 *
268 * Returns the number of written bytes on success, -1 on overflow
269 */
270int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
271{
272	char *buf;
273	size_t size = seq_buf_get_buf(s, &buf);
274	int res = -1;
275
276	WARN_ON(s->size == 0);
277
278	if (size) {
279		char *p = d_path(path, buf, size);
280		if (!IS_ERR(p)) {
281			char *end = mangle_path(buf, p, esc);
282			if (end)
283				res = end - buf;
284		}
285	}
286	seq_buf_commit(s, res);
287
288	return res;
289}
290
291/**
292 * seq_buf_to_user - copy the sequence buffer to user space
293 * @s: seq_buf descriptor
294 * @ubuf: The userspace memory location to copy to
 
295 * @cnt: The amount to copy
296 *
297 * Copies the sequence buffer into the userspace memory pointed to
298 * by @ubuf. It starts from the last read position (@s->readpos)
299 * and writes up to @cnt characters or till it reaches the end of
300 * the content in the buffer (@s->len), which ever comes first.
301 *
 
302 * On success, it returns a positive number of the number of bytes
303 * it copied.
304 *
305 * On failure it returns -EBUSY if all of the content in the
306 * sequence has been already read, which includes nothing in the
307 * sequence (@s->len == @s->readpos).
308 *
309 * Returns -EFAULT if the copy to userspace fails.
310 */
311int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, int cnt)
312{
313	int len;
314	int ret;
315
316	if (!cnt)
317		return 0;
318
319	len = seq_buf_used(s);
320
321	if (len <= s->readpos)
322		return -EBUSY;
323
324	len -= s->readpos;
325	if (cnt > len)
326		cnt = len;
327	ret = copy_to_user(ubuf, s->buffer + s->readpos, cnt);
328	if (ret == cnt)
329		return -EFAULT;
330
331	cnt -= ret;
332
333	s->readpos += cnt;
334	return cnt;
335}
336
337/**
338 * seq_buf_hex_dump - print formatted hex dump into the sequence buffer
339 * @s: seq_buf descriptor
340 * @prefix_str: string to prefix each line with;
341 *  caller supplies trailing spaces for alignment if desired
342 * @prefix_type: controls whether prefix of an offset, address, or none
343 *  is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
344 * @rowsize: number of bytes to print per line; must be 16 or 32
345 * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
346 * @buf: data blob to dump
347 * @len: number of bytes in the @buf
348 * @ascii: include ASCII after the hex output
349 *
350 * Function is an analogue of print_hex_dump() and thus has similar interface.
351 *
352 * linebuf size is maximal length for one line.
353 * 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
354 *	separating space
355 * 2 - spaces separating hex dump and ascii representation
356 * 32 - ascii representation
357 * 1 - terminating '\0'
358 *
359 * Returns zero on success, -1 on overflow
360 */
361int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str, int prefix_type,
362		     int rowsize, int groupsize,
363		     const void *buf, size_t len, bool ascii)
364{
365	const u8 *ptr = buf;
366	int i, linelen, remaining = len;
367	unsigned char linebuf[32 * 3 + 2 + 32 + 1];
368	int ret;
369
370	if (rowsize != 16 && rowsize != 32)
371		rowsize = 16;
372
373	for (i = 0; i < len; i += rowsize) {
374		linelen = min(remaining, rowsize);
375		remaining -= rowsize;
376
377		hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
378				   linebuf, sizeof(linebuf), ascii);
379
380		switch (prefix_type) {
381		case DUMP_PREFIX_ADDRESS:
382			ret = seq_buf_printf(s, "%s%p: %s\n",
383			       prefix_str, ptr + i, linebuf);
384			break;
385		case DUMP_PREFIX_OFFSET:
386			ret = seq_buf_printf(s, "%s%.8x: %s\n",
387					     prefix_str, i, linebuf);
388			break;
389		default:
390			ret = seq_buf_printf(s, "%s%s\n", prefix_str, linebuf);
391			break;
392		}
393		if (ret)
394			return ret;
395	}
396	return 0;
397}
v6.13.7
  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 */
 38static 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 */
 50int 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 */
 67int 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 */
 93int 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}
104EXPORT_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 */
115void 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}
134EXPORT_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 */
154int 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 */
182int 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}
200EXPORT_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 */
211int 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}
222EXPORT_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 */
236int 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 */
264int 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 */
312int 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 */
355int 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 */
402int 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}