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NEWS
574 строки21 KB
Paul Eggert
diff3: avoid reading uninitialized data
21 апр 2026, 20:59
21 апр 2026, 20:5904ef122
GNU diffutils NEWS                                    -*- outline -*-

* Noteworthy changes in release ?.? (????-??-??) [?]

** Bug fixes

  diff3 no longer has undefined behavior if the underlying diff
  program produces incorrect command lines, or enormous line numbers,
  or unexpectedly truncated data.
  [bugs present since "the beginning"]


* Noteworthy changes in release 3.12 (2025-04-08) [stable]

** Bug fixes

  diff -r no longer merely summarizes when comparing an empty regular
  file to a nonempty regular file.
  [bug#76452 introduced in 3.11]

  diff -y no longer crashes when given nontrivial differences.
  [bug#76613 introduced in 3.11]


* Noteworthy changes in release 3.11 (2025-02-02) [stable]

** Improvements

  Programs now quote file names more consistently in diagnostics.
  For example; "cmp 'none of' /etc/passwd" now might output
  "cmp: EOF on ‘none of’ which is empty" instead of outputting
  "cmp: EOF on none of which is empty".  In diagnostic messages
  that traditionally omit quotes and where backward compatibility
  seems to be important, programs continue to omit quotes unless
  a file name contains shell metacharacters, in which case programs
  use shell quoting.  For example, although diff continues to output
  "Only in a: b" as before for most file names, it now outputs
  "Only in 'a: b': 'c: d'" instead of "Only in a: b: c: d" because the
  file names 'a: b' and 'c: d' contain spaces.  For compatibility
  with previous practice, diff -c and -u headers continue to quote for
  C rather than for the shell.

  diff now outputs more information when symbolic links differ, e.g.,
  "Symbolic links ‘d/f’ -> ‘a’ and ‘e/f’ -> ‘b’ differ", not just
  "Symbolic links d/f and e/f differ".  Special files too, e.g.,
  "Character special files ‘d/f’ (1, 3) and ‘e/f’ (5, 0) differ", not
  "File d/f is a character special file while file e/f is a character
  special file".

  diff's --ignore-case (-i) and --ignore-file-name-case options now
  support multi-byte characters.  For example, they treat Greek
  capital Δ like small δ when input uses UTF-8.

  diff now supports multi-byte characters when treating white space.
  In options like --expand-tabs (-t), --ignore-space-change (-b) and
  --ignore-tab-expansion (-E), diff now recognizes non-ASCII space
  characters and counts columns for non-ASCII characters.

** Bug fixes

  cmp -bl no longer omits "M-" from bytes with the high bit set in
  single-byte locales like en_US.iso8859-1.  This fix causes the
  behavior to be locale independent, and to be the same as the
  longstanding behavior in the C locale and in locales using UTF-8.
  [bug introduced in 2.9]

  cmp -i N and -n N no longer fail merely because N is enormous.
  [bug present since "the beginning"]

  cmp -s no longer mishandles /proc files, for which the Linux kernel
  reports a zero size even when nonempty.  For example, the following
  shell command now outputs nothing, as it should:
    cp /proc/cmdline t; cmp -s /proc/cmdline t || echo files differ
  [bug present since "the beginning"]

  diff -E no longer mishandles some input lines containing '\a', '\b',
  '\f', '\r', '\v', or '\0'.
  [bug present since 2.8]

  diff -ly no longer mishandles non-ASCII input.
  [bug#64461 introduced in 2.9]

  diff - A/B now works correctly when standard input is a directory,
  by reading a file named B in that directory.
  [bug present since "the beginning"]

  diff no longer suffers from race conditions in some cases
  when comparing files in a mutating file system.
  [bug present since "the beginning"]

** Release

  distribute gzip-compressed tarballs once again


* Noteworthy changes in release 3.10 (2023-05-21) [stable]

** Bug fixes

  cmp/diff can again work with file dates past Y2K38
  [bug introduced in 3.9]

  diff -D no longer fails to output #ifndef lines.
  [bug#61193 introduced in 3.9]


* Noteworthy changes in release 3.9 (2023-01-15) [stable]

** Bug fixes

  diff -c and -u no longer output incorrect timezones in headers
  on platforms like Solaris where struct tm lacks tm_gmtoff.
  [bug#51228 introduced in 3.4]


* Noteworthy changes in release 3.8 (2021-08-01) [stable]

** Incompatible changes

  diff no longer treats a closed stdin as representing an absent file
  in usage like 'diff --new-file - foo <&-'.  This feature was rarely
  if ever used and was not portable to POSIX platforms that reopen
  stdin on exec, such as SELinux if the process underwent an AT_SECURE
  transition, or HP-UX even if not setuid.
  [bug#33965 introduced in 2.8]

** Bug fixes

  diff and related programs no longer get confused if stdin, stdout,
  or stderr are closed.  Previously, they sometimes opened files into
  file descriptors 0, 1, or 2 and then mistakenly did I/O with them
  that was intended for stdin, stdout, or stderr.
  [bug#33965 present since "the beginning"]

  cmp, diff and sdiff no longer treat negative command-line
  option-arguments as if they were large positive numbers.
  [bug#35256 introduced in 2.8]


* Noteworthy changes in release 3.7 (2018-12-31) [stable]

** Bug fixes

  diff --strip-trailing-cr with a single CR byte in one input file
  would provoke an uninitialized memory read, e.g.,
    diff -a --strip-trailing-cr <(printf '\r') <(echo a)
  [bug introduced in 2.8 with addition of the --strip-trailing-cr option]

** Improvements

  diff --color now produces output compatible with less -R.


* Noteworthy changes in release 3.6 (2017-05-21) [stable]

** New features

  When one file is a prefix of the other, cmp now appends the shorter
  file's size to the EOF diagnostic.

** Bug fixes

  Using an invalid regular expression with --ignore-matching-lines=RE (-I)
  no longer causes stack overflow.  Before, with an invocation like the
  following, diff would diagnose the error, but would still proceed to
  blow the stack: diff -Ia -I\\ <(echo) <(echo b)
  [bug introduced in 2.9]

  diff no longer mishandles line numbers exceeding 2**31 on Mingw-w64.

  the ---presume-output-tty (ostensibly test-only) option would cause
  diff --color to read an uninitialized variable
  [bug introduced in 3.4]

** Performance changes

  diff's default algorithm has been tweaked to deal better with larger
  files, reversing some of the changes made in diffutils-3.4.


* Noteworthy changes in release 3.5 (2016-08-20) [stable]

** Bug fixes

  diff3 no longer malfunctions due to use-after-free
  [bug introduced in 3.4]

  diff --color no longer colorizes when TERM=dumb


* Noteworthy changes in release 3.4 (2016-08-08) [stable]

** New features

   diff accepts two new options --color and --palette to generate
   and configure colored output.  --color takes an optional argument
   specifying when to colorize a line: --color=always, --color=auto,
   --color=never.  --palette is used to configure which colors are used.

** Bug fixes

  When binary files differ, diff now exits with status 1 as POSIX requires.
  Formerly it exited with status 2.

  Unless the --ignore-file-name-case option is used, diff now
  considers file names to be equal only if they are byte-for-byte
  equivalent.  This fixes a bug where diff in an English locale might
  consider two Asian file names to be the same merely because they
  contain no English characters.

  diff -B no longer generates incorrect output if the two inputs
  each end with a one-byte incomplete line.

  diff --brief no longer reports a difference for unusual identical files.
  For example, when comparing a file like /proc/cmdline (for which the linux
  kernel reports st_size of 0 even though it is not an empty file) to a
  copy of that file's contents residing on a "normal" file system:
    $ f=/proc/cmdline; cp $f k; diff --brief $f k
    Files /proc/cmdline and k differ

** Performance changes

  diff's default algorithm has been adjusted to output higher-quality
  results at somewhat greater computational cost, as CPUs have gotten
  faster since the algorithm was last tweaked in diffutils-2.6 (1993).


* Noteworthy changes in release 3.3 (2013-03-24) [stable]

** New features

  diff accepts a new option, --no-dereference.  With this option, symbolic
  links are treated specially: as a separate type of file that can compare
  equal only to another symbolic link with the same value.  For example,
  with --no-dereference, two symbolic links compare equal when they have
  the same value, even when that value does not reference a readable file.

  --new-file (-N) and --unidirectional-new-file now allow comparisons to "-".
  A standard input that's closed acts like a nonexistent file.

  A file name containing spaces, double quotes, backslashes or control
  characters is now encoded in a diff header as a double-quoted C string
  literal.  The escape sequences \\, \", \a, \b, \f, \n, \r, \t, \v and
  \ooo (a three-digit octal number between 0 and 255) are used.

** Packaging

  diffutils is now designed to build with Cygwin or MinGW rather than DJGPP.
  The ms subdirectory has been removed.


* Noteworthy changes in release 3.2 (2011-09-02) [stable]

** Changes in behavior

  --ignore-file-name-case now applies at the top level too.
  For example, "diff dir inIt" might compare "dir/Init" to "inIt".

** New features

  diff and sdiff have a new option --ignore-trailing-space (-Z).

** Packaging

  The texinfo documentation no longer specifies "front-cover" or "back-cover"
  texts, so that it may now be included in Debian's "main" section.


* Noteworthy changes in release 3.1 (2011-08-10) [stable]

** Bug fixes

  diff no longer reports spurious differences merely because two entries
  in the same directory have names that compare equal in the current
  locale, or compare equal because --ignore-file-name-case was given.

* Noteworthy changes in release 3.0 (2010-05-03) [stable]

** Bug fixes

  diff once again prints the required "\ No newline at end of file" line
  when at least one input lacks a newline-at-EOF and the final hunk plus
  context-length aligns exactly with the end of the newline-lacking file.
  [bug introduced between 2.8.7 and 2.9]

** Changes in behavior

  In context-style diffs, diff prints a portion of a preceding "function"
  line for each hunk, with --show-function-line=RE (-F) or
  --show-c-function (-p).  Now, it trims leading blanks from such lines
  before extracting a prefix.  This is useful especially when a function
  line is so far indented that the name itself would be truncated or not
  included in the limited-width substring that diff appends.

  diff once again reports a difference with the diagnostic
  "Binary files A and B differ" when at least one of the files
  appears to be binary.  From 2.8.4 through diffutils-2.9, it printed
  "Files A and B differ".


* Noteworthy changes in release 2.9 (2010-02-11) [stable]

** New features

  New diff option --suppress-blank-empty.

  Bring back support for 'diff -NUM', where NUM is a number,
  even when conforming to POSIX 1003.1-2001.  This change reverts to
  the behavior of GNU diff 2.7 and earlier.  This is a change only
  when conforming to POSIX 1003.1-2001; there is no effect when
  conforming to older POSIX versions.

  This change is in response to decisions taken in the January 2005
  Austin Group standardization meeting.  For more details, please see
  "Utility Syntax Guidelines" in the Minutes of the January 2005
  Meeting <http://www.opengroup.org/austin/docs/austin_239.html>.

  sdiff now understands '1' and '2' as synonyms for 'l' and 'r'.

** Changes in behavior

  sdiff and diff3 now invoke diff, not $(bindir)/diff

** Administrivia

  New discussion and bug-reporting address: bug-diffutils@gnu.org

  updated gnulib support


* Noteworthy changes in release 2.8.7 (2004-04-13) [stable]

  Version 2.8.7 contains no user-visible changes.

User-visible changes in version 2.8.6:

* New diff3 option --strip-trailing-cr.

* With -N and -P, inaccessible empty regular files (the kind of files
  that 'patch' creates to indicate nonexistent backups) are now
  treated as nonexistent when they are in the 'backup' file position.

* If multiple SKIP values are given to cmp, e.g., 'cmp -i 10 -i 20',
  cmp now uses the maximal value instead of the last one.

* diff now omits the ".000000000" on hosts that do not support
  fractional timestamps.

Version 2.8.5 was not publicly released.

User-visible changes in version 2.8.4:

* Diff now simply prints "Files A and B differ" instead of "Binary
  files A and B differ".  The message is output if either A or B
  appears to be a binary file, and the old wording was misleading
  because it implied that both files are binary, which is not
  necessarily the case.

User-visible changes in version 2.8.3:

* New locale: en_US.

User-visible changes in version 2.8.2:

* New diff and sdiff option:
  --tabsize=COLUMNS
* If --ignore-space-change or --ignore-all-space is also specified,
  --ignore-blank-lines now considers lines to be empty if they contain
  only white space.
* More platforms now handle multibyte characters correctly when
  excluding files by name (diff -x and -X).
* New locales: hu, pt_BR.

User-visible changes in version 2.8.1:

* Documentation fixes.

User-visible changes in version 2.8:

* cmp and diff now conform to POSIX 1003.1-2001 (IEEE Std 1003.1-2001)
  if the underlying system conforms to POSIX and if the _POSIX2_VERSION
  environment variable is set to 200112.  Conformance removes support
  for 'diff -NUM', where NUM is a number.  Use -C NUM or -U NUM instead.
* cmp now supports trailing operands SKIP1 and SKIP2, like BSD cmp.
* cmp -i or --ignore-initial now accepts SKIP1:SKIP2 option value.
* New cmp option: -n or --bytes.
* cmp's old -c or --print-chars option has been renamed;
  use -b or --print-bytes instead.
* cmp now outputs "byte" rather than "char" outside the POSIX locale.
* cmp -l's index column width now adjusts to fit larger (or smaller) files.
* cmp -l -s and cmp -s -l are not allowed.  Use cmp -s or cmp -l instead.
* diff uses ISO 8601 style timestamps for output times (e.g. "2001-11-23
  16:44:36.875702460 -0800") unless in the C or POSIX locale and the
  -c style is specified.
* diff's -I and -F options use the regexp syntax of grep, not of Emacs.
* diff now accepts multiple context arguments, and uses their maximum value.
* New diff and sdiff options:
  -E  --ignore-tab-expansion
  --strip-trailing-cr
* New diff options:
  --from-file=FILE, --to-file=FILE
  --ignore-file-name-case
  --no-ignore-file-name-case
* New diff3 and sdiff option:
  --diff-program=PROGRAM
* The following diff options are still accepted, but are no longer documented.
  They may be withdrawn in future releases.
  -h (omit; it has no effect)
  -H (use --speed-large-files instead)
  -L (use --label instead)
  -P (use --unidirectional-new-file instead)
  --inhibit-hunk-merge (omit; it has no effect)
* Recursive diffs now sort file names according to the LC_COLLATE locale
  category if possible, instead of using native byte comparison.
* Recursive diffs now detect and report directory loops.
* Diff printf specs can now use the "0" and "'" flags.
* The new sdiff interactive command 'ed' precedes each version with a header.
* On 64-bit hosts, files larger than 2 GB can be compared.
* Some internationalization support has been added, but multibyte locales
  are still not completely supported yet.
* Some diagnostics have been reworded slightly for consistency.
  Also, 'diff -D FOO' now outputs '/* ! FOO */' instead of '/* not FOO */'.
* The 'patch' part of the manual now describes 'patch' version 2.5.4.
* Man pages are now distributed and installed.
* There is support for DJGPP; see the 'ms' subdirectory and the files
  m4/dos.m4 and */setmode.*.


User-visible changes in version 2.7:

* New diff option: --binary (useful only on non-POSIX hosts)
* diff -b and -w now ignore line incompleteness; -B no longer does this.
* cmp -c now uses locale to decide which output characters to quote.
* Help and version messages are reorganized.


User-visible changes in version 2.6:

* New cmp, diff, diff3, sdiff option: --help
* A new heuristic for diff greatly reduces the time needed to compare
  large input files that contain many differences.
* Partly as a result, GNU diff's output is not exactly the same as before.
  Usually it is a bit smaller, but sometimes it is a bit larger.


User-visible changes in version 2.5:

* New cmp option: -v --version


User-visible changes in version 2.4:

* New cmp option: --ignore-initial=BYTES
* New diff3 option: -T --initial-tab
* New diff option: --line-format=FORMAT
* New diff group format specifications:
  <PRINTF_SPEC>[eflmnEFLMN]
      A printf spec followed by one of the following letters
      causes the integer corresponding to that letter to be
      printed according to the printf specification.
      E.g. '%5df' prints the number of the first line in the
      group in the old file using the "%5d" format.
        e: line number just before the group in old file; equals f - 1
        f: first line number in group in the old file
        l: last line number in group in the old file
        m: line number just after the group in old file; equals l + 1
        n: number of lines in group in the old file; equals l - f + 1
        E, F, L, M, N: likewise, for lines in the new file
  %(A=B?T:E)
      If A equals B then T else E.  A and B are each either a decimal
      constant or a single letter interpreted as above.  T and E are
      arbitrary format strings.  This format spec is equivalent to T if
      A's value equals B's; otherwise it is equivalent to E.  For
      example, '%(N=0?no:%dN) line%(N=1?:s)' is equivalent to 'no lines'
      if N (the number of lines in the group in the new file) is 0,
      to '1 line' if N is 1, and to '%dN lines' otherwise.
  %c'C'
      where C is a single character, stands for the character C.  C may not
      be a backslash or an apostrophe.  E.g. %c':' stands for a colon.
  %c'\O'
      where O is a string of 1, 2, or 3 octal digits, stands for the
      character with octal code O.  E.g. %c'\0' stands for a null character.
* New diff line format specifications:
  <PRINTF_SPEC>n
      The line number, printed with <PRINTF_SPEC>.
      E.g. '%5dn' prints the line number with a "%5d" format.
  %c'C'
  %c'\O'
      The character C, or with octal code O, as above.
* Supported <PRINTF_SPEC>s have the same meaning as with printf, but must
  match the extended regular expression %-*[0-9]*(\.[0-9]*)?[doxX].
* The format spec %0 introduced in version 2.1 has been removed, since it
  is incompatible with printf specs like %02d.  To represent a null char,
  use %c'\0' instead.
* cmp and diff now conform to POSIX 1003.2-1992 (ISO/IEC 9945-2:1993)
  if the underlying system conforms to POSIX:
  - Some messages' wordings are changed in minor ways.
  - "White space" is now whatever C's 'isspace' says it is.
  - When comparing directories, if 'diff' finds a file that is not a regular
    file or a directory, it reports the file's type instead of diffing it.
    (As usual, it follows symbolic links first.)
  - When signaled, sdiff exits with the signal's status, not with status 2.
* Now portable to hosts where int, long, pointer, etc. are not all the same
  size.
* 'cmp - -' now works like 'diff - -'.


User-visible changes in version 2.3:

* New diff option: --horizon-lines=lines


User-visible changes in version 2.1:

* New diff options:
  --{old,new,unchanged}-line-format='format'
  --{old,new,unchanged,changed}-group-format='format'
  -U
* New diff3 option:
  -A --show-all
* diff3 -m now defaults to -A, not -E.
* diff3 now takes up to three -L or --label options, not just two.
  If just two options are given, they refer to the first two input files,
  not the first and third input files.
* sdiff and diff -y handle incomplete lines.


User-visible changes in version 2.0:

* Add sdiff and cmp programs.
* Add Texinfo documentation.
* Add configure script.
* Improve diff performance.
* New diff options:
-x --exclude
-X --exclude-from
-P --unidirectional-new-file
-W --width
-y --side-by-side
--left-column
--sdiff-merge-assist
--suppress-common-lines
* diff options renamed:
--label renamed from --file-label
--forward-ed renamed from --reversed-ed
--paginate renamed from --print
--entire-new-file renamed from --entire-new-files
--new-file renamed from --new-files
--all-text removed
* New diff3 options:
-v --version
* Add long-named equivalents for other diff3 options.
* diff options -F (--show-function-line) and -I (--ignore-matching-lines)
  can now be given more than once.



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Software Foundation, Inc.

This file is part of GNU Diffutils.

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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