diff: Fix integer overflow.

The legacy Stone algorithm uses `int` to represent line numbers, array
indices, and array lengths. If given inputs approaching `INT_MAX` lines,
it would overflow and att

diff: Fix integer overflow.

The legacy Stone algorithm uses `int` to represent line numbers, array
indices, and array lengths. If given inputs approaching `INT_MAX` lines,
it would overflow and attempt to allocate ridiculously large amounts of
memory. To avoid this without penalizing non-pathological inputs,
switch a few variables to `size_t` and add checks while and immediately
after reading both inputs.

MFC after: 3 days
PR: 280371
Sponsored by: Klara, Inc.
Reviewed by: allanjude
Differential Revision: https://reviews.freebsd.org/D46169

(cherry picked from commit 9317242469f1ca682626d9806f8caf65d143c09a)

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diff: honour -B flag with -q

PR: 278988
Reviewed by: bapt
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D45220

(cherry picked from commit fb623aab3927a682

diff: honour -B flag with -q

PR: 278988
Reviewed by: bapt
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D45220

(cherry picked from commit fb623aab3927a6825ff7731198ec2e33426f7607)

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diff: Fix --expand-tabs and --side-by-side.

* Overhaul column width and padding calculation.
* Rewrite print_space() so it is now a) correct and b) understandable.
* Rewrite tab expansion in fetch()

diff: Fix --expand-tabs and --side-by-side.

* Overhaul column width and padding calculation.
* Rewrite print_space() so it is now a) correct and b) understandable.
* Rewrite tab expansion in fetch() for the same reason.

This brings us in line with GNU diff for all cases I could think of.

Sponsored by: Klara, Inc.
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D44014

(cherry picked from commit 53de23f4d140becc3166e87665b0064f215a220e)

diff: Bump manual page date.

Sponsored by: Klara, Inc.

(cherry picked from commit 312b1076c6b0aff9bbcaff058b93385eaf607685)

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Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

diff: Fully comment out the jackpot variable.

This fixes a set but unused warning.

diff: restyle loop a bit

This is a bit more readable, and this loop is probably unlikely to gain
any `continue` or `break`s.

Suggested by: pstef
Differential Revision: https://reviews.freebsd.org/D

diff: restyle loop a bit

This is a bit more readable, and this loop is probably unlikely to gain
any `continue` or `break`s.

Suggested by: pstef
Differential Revision: https://reviews.freebsd.org/D37676

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diff: fix side-by-side output with tabbed input

The previous logic conflated some things... in this block:
- j: input characters rendered so far
- nc: number of characters in the line
- col: columns

diff: fix side-by-side output with tabbed input

The previous logic conflated some things... in this block:
- j: input characters rendered so far
- nc: number of characters in the line
- col: columns rendered so far
- hw: column width ((h)ard (w)idth?)

Comparing j to hw or col to nc are naturally wrong, as col and hw are
limits on their respective counters and nc is already brought down to hw
if the input line should be truncated to start with.

Right now, we end up easily truncating lines with tabs in them as we
count each tab for $tabwidth lines in the input line, but we really
should only be accounting for them in the column count. The problem is
most easily demonstrated by the two input files added for the tests,
the two tabbed lines lose at least a word or two even though there's
plenty of space left in the row for each side.

Reviewed by: bapt, pstef
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D37676

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diff: Don't (ab)use sprintf() as a kind of strcat().

Previously print_header() used sprintf() of a buffer to itself as a
kind of string builder but without checking for overflows. This
raised -Wfor

diff: Don't (ab)use sprintf() as a kind of strcat().

Previously print_header() used sprintf() of a buffer to itself as a
kind of string builder but without checking for overflows. This
raised -Wformat-truncation and -Wrestrict warnings in GCC. Instead,
just conditionally print the new timestamp fields after the initial
strftime()-formatted string. While here, use sizeof(buf) with
strftime() rather than a magic number.

Reviewed by: bapt
Differential Revision: https://reviews.freebsd.org/D36814

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diff: Don't treat null characters like carriage returns in readhash().

The implicit fall-through in the !D_FORCEASCII case caused null
characters to be treated as carriage returns honoring the D_STR

diff: Don't treat null characters like carriage returns in readhash().

The implicit fall-through in the !D_FORCEASCII case caused null
characters to be treated as carriage returns honoring the D_STRIPCR,
D_FOLDBLANKS, and D_IGNOREBLANKS flags.

Reported by: GCC -Wimplicit-fallthrough
Reviewed by: bapt
Fixes: 3cbf98e2bee9 diff: read whole files to determine if they are ASCII text
Differential Revision: https://reviews.freebsd.org/D36813

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diff: Fix a use after free as well as a memory leak in change().

When -B or -I are used, change() evaluates the lines in a hunk to
determine if it is a hunk that should be ignored. It does this by

diff: Fix a use after free as well as a memory leak in change().

When -B or -I are used, change() evaluates the lines in a hunk to
determine if it is a hunk that should be ignored. It does this by
reading each candidate line into a mallocated buffer via preadline()
and then calling ignoreline(). Previously the buffer was freed as a
side effect of ignoreline_pattern() called from ignoreline().
However, if only -B was specified, then ignoreline_pattern() was not
called and the lines were leaked. If both options were specified,
then ignoreline_pattern() was called before checking for a blank line
so that the second check was a use after free.

To fix, pull the free() out of ignoreline_pattern() and instead do it
up in change() so that is paired with preadline().

While here, simplify ignoreline() by checking for the -B and -I cases
individually without a separate clause for when both are set. Also,
do the cheaper check (-B) first, and remove a false comment (this
function is only called if at least one of -I or -B are specified).

Reviewed by: emaste
Reported by: GCC 12 -Wuse-after-free
Differential Revision: https://reviews.freebsd.org/D36822

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diff: Use start of change when searching for function

Use the start of change when searching for a function rather than the
start of the context. In short functions if this could result in search
fo

diff: Use start of change when searching for function

Use the start of change when searching for a function rather than the
start of the context. In short functions if this could result in search
for the function name starting from before the function definition.

PR: 262086
Reviewed by: bapt, mckusick, mhorne
Sponsored by: Klara Inc.
Differential Revision: https://reviews.freebsd.org/D34328

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diff: Detect Objective-C methods

When searching back for function definitions, consider lines starting
with '+' and '-', this allows us to pick up Objective-C methods as well
as C style function def

diff: Detect Objective-C methods

When searching back for function definitions, consider lines starting
with '+' and '-', this allows us to pick up Objective-C methods as well
as C style function definitions.

Reviewed by: bapt
Sponsored by: Klara Inc.
Differential Revision: https://reviews.freebsd.org/D34202

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diff: consider two files with same inodes as identical

Obtained from: OpenBSD
MFC after: 1 week

diff: implement option -F (--show-function-line)

With unified and context diffs, show the last line that matches the
provided pattern before the context.

Reviewed by: bapt
Differential Revision: ht

diff: implement option -F (--show-function-line)

With unified and context diffs, show the last line that matches the
provided pattern before the context.

Reviewed by: bapt
Differential Revision: https://reviews.freebsd.org/D31714

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diff(1): Add --color support

Adds a --color flag to diff(1) that supports the same options as GNU's
diff(1). The colors are customizable with the env var DIFFCOLORS in
a format similar to grep(1)'s

diff(1): Add --color support

Adds a --color flag to diff(1) that supports the same options as GNU's
diff(1). The colors are customizable with the env var DIFFCOLORS in
a format similar to grep(1)'s GREPCOLORS. An example would be 04;36:41
for additions to be underlined light blue, and deletions have a red
background.

Differential Revision: https://reviews.freebsd.org/D30545

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diff: decrease indent level

An upcoming change will add more code in the loop.

diff: avoid applying offsets to null pointer

This was the only instance of undefined behavior I could find so far.

diff: replace isqrt() with sqrt()

Remove cruft and use a system-provided and maintained function instead.

diff: move functions around and reduce their visibility

Most of them become static. There will be more such functions added in
upcoming commits, so they would be inconsistent with existing code.
Imp

diff: move functions around and reduce their visibility

Most of them become static. There will be more such functions added in
upcoming commits, so they would be inconsistent with existing code.
Improve the existing code instead of reinforcing the unwanted pattern.

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diff: improve code style

Reflow comments, strip trailing space, improve wrapping of lines.

diff: read whole files to determine if they are ASCII text

Before this change, only the first BUFSIZE bytes were checked.

Reviewed by: bapt (previous version)
Differential Revision: https://reviews

diff: read whole files to determine if they are ASCII text

Before this change, only the first BUFSIZE bytes were checked.

Reviewed by: bapt (previous version)
Differential Revision: https://reviews.freebsd.org/D31639

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diff: don't output carriage returns that were stripped on input

--strip-trailing-cr worked as intended for comparison between files,
but the characters were still present in final output.

usr.bin/diff: fix UBSan error in readhash

UBSan complains about the `sum = sum * 127 + chrtran(t);` line below since
that can overflow an `int`. Use `unsigned int` instead to ensure that
overflow is

usr.bin/diff: fix UBSan error in readhash

UBSan complains about the `sum = sum * 127 + chrtran(t);` line below since
that can overflow an `int`. Use `unsigned int` instead to ensure that
overflow is well-defined.

Reviewed By: imp
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D31075

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Revert "diff: eliminate a useless lseek"

This changes breaks when one of the files is stdin

This reverts commit fa977a3b2bb2d0e6c2957b14474c31b58dd3a8e1.

Reported by: olivier

diff: eleminitate useless macros

The diff_output was not bringing any values but was obfuscating
the code.