ckormanyos/xxd

This is the well-known hex-dump-type utility xxd commonly distributed as a part of the vim-project. The version of xxd in this repository has been adapted for MSVC/GCC/clang standalone build.

Releases and build artifacts

Occasional releases and build artifacts consisting of the executable xxd program are created for Windows, LINUX and MacOS . These can be readily found on the repo front page and in CI workflow-run download-areas for immediate client use.

Using released or CI-built artifacts can be convenient when you do not actually want to nor need to manually build ckormanyos/xxd.

Build

Building ckormanyos/xxd (if needed) is straightforward.

The source code in ckormanyos/xxd has been adapted for standalone build on most common operating systems.

The source code of ckormanyos/xxd is written in the C language. It is compatible with language standards C99, 11, 17, 23 and beyond.

Build on Windows with MSVC

On Windows with MSVC simply build ckormanyos/xxd with the following.

• Open the xxd.sln workspace.
• Rebuild Release (i.e., for the x64 project configuration).
• After building, find the executable xxd.exe in the expected output directory.

Build on the LINUX command line

On LINUX it is straightforward to build ckormanyos/xxd on the command line.

• Switch to the xxddirectory.
• Build (for instance with GCC) using an easy command, as shown below.
• This compiles src/xxd.c to xxd.

In other words,

cd xxd
g++ -x c -std=c17 -O2 -Wall -Wextra -Wpedantic -Wconversion -Wsign-conversion src/xxd.c -o xxd

Build on the MacOS command line

When on MacOS, it is also easy to build ckormanyos/xxd on the command line.

• Switch to the xxddirectory.
• Build (for instance with clang) using an easy command, as shown below.
• This compiles src/xxd.c to xxd.

In other words,

cd xxd
clang++ -x c -std=c17 -O2 -Wall -Wextra -Wpedantic -Wconversion -Wsign-conversion src/xxd.c -o xxd

Platform-independent build with CMake (and ninja)

Building ckormanyos/xxd on the command line is also supported with platform-independent CMake (and ninja). This has been motivated by issue 16.

cd xxd
mkdir build
cd build
cmake .. -G Ninja && ninja

Adaptions

The following adaptions have been undertaken.

• Create an MSVC *.sln workspace and associated project configuration.
• Disregard (i.e., delete and do not use) the configuration header config.h.in.
• Replace the compiler switch WIN32 with MSVC's standard _WIN32.
• Run the xxd.c/config.h files through the Artistic Style automatic code formatter, using a version of AStyle from somewhere around 2015.
• Handle Level-3 warnings found in MSVC.
• Handle GCC warnings from -Wall, -Wextra, -Wpedantic, -Wconversion and -Wsign-conversion.
• Add CI consisting of MSVC/GCC/clang builds and a handful of straightforward test cases.
• Upload build artifacts in CI for xxd-x86_64-linux-gnu and xxd-win64-msvc, see also discussion in issue 11.
• Resolve code-technical issues (and/or disable some) found via quality checks performed with CodeSonar, as described in issue 15 and issue 23.
• Implementation of the -n flag, as seen in vim/vim@83e1180 and added in PR 45.
• Use fgetc()/fputc() instead of getc()/putc(). See also PR 50 which fixes a bug where sometimes line feeds 0x0A (i.e., \n) get an additional (unexpected) carriage return 0x0D (i.e., \r) - or sometimes even two - with them on Win* when reading/writing files.
• Employ shell scripts in combination with gcov, lcov (and locally) htmlgen to obtain code coverage results in CI for this repo.

Usage

The program manual at the xxd(1) - Linux man page states:

xxd - make a hexdump or do the reverse.

It can do nearly everything hexdump can and moreover perform the reversal translation of hex-like text back to binary representation. Like uuencode and uudecode it allows the transmission of binary data in a mail-safe ASCII representation, but has the advantage of decoding to standard output. Moreover, it can be used to perform binary file patching.

Examples

Print everything but the first three lines (hex 0x30 bytes) of file.

% xxd -s 0x30 file

Print 3 lines (hex 0x30 bytes) from the end of file.

% xxd -s -0x30 file

Print 120 bytes as continuous hexdump with 20 octets per line.

% xxd -l 120 -ps -c 20 xxd.1
2e54482058584420312022417567757374203139
39362220224d616e75616c207061676520666f72
20787864220a2e5c220a2e5c222032317374204d
617920313939360a2e5c22204d616e2070616765
20617574686f723a0a2e5c2220202020546f6e79
204e7567656e74203c746f6e79407363746e7567

Hexdump the first 120 bytes of this man page with 12 octets per line.

% xxd -l 120 -c 12 xxd.1
0000000: 2e54 4820 5858 4420 3120 2241  .TH XXD 1 "A
000000c: 7567 7573 7420 3139 3936 2220  ugust 1996"
0000018: 224d 616e 7561 6c20 7061 6765  "Manual page
0000024: 2066 6f72 2078 7864 220a 2e5c   for xxd"..\
0000030: 220a 2e5c 2220 3231 7374 204d  "..\" 21st M
000003c: 6179 2031 3939 360a 2e5c 2220  ay 1996..\"
0000048: 4d61 6e20 7061 6765 2061 7574  Man page aut
0000054: 686f 723a 0a2e 5c22 2020 2020  hor:..\"
0000060: 546f 6e79 204e 7567 656e 7420  Tony Nugent
000006c: 3c74 6f6e 7940 7363 746e 7567  <tony@sctnug

Display just the date from the file xxd.1

% xxd -s 0x36 -l 13 -c 13 xxd.1
0000036: 3231 7374 204d 6179 2031 3939 36  21st May 1996

Copy input_file to output_file and prepend 100 bytes of value 0x00.

% xxd input_file | xxd -r -s 100 > output_file

Patch the date in the file xxd.1

% echo "0000037: 3574 68" | xxd -r - xxd.1
% xxd -s 0x36 -l 13 -c 13 xxd.1
0000036: 3235 7468 204d 6179 2031 3939 36  25th May 1996

Create a 65537 byte file with all bytes 0x00, except for the last one which is 'A' (hex 0x41).

% echo "010000: 41" | xxd -r > file

Hexdump this file with autoskip.

% xxd -a -c 12 file
0000000: 0000 0000 0000 0000 0000 0000  ............
*
000fffc: 0000 0000 40                   ....A

Create a 1 byte file containing a single 'A' character. The number after '-r -s' adds to the linenumbers found in the file; in effect, the leading bytes are suppressed.

% echo "010000: 41" | xxd -r -s -0x10000 > file

Read single characters from a serial line

% xxd -c1 < /dev/term/b &
% stty < /dev/term/b -echo -opost -isig -icanon min 1
% echo -n foo > /dev/term/b

Additional Details

Continuous Integration and Testing

Continuous integration (CI) runs with GCC, clang and MSVC with both tool-specific builds as well as platform-independent CMake builds. CI exercises both building xxd as well as running several straightforward xxd test cases.

A (growing) test suite is present in xxd_tests.sh. These tests are used in CI to verify the expected functionality and also to obtain code coverage results.

Origins and Licensing

When searching for the xxd utility one finds it distributed as a part of vim-project and its packages. This project extracts the code, creates an MSVC solution workspace and provides the ability to easily build xxd on Win* or *nix.

The original code was taken from: vim github repo on 28-March-2022. The simplicity of the code port has been previously established (among other places) in fancer/xxd.

The xxd code copyrights are left untouched except for adding an additional note regarding the MSVC build. The license as well as the license declaration are left untouched. This original package is licensed by GPL-2.0. This version retains compatibility with the licensing of the original utility.

Other code parts (such as continuous integration scripts) are licensed under BSL 1.0.