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692 lines
20 KiB
Groff
692 lines
20 KiB
Groff
.\"-
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.\" Copyright 1986, Larry Wall
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following condition
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.\" is met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this condition and the following disclaimer.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $OpenBSD: patch.1,v 1.27 2014/04/15 06:26:54 jmc Exp $
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.Dd November 3, 2019
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.Dt PATCH 1
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.Os
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.Sh NAME
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.Nm patch
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.Nd apply a diff file to an original
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.Sh SYNOPSIS
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.Nm
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.Bk -words
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.Op Fl bCcEeflNnRstuv
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.Op Fl B Ar backup-prefix
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.Op Fl D Ar symbol
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.Op Fl d Ar directory
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.Op Fl F Ar max-fuzz
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.Op Fl i Ar patchfile
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.Op Fl o Ar out-file
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.Op Fl p Ar strip-count
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.Op Fl r Ar rej-name
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.Op Fl V Cm t | nil | never | none
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.Op Fl x Ar number
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.Op Fl z Ar backup-ext
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.Op Fl Fl posix
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.Op Ar origfile Op Ar patchfile
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.Ek
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.Nm
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.Pf \*(Lt Ar patchfile
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.Sh DESCRIPTION
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.Nm
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will take a patch file containing any of the four forms of difference
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listing produced by the
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.Xr diff 1
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program and apply those differences to an original file,
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producing a patched version.
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If
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.Ar patchfile
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is omitted, or is a hyphen, the patch will be read from the standard input.
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.Pp
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.Nm
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will attempt to determine the type of the diff listing, unless overruled by a
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.Fl c ,
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.Fl e ,
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.Fl n ,
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or
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.Fl u
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option.
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Context diffs (old-style, new-style, and unified) and
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normal diffs are applied directly by the
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.Nm
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program itself, whereas ed diffs are simply fed to the
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.Xr ed 1
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editor via a pipe.
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.Pp
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If the
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.Ar patchfile
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contains more than one patch,
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.Nm
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will try to apply each of them as if they came from separate patch files.
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This means, among other things, that it is assumed that the name of the file
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to patch must be determined for each diff listing, and that the garbage before
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each diff listing will be examined for interesting things such as file names
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and revision level (see the section on
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.Sx Filename Determination
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below).
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.Pp
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The options are as follows:
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.Bl -tag -width Ds
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.It Xo
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.Fl B Ar backup-prefix ,
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.Fl Fl prefix Ar backup-prefix
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.Xc
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Causes the next argument to be interpreted as a prefix to the backup file
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name.
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If this argument is specified, any argument to
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.Fl z
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will be ignored.
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.It Fl b , Fl Fl backup
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Save a backup copy of the file before it is modified.
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By default the original file is saved with a backup extension of
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.Qq .orig
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unless the file already has a numbered backup, in which case a numbered
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backup is made.
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This is equivalent to specifying
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.Qo Fl V Cm existing Qc .
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This option is currently the default, unless
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.Fl -posix
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is specified.
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.It Fl C , Fl Fl check , Fl Fl dry-run
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Checks that the patch would apply cleanly, but does not modify anything.
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.It Fl c , Fl Fl context
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Forces
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.Nm
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to interpret the patch file as a context diff.
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.It Xo
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.Fl D Ar symbol ,
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.Fl Fl ifdef Ar symbol
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.Xc
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Causes
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.Nm
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to use the
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.Qq #ifdef...#endif
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construct to mark changes.
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The argument following will be used as the differentiating symbol.
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Note that, unlike the C compiler, there must be a space between the
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.Fl D
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and the argument.
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.It Xo
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.Fl d Ar directory ,
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.Fl Fl directory Ar directory
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.Xc
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Causes
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.Nm
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to interpret the next argument as a directory,
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and change the working directory to it before doing anything else.
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.It Fl E , Fl Fl remove-empty-files
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Causes
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.Nm
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to remove output files that are empty after the patches have been applied.
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This option is useful when applying patches that create or remove files.
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.It Fl e , Fl Fl ed
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Forces
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.Nm
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to interpret the patch file as an
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.Xr ed 1
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script.
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.It Xo
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.Fl F Ar max-fuzz ,
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.Fl Fl fuzz Ar max-fuzz
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.Xc
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Sets the maximum fuzz factor.
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This option only applies to context diffs, and causes
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.Nm
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to ignore up to that many lines in looking for places to install a hunk.
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Note that a larger fuzz factor increases the odds of a faulty patch.
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The default fuzz factor is 2, and it may not be set to more than
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the number of lines of context in the context diff, ordinarily 3.
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.It Fl f , Fl Fl force
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Forces
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.Nm
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to assume that the user knows exactly what he or she is doing, and to not
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ask any questions.
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It assumes the following:
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skip patches for which a file to patch cannot be found;
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patch files even though they have the wrong version for the
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.Qq Prereq :
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line in the patch;
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and assume that patches are not reversed even if they look like they are.
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This option does not suppress commentary; use
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.Fl s
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for that.
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.It Xo
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.Fl i Ar patchfile ,
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.Fl Fl input Ar patchfile
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.Xc
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Causes the next argument to be interpreted as the input file name
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(i.e., a patchfile).
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This option may be specified multiple times.
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.It Fl l , Fl Fl ignore-whitespace
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Causes the pattern matching to be done loosely, in case the tabs and
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spaces have been munged in your input file.
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Any sequence of whitespace in the pattern line will match any sequence
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in the input file.
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Normal characters must still match exactly.
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Each line of the context must still match a line in the input file.
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.It Fl N , Fl Fl forward
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Causes
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.Nm
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to ignore patches that it thinks are reversed or already applied.
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See also
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.Fl R .
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.It Fl n , Fl Fl normal
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Forces
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.Nm
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to interpret the patch file as a normal diff.
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.It Xo
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.Fl o Ar out-file ,
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.Fl Fl output Ar out-file
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.Xc
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Causes the next argument to be interpreted as the output file name.
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.It Xo
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.Fl p Ar strip-count ,
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.Fl Fl strip Ar strip-count
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.Xc
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Sets the pathname strip count,
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which controls how pathnames found in the patch file are treated,
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in case you keep your files in a different directory than the person who sent
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out the patch.
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The strip count specifies how many slashes are to be stripped from
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the front of the pathname.
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(Any intervening directory names also go away.)
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For example, supposing the file name in the patch file was
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.Pa /u/howard/src/blurfl/blurfl.c :
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.Pp
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Setting
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.Fl p Ns Ar 0
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gives the entire pathname unmodified.
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.Pp
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.Fl p Ns Ar 1
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gives
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.Pp
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.D1 Pa u/howard/src/blurfl/blurfl.c
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.Pp
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without the leading slash.
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.Pp
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.Fl p Ns Ar 4
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gives
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.Pp
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.D1 Pa blurfl/blurfl.c
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.Pp
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Not specifying
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.Fl p
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at all just gives you
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.Pa blurfl.c ,
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unless all of the directories in the leading path
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.Pq Pa u/howard/src/blurfl
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exist and that path is relative,
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in which case you get the entire pathname unmodified.
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Whatever you end up with is looked for either in the current directory,
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or the directory specified by the
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.Fl d
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option.
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.It Fl R , Fl Fl reverse
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Tells
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.Nm
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that this patch was created with the old and new files swapped.
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(Yes, I am afraid that does happen occasionally, human nature being what it
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is.)
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.Nm
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will attempt to swap each hunk around before applying it.
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Rejects will come out in the swapped format.
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The
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.Fl R
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option will not work with ed diff scripts because there is too little
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information to reconstruct the reverse operation.
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.Pp
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If the first hunk of a patch fails,
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.Nm
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will reverse the hunk to see if it can be applied that way.
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If it can, you will be asked if you want to have the
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.Fl R
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option set.
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If it cannot, the patch will continue to be applied normally.
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(Note: this method cannot detect a reversed patch if it is a normal diff
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and if the first command is an append (i.e., it should have been a delete)
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since appends always succeed, due to the fact that a null context will match
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anywhere.
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Luckily, most patches add or change lines rather than delete them, so most
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reversed normal diffs will begin with a delete, which will fail, triggering
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the heuristic.)
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.It Xo
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.Fl r Ar rej-name ,
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.Fl Fl reject-file Ar rej-name
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.Xc
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Causes the next argument to be interpreted as the reject file name.
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.It Xo
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.Fl s , Fl Fl quiet ,
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.Fl Fl silent
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.Xc
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Makes
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.Nm
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do its work silently, unless an error occurs.
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.It Fl t , Fl Fl batch
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Similar to
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.Fl f ,
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in that it suppresses questions, but makes some different assumptions:
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skip patches for which a file to patch cannot be found (the same as
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.Fl f ) ;
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skip patches for which the file has the wrong version for the
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.Qq Prereq :
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line in the patch;
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and assume that patches are reversed if they look like they are.
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.It Fl u , Fl Fl unified
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Forces
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.Nm
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to interpret the patch file as a unified context diff (a unidiff).
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.It Xo
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.Fl V Cm t | nil | never | none ,
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.Fl Fl version-control Cm t | nil | never | none
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.Xc
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Causes the next argument to be interpreted as a method for creating
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backup file names.
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The type of backups made can also be given in the
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.Ev PATCH_VERSION_CONTROL
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or
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.Ev VERSION_CONTROL
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environment variables, which are overridden by this option.
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The
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.Fl B
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option overrides this option, causing the prefix to always be used for
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making backup file names.
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The values of the
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.Ev PATCH_VERSION_CONTROL
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and
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.Ev VERSION_CONTROL
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environment variables and the argument to the
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.Fl V
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option are like the GNU Emacs
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.Dq version-control
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variable; they also recognize synonyms that are more descriptive.
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The valid values are (unique abbreviations are accepted):
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.Bl -tag -width Ds -offset indent
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.It Cm t , numbered
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Always make numbered backups.
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.It Cm nil , existing
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Make numbered backups of files that already have them,
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simple backups of the others.
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.It Cm never , simple
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Always make simple backups.
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.It Cm none
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Do not make backups.
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.El
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.It Fl v , Fl Fl version
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Causes
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.Nm
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to print out its revision header and patch level.
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.It Xo
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.Fl x Ar number ,
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.Fl Fl debug Ar number
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.Xc
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Sets internal debugging flags, and is of interest only to
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.Nm
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patchers.
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.It Xo
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.Fl z Ar backup-ext ,
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.Fl Fl suffix Ar backup-ext
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.Xc
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Causes the next argument to be interpreted as the backup extension, to be
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used in place of
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.Qq .orig .
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.It Fl Fl posix
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Enables strict
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.St -p1003.1-2008
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conformance, specifically:
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.Bl -enum
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.It
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Backup files are not created unless the
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.Fl b
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option is specified.
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.It
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If unspecified, the file name used is the first of the old, new and
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index files that exists.
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.El
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.El
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.Ss Patch Application
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.Nm
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will try to skip any leading garbage, apply the diff,
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and then skip any trailing garbage.
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Thus you could feed an article or message containing a
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diff listing to
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.Nm ,
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and it should work.
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If the entire diff is indented by a consistent amount,
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this will be taken into account.
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.Pp
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With context diffs, and to a lesser extent with normal diffs,
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.Nm
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can detect when the line numbers mentioned in the patch are incorrect,
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and will attempt to find the correct place to apply each hunk of the patch.
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As a first guess, it takes the line number mentioned for the hunk, plus or
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minus any offset used in applying the previous hunk.
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If that is not the correct place,
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.Nm
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will scan both forwards and backwards for a set of lines matching the context
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given in the hunk.
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First
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.Nm
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looks for a place where all lines of the context match.
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If no such place is found, and it is a context diff, and the maximum fuzz factor
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is set to 1 or more, then another scan takes place ignoring the first and last
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line of context.
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If that fails, and the maximum fuzz factor is set to 2 or more,
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the first two and last two lines of context are ignored,
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and another scan is made.
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.Pq The default maximum fuzz factor is 2 .
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.Pp
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If
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.Nm
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cannot find a place to install that hunk of the patch, it will put the hunk
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out to a reject file, which normally is the name of the output file plus
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.Qq .rej .
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(Note that the rejected hunk will come out in context diff form whether the
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input patch was a context diff or a normal diff.
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If the input was a normal diff, many of the contexts will simply be null.)
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The line numbers on the hunks in the reject file may be different than
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in the patch file: they reflect the approximate location patch thinks the
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failed hunks belong in the new file rather than the old one.
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.Pp
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As each hunk is completed, you will be told whether the hunk succeeded or
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failed, and which line (in the new file)
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.Nm
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thought the hunk should go on.
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If this is different from the line number specified in the diff,
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you will be told the offset.
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A single large offset MAY be an indication that a hunk was installed in the
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wrong place.
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You will also be told if a fuzz factor was used to make the match, in which
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case you should also be slightly suspicious.
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.Ss Filename Determination
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If no original file is specified on the command line,
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.Nm
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will try to figure out from the leading garbage what the name of the file
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to edit is.
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When checking a prospective file name, pathname components are stripped
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as specified by the
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.Fl p
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option and the file's existence and writability are checked relative
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to the current working directory (or the directory specified by the
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.Fl d
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option).
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.Pp
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If the diff is a context or unified diff,
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.Nm
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is able to determine the old and new file names from the diff header.
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For context diffs, the
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.Dq old
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file is specified in the line beginning with
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.Qq ***
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and the
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.Dq new
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file is specified in the line beginning with
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.Qq --- .
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For a unified diff, the
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.Dq old
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file is specified in the line beginning with
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.Qq ---
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and the
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.Dq new
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file is specified in the line beginning with
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.Qq +++ .
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If there is an
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.Qq Index :
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line in the leading garbage (regardless of the diff type),
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.Nm
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will use the file name from that line as the
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.Dq index
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file.
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.Pp
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.Nm
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will choose the file name by performing the following steps, with the first
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match used:
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.Bl -enum
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.It
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If
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.Nm
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is operating in strict
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.St -p1003.1-2008
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mode, the first of the
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.Dq old ,
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.Dq new
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and
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.Dq index
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file names that exist is used.
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Otherwise,
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.Nm
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will examine either the
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.Dq old
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and
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.Dq new
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file names or, for a non-context diff, the
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.Dq index
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file name, and choose the file name with the fewest path components,
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the shortest basename, and the shortest total file name length (in that order).
|
|
.It
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|
If no suitable file was found to patch, the patch file is a context or
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|
unified diff, and the old file was zero length, the new file name is
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created and used.
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.It
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If the file name still cannot be determined,
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.Nm
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will prompt the user for the file name to use.
|
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.El
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.Pp
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|
Additionally, if the leading garbage contains a
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.Qq Prereq:\ \&
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line,
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.Nm
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|
will take the first word from the prerequisites line (normally a version
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number) and check the input file to see if that word can be found.
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If not,
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.Nm
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will ask for confirmation before proceeding.
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.Pp
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|
The upshot of all this is that you should be able to say, while in a news
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interface, the following:
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.Pp
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.Dl | patch -d /usr/src/local/blurfl
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.Pp
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|
and patch a file in the blurfl directory directly from the article containing
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the patch.
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|
.Ss Backup Files
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|
By default, the patched version is put in place of the original, with
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the original file backed up to the same name with the extension
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.Qq .orig ,
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or as specified by the
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.Fl B ,
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.Fl V ,
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or
|
|
.Fl z
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|
options.
|
|
The extension used for making backup files may also be specified in the
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.Ev SIMPLE_BACKUP_SUFFIX
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|
environment variable, which is overridden by the options above.
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|
.Pp
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|
If the backup file is a symbolic or hard link to the original file,
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.Nm
|
|
creates a new backup file name by changing the first lowercase letter
|
|
in the last component of the file's name into uppercase.
|
|
If there are no more lowercase letters in the name,
|
|
it removes the first character from the name.
|
|
It repeats this process until it comes up with a
|
|
backup file that does not already exist or is not linked to the original file.
|
|
.Pp
|
|
You may also specify where you want the output to go with the
|
|
.Fl o
|
|
option; if that file already exists, it is backed up first.
|
|
.Ss Notes For Patch Senders
|
|
There are several things you should bear in mind if you are going to
|
|
be sending out patches:
|
|
.Pp
|
|
First, you can save people a lot of grief by keeping a
|
|
.Pa patchlevel.h
|
|
file which is patched to increment the patch level as the first diff in the
|
|
patch file you send out.
|
|
If you put a
|
|
.Qq Prereq :
|
|
line in with the patch, it will not let them apply
|
|
patches out of order without some warning.
|
|
.Pp
|
|
Second, make sure you have specified the file names right, either in a
|
|
context diff header, or with an
|
|
.Qq Index :
|
|
line.
|
|
If you are patching something in a subdirectory, be sure to tell the patch
|
|
user to specify a
|
|
.Fl p
|
|
option as needed.
|
|
.Pp
|
|
Third, you can create a file by sending out a diff that compares a
|
|
null file to the file you want to create.
|
|
If the file you want to create already exists in the target directory when the
|
|
diff is applied, then
|
|
.Nm
|
|
will identify the patch as potentially reversed and offer to reverse the patch.
|
|
.Pp
|
|
Fourth, take care not to send out reversed patches, since it makes people wonder
|
|
whether they already applied the patch.
|
|
.Pp
|
|
Fifth, while you may be able to get away with putting 582 diff listings into
|
|
one file, it is probably wiser to group related patches into separate files in
|
|
case something goes haywire.
|
|
.Sh ENVIRONMENT
|
|
.Bl -tag -width "PATCH_VERSION_CONTROL" -compact
|
|
.It Ev POSIXLY_CORRECT
|
|
When set,
|
|
.Nm
|
|
behaves as if the
|
|
.Fl Fl posix
|
|
option has been specified.
|
|
.It Ev SIMPLE_BACKUP_SUFFIX
|
|
Extension to use for backup file names instead of
|
|
.Qq .orig .
|
|
.It Ev TMPDIR
|
|
Directory to put temporary files in; default is
|
|
.Pa /tmp .
|
|
.It Ev PATCH_VERSION_CONTROL
|
|
Selects when numbered backup files are made.
|
|
.It Ev VERSION_CONTROL
|
|
Same as
|
|
.Ev PATCH_VERSION_CONTROL .
|
|
.El
|
|
.Sh FILES
|
|
.Bl -tag -width "$TMPDIR/patch*" -compact
|
|
.It Pa $TMPDIR/patch*
|
|
.Nm
|
|
temporary files
|
|
.It Pa /dev/tty
|
|
used to read input when
|
|
.Nm
|
|
prompts the user
|
|
.El
|
|
.Sh EXIT STATUS
|
|
The
|
|
.Nm
|
|
utility exits with one of the following values:
|
|
.Pp
|
|
.Bl -tag -width Ds -offset indent -compact
|
|
.It 0
|
|
Successful completion.
|
|
.It 1
|
|
One or more lines were written to a reject file.
|
|
.It \*(Gt1
|
|
An error occurred.
|
|
.El
|
|
.Pp
|
|
When applying a set of patches in a loop it behooves you to check this
|
|
exit status so you do not apply a later patch to a partially patched file.
|
|
.Sh DIAGNOSTICS
|
|
Too many to list here, but generally indicative that
|
|
.Nm
|
|
couldn't parse your patch file.
|
|
.Pp
|
|
The message
|
|
.Qq Hmm...
|
|
indicates that there is unprocessed text in the patch file and that
|
|
.Nm
|
|
is attempting to intuit whether there is a patch in that text and, if so,
|
|
what kind of patch it is.
|
|
.Sh SEE ALSO
|
|
.Xr diff 1
|
|
.Sh STANDARDS
|
|
The
|
|
.Nm
|
|
utility is compliant with the
|
|
.St -p1003.1-2008
|
|
specification,
|
|
except as detailed above for the
|
|
.Fl -posix
|
|
option.
|
|
.Pp
|
|
The flags
|
|
.Op Fl BCEFfstVvxz
|
|
and
|
|
.Op Fl -posix
|
|
are extensions to that specification.
|
|
.Sh AUTHORS
|
|
.An Larry Wall
|
|
with many other contributors.
|
|
.Sh CAVEATS
|
|
.Nm
|
|
cannot tell if the line numbers are off in an ed script, and can only detect
|
|
bad line numbers in a normal diff when it finds a
|
|
.Qq change
|
|
or a
|
|
.Qq delete
|
|
command.
|
|
A context diff using fuzz factor 3 may have the same problem.
|
|
Until a suitable interactive interface is added, you should probably do
|
|
a context diff in these cases to see if the changes made sense.
|
|
Of course, compiling without errors is a pretty good indication that the patch
|
|
worked, but not always.
|
|
.Pp
|
|
.Nm
|
|
usually produces the correct results, even when it has to do a lot of
|
|
guessing.
|
|
However, the results are guaranteed to be correct only when the patch is
|
|
applied to exactly the same version of the file that the patch was
|
|
generated from.
|
|
.Sh BUGS
|
|
Could be smarter about partial matches, excessively deviant offsets and
|
|
swapped code, but that would take an extra pass.
|
|
.Pp
|
|
Check patch mode
|
|
.Pq Fl C
|
|
will fail if you try to check several patches in succession that build on
|
|
each other.
|
|
The entire
|
|
.Nm
|
|
code would have to be restructured to keep temporary files around so that it
|
|
can handle this situation.
|
|
.Pp
|
|
If code has been duplicated (for instance with #ifdef OLDCODE ... #else ...
|
|
#endif),
|
|
.Nm
|
|
is incapable of patching both versions, and, if it works at all, will likely
|
|
patch the wrong one, and tell you that it succeeded to boot.
|
|
.Pp
|
|
If you apply a patch you have already applied,
|
|
.Nm
|
|
will think it is a reversed patch, and offer to un-apply the patch.
|
|
This could be construed as a feature.
|