fs/seq_file.c

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This source file includes following definitions.
seq_set_overflow
seq_buf_alloc
seq_open
traverse
seq_read
seq_lseek
seq_release
seq_escape
seq_escape_mem_ascii
seq_vprintf
seq_printf
mangle_path
seq_path
seq_file_path
seq_path_root
seq_dentry
single_start
single_next
single_stop
single_open
single_open_size
single_release
seq_release_private
__seq_open_private
seq_open_private
seq_putc
seq_puts
seq_put_decimal_ull_width
seq_put_decimal_ull
seq_put_hex_ll
seq_put_decimal_ll
seq_write
seq_pad
seq_hex_dump
seq_list_start
seq_list_start_head
seq_list_next
seq_hlist_start
seq_hlist_start_head
seq_hlist_next
seq_hlist_start_rcu
seq_hlist_start_head_rcu
seq_hlist_next_rcu
seq_hlist_start_percpu
seq_hlist_next_percpu
seq_file_init
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/seq_file.c
   4  *
   5  * helper functions for making synthetic files from sequences of records.
   6  * initial implementation -- AV, Oct 2001.
   7  */
   8 
   9 #include <linux/cache.h>
  10 #include <linux/fs.h>
  11 #include <linux/export.h>
  12 #include <linux/seq_file.h>
  13 #include <linux/vmalloc.h>
  14 #include <linux/slab.h>
  15 #include <linux/cred.h>
  16 #include <linux/mm.h>
  17 #include <linux/printk.h>
  18 #include <linux/string_helpers.h>
  19 
  20 #include <linux/uaccess.h>
  21 #include <asm/page.h>
  22 
  23 static struct kmem_cache *seq_file_cache __ro_after_init;
  24 
  25 static void seq_set_overflow(struct seq_file *m)
  26 {
  27         m->count = m->size;
  28 }
  29 
  30 static void *seq_buf_alloc(unsigned long size)
  31 {
  32         return kvmalloc(size, GFP_KERNEL_ACCOUNT);
  33 }
  34 
  35 /**
  36  *      seq_open -      initialize sequential file
  37  *      @file: file we initialize
  38  *      @op: method table describing the sequence
  39  *
  40  *      seq_open() sets @file, associating it with a sequence described
  41  *      by @op.  @op->start() sets the iterator up and returns the first
  42  *      element of sequence. @op->stop() shuts it down.  @op->next()
  43  *      returns the next element of sequence.  @op->show() prints element
  44  *      into the buffer.  In case of error ->start() and ->next() return
  45  *      ERR_PTR(error).  In the end of sequence they return %NULL. ->show()
  46  *      returns 0 in case of success and negative number in case of error.
  47  *      Returning SEQ_SKIP means "discard this element and move on".
  48  *      Note: seq_open() will allocate a struct seq_file and store its
  49  *      pointer in @file->private_data. This pointer should not be modified.
  50  */
  51 int seq_open(struct file *file, const struct seq_operations *op)
  52 {
  53         struct seq_file *p;
  54 
  55         WARN_ON(file->private_data);
  56 
  57         p = kmem_cache_zalloc(seq_file_cache, GFP_KERNEL);
  58         if (!p)
  59                 return -ENOMEM;
  60 
  61         file->private_data = p;
  62 
  63         mutex_init(&p->lock);
  64         p->op = op;
  65 
  66         // No refcounting: the lifetime of 'p' is constrained
  67         // to the lifetime of the file.
  68         p->file = file;
  69 
  70         /*
  71          * Wrappers around seq_open(e.g. swaps_open) need to be
  72          * aware of this. If they set f_version themselves, they
  73          * should call seq_open first and then set f_version.
  74          */
  75         file->f_version = 0;
  76 
  77         /*
  78          * seq_files support lseek() and pread().  They do not implement
  79          * write() at all, but we clear FMODE_PWRITE here for historical
  80          * reasons.
  81          *
  82          * If a client of seq_files a) implements file.write() and b) wishes to
  83          * support pwrite() then that client will need to implement its own
  84          * file.open() which calls seq_open() and then sets FMODE_PWRITE.
  85          */
  86         file->f_mode &= ~FMODE_PWRITE;
  87         return 0;
  88 }
  89 EXPORT_SYMBOL(seq_open);
  90 
  91 static int traverse(struct seq_file *m, loff_t offset)
  92 {
  93         loff_t pos = 0;
  94         int error = 0;
  95         void *p;
  96 
  97         m->version = 0;
  98         m->index = 0;
  99         m->count = m->from = 0;
 100         if (!offset)
 101                 return 0;
 102 
 103         if (!m->buf) {
 104                 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
 105                 if (!m->buf)
 106                         return -ENOMEM;
 107         }
 108         p = m->op->start(m, &m->index);
 109         while (p) {
 110                 error = PTR_ERR(p);
 111                 if (IS_ERR(p))
 112                         break;
 113                 error = m->op->show(m, p);
 114                 if (error < 0)
 115                         break;
 116                 if (unlikely(error)) {
 117                         error = 0;
 118                         m->count = 0;
 119                 }
 120                 if (seq_has_overflowed(m))
 121                         goto Eoverflow;
 122                 p = m->op->next(m, p, &m->index);
 123                 if (pos + m->count > offset) {
 124                         m->from = offset - pos;
 125                         m->count -= m->from;
 126                         break;
 127                 }
 128                 pos += m->count;
 129                 m->count = 0;
 130                 if (pos == offset)
 131                         break;
 132         }
 133         m->op->stop(m, p);
 134         return error;
 135 
 136 Eoverflow:
 137         m->op->stop(m, p);
 138         kvfree(m->buf);
 139         m->count = 0;
 140         m->buf = seq_buf_alloc(m->size <<= 1);
 141         return !m->buf ? -ENOMEM : -EAGAIN;
 142 }
 143 
 144 /**
 145  *      seq_read -      ->read() method for sequential files.
 146  *      @file: the file to read from
 147  *      @buf: the buffer to read to
 148  *      @size: the maximum number of bytes to read
 149  *      @ppos: the current position in the file
 150  *
 151  *      Ready-made ->f_op->read()
 152  */
 153 ssize_t seq_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
 154 {
 155         struct seq_file *m = file->private_data;
 156         size_t copied = 0;
 157         size_t n;
 158         void *p;
 159         int err = 0;
 160 
 161         mutex_lock(&m->lock);
 162 
 163         /*
 164          * seq_file->op->..m_start/m_stop/m_next may do special actions
 165          * or optimisations based on the file->f_version, so we want to
 166          * pass the file->f_version to those methods.
 167          *
 168          * seq_file->version is just copy of f_version, and seq_file
 169          * methods can treat it simply as file version.
 170          * It is copied in first and copied out after all operations.
 171          * It is convenient to have it as  part of structure to avoid the
 172          * need of passing another argument to all the seq_file methods.
 173          */
 174         m->version = file->f_version;
 175 
 176         /*
 177          * if request is to read from zero offset, reset iterator to first
 178          * record as it might have been already advanced by previous requests
 179          */
 180         if (*ppos == 0) {
 181                 m->index = 0;
 182                 m->version = 0;
 183                 m->count = 0;
 184         }
 185 
 186         /* Don't assume *ppos is where we left it */
 187         if (unlikely(*ppos != m->read_pos)) {
 188                 while ((err = traverse(m, *ppos)) == -EAGAIN)
 189                         ;
 190                 if (err) {
 191                         /* With prejudice... */
 192                         m->read_pos = 0;
 193                         m->version = 0;
 194                         m->index = 0;
 195                         m->count = 0;
 196                         goto Done;
 197                 } else {
 198                         m->read_pos = *ppos;
 199                 }
 200         }
 201 
 202         /* grab buffer if we didn't have one */
 203         if (!m->buf) {
 204                 m->buf = seq_buf_alloc(m->size = PAGE_SIZE);
 205                 if (!m->buf)
 206                         goto Enomem;
 207         }
 208         /* if not empty - flush it first */
 209         if (m->count) {
 210                 n = min(m->count, size);
 211                 err = copy_to_user(buf, m->buf + m->from, n);
 212                 if (err)
 213                         goto Efault;
 214                 m->count -= n;
 215                 m->from += n;
 216                 size -= n;
 217                 buf += n;
 218                 copied += n;
 219                 if (!size)
 220                         goto Done;
 221         }
 222         /* we need at least one record in buffer */
 223         m->from = 0;
 224         p = m->op->start(m, &m->index);
 225         while (1) {
 226                 err = PTR_ERR(p);
 227                 if (!p || IS_ERR(p))
 228                         break;
 229                 err = m->op->show(m, p);
 230                 if (err < 0)
 231                         break;
 232                 if (unlikely(err))
 233                         m->count = 0;
 234                 if (unlikely(!m->count)) {
 235                         p = m->op->next(m, p, &m->index);
 236                         continue;
 237                 }
 238                 if (m->count < m->size)
 239                         goto Fill;
 240                 m->op->stop(m, p);
 241                 kvfree(m->buf);
 242                 m->count = 0;
 243                 m->buf = seq_buf_alloc(m->size <<= 1);
 244                 if (!m->buf)
 245                         goto Enomem;
 246                 m->version = 0;
 247                 p = m->op->start(m, &m->index);
 248         }
 249         m->op->stop(m, p);
 250         m->count = 0;
 251         goto Done;
 252 Fill:
 253         /* they want more? let's try to get some more */
 254         while (1) {
 255                 size_t offs = m->count;
 256                 loff_t pos = m->index;
 257 
 258                 p = m->op->next(m, p, &m->index);
 259                 if (pos == m->index)
 260                         /* Buggy ->next function */
 261                         m->index++;
 262                 if (!p || IS_ERR(p)) {
 263                         err = PTR_ERR(p);
 264                         break;
 265                 }
 266                 if (m->count >= size)
 267                         break;
 268                 err = m->op->show(m, p);
 269                 if (seq_has_overflowed(m) || err) {
 270                         m->count = offs;
 271                         if (likely(err <= 0))
 272                                 break;
 273                 }
 274         }
 275         m->op->stop(m, p);
 276         n = min(m->count, size);
 277         err = copy_to_user(buf, m->buf, n);
 278         if (err)
 279                 goto Efault;
 280         copied += n;
 281         m->count -= n;
 282         m->from = n;
 283 Done:
 284         if (!copied)
 285                 copied = err;
 286         else {
 287                 *ppos += copied;
 288                 m->read_pos += copied;
 289         }
 290         file->f_version = m->version;
 291         mutex_unlock(&m->lock);
 292         return copied;
 293 Enomem:
 294         err = -ENOMEM;
 295         goto Done;
 296 Efault:
 297         err = -EFAULT;
 298         goto Done;
 299 }
 300 EXPORT_SYMBOL(seq_read);
 301 
 302 /**
 303  *      seq_lseek -     ->llseek() method for sequential files.
 304  *      @file: the file in question
 305  *      @offset: new position
 306  *      @whence: 0 for absolute, 1 for relative position
 307  *
 308  *      Ready-made ->f_op->llseek()
 309  */
 310 loff_t seq_lseek(struct file *file, loff_t offset, int whence)
 311 {
 312         struct seq_file *m = file->private_data;
 313         loff_t retval = -EINVAL;
 314 
 315         mutex_lock(&m->lock);
 316         m->version = file->f_version;
 317         switch (whence) {
 318         case SEEK_CUR:
 319                 offset += file->f_pos;
 320                 /* fall through */
 321         case SEEK_SET:
 322                 if (offset < 0)
 323                         break;
 324                 retval = offset;
 325                 if (offset != m->read_pos) {
 326                         while ((retval = traverse(m, offset)) == -EAGAIN)
 327                                 ;
 328                         if (retval) {
 329                                 /* with extreme prejudice... */
 330                                 file->f_pos = 0;
 331                                 m->read_pos = 0;
 332                                 m->version = 0;
 333                                 m->index = 0;
 334                                 m->count = 0;
 335                         } else {
 336                                 m->read_pos = offset;
 337                                 retval = file->f_pos = offset;
 338                         }
 339                 } else {
 340                         file->f_pos = offset;
 341                 }
 342         }
 343         file->f_version = m->version;
 344         mutex_unlock(&m->lock);
 345         return retval;
 346 }
 347 EXPORT_SYMBOL(seq_lseek);
 348 
 349 /**
 350  *      seq_release -   free the structures associated with sequential file.
 351  *      @file: file in question
 352  *      @inode: its inode
 353  *
 354  *      Frees the structures associated with sequential file; can be used
 355  *      as ->f_op->release() if you don't have private data to destroy.
 356  */
 357 int seq_release(struct inode *inode, struct file *file)
 358 {
 359         struct seq_file *m = file->private_data;
 360         kvfree(m->buf);
 361         kmem_cache_free(seq_file_cache, m);
 362         return 0;
 363 }
 364 EXPORT_SYMBOL(seq_release);
 365 
 366 /**
 367  *      seq_escape -    print string into buffer, escaping some characters
 368  *      @m:     target buffer
 369  *      @s:     string
 370  *      @esc:   set of characters that need escaping
 371  *
 372  *      Puts string into buffer, replacing each occurrence of character from
 373  *      @esc with usual octal escape.
 374  *      Use seq_has_overflowed() to check for errors.
 375  */
 376 void seq_escape(struct seq_file *m, const char *s, const char *esc)
 377 {
 378         char *buf;
 379         size_t size = seq_get_buf(m, &buf);
 380         int ret;
 381 
 382         ret = string_escape_str(s, buf, size, ESCAPE_OCTAL, esc);
 383         seq_commit(m, ret < size ? ret : -1);
 384 }
 385 EXPORT_SYMBOL(seq_escape);
 386 
 387 void seq_escape_mem_ascii(struct seq_file *m, const char *src, size_t isz)
 388 {
 389         char *buf;
 390         size_t size = seq_get_buf(m, &buf);
 391         int ret;
 392 
 393         ret = string_escape_mem_ascii(src, isz, buf, size);
 394         seq_commit(m, ret < size ? ret : -1);
 395 }
 396 EXPORT_SYMBOL(seq_escape_mem_ascii);
 397 
 398 void seq_vprintf(struct seq_file *m, const char *f, va_list args)
 399 {
 400         int len;
 401 
 402         if (m->count < m->size) {
 403                 len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
 404                 if (m->count + len < m->size) {
 405                         m->count += len;
 406                         return;
 407                 }
 408         }
 409         seq_set_overflow(m);
 410 }
 411 EXPORT_SYMBOL(seq_vprintf);
 412 
 413 void seq_printf(struct seq_file *m, const char *f, ...)
 414 {
 415         va_list args;
 416 
 417         va_start(args, f);
 418         seq_vprintf(m, f, args);
 419         va_end(args);
 420 }
 421 EXPORT_SYMBOL(seq_printf);
 422 
 423 /**
 424  *      mangle_path -   mangle and copy path to buffer beginning
 425  *      @s: buffer start
 426  *      @p: beginning of path in above buffer
 427  *      @esc: set of characters that need escaping
 428  *
 429  *      Copy the path from @p to @s, replacing each occurrence of character from
 430  *      @esc with usual octal escape.
 431  *      Returns pointer past last written character in @s, or NULL in case of
 432  *      failure.
 433  */
 434 char *mangle_path(char *s, const char *p, const char *esc)
 435 {
 436         while (s <= p) {
 437                 char c = *p++;
 438                 if (!c) {
 439                         return s;
 440                 } else if (!strchr(esc, c)) {
 441                         *s++ = c;
 442                 } else if (s + 4 > p) {
 443                         break;
 444                 } else {
 445                         *s++ = '\\';
 446                         *s++ = '0' + ((c & 0300) >> 6);
 447                         *s++ = '0' + ((c & 070) >> 3);
 448                         *s++ = '0' + (c & 07);
 449                 }
 450         }
 451         return NULL;
 452 }
 453 EXPORT_SYMBOL(mangle_path);
 454 
 455 /**
 456  * seq_path - seq_file interface to print a pathname
 457  * @m: the seq_file handle
 458  * @path: the struct path to print
 459  * @esc: set of characters to escape in the output
 460  *
 461  * return the absolute path of 'path', as represented by the
 462  * dentry / mnt pair in the path parameter.
 463  */
 464 int seq_path(struct seq_file *m, const struct path *path, const char *esc)
 465 {
 466         char *buf;
 467         size_t size = seq_get_buf(m, &buf);
 468         int res = -1;
 469 
 470         if (size) {
 471                 char *p = d_path(path, buf, size);
 472                 if (!IS_ERR(p)) {
 473                         char *end = mangle_path(buf, p, esc);
 474                         if (end)
 475                                 res = end - buf;
 476                 }
 477         }
 478         seq_commit(m, res);
 479 
 480         return res;
 481 }
 482 EXPORT_SYMBOL(seq_path);
 483 
 484 /**
 485  * seq_file_path - seq_file interface to print a pathname of a file
 486  * @m: the seq_file handle
 487  * @file: the struct file to print
 488  * @esc: set of characters to escape in the output
 489  *
 490  * return the absolute path to the file.
 491  */
 492 int seq_file_path(struct seq_file *m, struct file *file, const char *esc)
 493 {
 494         return seq_path(m, &file->f_path, esc);
 495 }
 496 EXPORT_SYMBOL(seq_file_path);
 497 
 498 /*
 499  * Same as seq_path, but relative to supplied root.
 500  */
 501 int seq_path_root(struct seq_file *m, const struct path *path,
 502                   const struct path *root, const char *esc)
 503 {
 504         char *buf;
 505         size_t size = seq_get_buf(m, &buf);
 506         int res = -ENAMETOOLONG;
 507 
 508         if (size) {
 509                 char *p;
 510 
 511                 p = __d_path(path, root, buf, size);
 512                 if (!p)
 513                         return SEQ_SKIP;
 514                 res = PTR_ERR(p);
 515                 if (!IS_ERR(p)) {
 516                         char *end = mangle_path(buf, p, esc);
 517                         if (end)
 518                                 res = end - buf;
 519                         else
 520                                 res = -ENAMETOOLONG;
 521                 }
 522         }
 523         seq_commit(m, res);
 524 
 525         return res < 0 && res != -ENAMETOOLONG ? res : 0;
 526 }
 527 
 528 /*
 529  * returns the path of the 'dentry' from the root of its filesystem.
 530  */
 531 int seq_dentry(struct seq_file *m, struct dentry *dentry, const char *esc)
 532 {
 533         char *buf;
 534         size_t size = seq_get_buf(m, &buf);
 535         int res = -1;
 536 
 537         if (size) {
 538                 char *p = dentry_path(dentry, buf, size);
 539                 if (!IS_ERR(p)) {
 540                         char *end = mangle_path(buf, p, esc);
 541                         if (end)
 542                                 res = end - buf;
 543                 }
 544         }
 545         seq_commit(m, res);
 546 
 547         return res;
 548 }
 549 EXPORT_SYMBOL(seq_dentry);
 550 
 551 static void *single_start(struct seq_file *p, loff_t *pos)
 552 {
 553         return NULL + (*pos == 0);
 554 }
 555 
 556 static void *single_next(struct seq_file *p, void *v, loff_t *pos)
 557 {
 558         ++*pos;
 559         return NULL;
 560 }
 561 
 562 static void single_stop(struct seq_file *p, void *v)
 563 {
 564 }
 565 
 566 int single_open(struct file *file, int (*show)(struct seq_file *, void *),
 567                 void *data)
 568 {
 569         struct seq_operations *op = kmalloc(sizeof(*op), GFP_KERNEL_ACCOUNT);
 570         int res = -ENOMEM;
 571 
 572         if (op) {
 573                 op->start = single_start;
 574                 op->next = single_next;
 575                 op->stop = single_stop;
 576                 op->show = show;
 577                 res = seq_open(file, op);
 578                 if (!res)
 579                         ((struct seq_file *)file->private_data)->private = data;
 580                 else
 581                         kfree(op);
 582         }
 583         return res;
 584 }
 585 EXPORT_SYMBOL(single_open);
 586 
 587 int single_open_size(struct file *file, int (*show)(struct seq_file *, void *),
 588                 void *data, size_t size)
 589 {
 590         char *buf = seq_buf_alloc(size);
 591         int ret;
 592         if (!buf)
 593                 return -ENOMEM;
 594         ret = single_open(file, show, data);
 595         if (ret) {
 596                 kvfree(buf);
 597                 return ret;
 598         }
 599         ((struct seq_file *)file->private_data)->buf = buf;
 600         ((struct seq_file *)file->private_data)->size = size;
 601         return 0;
 602 }
 603 EXPORT_SYMBOL(single_open_size);
 604 
 605 int single_release(struct inode *inode, struct file *file)
 606 {
 607         const struct seq_operations *op = ((struct seq_file *)file->private_data)->op;
 608         int res = seq_release(inode, file);
 609         kfree(op);
 610         return res;
 611 }
 612 EXPORT_SYMBOL(single_release);
 613 
 614 int seq_release_private(struct inode *inode, struct file *file)
 615 {
 616         struct seq_file *seq = file->private_data;
 617 
 618         kfree(seq->private);
 619         seq->private = NULL;
 620         return seq_release(inode, file);
 621 }
 622 EXPORT_SYMBOL(seq_release_private);
 623 
 624 void *__seq_open_private(struct file *f, const struct seq_operations *ops,
 625                 int psize)
 626 {
 627         int rc;
 628         void *private;
 629         struct seq_file *seq;
 630 
 631         private = kzalloc(psize, GFP_KERNEL_ACCOUNT);
 632         if (private == NULL)
 633                 goto out;
 634 
 635         rc = seq_open(f, ops);
 636         if (rc < 0)
 637                 goto out_free;
 638 
 639         seq = f->private_data;
 640         seq->private = private;
 641         return private;
 642 
 643 out_free:
 644         kfree(private);
 645 out:
 646         return NULL;
 647 }
 648 EXPORT_SYMBOL(__seq_open_private);
 649 
 650 int seq_open_private(struct file *filp, const struct seq_operations *ops,
 651                 int psize)
 652 {
 653         return __seq_open_private(filp, ops, psize) ? 0 : -ENOMEM;
 654 }
 655 EXPORT_SYMBOL(seq_open_private);
 656 
 657 void seq_putc(struct seq_file *m, char c)
 658 {
 659         if (m->count >= m->size)
 660                 return;
 661 
 662         m->buf[m->count++] = c;
 663 }
 664 EXPORT_SYMBOL(seq_putc);
 665 
 666 void seq_puts(struct seq_file *m, const char *s)
 667 {
 668         int len = strlen(s);
 669 
 670         if (m->count + len >= m->size) {
 671                 seq_set_overflow(m);
 672                 return;
 673         }
 674         memcpy(m->buf + m->count, s, len);
 675         m->count += len;
 676 }
 677 EXPORT_SYMBOL(seq_puts);
 678 
 679 /**
 680  * A helper routine for putting decimal numbers without rich format of printf().
 681  * only 'unsigned long long' is supported.
 682  * @m: seq_file identifying the buffer to which data should be written
 683  * @delimiter: a string which is printed before the number
 684  * @num: the number
 685  * @width: a minimum field width
 686  *
 687  * This routine will put strlen(delimiter) + number into seq_filed.
 688  * This routine is very quick when you show lots of numbers.
 689  * In usual cases, it will be better to use seq_printf(). It's easier to read.
 690  */
 691 void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
 692                          unsigned long long num, unsigned int width)
 693 {
 694         int len;
 695 
 696         if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */
 697                 goto overflow;
 698 
 699         if (delimiter && delimiter[0]) {
 700                 if (delimiter[1] == 0)
 701                         seq_putc(m, delimiter[0]);
 702                 else
 703                         seq_puts(m, delimiter);
 704         }
 705 
 706         if (!width)
 707                 width = 1;
 708 
 709         if (m->count + width >= m->size)
 710                 goto overflow;
 711 
 712         len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
 713         if (!len)
 714                 goto overflow;
 715 
 716         m->count += len;
 717         return;
 718 
 719 overflow:
 720         seq_set_overflow(m);
 721 }
 722 
 723 void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
 724                          unsigned long long num)
 725 {
 726         return seq_put_decimal_ull_width(m, delimiter, num, 0);
 727 }
 728 EXPORT_SYMBOL(seq_put_decimal_ull);
 729 
 730 /**
 731  * seq_put_hex_ll - put a number in hexadecimal notation
 732  * @m: seq_file identifying the buffer to which data should be written
 733  * @delimiter: a string which is printed before the number
 734  * @v: the number
 735  * @width: a minimum field width
 736  *
 737  * seq_put_hex_ll(m, "", v, 8) is equal to seq_printf(m, "%08llx", v)
 738  *
 739  * This routine is very quick when you show lots of numbers.
 740  * In usual cases, it will be better to use seq_printf(). It's easier to read.
 741  */
 742 void seq_put_hex_ll(struct seq_file *m, const char *delimiter,
 743                                 unsigned long long v, unsigned int width)
 744 {
 745         unsigned int len;
 746         int i;
 747 
 748         if (delimiter && delimiter[0]) {
 749                 if (delimiter[1] == 0)
 750                         seq_putc(m, delimiter[0]);
 751                 else
 752                         seq_puts(m, delimiter);
 753         }
 754 
 755         /* If x is 0, the result of __builtin_clzll is undefined */
 756         if (v == 0)
 757                 len = 1;
 758         else
 759                 len = (sizeof(v) * 8 - __builtin_clzll(v) + 3) / 4;
 760 
 761         if (len < width)
 762                 len = width;
 763 
 764         if (m->count + len > m->size) {
 765                 seq_set_overflow(m);
 766                 return;
 767         }
 768 
 769         for (i = len - 1; i >= 0; i--) {
 770                 m->buf[m->count + i] = hex_asc[0xf & v];
 771                 v = v >> 4;
 772         }
 773         m->count += len;
 774 }
 775 
 776 void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num)
 777 {
 778         int len;
 779 
 780         if (m->count + 3 >= m->size) /* we'll write 2 bytes at least */
 781                 goto overflow;
 782 
 783         if (delimiter && delimiter[0]) {
 784                 if (delimiter[1] == 0)
 785                         seq_putc(m, delimiter[0]);
 786                 else
 787                         seq_puts(m, delimiter);
 788         }
 789 
 790         if (m->count + 2 >= m->size)
 791                 goto overflow;
 792 
 793         if (num < 0) {
 794                 m->buf[m->count++] = '-';
 795                 num = -num;
 796         }
 797 
 798         if (num < 10) {
 799                 m->buf[m->count++] = num + '0';
 800                 return;
 801         }
 802 
 803         len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
 804         if (!len)
 805                 goto overflow;
 806 
 807         m->count += len;
 808         return;
 809 
 810 overflow:
 811         seq_set_overflow(m);
 812 }
 813 EXPORT_SYMBOL(seq_put_decimal_ll);
 814 
 815 /**
 816  * seq_write - write arbitrary data to buffer
 817  * @seq: seq_file identifying the buffer to which data should be written
 818  * @data: data address
 819  * @len: number of bytes
 820  *
 821  * Return 0 on success, non-zero otherwise.
 822  */
 823 int seq_write(struct seq_file *seq, const void *data, size_t len)
 824 {
 825         if (seq->count + len < seq->size) {
 826                 memcpy(seq->buf + seq->count, data, len);
 827                 seq->count += len;
 828                 return 0;
 829         }
 830         seq_set_overflow(seq);
 831         return -1;
 832 }
 833 EXPORT_SYMBOL(seq_write);
 834 
 835 /**
 836  * seq_pad - write padding spaces to buffer
 837  * @m: seq_file identifying the buffer to which data should be written
 838  * @c: the byte to append after padding if non-zero
 839  */
 840 void seq_pad(struct seq_file *m, char c)
 841 {
 842         int size = m->pad_until - m->count;
 843         if (size > 0) {
 844                 if (size + m->count > m->size) {
 845                         seq_set_overflow(m);
 846                         return;
 847                 }
 848                 memset(m->buf + m->count, ' ', size);
 849                 m->count += size;
 850         }
 851         if (c)
 852                 seq_putc(m, c);
 853 }
 854 EXPORT_SYMBOL(seq_pad);
 855 
 856 /* A complete analogue of print_hex_dump() */
 857 void seq_hex_dump(struct seq_file *m, const char *prefix_str, int prefix_type,
 858                   int rowsize, int groupsize, const void *buf, size_t len,
 859                   bool ascii)
 860 {
 861         const u8 *ptr = buf;
 862         int i, linelen, remaining = len;
 863         char *buffer;
 864         size_t size;
 865         int ret;
 866 
 867         if (rowsize != 16 && rowsize != 32)
 868                 rowsize = 16;
 869 
 870         for (i = 0; i < len && !seq_has_overflowed(m); i += rowsize) {
 871                 linelen = min(remaining, rowsize);
 872                 remaining -= rowsize;
 873 
 874                 switch (prefix_type) {
 875                 case DUMP_PREFIX_ADDRESS:
 876                         seq_printf(m, "%s%p: ", prefix_str, ptr + i);
 877                         break;
 878                 case DUMP_PREFIX_OFFSET:
 879                         seq_printf(m, "%s%.8x: ", prefix_str, i);
 880                         break;
 881                 default:
 882                         seq_printf(m, "%s", prefix_str);
 883                         break;
 884                 }
 885 
 886                 size = seq_get_buf(m, &buffer);
 887                 ret = hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
 888                                          buffer, size, ascii);
 889                 seq_commit(m, ret < size ? ret : -1);
 890 
 891                 seq_putc(m, '\n');
 892         }
 893 }
 894 EXPORT_SYMBOL(seq_hex_dump);
 895 
 896 struct list_head *seq_list_start(struct list_head *head, loff_t pos)
 897 {
 898         struct list_head *lh;
 899 
 900         list_for_each(lh, head)
 901                 if (pos-- == 0)
 902                         return lh;
 903 
 904         return NULL;
 905 }
 906 EXPORT_SYMBOL(seq_list_start);
 907 
 908 struct list_head *seq_list_start_head(struct list_head *head, loff_t pos)
 909 {
 910         if (!pos)
 911                 return head;
 912 
 913         return seq_list_start(head, pos - 1);
 914 }
 915 EXPORT_SYMBOL(seq_list_start_head);
 916 
 917 struct list_head *seq_list_next(void *v, struct list_head *head, loff_t *ppos)
 918 {
 919         struct list_head *lh;
 920 
 921         lh = ((struct list_head *)v)->next;
 922         ++*ppos;
 923         return lh == head ? NULL : lh;
 924 }
 925 EXPORT_SYMBOL(seq_list_next);
 926 
 927 /**
 928  * seq_hlist_start - start an iteration of a hlist
 929  * @head: the head of the hlist
 930  * @pos:  the start position of the sequence
 931  *
 932  * Called at seq_file->op->start().
 933  */
 934 struct hlist_node *seq_hlist_start(struct hlist_head *head, loff_t pos)
 935 {
 936         struct hlist_node *node;
 937 
 938         hlist_for_each(node, head)
 939                 if (pos-- == 0)
 940                         return node;
 941         return NULL;
 942 }
 943 EXPORT_SYMBOL(seq_hlist_start);
 944 
 945 /**
 946  * seq_hlist_start_head - start an iteration of a hlist
 947  * @head: the head of the hlist
 948  * @pos:  the start position of the sequence
 949  *
 950  * Called at seq_file->op->start(). Call this function if you want to
 951  * print a header at the top of the output.
 952  */
 953 struct hlist_node *seq_hlist_start_head(struct hlist_head *head, loff_t pos)
 954 {
 955         if (!pos)
 956                 return SEQ_START_TOKEN;
 957 
 958         return seq_hlist_start(head, pos - 1);
 959 }
 960 EXPORT_SYMBOL(seq_hlist_start_head);
 961 
 962 /**
 963  * seq_hlist_next - move to the next position of the hlist
 964  * @v:    the current iterator
 965  * @head: the head of the hlist
 966  * @ppos: the current position
 967  *
 968  * Called at seq_file->op->next().
 969  */
 970 struct hlist_node *seq_hlist_next(void *v, struct hlist_head *head,
 971                                   loff_t *ppos)
 972 {
 973         struct hlist_node *node = v;
 974 
 975         ++*ppos;
 976         if (v == SEQ_START_TOKEN)
 977                 return head->first;
 978         else
 979                 return node->next;
 980 }
 981 EXPORT_SYMBOL(seq_hlist_next);
 982 
 983 /**
 984  * seq_hlist_start_rcu - start an iteration of a hlist protected by RCU
 985  * @head: the head of the hlist
 986  * @pos:  the start position of the sequence
 987  *
 988  * Called at seq_file->op->start().
 989  *
 990  * This list-traversal primitive may safely run concurrently with
 991  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
 992  * as long as the traversal is guarded by rcu_read_lock().
 993  */
 994 struct hlist_node *seq_hlist_start_rcu(struct hlist_head *head,
 995                                        loff_t pos)
 996 {
 997         struct hlist_node *node;
 998 
 999         __hlist_for_each_rcu(node, head)
1000                 if (pos-- == 0)
1001                         return node;
1002         return NULL;
1003 }
1004 EXPORT_SYMBOL(seq_hlist_start_rcu);
1005 
1006 /**
1007  * seq_hlist_start_head_rcu - start an iteration of a hlist protected by RCU
1008  * @head: the head of the hlist
1009  * @pos:  the start position of the sequence
1010  *
1011  * Called at seq_file->op->start(). Call this function if you want to
1012  * print a header at the top of the output.
1013  *
1014  * This list-traversal primitive may safely run concurrently with
1015  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1016  * as long as the traversal is guarded by rcu_read_lock().
1017  */
1018 struct hlist_node *seq_hlist_start_head_rcu(struct hlist_head *head,
1019                                             loff_t pos)
1020 {
1021         if (!pos)
1022                 return SEQ_START_TOKEN;
1023 
1024         return seq_hlist_start_rcu(head, pos - 1);
1025 }
1026 EXPORT_SYMBOL(seq_hlist_start_head_rcu);
1027 
1028 /**
1029  * seq_hlist_next_rcu - move to the next position of the hlist protected by RCU
1030  * @v:    the current iterator
1031  * @head: the head of the hlist
1032  * @ppos: the current position
1033  *
1034  * Called at seq_file->op->next().
1035  *
1036  * This list-traversal primitive may safely run concurrently with
1037  * the _rcu list-mutation primitives such as hlist_add_head_rcu()
1038  * as long as the traversal is guarded by rcu_read_lock().
1039  */
1040 struct hlist_node *seq_hlist_next_rcu(void *v,
1041                                       struct hlist_head *head,
1042                                       loff_t *ppos)
1043 {
1044         struct hlist_node *node = v;
1045 
1046         ++*ppos;
1047         if (v == SEQ_START_TOKEN)
1048                 return rcu_dereference(head->first);
1049         else
1050                 return rcu_dereference(node->next);
1051 }
1052 EXPORT_SYMBOL(seq_hlist_next_rcu);
1053 
1054 /**
1055  * seq_hlist_start_precpu - start an iteration of a percpu hlist array
1056  * @head: pointer to percpu array of struct hlist_heads
1057  * @cpu:  pointer to cpu "cursor"
1058  * @pos:  start position of sequence
1059  *
1060  * Called at seq_file->op->start().
1061  */
1062 struct hlist_node *
1063 seq_hlist_start_percpu(struct hlist_head __percpu *head, int *cpu, loff_t pos)
1064 {
1065         struct hlist_node *node;
1066 
1067         for_each_possible_cpu(*cpu) {
1068                 hlist_for_each(node, per_cpu_ptr(head, *cpu)) {
1069                         if (pos-- == 0)
1070                                 return node;
1071                 }
1072         }
1073         return NULL;
1074 }
1075 EXPORT_SYMBOL(seq_hlist_start_percpu);
1076 
1077 /**
1078  * seq_hlist_next_percpu - move to the next position of the percpu hlist array
1079  * @v:    pointer to current hlist_node
1080  * @head: pointer to percpu array of struct hlist_heads
1081  * @cpu:  pointer to cpu "cursor"
1082  * @pos:  start position of sequence
1083  *
1084  * Called at seq_file->op->next().
1085  */
1086 struct hlist_node *
1087 seq_hlist_next_percpu(void *v, struct hlist_head __percpu *head,
1088                         int *cpu, loff_t *pos)
1089 {
1090         struct hlist_node *node = v;
1091 
1092         ++*pos;
1093 
1094         if (node->next)
1095                 return node->next;
1096 
1097         for (*cpu = cpumask_next(*cpu, cpu_possible_mask); *cpu < nr_cpu_ids;
1098              *cpu = cpumask_next(*cpu, cpu_possible_mask)) {
1099                 struct hlist_head *bucket = per_cpu_ptr(head, *cpu);
1100 
1101                 if (!hlist_empty(bucket))
1102                         return bucket->first;
1103         }
1104         return NULL;
1105 }
1106 EXPORT_SYMBOL(seq_hlist_next_percpu);
1107 
1108 void __init seq_file_init(void)
1109 {
1110         seq_file_cache = KMEM_CACHE(seq_file, SLAB_ACCOUNT|SLAB_PANIC);
1111 }
/* [<][>][^][v][top][bottom][index][help] */
root/fs/seq_file.c

DEFINITIONS
