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1\input texinfo    @c -*-texinfo-*-
2@c %**start of header
3@setfilename libext2fs.info
4@settitle The EXT2FS Library (version 1.45.4)
5@synindex tp fn
6@comment %**end of header
7
8@ifinfo
9@dircategory Development
10@direntry
11* libext2fs: (libext2fs).                  The EXT2FS library.
12@end direntry
13@end ifinfo
14
15@c smallbook
16
17@iftex
18@finalout
19@end iftex
20
21@c Note: the edition number is listed in *three* places; please update
22@c all three.  Also, update the month and year where appropriate.
23
24@c ==> Update edition number for settitle and subtitle, and in the
25@c ==> following paragraph; update date, too.
26
27
28@ifinfo
29This file documents the ext2fs library, a library for manipulating the
30ext2 filesystem.
31
32Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
332006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 by Theodore Ts'o
34
35Permission is granted to make and distribute verbatim copies of
36this manual provided the copyright notice and this permission notice
37are preserved on all copies.
38
39@ignore
40Permission is granted to process this file through TeX and print the
41results, provided the printed document carries copying permission
42notice identical to this one except for the removal of this paragraph
43(this paragraph not being relevant to the printed manual).
44
45@end ignore
46Permission is granted to copy and distribute modified versions of this
47manual under the conditions for verbatim copying, provided that the entire
48resulting derived work is distributed under the terms of a permission
49notice identical to this one.
50
51Permission is granted to copy and distribute translations of this manual
52into another language, under the above conditions for modified versions,
53except that this permission notice may be stated in a translation approved
54by the author.
55@end ifinfo
56
57@setchapternewpage on
58@titlepage
59@c  use the new format for titles
60
61@title The EXT2FS Library
62@subtitle The EXT2FS Library
63@subtitle Version 1.45.4
64@subtitle September 2019
65
66@author by Theodore Ts'o
67
68@c Include the Distribution inside the titlepage so
69@c that headings are turned off.
70
71@tex
72\global\parindent=0pt
73\global\parskip=8pt
74\global\baselineskip=13pt
75@end tex
76
77@page
78@vskip 0pt plus 1filll
79Copyright @copyright{} 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
802005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 Theodore Ts'o
81
82@sp 2
83
84Permission is granted to make and distribute verbatim copies of
85this manual provided the copyright notice and this permission notice
86are preserved on all copies.
87
88Permission is granted to copy and distribute modified versions of this
89manual under the conditions for verbatim copying, provided that the entire
90resulting derived work is distributed under the terms of a permission
91notice identical to this one.
92
93Permission is granted to copy and distribute translations of this manual
94into another language, under the above conditions for modified versions,
95except that this permission notice may be stated in a translation approved
96by the Foundation.
97@end titlepage
98@headings double
99
100@node Top, Introduction to the EXT2FS Library, (dir), (dir)
101
102@top The EXT2FS Library
103
104This manual documents the EXT2FS Library, version 1.45.4.
105
106@menu
107* Introduction to the EXT2FS Library::
108* EXT2FS Library Functions::
109* Concept Index::
110* Function Index::
111@end menu
112
113@c ----------------------------------------------------------------------
114
115@node Introduction to the EXT2FS Library, EXT2FS Library Functions, Top, Top
116@comment  node-name,  next,  previous,  up
117@chapter Introduction to the EXT2FS Library
118
119The EXT2FS library is designed to allow user-level programs to
120manipulate an ext2 filesystem.
121
122@node EXT2FS Library Functions, Concept Index, Introduction to the EXT2FS Library, Top
123@comment  node-name,  next,  previous,  up
124@chapter EXT2FS Library Functions
125
126@menu
127* Filesystem-level functions::
128* File I/O Functions::
129* Inode Functions::
130* Directory functions::
131* Bitmap Functions::
132* EXT2 data abstractions::
133* Byte-swapping functions::
134* Other functions::
135@end menu
136
137@c ----------------------------------------------------------------------
138
139@node Filesystem-level functions, File I/O Functions, EXT2FS Library Functions, EXT2FS Library Functions
140@comment  node-name,  next,  previous,  up
141@section Filesystem-level functions
142
143The following functions operate on a filesystem handle.  Most EXT2FS
144Library functions require a filesystem handle as their first argument.
145There are two functions which create a filesystem handle,
146@code{ext2fs_open} and @code{ext2fs_initialize}.
147
148The filesystem can also be closed using @code{ext2fs_close}, and any
149changes to the superblock and group descriptors can be written out to disk
150using @code{ext2fs_flush}.
151
152@menu
153* Opening an ext2 filesystem::
154* Closing and flushing out changes::
155* Initializing a filesystem::
156* Filesystem flag functions::
157@end menu
158
159@c ----------------------------------------------------------------------
160
161@node Opening an ext2 filesystem, Closing and flushing out changes, Filesystem-level functions, Filesystem-level functions
162@comment  node-name,  next,  previous,  up
163@subsection Opening an ext2 filesystem
164
165Most libext2fs functions take a filesystem handle of type
166@code{ext2_filsys}.  A filesystem handle is created either by opening
167an existing filesystem using @code{ext2fs_open}, or by initializing a new
168filesystem using @code{ext2fs_initialize}.
169
170@deftypefun errcode_t ext2fs_open (const char *@var{name}, int @var{flags}, int @var{superblock}, int @var{block_size}, io_manager @var{manager}, ext2_filsys *@var{ret_fs})
171
172Opens a filesystem named @var{name}, using the the io_manager
173@var{manager} to define the input/output routines needed to read and
174write the filesystem.  In the case of the @code{unix_io} io_manager,
175@var{name} is interpreted as the Unix filename of the filesystem image.
176This is often a device file, such as @file{/dev/hda1}.
177
178The @var{superblock} parameter specifies the block number of the
179superblock which should be used when opening the filesystem.
180If @var{superblock} is zero, @code{ext2fs_open} will use the primary
181superblock located at offset 1024 bytes from the start of the filesystem
182image.
183
184The @var{block_size} parameter specifies the block size used by the
185filesystem.  Normally this is determined automatically from the
186filesystem superblock.  If @var{block_size} is non-zero, it must match
187the block size found in the superblock, or the error
188@code{EXT2_ET_UNEXPECTED_BLOCK_SIZE} will be returned.  The
189@var{block_size} parameter is also used to help find the superblock when
190@var{superblock} is non-zero.
191
192The @var{flags} argument contains a bitmask of flags which control how
193the filesystem open should be handled.
194
195@table @code
196@item EXT2_FLAG_RW
197Open the filesystem for reading and writing.  Without this flag, the
198filesystem is opened for reading only.
199
200@item EXT2_FLAG_FORCE
201Open the filesystem regardless of the feature sets listed in the
202superblock.
203
204@end table
205@end deftypefun
206
207@c ----------------------------------------------------------------------
208
209@node Closing and flushing out changes, Initializing a filesystem, Opening an ext2 filesystem, Filesystem-level functions
210@comment  node-name,  next,  previous,  up
211@subsection Closing and flushing out changes
212
213@deftypefun errcode_t ext2fs_flush (ext2_filsys @var{fs})
214
215Write any changes to the high-level filesystem data structures in the
216@var{fs} filesystem.  The following data structures will be written out:
217
218@itemize @bullet
219@item The filesystem superblock
220@item The filesystem group descriptors
221@item The filesystem bitmaps, if read in via @code{ext2fs_read_bitmaps}.
222@end itemize
223
224@end deftypefun
225
226@deftypefun void ext2fs_free (ext2_filsys @var{fs})
227
228Close the io_manager abstraction for @var{fs} and release all memory
229associated with the filesystem handle.
230@end deftypefun
231
232@deftypefun errcode_t ext2fs_close (ext2_filsys @var{fs})
233
234Flush out any changes to the high-level filesystem data structures using
235@code{ext2fs_flush} if the filesystem is marked dirty; then close and
236free the filesystem using @code{ext2fs_free}.
237
238@end deftypefun
239
240@c ----------------------------------------------------------------------
241
242@node Initializing a filesystem, Filesystem flag functions, Closing and flushing out changes, Filesystem-level functions
243@comment  node-name,  next,  previous,  up
244@subsection Initializing a filesystem
245
246An ext2 filesystem is initializing by the @code{mke2fs} program.  The
247two functions described here, @code{ext2fs_initialize} and
248@code{ext2fs_allocate_tables} do much of the initial work for setting up
249a filesystem.  However, they don't do the whole job.  @code{mke2fs}
250calls @code{ext2fs_initialize} to set up the filesystem superblock, and
251calls @code{ext2fs_allocate_tables} to allocate space for the inode
252table, and the inode and block bitmaps.  In addition, @code{mke2fs} must
253also initialize the inode tables by clearing them with zeros, create the
254root and lost+found directories, and reserve the reserved inodes.
255
256@deftypefun errcode_t ext2fs_initialize (const char *@var{name}, int @var{flags}, struct ext2_super_block *@var{param}, io_manager @var{manager}, ext2_filsys *@var{ret_fs})
257
258This function is used by the @code{mke2fs} program to initialize a
259filesystem.  The @code{ext2fs_initialize} function creates a filesystem
260handle which is returned in @var{ret_fs} that has been properly setup
261for a filesystem to be located in @var{name}, using the io_manager
262@var{manager}.  The prototype superblock in @var{param} is used to
263supply parameters such as the number of blocks in the filesystem, the
264block size, etc.
265
266The @code{ext2fs_initialize} function does not actually do any I/O; that
267will be done when the application program calls @code{ext2fs_close} or
268@code{ext2fs_flush}.  Also, this function only initializes the
269superblock and group descriptor structures.  It does not create the
270inode table or the root directory.  This must be done by the calling
271application, such as @code{mke2fs}.
272
273The following values may be set in the @var{param} prototype superblock;
274if a value of 0 is found in a field, @code{ext2fs_initialize} will use a
275default value.  The calling application should zero out the prototype
276entire superblock, and then fill in any appropriate values.
277
278@table @code
279
280@item s_blocks_count
281The number of blocks in the filesystem.  This parameter is mandatory and
282must be set by the calling application.
283
284@item s_inodes_count
285The number of inodes in the filesystem.  The
286default value is determined by calculating the size of the filesystem,
287and creating one inode for every 4096 bytes.
288
289@item s_r_blocks_count
290The number of blocks which should be reserved for the superuser.  The
291default value is zero blocks.
292
293@item s_log_block_size
294The blocksize of the filesystem.  Valid values are 0 (1024 bytes), 1
295(2048 bytes), or 2 (4096 bytes).  The default blocksize is 1024 bytes.
296
297@item s_log_frag_size
298The size of fragments.  The ext2 filesystem does not support fragments
299(and may never support fragments).  Currently this field must be the
300same as @code{s_log_block_size}.
301
302@item s_first_data_block
303The first data block for the filesystem.  For filesystem with a
304blocksize of 1024 bytes, this value must be at least 1, since the
305superblock is located in block number 1.  For filesystems with larger
306blocksizes, the superblock is still located at an offset of 1024 bytes,
307so the superblock is located in block number 0.  By default, this value
308is set to 1 for filesystems with a block size of 1024 bytes, or 0 for
309filesystems with larger blocksizes.
310
311@item s_max_mnt_count
312This field defines the number of times that the filesystem can be
313mounted before it should be checked using @code{e2fsck}.  When
314@code{e2fsck} is run without the @samp{-f} option, @code{e2fsck} will
315skip the filesystem check if the number of times that the filesystem has
316been mounted is less than @code{s_max_mnt_count} and if the interval
317between the last time a filesystem check was performed and the current
318time is less than @code{s_checkinterval} (see below).  The default value
319of @code{s_max_mnt_count} is 20.
320
321@item s_checkinterval
322This field defines the minimal interval between filesystem checks.  See
323the previous entry for a discussion of how this field is used by
324@code{e2fsck}.  The default value of this field is 180 days (six
325months).
326
327@item s_errors
328This field defines the behavior which should be used by the kernel of
329errors are detected in the filesystem.  Possible values include:
330
331@table @samp
332@item EXT2_ERRORS_CONTINUE
333Continue execution when errors are detected.
334
335@item EXT2_ERRORS_RO
336Remount the filesystem read-only.
337
338@item EXT2_ERRORS_PANIC
339Panic.
340
341@end table
342
343The default behavior is @samp{EXT2_ERRORS_CONTINUE}.
344
345@end table
346
347@end deftypefun
348
349@deftypefun errcode_t ext2fs_allocate_tables (ext2_filsys @var{fs})
350Allocate space for the inode table and the block and inode bitmaps.  The
351inode tables and block and inode bitmaps aren't actually initialized;
352this function just allocates the space for them.
353@end deftypefun
354
355@c ----------------------------------------------------------------------
356
357@node Filesystem flag functions,  , Initializing a filesystem, Filesystem-level functions
358@comment  node-name,  next,  previous,  up
359@subsection Filesystem flag functions
360
361The filesystem handle has a number of flags which can be manipulated
362using the following function.  Some of these flags affect how the
363libext2fs filesystem behaves; others are provided solely for the
364application's convenience.
365
366@deftypefun void ext2fs_mark_changed (ext2_filsys @var{fs})
367@deftypefunx int ext2fs_test_changed (ext2_filsys @var{fs})
368This flag indicates whether or not the filesystem has been changed.
369It is not used by the ext2fs library.
370@end deftypefun
371
372@deftypefun void ext2fs_mark_super_dirty (ext2_filsys @var{fs})
373Mark the filesystem @var{fs} as being dirty; this will cause
374the superblock information to be flushed out when @code{ext2fs_close} is
375called.  @code{ext2fs_mark_super_dirty} will also set the filesystem
376changed flag.  The dirty flag is automatically cleared by
377@code{ext2fs_flush} when the superblock is written to disk.
378@end deftypefun
379
380@deftypefun void ext2fs_mark_valid (ext2_filsys @var{fs})
381@deftypefunx void ext2fs_unmark_valid (ext2_filsys @var{fs})
382@deftypefunx int ext2fs_test_valid (ext2_filsys @var{fs})
383This flag indicates whether or not the filesystem is free of errors.
384It is not used by libext2fs, and is solely for the application's
385convenience.
386@end deftypefun
387
388@deftypefun void ext2fs_mark_ib_dirty (ext2_filsys @var{fs})
389@deftypefunx void ext2fs_mark_bb_dirty (ext2_filsys @var{fs})
390@deftypefunx int ext2fs_test_ib_dirty (ext2_filsys @var{fs})
391@deftypefunx int ext2fs_test_bb_dirty (ext2_filsys @var{fs})
392These flags indicate whether or not the inode or block bitmaps have been
393modified.   If the flag is set, it will cause the appropriate bitmap
394to be written when the filesystem is closed or flushed.
395@end deftypefun
396
397@c ----------------------------------------------------------------------
398
399@node File I/O Functions, Inode Functions, Filesystem-level functions, EXT2FS Library Functions
400@comment  node-name,  next,  previous,  up
401@section File I/O Functions
402
403The following functions provide a convenient abstraction to read or
404write a file in an filesystem.  The interface is similar in spirit to
405the Linux/POSIX file I/O system calls.
406
407@menu
408* File handle manipulation::
409* Reading and writing data::
410* Changing the file offset ::
411* Getting the file size::
412@end menu
413
414@c ----------------------------------------------------------------------
415
416@node File handle manipulation, Reading and writing data, File I/O Functions, File I/O Functions
417@comment  node-name,  next,  previous,  up
418@subsection File handle manipulation
419
420The file handle functions much like a file descriptor in the Linux/POSIX
421file I/O system calls.  Unlike the Linux/POSIX system calls, files are
422opened via inode numbers instead of via pathnames.  To resolve a
423pathname to an inode number, use the function @code{ext2fs_namei} or to
424create a new file, use @code{ext2fs_new_inode} and @code{ext2fs_link}.
425
426@deftypefun errcode_t ext2fs_file_open2 (ext2_filsys @var{fs}, ext2_ino_t @var{ino}, struct ext2_inode *@var{inode}, int @var{flags}, ext2_file_t *@var{ret})
427@deftypefunx errcode_t ext2fs_file_open (ext2_filsys @var{fs}, ext2_ino_t @var{ino}, int @var{flags}, ext2_file_t *@var{ret})
428
429Opens a file identified by inode number @var{ino} in filesystem @var{fs}
430and returns a file handle in @var{ret}.  If an inode structure is
431provided in @var{inode}, then it is used instead of reading the inode
432from the filesystem.
433
434The @var{flags} argument contains a bitmask of flags which control how
435the file should be opened.
436
437@table @code
438@item EXT2_FILE_WRITE
439Open the file for reading and writing.  Without this flag, the file is
440opened for writing only.
441
442@item EXT2_FILE_CREATE
443Create the file if it is not already present.
444
445@end table
446@end deftypefun
447
448@deftypefun ext2_filsys ext2fs_file_get_fs (ext2_file_t @var{file})
449Return the filesystem handle where the open file @var{file} was opened.
450@end deftypefun
451
452@deftypefun errcode_t ext2fs_file_close (ext2_file_t @var{file})
453Close the file handle @var{file}.
454@end deftypefun
455
456@deftypefun errcode_t ext2fs_file_flush (ext2_file_t @var{file})
457Force any data written via @code{ext2fs_file_write} to disk.
458@end deftypefun
459
460@c ----------------------------------------------------------------------
461
462@node Reading and writing data, Changing the file offset , File handle manipulation, File I/O Functions
463@comment  node-name,  next,  previous,  up
464@subsection Reading and writing data
465
466@deftypefun errcode_t ext2fs_file_read (ext2_file_t @var{file}, void *@var{buf}, unsigned int @var{wanted}, unsigned int *@var{got})
467Read @var{wanted} bytes of data from @var{file} store it in the buffer
468@var{buf}.  The number of bytes that was actually read is returned
469via @var{got}.
470@end deftypefun
471
472@deftypefun errcode_t ext2fs_file_write (ext2_file_t @var{file}, const void *@var{buf}, unsigned int @var{nbytes}, unsigned int *@var{written})
473Write @var{wanted} bytes of data from the buffer @var{buf} to the
474current file position of @var{file}.  The number of bytes that was
475actually written is returned via @var{written}.
476@end deftypefun
477
478@c ----------------------------------------------------------------------
479
480@node Changing the file offset , Getting the file size, Reading and writing data, File I/O Functions
481@comment  node-name,  next,  previous,  up
482@subsection Changing the file offset
483
484@deftypefun errcode_t ext2fs_file_llseek (ext2_file_t @var{file}, __u64 @var{offset}, int @var{whence}, __u64 *@var{ret_pos})
485@deftypefunx errcode_t ext2fs_file_lseek (ext2_file_t @var{file}, ext2_off_t @var{offset}, int @var{whence}, ext2_off_t *@var{ret_pos})
486Change the current file position of @var{file} according to the
487directive @var{whence} as follows:
488
489@table @code
490@item EXT2_SEEK_SET
491The file position is set to @var{offset} bytes from the beginning of the
492file.
493
494@item EXT2_SEEK_CUR
495The file position set to its current location plus @var{offset} bytes.
496
497@item EXT2_SEEK_END
498The file position is set to the size of the file plus @var{offset}
499bytes.
500@end table
501
502The current offset is returned via @var{ret_pos}.
503@end deftypefun
504
505@c ----------------------------------------------------------------------
506
507@node Getting the file size,  , Changing the file offset , File I/O Functions
508@comment  node-name,  next,  previous,  up
509@subsection Getting the file size
510
511@deftypefun errcode_t ext2fs_file_get_lsize (ext2_file_t @var{file}, __u64 *@var{ret_size})
512Return the size of the file @var{file} in @var{ret_size}.
513@end deftypefun
514
515@deftypefun ext2_off_t ext2fs_file_get_size (ext2_file_t @var{file})
516Return the size of the file @var{file}.
517@end deftypefun
518
519@c ----------------------------------------------------------------------
520
521@node Inode Functions, Directory functions, File I/O Functions, EXT2FS Library Functions
522@comment  node-name,  next,  previous,  up
523@section Inode Functions
524
525@menu
526* Reading and writing inodes::
527* Iterating over inodes in a filesystem::
528* Iterating over blocks in an inode::
529* Inode Convenience Functions::
530@end menu
531
532@c ----------------------------------------------------------------------
533
534@node Reading and writing inodes, Iterating over inodes in a filesystem, Inode Functions, Inode Functions
535@comment  node-name,  next,  previous,  up
536@subsection Reading and writing inodes
537
538@deftypefun errcode_t ext2fs_read_inode (ext2_filsys @var{fs}, ext2_ino_t @var{ino}, struct ext2_inode *@var{inode})
539Read the inode number @var{ino} into @var{inode}.
540@end deftypefun
541
542@deftypefun errcode_t ext2fs_write_inode (ext2_filsys @var{fs}, ext2_ino_t @var{ino}, struct ext2_inode *@var{inode})
543Write @var{inode} to inode @var{ino}.
544@end deftypefun
545
546
547@c ----------------------------------------------------------------------
548
549@node Iterating over inodes in a filesystem, Iterating over blocks in an inode, Reading and writing inodes, Inode Functions
550@comment  node-name,  next,  previous,  up
551@subsection Iterating over inodes in a filesystem
552
553The inode_scan abstraction is useful for iterating over all the inodes
554in a filesystem.
555
556@deftypefun errcode_t ext2fs_open_inode_scan (ext2_filsys @var{fs}, int @var{buffer_blocks}, ext2_inode_scan *@var{scan})
557Initialize the iteration variable @var{scan}.  This variable is used by
558@code{ext2fs_get_next_inode}.  The @var{buffer_blocks} parameter
559controls how many blocks of the inode table are read in at a time.  A
560large number of blocks requires more memory, but reduces the overhead in
561seeking and reading from the disk.  If @var{buffer_blocks} is zero, a
562suitable default value will be used.
563@end deftypefun
564
565@deftypefun void ext2fs_close_inode_scan (ext2_inode_scan @var{scan})
566Release the memory associated with @var{scan} and invalidate it.
567@end deftypefun
568
569@deftypefun errcode_t ext2fs_get_next_inode (ext2_inode_scan @var{scan}, ext2_ino_t *@var{ino}, struct ext2_inode *@var{inode})
570
571This function returns the next inode from the filesystem; the inode
572number of the inode is stored in @var{ino}, and the inode is stored in
573@var{inode}.
574
575If the inode is located in a block that has been marked as bad,
576@code{ext2fs_get_next_inode} will return the error
577@code{EXT2_ET_BAD_BLOCK_IN_INODE_TABLE}.
578@end deftypefun
579
580@deftypefun errcode_t ext2fs_inode_scan_goto_blockgroup (ext2_inode_scan @var{scan}, int @var{group})
581Start the inode scan at a particular ext2 blockgroup, @var{group}.
582This function may be safely called at any time while @var{scan} is valid.
583@end deftypefun
584
585@deftypefun void ext2fs_set_inode_callback (ext2_inode_scan @var{scan}, errcode_t (*done_group)(ext2_filsys @var{fs}, ext2_inode_scan @var{scan}, dgrp_t @var{group}, void * @var{private}), void *@var{done_group_data})
586Register a callback function which will be called by
587@code{ext2_get_next_inode} when all of the inodes in a block group have
588been processed.
589@end deftypefun
590
591@deftypefun int ext2fs_inode_scan_flags (ext2_inode_scan @var{scan}, int @var{set_flags}, int @var{clear_flags})
592
593Set the scan_flags @var{set_flags} and clear the scan_flags @var{clear_flags}.
594The following flags can be set using this interface:
595
596@table @samp
597
598@item EXT2_SF_SKIP_MISSING_ITABLE
599When a block group is missing an inode table, skip it.  If this flag is
600not set @code{ext2fs_get_next_inode} will return the error
601EXT2_ET_MISSING_INODE_TABLE.
602
603@end table
604
605@end deftypefun
606
607@c ----------------------------------------------------------------------
608
609@node Iterating over blocks in an inode, Inode Convenience Functions, Iterating over inodes in a filesystem, Inode Functions
610@comment  node-name,  next,  previous,  up
611@subsection Iterating over blocks in an inode
612
613@deftypefun errcode_t ext2fs_block_iterate (ext2_filsys @var{fs}, ext2_ino_t @var{ino}, int @var{flags}, char *block_buf, int (*func)(ext2_filsys @var{fs}, blk_t *@var{blocknr}, int @var{blockcnt}, void *@var{private}), void *@var{private})
614
615Iterate over all of the blocks in inode number @var{ino} in filesystem
616@var{fs}, by calling the function @var{func} for each block in the
617inode.  The @var{block_buf} parameter should either be NULL, or if the
618@code{ext2fs_block_iterate} function is called repeatedly, the overhead
619of allocating and freeing scratch memory can be avoided by passing a
620pointer to a scratch buffer which must be at least as big as three times the
621filesystem's blocksize.
622
623The @var{flags} parameter controls how the iterator will function:
624
625@table @samp
626
627@item BLOCK_FLAG_HOLE
628This flag indicates that the interator function should be called on
629blocks where the block number is zero (also known as ``holes''.)  It is
630also known as BLOCK_FLAG_APPEND, since it is also used by functions
631such as ext2fs_expand_dir() to add a new block to an inode.
632
633@item BLOCK_FLAG_DEPTH_TRAVERSE
634This flag indicates that the iterator function for the
635indirect, doubly indirect, etc. blocks should be called after all
636of the blocks contained in the indirect blocks are processed.
637This is useful if you are going to be deallocating blocks from an
638inode.
639
640@item BLOCK_FLAG_DATA_ONLY
641This flag indicates that the iterator function should be
642called for data blocks only.
643
644@end table
645
646The callback function @var{func} is called with a number of parameters;
647the @var{fs} and @var{private} parameters are self-explanatory, and
648their values are taken from the parameters to
649@code{ext2fs_block_iterate}.  (The @var{private} data structure is
650generally used by callers to @code{ext2fs_block_iterate} so that some
651private data structure can be passed to the callback function.  The
652@var{blockcnt} parameter, if non-negative, indicates the logical block
653number of a data block in the inode.  If @var{blockcnt} is less than
654zero, then @var{func} was called on a metadata block, and @var{blockcnt}
655will be one of the following values:  BLOCK_COUNT_IND, BLOCK_COUNT_DIND,
656BLOCK_COUNT_TIND, or BLOCK_COUNT_TRANSLATOR.  The @var{blocknr} is a
657pointer to the inode or indirect block entry listing physical block
658number.  The callback function may modify the physical block number, if
659it returns the @var{BLOCK_CHANGED} flag.
660
661
662The callback function @var{func} returns a result code which is composed of
663the logical OR of the following flags:
664
665@table @samp
666
667@item BLOCK_CHANGED
668
669This flag indicates that callback function has modified the physical
670block number pointed to by @var{blocknr}.
671
672@item BLOCK_ABORT
673
674This flag requests that @code{ext2fs_block_iterate} to stop immediately
675and return to the caller.
676
677@end table
678
679@end deftypefun
680
681@deftypefun errcode_t ext2fs_block_iterate2 (ext2_filsys @var{fs}, ext2_ino_t @var{ino}, int @var{flags}, char *@var{block}_buf, int (*func)(ext2_filsys @var{fs}, blk_t *@var{blocknr}, e2_blkcnt_t @var{blockcnt}, blk_t @var{ref_blk}, int  @var{ref_offset}, void *@var{private}), void *@var{private})
682
683This function is much like @code{ext2fs_block_iterate}, except that the
684@var{blockcnt} type is a 64-bit signed quantity, to support larger
685files, and the addition of the @var{ref_blk} and @var{ref_offset}
686arguments passed to the callback function, which identify the location
687of the physical block pointed to by pointer @var{blocknr}.  If
688@var{ref_blk} is zero, then @var{ref_offset} contains the offset into
689the @code{i_blocks} array.  If @var{ref_blk} is non-zero, then the physical
690block location is contained inside an indirect block group, and
691@var{ref_offset} contains the offset into the indirect block.
692
693@end deftypefun
694
695@c ----------------------------------------------------------------------
696
697@node Inode Convenience Functions,  , Iterating over blocks in an inode, Inode Functions
698@comment  node-name,  next,  previous,  up
699@subsection Convenience functions for Inodes
700
701@deftypefun errcode_t ext2fs_get_blocks (ext2_filsys @var{fs}, ext2_ino_t @var{ino}, blk_t *@var{blocks})
702
703Returns an array of blocks corresponding to the direct,
704indirect, doubly indirect, and triply indirect blocks as stored in the
705inode structure.
706@end deftypefun
707
708@deftypefun errcode_t ext2fs_check_directory (ext2_filsys @var{fs}, ext2_ino_t @var{ino})
709Returns 0 if @var{ino} is a directory, and @code{ENOTDIR} if it is not.
710@end deftypefun
711
712@deftypefun int ext2fs_inode_has_valid_blocks (struct ext2_inode *@var{inode})
713
714Returns 1 if the inode's block entries actually valid block entries, and
7150 if not.  Inodes which represent devices and fast symbolic links do not
716contain valid block entries.
717@end deftypefun
718
719@c ----------------------------------------------------------------------
720
721@node Directory functions, Bitmap Functions, Inode Functions, EXT2FS Library Functions
722@comment  node-name,  next,  previous,  up
723@section Directory functions
724
725@menu
726* Directory block functions::
727* Iterating over a directory::
728* Creating and expanding directories::
729* Creating and removing directory entries::
730* Looking up filenames::
731* Translating inode numbers to filenames::
732@end menu
733
734@c ----------------------------------------------------------------------
735
736@node Directory block functions, Iterating over a directory, Directory functions, Directory functions
737@comment  node-name,  next,  previous,  up
738@subsection Directory block functions
739
740@deftypefun errcode_t ext2fs_read_dir_block (ext2_filsys @var{fs}, blk_t @var{block}, void *@var{buf})
741
742This function reads a directory block, performing
743byte swapping if necessary.
744@end deftypefun
745
746@deftypefun errcode_t ext2fs_write_dir_block (ext2_filsys @var{fs}, blk_t @var{block}, void *@var{buf})
747
748This function writes a directory block, performing
749byte swapping if necessary.
750@end deftypefun
751
752@deftypefun errcode_t ext2fs_new_dir_block (ext2_filsys @var{fs}, ext2_ino_t @var{dir_ino}, ext2_ino_t @var{parent_ino}, char **@var{block})
753
754This function creates a new directory block in @var{block}.  If
755@var{dir_ino} is non-zero, then @var{dir_ino} and @var{parent_ino} are used
756to initialize directory entries for @file{.} and @file{..}, respectively.
757@end deftypefun
758
759@c ----------------------------------------------------------------------
760
761@node Iterating over a directory, Creating and expanding directories, Directory block functions, Directory functions
762@comment  node-name,  next,  previous,  up
763@subsection Iterating over a directory
764
765@deftypefun errcode_t ext2fs_dir_iterate (ext2_filsys @var{fs}, ext2_ino_t @var{dir}, int @var{flags}, char *@var{block_buf}, int (*@var{func})(struct ext2_dir_entry *@var{dirent}, int @var{offset}, int @var{blocksize}, char *@var{buf}, void *@var{private}), void *@var{private})
766
767This function iterates over all of the directory entries in the
768directory @var{dir}, calling the callback function @var{func} for each
769directory entry in the directory.  The @var{block_buf} parameter should
770either be NULL, or if the @code{ext2fs_dir_iterate} function is
771called repeatedly, the overhead of allocating and freeing
772scratch memory can be avoided by passing a pointer to a scratch buffer
773which must be at least as big as the filesystem's blocksize.
774
775The @var{flags} parameter controls how the iterator will function:
776
777@table @samp
778
779@item DIRENT_FLAG_INCLUDE_EMPTY
780
781This flag indicates that the callback function should be called even
782for deleted or empty directory entries.
783
784@end table
785
786@end deftypefun
787
788@c ----------------------------------------------------------------------
789
790@node Creating and expanding directories, Creating and removing directory entries, Iterating over a directory, Directory functions
791@comment  node-name,  next,  previous,  up
792@subsection Creating and expanding directories
793
794@deftypefun errcode_t ext2fs_mkdir (ext2_filsys @var{fs}, ext2_ino_t @var{parent}, ext2_ino_t @var{inum}, const char *@var{name})
795
796This function creates a new directory.  If @var{inum} is zero, then a
797new inode will be allocated; otherwise, the directory will be created in
798the inode specified by @var{inum}.  If @var{name} specifies the name of
799the new directory; if it is non-NULL, then the new directory will be
800linked into the parent directory @var{parent}.
801@end deftypefun
802
803@deftypefun errcode_t ext2fs_expand_dir (ext2_filsys @var{fs}, ext2_ino_t @var{dir})
804
805This function adds a new empty directory block and appends it to
806the directory @var{dir}.  This allows functions such as
807@code{ext2fs_link} to add new directory entries to a directory which is full.
808
809@end deftypefun
810
811@c ----------------------------------------------------------------------
812
813@node Creating and removing directory entries, Looking up filenames, Creating and expanding directories, Directory functions
814@comment  node-name,  next,  previous,  up
815@subsection Creating and removing directory entries
816
817@deftypefun errcode_t ext2fs_link (ext2_filsys @var{fs}, ext2_ino_t @var{dir}, const char *@var{name}, ext2_ino_t @var{ino}, int flags)
818
819This function adds a new directory entry to the directory @var{dir},
820with @var{name} and @var{ino} specifying the name and inode number in
821the directory entry, respectively.
822
823The low 3 bits of the flags field is used to specify the file type of
824inode:   (No other flags are currently defined.)
825
826@table @samp
827
828@item EXT2_FT_UNKNOWN
829
830The file type is unknown.
831
832@item EXT2_FT_REG_FILE
833
834The file type is a normal file.
835
836@item EXT2_FT_DIR
837
838The file type is a directory.
839
840@item EXT2_FT_CHRDEV
841
842The file type is a character device.
843
844@item EXT2_FT_BLKDEV
845
846The file type is a block device.
847
848@item EXT2_FT_FIFO
849
850The file type is a named pipe.
851
852@item EXT2_FT_SOCK
853
854The file type is a unix domain socket.
855
856@item EXT2_FT_SYMLINK
857
858The file type is a symbolic link.
859@end table
860
861@end deftypefun
862
863@deftypefun errcode_t ext2fs_unlink (ext2_filsys @var{fs}, ext2_ino_t @var{dir}, const char *@var{name}, ext2_ino_t @var{ino}, int @var{flags})
864
865This function removes a directory entry from @var{dir}.
866The directory entry to be removed is the first one which is
867matched by @var{name} and @var{ino}.  If @var{name} is non-NULL,
868the directory entry's name must match @var{name}.  If @var{ino} is
869non-zero, the directory entry's inode number must match @var{ino}.
870No flags are currently defined for @code{ext2fs_unlink}; callers should
871pass in zero to this parameter.
872
873@end deftypefun
874
875@c ----------------------------------------------------------------------
876
877@node Looking up filenames, Translating inode numbers to filenames, Creating and removing directory entries, Directory functions
878@comment  node-name,  next,  previous,  up
879@subsection Looking up filenames
880
881@deftypefun errcode_t ext2fs_lookup (ext2_filsys @var{fs}, ext2_ino_t @var{dir}, const char *@var{name}, int @var{namelen}, char *@var{buf}, ext2_ino_t *@var{inode})
882@end deftypefun
883
884@deftypefun errcode_t ext2fs_namei (ext2_filsys @var{fs}, ext2_ino_t @var{root}, ext2_ino_t @var{cwd}, const char *@var{name}, ext2_ino_t *@var{inode})
885@end deftypefun
886
887@deftypefun errcode_t ext2fs_namei_follow (ext2_filsys @var{fs}, ext2_ino_t @var{root}, ext2_ino_t @var{cwd}, const char *@var{name}, ext2_ino_t *@var{inode})
888@end deftypefun
889
890@deftypefun errcode_t ext2fs_follow_link (ext2_filsys @var{fs}, ext2_ino_t @var{root}, ext2_ino_t @var{cwd}, ext2_ino_t @var{inode}, ext2_ino_t *@var{res}_inode)
891@end deftypefun
892
893@c ----------------------------------------------------------------------
894
895@node Translating inode numbers to filenames,  , Looking up filenames, Directory functions
896@comment  node-name,  next,  previous,  up
897@subsection Translating inode numbers to filenames
898
899@deftypefun errcode_t ext2fs_get_pathname (ext2_filsys @var{fs}, ext2_ino_t @var{dir}, ext2_ino_t @var{ino}, char **@var{name})
900@end deftypefun
901
902
903@c ----------------------------------------------------------------------
904
905@node Bitmap Functions, EXT2 data abstractions, Directory functions, EXT2FS Library Functions
906@comment  node-name,  next,  previous,  up
907@section Bitmap Functions
908
909@menu
910* Reading and Writing Bitmaps::
911* Allocating Bitmaps::
912* Free bitmaps::
913* Bitmap Operations::
914* Comparing bitmaps::
915* Modifying Bitmaps::
916* Resizing Bitmaps::
917* Clearing Bitmaps::
918@end menu
919
920@c ----------------------------------------------------------------------
921
922@node Reading and Writing Bitmaps, Allocating Bitmaps, Bitmap Functions, Bitmap Functions
923@comment  node-name,  next,  previous,  up
924@subsection Reading and Writing Bitmaps
925
926@deftypefun errcode_t ext2fs_write_inode_bitmap (ext2_filsys @var{fs})
927@end deftypefun
928
929@deftypefun errcode_t ext2fs_write_block_bitmap (ext2_filsys @var{fs})
930@end deftypefun
931
932@deftypefun errcode_t ext2fs_read_inode_bitmap (ext2_filsys @var{fs})
933@end deftypefun
934
935@deftypefun errcode_t ext2fs_read_block_bitmap (ext2_filsys @var{fs})
936@end deftypefun
937
938@deftypefun errcode_t ext2fs_read_bitmaps (ext2_filsys @var{fs})
939@end deftypefun
940
941@deftypefun errcode_t ext2fs_write_bitmaps (ext2_filsys @var{fs})
942@end deftypefun
943
944@c ----------------------------------------------------------------------
945
946@node Allocating Bitmaps, Free bitmaps, Reading and Writing Bitmaps, Bitmap Functions
947@comment  node-name,  next,  previous,  up
948@subsection Allocating Bitmaps
949
950@deftypefun errcode_t ext2fs_allocate_generic_bitmap (__u32 @var{start}, __u32 @var{end}, _u32 @var{real_end}, const char *@var{descr}, ext2fs_generic_bitmap *@var{ret})
951@end deftypefun
952
953@deftypefun errcode_t ext2fs_allocate_block_bitmap (ext2_filsys @var{fs}, const char *@var{descr}, ext2fs_block_bitmap *@var{ret})
954@end deftypefun
955
956@deftypefun errcode_t ext2fs_allocate_inode_bitmap (ext2_filsys @var{fs}, const char *@var{descr}, ext2fs_inode_bitmap *@var{ret})
957@end deftypefun
958
959@c ----------------------------------------------------------------------
960
961@node Free bitmaps, Bitmap Operations, Allocating Bitmaps, Bitmap Functions
962@comment  node-name,  next,  previous,  up
963@subsection Freeing bitmaps
964
965
966@deftypefun void ext2fs_free_generic_bitmap (ext2fs_inode_bitmap @var{bitmap})
967@end deftypefun
968
969@deftypefun void ext2fs_free_block_bitmap (ext2fs_block_bitmap @var{bitmap})
970@end deftypefun
971
972@deftypefun void ext2fs_free_inode_bitmap (ext2fs_inode_bitmap @var{bitmap})
973@end deftypefun
974
975
976@c ----------------------------------------------------------------------
977
978@node Bitmap Operations, Comparing bitmaps, Free bitmaps, Bitmap Functions
979@comment  node-name,  next,  previous,  up
980@subsection Bitmap Operations
981
982@deftypefun void ext2fs_mark_block_bitmap (ext2fs_block_bitmap @var{bitmap}, blk_t @var{block})
983
984@deftypefunx void ext2fs_unmark_block_bitmap (ext2fs_block_bitmap @var{bitmap}, blk_t @var{block})
985
986@deftypefunx int ext2fs_test_block_bitmap (ext2fs_block_bitmap @var{bitmap}, blk_t @var{block})
987
988These functions set, clear, and test bits in a block bitmap @var{bitmap}.
989@end deftypefun
990
991
992@deftypefun void ext2fs_mark_inode_bitmap (ext2fs_inode_bitmap @var{bitmap}, ext2_ino_t @var{inode})
993
994@deftypefunx void ext2fs_unmark_inode_bitmap (ext2fs_inode_bitmap @var{bitmap}, ext2_ino_t @var{inode})
995
996@deftypefunx int ext2fs_test_inode_bitmap (ext2fs_inode_bitmap @var{bitmap}, ext2_ino_t @var{inode})
997
998These functions set, clear, and test bits in an inode bitmap @var{bitmap}.
999@end deftypefun
1000
1001@deftypefun void ext2fs_fast_mark_block_bitmap (ext2fs_block_bitmap @var{bitmap}, blk_t @var{block})
1002
1003@deftypefunx void ext2fs_fast_unmark_block_bitmap (ext2fs_block_bitmap @var{bitmap}, blk_t @var{block})
1004
1005@deftypefunx int ext2fs_fast_test_block_bitmap (ext2fs_block_bitmap @var{bitmap}, blk_t @var{block})
1006
1007@deftypefunx void ext2fs_fast_mark_inode_bitmap (ext2fs_inode_bitmap @var{bitmap}, ext2_ino_t @var{inode})
1008
1009@deftypefunx void ext2fs_fast_unmark_inode_bitmap (ext2fs_inode_bitmap @var{bitmap}, ext2_ino_t @var{inode})
1010
1011@deftypefunx int ext2fs_fast_test_inode_bitmap (ext2fs_inode_bitmap @var{bitmap}, ext2_ino_t @var{inode})
1012
1013These ``fast'' functions are like their normal counterparts; however,
1014they are implemented as inline functions and do not perform bounds
1015checks on the inode number or block number; they are assumed to be
1016correct.  They should only be used in speed-critical applications, where
1017the inode or block number has already been validated by other means.
1018@end deftypefun
1019
1020@deftypefun blk_t ext2fs_get_block_bitmap_start (ext2fs_block_bitmap @var{bitmap})
1021@deftypefunx ext2_ino_t ext2fs_get_inode_bitmap_start (ext2fs_inode_bitmap @var{bitmap})
1022Return the first inode or block which is stored in the bitmap.
1023@end deftypefun
1024
1025@deftypefun blk_t ext2fs_get_block_bitmap_end (ext2fs_block_bitmap @var{bitmap})
1026@deftypefunx ext2_ino_t ext2fs_get_inode_bitmap_end (ext2fs_inode_bitmap @var{bitmap})
1027
1028Return the last inode or block which is stored in the bitmap.
1029@end deftypefun
1030
1031
1032@c ----------------------------------------------------------------------
1033
1034@node Comparing bitmaps, Modifying Bitmaps, Bitmap Operations, Bitmap Functions
1035@comment  node-name,  next,  previous,  up
1036@subsection Comparing bitmaps
1037
1038@deftypefun errcode_t ext2fs_compare_block_bitmap (ext2fs_block_bitmap @var{bm1}, ext2fs_block_bitmap @var{bm2})
1039@end deftypefun
1040
1041@deftypefun errcode_t ext2fs_compare_inode_bitmap (ext2fs_inode_bitmap @var{bm1}, ext2fs_inode_bitmap @var{bm2})
1042@end deftypefun
1043
1044
1045@c ----------------------------------------------------------------------
1046
1047@node Modifying Bitmaps, Resizing Bitmaps, Comparing bitmaps, Bitmap Functions
1048@comment  node-name,  next,  previous,  up
1049@subsection Modifying Bitmaps
1050
1051@deftypefun errcode_t ext2fs_fudge_inode_bitmap_end (ext2fs_inode_bitmap @var{bitmap}, ext2_ino_t @var{end}, ext2_ino_t *@var{oend})
1052@end deftypefun
1053
1054@deftypefun errcode_t ext2fs_fudge_block_bitmap_end (ext2fs_block_bitmap @var{bitmap}, blk_t @var{end}, blk_t *@var{oend})
1055@end deftypefun
1056
1057@c ----------------------------------------------------------------------
1058
1059@node Resizing Bitmaps, Clearing Bitmaps, Modifying Bitmaps, Bitmap Functions
1060@comment  node-name,  next,  previous,  up
1061@subsection Resizing Bitmaps
1062
1063@deftypefun errcode_t ext2fs_resize_generic_bitmap (__u32 @var{new_end}, __u32 @var{new_real_end}, ext2fs_generic_bitmap @var{bmap})
1064@end deftypefun
1065
1066@deftypefun errcode_t ext2fs_resize_inode_bitmap (__u32 @var{new_end}, __u32 @var{new_real_end}, ext2fs_inode_bitmap @var{bmap})
1067@end deftypefun
1068
1069@deftypefun errcode_t ext2fs_resize_block_bitmap (__u32 @var{new_end}, __u32 @var{new_real_end}, ext2fs_block_bitmap @var{bmap})
1070@end deftypefun
1071
1072
1073@c ----------------------------------------------------------------------
1074
1075@node Clearing Bitmaps,  , Resizing Bitmaps, Bitmap Functions
1076@comment  node-name,  next,  previous,  up
1077@subsection Clearing Bitmaps
1078
1079@deftypefun void ext2fs_clear_inode_bitmap (ext2fs_inode_bitmap @var{bitmap})
1080
1081This function sets all of the bits in the inode bitmap @var{bitmap} to
1082be zero.
1083
1084@end deftypefun
1085
1086@deftypefun void ext2fs_clear_block_bitmap (ext2fs_block_bitmap @var{bitmap})
1087
1088This function sets all of the bits in the block bitmap @var{bitmap} to
1089be zero.
1090@end deftypefun
1091
1092
1093@c ----------------------------------------------------------------------
1094
1095@node EXT2 data abstractions, Byte-swapping functions, Bitmap Functions, EXT2FS Library Functions
1096@comment  node-name,  next,  previous,  up
1097@section EXT2 data abstractions
1098
1099The ext2 library has a number of abstractions which are useful for ext2
1100utility programs.
1101
1102@menu
1103* Badblocks list management::
1104* Directory-block list management::
1105* Inode count functions::
1106@end menu
1107
1108@c ----------------------------------------------------------------------
1109
1110@node Badblocks list management, Directory-block list management, EXT2 data abstractions, EXT2 data abstractions
1111@comment  node-name,  next,  previous,  up
1112@subsection Badblocks list management
1113
1114
1115@deftypefun errcode_t ext2fs_badblocks_list_create (ext2_badblocks_list *@var{ret}, int @var{size})
1116@end deftypefun
1117
1118@deftypefun void ext2fs_badblocks_list_free (ext2_badblocks_list @var{bb})
1119@end deftypefun
1120
1121@deftypefun errcode_t ext2fs_badblocks_list_add (ext2_badblocks_list @var{bb}, blk_t @var{blk})
1122@end deftypefun
1123
1124@deftypefun int ext2fs_badblocks_list_test (ext2_badblocks_list @var{bb}, blk_t @var{blk})
1125@end deftypefun
1126
1127@deftypefun errcode_t ext2fs_badblocks_list_iterate_begin (ext2_badblocks_list @var{bb}, ext2_badblocks_iterate *@var{ret})
1128@end deftypefun
1129
1130@deftypefun int ext2fs_badblocks_list_iterate (ext2_badblocks_iterate iter, blk_t *@var{blk})
1131@end deftypefun
1132
1133@deftypefun void ext2fs_badblocks_list_iterate_end (ext2_badblocks_iterate @var{iter})
1134@end deftypefun
1135
1136@deftypefun errcode_t ext2fs_update_bb_inode (ext2_filsys @var{fs}, ext2_badblocks_list @var{bb_list})
1137@end deftypefun
1138
1139@deftypefun errcode_t ext2fs_read_bb_inode (ext2_filsys @var{fs}, ext2_badblocks_list *@var{bb_list})
1140@end deftypefun
1141
1142@deftypefun errcode_t ext2fs_read_bb_FILE (ext2_filsys @var{fs}, FILE *f, ext2_badblocks_list *@var{bb_list}, void (*invalid)(ext2_filsys @var{fs}, blk_t @var{blk}))
1143@end deftypefun
1144
1145
1146@c ----------------------------------------------------------------------
1147
1148@node Directory-block list management, Inode count functions, Badblocks list management, EXT2 data abstractions
1149@comment  node-name,  next,  previous,  up
1150@subsection Directory-block list management
1151
1152The dblist abstraction stores a list of blocks belonging to
1153directories.  This list can be useful when a program needs to interate
1154over all directory entries in a filesystem; @code{e2fsck} does this in
1155pass 2 of its operations, and @code{debugfs} needs to do this when it is
1156trying to turn an inode number into a pathname.
1157
1158@deftypefun errcode_t ext2fs_init_dblist (ext2_filsys @var{fs}, ext2_dblist *@var{ret_dblist})
1159
1160Creates a dblist data structure and returns it in @var{ret_dblist}.
1161@end deftypefun
1162
1163@deftypefun void ext2fs_free_dblist (ext2_dblist @var{dblist})
1164
1165Free a dblist data structure.
1166@end deftypefun
1167
1168@deftypefun errcode_t ext2fs_add_dir_block (ext2_dblist @var{dblist}, ext2_ino_t @var{ino}, blk_t @var{blk}, int @var{blockcnt})
1169
1170Add an entry to the dblist data structure.  This call records the fact
1171that block number @var{blockcnt} of directory inode @var{ino} is stored
1172in block @var{blk}.
1173@end deftypefun
1174
1175@deftypefun errcode_t ext2fs_set_dir_block (ext2_dblist @var{dblist}, ext2_ino_t @var{ino}, blk_t @var{blk}, int @var{blockcnt})
1176
1177Change an entry in the dblist data structure; this changes the location
1178of block number @var{blockcnt} of directory inode @var{ino} to be block
1179@var{blk}.
1180@end deftypefun
1181
1182@deftypefun errcode_t ext2fs_dblist_iterate (ext2_dblist @var{dblist}, int (*func)(ext2_filsys @var{fs}, struct ext2_db_entry *@var{db_info}, void *@var{private}), void *@var{private})
1183
1184This iterator calls @var{func} for every entry in the dblist data structure.
1185@end deftypefun
1186
1187@deftypefun errcode_t ext2fs_dblist_dir_iterate (ext2_dblist @var{dblist}, int flags, char *@var{block_buf}, int (*func)(ext2_ino_t @var{dir}, int  @var{entry}, struct ext2_dir_entry *@var{dirent}, int @var{offset}, int @var{blocksize}, char *@var{buf}, void *@var{private}), void *@var{private})
1188
1189This iterator takes reads in the directory block indicated in each
1190dblist entry, and calls @var{func} for each directory entry in each
1191directory block.  If @var{dblist} contains all the directory blocks in a
1192filesystem, this function provides a convenient way to iterate over all
1193directory entries for that filesystem.
1194@end deftypefun
1195
1196@c ----------------------------------------------------------------------
1197
1198@node Inode count functions,  , Directory-block list management, EXT2 data abstractions
1199@comment  node-name,  next,  previous,  up
1200@subsection Inode count functions
1201
1202The icount abstraction is a specialized data type used by @code{e2fsck}
1203to store how many times a particular inode is referenced by the
1204filesystem.  This is used twice; once to store the actual number of times
1205that the inode is reference; and once to store the claimed number of times
1206the inode is referenced according to the inode structure.
1207
1208This abstraction is designed to be extremely efficient for storing this
1209sort of information, by taking advantage of the following properties of
1210inode counts, namely (1) inode counts are very often zero (because
1211the inode is currently not in use), and (2) many files have a inode
1212count of 1 (because they are a file which has no additional hard links).
1213
1214@deftypefun errcode_t ext2fs_create_icount2 (ext2_filsys @var{fs}, int @var{flags}, int @var{size}, ext2_icount_t @var{hint}, ext2_icount_t *@var{ret})
1215
1216Creates an icount structure for a filesystem @var{fs}, with initial space
1217for @var{size} inodes whose count is greater than 1.  The @var{flags}
1218parameter is either 0 or @code{EXT2_ICOUNT_OPT_INCREMENT}, which
1219indicates that icount structure should be able to increment inode counts
1220quickly.  The icount structure is returned in @var{ret}.  The returned
1221icount structure initially has a count of zero for all inodes.
1222
1223The @var{hint} parameter allows the caller to optionally pass in another
1224icount structure which is used to initialize the array of inodes whose
1225count is greater than 1.  It is used purely as a speed optimization so
1226that the icount structure can determine in advance which inodes are
1227likely to contain a count grater than 1.
1228@end deftypefun
1229
1230@deftypefun void ext2fs_free_icount (ext2_icount_t @var{icount})
1231
1232Frees an icount structure.
1233@end deftypefun
1234
1235@deftypefun errcode_t ext2fs_icount_fetch (ext2_icount_t @var{icount}, ext2_ino_t @var{ino}, __u16 *@var{ret})
1236
1237Returns in @var{ret} the count for a particular inode @var{ino}.
1238@end deftypefun
1239
1240@deftypefun errcode_t ext2fs_icount_increment (ext2_icount_t @var{icount}, ext2_ino_t @var{ino}, __u16 *@var{ret})
1241
1242Increments the ref count for inode @var{ino}.
1243@end deftypefun
1244
1245@deftypefun errcode_t ext2fs_icount_decrement (ext2_icount_t @var{icount}, ext2_ino_t @var{ino}, __u16 *@var{ret})
1246
1247Decrements the ref count for inode @var{ino}.
1248@end deftypefun
1249
1250@deftypefun errcode_t ext2fs_icount_store (ext2_icount_t @var{icount}, ext2_ino_t @var{ino}, __u16 @var{count})
1251
1252Sets the reference count for inode @var{ino} to be @var{count}.
1253@end deftypefun
1254
1255@deftypefun ext2_ino_t ext2fs_get_icount_size (ext2_icount_t @var{icount})
1256
1257Returns the current number of inodes in @var{icount} which has a count
1258greater than 1.
1259@end deftypefun
1260
1261@deftypefun errcode_t ext2fs_icount_validate (ext2_icount_t @var{icount}, FILE *@var{f})
1262
1263Validates the internal rep invariant of @var{icount}; if there are any
1264problems, print out debugging information to @var{f}.  This function is
1265intended for debugging and testing use only.
1266@end deftypefun
1267
1268
1269@c ----------------------------------------------------------------------
1270
1271@node Byte-swapping functions, Other functions, EXT2 data abstractions, EXT2FS Library Functions
1272@comment  node-name,  next,  previous,  up
1273@section Byte-swapping functions
1274
1275@deftypefun void ext2fs_swap_super (struct ext2_super_block * @var{super})
1276@end deftypefun
1277
1278@deftypefun void ext2fs_swap_group_desc (struct ext2_group_desc *@var{gdp})
1279@end deftypefun
1280
1281@deftypefun void ext2fs_swap_inode (ext2_filsys @var{fs}, struct ext2_inode *@var{to}, struct ext2_inode *@var{from}, int @var{hostorder})
1282@end deftypefun
1283
1284@deftypefun int ext2fs_native_flag (void)
1285@end deftypefun
1286
1287
1288@c ----------------------------------------------------------------------
1289
1290@node Other functions,  , Byte-swapping functions, EXT2FS Library Functions
1291@comment  node-name,  next,  previous,  up
1292@section Other functions
1293
1294/* alloc.c */
1295@deftypefun errcode_t ext2fs_new_inode (ext2_filsys @var{fs}, ext2_ino_t @var{dir}, int @var{mode}, ext2fs_inode_bitmap @var{map}, ext2_ino_t *@var{ret})
1296@end deftypefun
1297
1298@deftypefun errcode_t ext2fs_new_block (ext2_filsys @var{fs}, blk_t @var{goal}, ext2fs_block_bitmap @var{map}, blk_t *@var{ret})
1299@end deftypefun
1300
1301@deftypefun errcode_t ext2fs_get_free_blocks (ext2_filsys @var{fs}, blk_t @var{start}, blk_t @var{finish}, int @var{num}, ext2fs_block_bitmap @var{map}, blk_t *@var{ret})
1302@end deftypefun
1303
1304/* check_desc.c */
1305@deftypefun errcode_t ext2fs_check_desc (ext2_filsys @var{fs})
1306@end deftypefun
1307
1308@deftypefun errcode_t ext2fs_get_num_dirs (ext2_filsys @var{fs}, ext2_ino_t *@var{ret_num_dirs})
1309@end deftypefun
1310
1311
1312/* getsize.c */
1313@deftypefun errcode_t ext2fs_get_device_size (const char *@var{file}, int @var{blocksize}, blk_t *@var{retblocks})
1314@end deftypefun
1315
1316
1317/* ismounted.c */
1318@deftypefun errcode_t ext2fs_check_if_mounted (const char *@var{file}, int *@var{mount_flags})
1319@end deftypefun
1320
1321/* version.c */
1322
1323@deftypefun int ext2fs_get_library_version (const char **@var{ver_string}, const char **@var{date_string})
1324
1325This function returns the current version of the ext2 library.  The
1326return value contains an integer version code, which consists of the
1327major version number of the library multiplied by 100, plus the minor
1328version number of the library.  Hence, if the library version is 1.08,
1329the returned value will be 108.
1330
1331If @var{ver_string} and/or @var{date_string} are non-NULL, they will be
1332set to point at a constant string containing the library version and/or
1333release date, respectively.
1334@end deftypefun
1335
1336@deftypefun int ext2fs_parse_version_string (const char *@var{ver_string})
1337
1338This function takes a version string which may included in an
1339application and returns a version code using the same algorithm used by
1340@code{ext2fs_get_library_version}.  It can be used by programs included
1341in the @code{e2fsprogs} distribution to assure that they are using an
1342up-to-date ext2 shared library.
1343@end deftypefun
1344
1345/* inline functions */
1346@deftypefun int ext2fs_group_of_blk (ext2_filsys @var{fs}, blk_t @var{blk})
1347
1348This function returns the block group which contains the block @var{blk}.
1349
1350@end deftypefun
1351
1352@deftypefun int ext2fs_group_of_ino (ext2_filsys @var{fs}, ext2_ino_t @var{ino})
1353
1354This function returns the block group which contains the inode @var{ino}.
1355@end deftypefun
1356
1357
1358@c ----------------------------------------------------------------------
1359
1360@node Concept Index, Function Index, EXT2FS Library Functions, Top
1361@comment  node-name,  next,  previous,  up
1362@unnumbered Concept Index
1363@printindex cp
1364
1365@c ----------------------------------------------------------------------
1366
1367@node Function Index,  , Concept Index, Top
1368@comment  node-name,  next,  previous,  up
1369@unnumbered Function and Type Index
1370@printindex fn
1371
1372
1373@contents
1374@bye
1375