Mail Archives: djgpp/2015/12/28/21:23:21
This is a port of GNU patch 2.7.5 to MSDOS/DJGPP.
GNU patch is a program to apply patches to files. It accepts a "patch script",
usually produced by file-comparison utility such as Diff, and produces
modified files by applying this script to old versions of files.
More often than not, Patch is used with text, usually source, files.
But it can also patch binary files, although the patch scripts for binary
files tend to be large.
DJGPP specific changes.
=======================
The port offers the same djgpp specific functionality than the previous
port. These are:
- support for numbered backups even on 8+3 file systems;
- Patch can now ignore the CR characters at the end of each line
of the patch script, so patching Unix-style text files does not
convert them to DOS-style files anymore (if you use the --binary
switch).
To build this port you will need:
- to have an OS with LFN support to configure and compile the source
package. I have no plans to support SFN systems to build the patch
binaries.
- to run the test suite you will need to install the latest mktmpNNb.zip
As usual, all djgpp specific files (config.bat, diffs, README files, etc.)
are stored in the /djgpp directory.
Please note that there is a directory called /pc/djgpp that contains files
that are part of the official FSF patch distribution. I have inspected those
files but I have never used them nor I have plans to change this in the future.
Due to the massive use of gnulib code it is no longer possible to compile the
official FSF distribution out-of-the-box. So I will neither try to use those
files nor to keep them up to date. I will only use my own ones. If someone
else would like to keep those files up to date it will be OK with me.
Please also note that some of the tests of the test suite will fail. This is
not a port issue but a test suite issue. The test suite is very posix centric
so that some test will fail in an environment like DOS/Windows. The most
notorious test to fail is crlf-handling. Here the behaviour of patch in a
posix environment is tested and how it works when files to patch or the diffs
file has DOS style EOL. This is not the same behaviour than a DOS/DJGPP port
of patch to work in a DOS/WINDOWS environment. Not all those test will fail
but some of them. It makes no sense to try to adjust them because they test
for a behaviour that the port will not offer. Other tests that will fully
or partially fail are preserve-mode-and-timestamp, file-modes and fifo.
One of the most notorious change between this patch version and the previous
one is that this one uses a hash table to administrate the names of the files
it wants to modify or create. The hash keys are created using the st_dev and
st_ino values. Especially DJGPP creates the st_ino value using the starting
cluster of the file. This has the consequence that every time the file is
changed by the patch program by appending some new contents it gets a new
st_ino. This has the consequence that stat()ing again produces a different
st_ino for the same file and indeed a new hash key that makes it impossible
to find the already existing entry for this file in the hash table. This has
the nasty consequence, that when patch appends something new to this file, it
does not see that the file already exists and instead of appending to it, it
creates a new one at the same location with the same name overwriting the old
one with the new contains. To solve this issue it was necessary to create
unique and persistent inode numbers for every file produced by patch.
Wrapper functions to stat, fstat, open, fopen, close and fclose have been
written that will keep in sync file name, file descriptor and invented inode
number for every file produced by patch. See /pc/pc_inode.c for details
concerning the implementation.
Another change is that the patch program relaies on some explicit values of
the file type bits stored in the st_mode member of stat. Especially it is
assumed that every S_IF* bit is encoded by 1 and not by 0. But unfortunately
this is the case in DJGPP. DJGPP encodes S_IFREG with zero. This makes the
code fail. To avoid to have to change alot of code lines, S_IFREG is mapped
to another value different from zero before used.
This port supports git-style of patch files. Unfortunately this type of
patches encode the file type (like regular file or symlink) of the files
to be patched as number in the header of the patch file. This means that
the patch program reads a git-style patch file and parses the header and
tries to determinate if the file to be patched will be a regular file
(S_IFREG) or a symlink (S_IFLNK) or something else. This means that the
values of S_IFREG or S_IFLNK are not stored as some kind of symbols but as
those real numbers used to encode them on the OS where the patch file has
been produced. This has the consequence that if on a different OS/compiler
this encoding does not match, the patch program will not work properly. An
inspection of sys/stat.h of linux, bsd and cygwin shows that they all use
the same encodings for all values stored in the st_mode member of the stat
structure. Unfortunately DJGPP encodes these values in an incompatible way.
When this port parses that file type number, it _ALWAYS_ interprets it as
linux/bsd/cygwin encoding of the S_IF* bits and maps it to the DJGPP specifc
values of those bits. Please note, that the port has no way to determinate
if the number really represents linux/bsd/cygwin encoding or not. If the
number is not a linux/bsd/cygwin encoding, the mapping will fail an the
patch cannot be applied. The port assumes that the following encoding for
the S_IF* bits is valid:
/* Encoding of the file mode. */
#define S_IFMT 0170000 /* These bits determine file type. */
/* File types. */
#define S_IFDIR 0040000 /* Directory. */
#define S_IFCHR 0020000 /* Character device. */
#define S_IFBLK 0060000 /* Block device. */
#define S_IFREG 0100000 /* Regular file. */
#define S_IFIFO 0010000 /* FIFO. */
#define S_IFLNK 0120000 /* Symbolic link. */
#define S_IFSOCK 0140000 /* Socket. */
If this assumption is not true, the mapping to DJGPP values of S_IF* bits
will fail.
Please note that the FSF distribution of patch no longer can be compiled with
DJGPP out-of-the-box. If something seems not to work with this port, please
report it first at c.o.m.d. and not at bug-patch AT gnu DOT org. The maintainer
will have no idea about what I have done.
The source package is configured to be build in the "_build" directory.
The DJGPP 2.05 version of the port has been compiled using gcc530 and bnu225br2.
The port has been configured and compiled on WinXP SP3. There is no guarantee
that this may be possible with any other DOS-like OS. Due to the use of long
file names it will not be possible to configure and compile without LFN support.
For further information about GNU patch please read the info docs and NEWS
file.
Here is an extract of the NEWS file showing the user visible changes from
the last port (GNU patch 2.7.1) to this one:
-------------------------------------------------------------------------------
Changes in version 2.7.5:
* There are users which expect patch to follow symbolic links in the working
directory, so patch now again follows symbolic links as long as they do not
leave the working directory.
Changes until version 2.7.4:
* When a file isn't being deleted because the file contents don't match the
patch, the resulting message is now "Not deleting file ... as content
differs from patch" instead of "File ... is not empty after patch; not
deleting".
* Function names in hunks (from diff -p) are now preserved in reject files.
* Patch no longer follows symbolic links to input and output files. This
ensures that symbolic links created by git-style patches cannot cause
patch to write outside the working directory (CVE-2015-1196).
* Various fixes.
-------------------------------------------------------------------------------
The port consists of the usual two packages produced using djdev205
that can be downloaded from ftp.delorie.com and mirrors as (time stamp 2015-12-24):
Patch 2.7.5 binary and man format documentation:
ftp://ftp.delorie.com/pub/djgpp/beta/v2gnu/pat275b.zip
Patch 2.7.5 source:
ftp://ftp.delorie.com/pub/djgpp/beta/v2gnu/pat275s.zip
Send Patch specific bug reports to <bug-patch AT gnu DOT org>.
Send suggestions and bug reports concerning the DJGPP port
to comp.os.msdos.djgpp or <djgpp AT delorie DOT com>.
Enjoy.
Guerrero, Juan Manuel <juan DOT guerrero AT gmx DOT de>
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