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1// SPDX-License-Identifier: GPL-2.02/*3 * seq_buf.c4 *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 around8 * to a buffer that other functions can write to. It is similar to the9 * 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 call13 * seq_buf_init() more than once to reset the seq_buf to start14 * 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 descriptor33 * @len: The length to see if it can fit in the current buffer34 *35 * Returns: true if there's enough unused space in the seq_buf buffer36 * 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_file45 * @m: the seq_file descriptor that is the destination46 * @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 descriptor60 * @fmt: printf format string61 * @args: va_list of arguments from a printf() type function62 *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 information86 * @s: seq_buf descriptor87 * @fmt: printf format string88 *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 line108 * @s: seq_buf descriptor109 * @lvl: printk level110 *111 * printk()-s a multi-line sequential buffer line by line. The function112 * makes sure that the buffer in @s is NUL-terminated and safe to read113 * 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_PRINTF137/**138 * seq_buf_bprintf - Write the printf string from binary arguments139 * @s: seq_buf descriptor140 * @fmt: The format string for the @binary arguments141 * @binary: The binary arguments for @fmt.142 *143 * When recording in a fast path, a printf may be recorded with just144 * saving the format and the arguments as they were passed to the145 * function, instead of wasting cycles converting the arguments into146 * ASCII characters. Instead, the arguments are saved in a 32 bit147 * word array that is defined by the format string constraints.148 *149 * This function will take the format and the binary array and finish150 * 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 string175 * @s: seq_buf descriptor176 * @str: simple string to record177 *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 character204 * @s: seq_buf descriptor205 * @c: simple character to record206 *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 buffer226 * @s: seq_buf descriptor227 * @mem: The raw memory to copy into the buffer228 * @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 the231 * buffer and a strcpy() would not work. Using this function allows232 * 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 8U250#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)251 252/**253 * seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex254 * @s: seq_buf descriptor255 * @mem: The raw memory to write its hex ASCII representation of256 * @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 the259 * raw memory into the buffer it writes its ASCII representation of it260 * 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_ENDIAN279 for (i = 0, j = 0; i < start_len; i++) {280#else281 for (i = start_len-1, j = 0; i >= 0; i--) {282#endif283 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 buffer304 * @s: seq_buf descriptor305 * @path: path to write into the sequence buffer.306 * @esc: set of characters to escape in the output307 *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 space335 * @s: seq_buf descriptor336 * @ubuf: The userspace memory location to copy to337 * @start: The first byte in the buffer to copy338 * @cnt: The amount to copy339 *340 * Copies the sequence buffer into the userspace memory pointed to341 * by @ubuf. It starts from @start and writes up to @cnt characters342 * 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 bytes347 * it copied.348 *349 * On failure it returns -EBUSY if all of the content in the350 * sequence has been already read, which includes nothing in the351 * 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 buffer380 * @s: seq_buf descriptor381 * @prefix_str: string to prefix each line with;382 * caller supplies trailing spaces for alignment if desired383 * @prefix_type: controls whether prefix of an offset, address, or none384 * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)385 * @rowsize: number of bytes to print per line; must be 16 or 32386 * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)387 * @buf: data blob to dump388 * @len: number of bytes in the @buf389 * @ascii: include ASCII after the hex output390 *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 for395 * separating space396 * 2 - spaces separating hex dump and ASCII representation397 * 32 - ASCII representation398 * 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}439