Add CMake support; MSPACK_ERROR() to mspack API #32
Conversation
micahsnyder
force-pushed
the
cmake-tooling
branch
2 times, most recently
from
6e878e4 to
8f2ca36
Compare
|
Fixed: Updated the PR to get the unit test working. I thought they'd worked before, but perhaps I lost a code fix switching between Mac & Windows. I've also:
Remaining issues: The CMake tooling currently does not define While iconv detection will be easy, I don't yet know of a way to determine the value of I have the unit tests passing on Mac, but the cabd & chmd tests currently fail on Windows. Not sure why. Any insights would be helpful. C:\Users\micah\workspace\libmspack\libmspack\build [cmake-tooling ≡ +2 ~0 -0 !]> ctest -C Release -VV --output-on-failure
UpdateCTestConfiguration from :C:/Users/micah/workspace/libmspack/libmspack/build/DartConfiguration.tcl
UpdateCTestConfiguration from :C:/Users/micah/workspace/libmspack/libmspack/build/DartConfiguration.tcl
Test project C:/Users/micah/workspace/libmspack/libmspack/build
Constructing a list of tests
Done constructing a list of tests
Updating test list for fixtures
Added 0 tests to meet fixture requirements
Checking test dependency graph...
Checking test dependency graph end
test 1
Start 1: cabd_test
1: Test command: C:\Users\micah\workspace\libmspack\libmspack\build\test\Release\cabd_test.exe
1: Test timeout computed to be: 10000000
1: <unknown>:44 FAILED cab = cabd->open(cabd, TESTFILE("normal_2files_1folder.cab"))
1/3 Test #1: cabd_test ........................***Failed 0.02 sec
<unknown>:44 FAILED cab = cabd->open(cabd, TESTFILE("normal_2files_1folder.cab"))
test 2
Start 2: chmd_test
2: Test command: C:\Users\micah\workspace\libmspack\libmspack\build\test\Release\chmd_test.exe
2: Test timeout computed to be: 10000000
2: C:/Users/micah/workspace/libmspack/libmspack/test/test_files/chmd/blank-filenames.chm: invalid section number '58'.
2: <unknown>:80 FAILED chm1 = chmd->open(chmd, files[i])
2/3 Test #2: chmd_test ........................***Failed 0.02 sec
C:/Users/micah/workspace/libmspack/libmspack/test/test_files/chmd/blank-filenames.chm: invalid section number '58'.
<unknown>:80 FAILED chm1 = chmd->open(chmd, files[i])
test 3
Start 3: kwajd_test
3: Test command: C:\Users\micah\workspace\libmspack\libmspack\build\test\Release\kwajd_test.exe
3: Test timeout computed to be: 10000000
3: ALL 102 TESTS PASSED.
3/3 Test #3: kwajd_test ....................... Passed 0.02 sec
33% tests passed, 2 tests failed out of 3
Total Test time (real) = 0.09 sec
The following tests FAILED:
1 - cabd_test (Failed)
2 - chmd_test (Failed)
Errors while running CTestOther notes: I'd like to add a Github workflow to build & test on a few different systems and architectures. Maybe after the above concerns are resolved and the cabextract tooling has been added. |
micahsnyder
force-pushed
the
cmake-tooling
branch
from
8f2ca36 to
752c94c
Compare
|
Update: The initial test |
|
I've figured out why the Windows tests fail. Two reasons:
This second issue manifests as failures for cabd where diff --git a/libmspack/mspack/cabd.c b/libmspack/mspack/cabd.c
index 56549b8..75956da 100644
--- a/libmspack/mspack/cabd.c
+++ b/libmspack/mspack/cabd.c
@@ -1012,7 +1012,7 @@ static int cabd_extract(struct mscab_decompressor *base,
struct mscabd_folder_p *fol;
struct mspack_system *sys;
struct mspack_file *fh;
- off_t filelen;
+ unsigned int filelen;
if (!self) return MSPACK_ERR_ARGS;
if (!file) return self->error = MSPACK_ERR_ARGS;
@@ -1049,7 +1049,7 @@ static int cabd_extract(struct mscab_decompressor *base,
* In salvage mode, don't assume block sizes, just try decoding
*/
if (!self->salvage) {
- off_t maxlen = fol->base.num_blocks * CAB_BLOCKMAX;
+ unsigned int maxlen = fol->base.num_blocks * CAB_BLOCKMAX;
if ((file->offset + filelen) > maxlen) {
sys->message(NULL, "ERROR; file \"%s\" cannot be extracted, "
"cabinet set is incomplete", file->filename);A larger problem is test failures with chmd caused by the same underlying issue, which I observed debugging a test where
For reference, this is in I can get test passes on Windows by converting all A better solution I believe would be to swap out all I'm going to push what I have now, and then take a break and wait for comments before I go any further. |
|
Thanks very much for working on this! The support for building on Windows has been in need of modernisation for a while, and it's great that this works in harmony with the autotools rather than try to replace it. I'll take a look a the changes and review them. |
It seems reasonable to put in a Windows-specific filename here.
Yes. This is an issue, and it's why you can see in commits 49d8a2a and bb5e2b6 that I had to put the autotools SIZEOF_OFF_T test back in place. I thought I could get away from it, but I can't. Several platforms have 64-bit I/O without needing any preprocessor flags. libmspack has two modes of operation:
The current tests in system.h are not ideal, only SIZEOF_OFF_T is really testing for 64-bit I/O, LARGEFILE*_SOURCE and _FILE_OFFSET_BITS are just meant for transition, FILESIZEBITS is not whether 64-bit I/O is supported but what is the maximum size of a file (this is really filesystem and path dependent, but in practical terms the limits.h value reveals if the system generally supports 64-bit I/O or not), and I could also have used SSIZE_MAX as another proxy (it's not whether fseek/fseeko supports 64-bit offsets, it's whether read/write support 64-bit sizes). There is an argument for making the code explicitly use 64-bit datatypes, regardless of the size of off_t, but that has the tradeoff of ending support for 32-bit-only platforms (that have no 64-bit integers or in-compiler workarounds) and would require at least C99 to be absolutely certain of a 64-bit integer datatype. From a build-system perspective, what should happen is:
|
There was a problem hiding this comment.
Overall this looks very good.
I must confess I haven't fully learned up how CMake works, so I haven't added any commentary on that, but I can now see how some of the Windows build process hangs together, and this is a great improvement over winbuild.sh, which could definitely be removed.
I'll look more into how CMake works, and also try building this with MSVC to see how it works, but I thought I'd leave some feedback on the changes for now.
cabextract/autogen.sh
Outdated
| autoreconf -i -W all | ||
| echo you can now run ./configure | ||
| rc=$?; if [[ $rc != 0 ]]; then | ||
| echo "Error: Failed to generate autojunk!"; exit $rc | ||
| else | ||
| echo "You can now run ./configure" | ||
| fi |
There was a problem hiding this comment.
This could also be:
if autoreconf -i -W all; then
echo "You can now ..."
else
echo "Error: ..."
fi
There was a problem hiding this comment.
I didn't have any luck with this. This does work though:
if [[ $(autoreconf -i -W all) ]]; then
I just thought about this... is [[ ... ]] bash-only? Will it upset people without bash?
Unrelated, a coworker recommend this improvement for clamav's autogen.sh which lets you run autogen.sh from a different directory (like if you're using a subdirectory for your build).
BASEDIR="$( cd "$(dirname "$0")" ; pwd -P )"
echo "Generating autotools files in: $BASEDIR ..."
cd $BASEDIR
# If this is a source checkout then call autoreconf with error as well
if test -d .git; then
WARNINGS="all,error"
else
WARNINGS="all"
fi
autoreconf -i -f
rc=$?; if [[ $rc != 0 ]]; then
echo "Error: Failed to generate autojunk!"; exit $rc
else
echo "You can now run ./configure"
fiThoughts?
libmspack/autogen.sh
Outdated
| autoreconf -i -W all | ||
| echo you can now run ./configure | ||
| rc=$?; if [[ $rc != 0 ]]; then | ||
| echo "Error: Failed to generate autojunk!"; exit $rc | ||
| else | ||
| echo "You can now run ./configure" | ||
| fi |
There was a problem hiding this comment.
As before, this could be if autoreconf ...
| * @macro | ||
| * Version string of the mspack project release. | ||
| */ | ||
| #define MSPACK_VERSION "@PROJECT_VERSION@" |
There was a problem hiding this comment.
I'm not sure what value mspack-version.h adds. Could you explain why it would be useful?
libmspack currently has these version numbers and interfaces for the benefit of clients:
- At build time: the project version number is available via
pkg-config. libmspack.pc is installed for this purpose. If your code needs libmspack 0.10 or higher, this is the right time to check with a pkg-config macro in your build system, to check that the library is both installed and has a high enough version number. - At runtime: libmspack has always been and always intends to be backwards-compatibile, but if it were not, the libtool version number embedded in libmspack.so will ensure that your program links to the binary-compatible version of the library you need (hence why this value is independent of the project version). Is this binary-compatibility versioning also supported in the Windows DLL? From what I can see, it embeds the project version number rather than the libtool-like binary compatibility version numbers.
- Runtime feature detection: if you depend on a specific feature, rather that keep a chart of which libmspack releases introduced which features, there is an
mspack_version()function to test that features exist, and what version of support is available.
For example, if your code cannot work without MSCABD_PARAM_SALVAGE, you can check at compile time using pkg-config that libmspack is even installed, and if it is that the version installed is at least 0.9. I'm not sure if CMake supports pkg-config on Windows, but from what I see it has find_package, would this be suitable for checking version numbers at build time?
If your code can optionally work with MSCABD_PARAM_SALVAGE, it should check if (mspack_version(MSPACK_VER_MSCABD) >= 2) at runtime rather than #if LIBMSPACK_VERSION >0x90000 at compile time, because the include header installed is no guarantee that your code will be linked to the same version of libmspack library.
Just as an example, imagine that libmspack 0.9, 0.10 and 0.11 exist and they all are compatible with each other. Would cabextract built against libmspack 0.9 link with libmspack.dll from 0.11, and vice versa?
Now imagine that libmspack 2.0 was deliberately binary incompatible, and its LT_ parameters were changed appropriately. On unix we could be sure that cabextract linked against libmspack.so.0 would intentionally not load libmspack.so.1, would the same mechanism stop cabextract.exe (built with libmspack 0.9) from linking to libmspack.dll built with 2.0?
There was a problem hiding this comment.
Disclaimer: I don't pretend to be an expert at library package management stuff. I mostly just grumble about it (especially when it has to do with freebsd 😀 ).
As far as I know there is no pkg-config on Windows (native - not counting MingW/Cygwin), on macOS, or on a few other operating systems. Granted on Windows applications are generally deployed with their dependencies. Afaik, no-one installs DLLs to a common location to be shared between different applications. I have to wonder if Microsoft is planning to change that with the new "winget" package manager 😕.
In any case, I don't think pkg-config can be relied on to exist everywhere. I think version macros are most reliable way for an app developer to support multiple versions of a library.
There was a problem hiding this comment.
I'm not a packaging expert either, but I see a lot of value in it, which is why I use Cygwin, macports and so on. Hopefully Microsoft will too with AppGetWinGet.
To me, it looks like the CMake way of doing things should involve find_package. The value in find_package is:
- it will import the config from the package you want to use, so both library and caller have the same build settings
- if you don't have the required version, cmake will say this unambigiously
I feel that trying to do package management in header files is too late (header files can't make the build system import necessary config/defines), and using headers to fail a build by checking version numbers is doing the packaging/build system's job for it.
From the other direction, I also don't see the value of version numbers in headers to control conditional code execution, because libmspack is always backwards compatible, and provides runtime feature checking.
Whatever version of <mspack.h> you have, you can compile code that uses all fields of all structures it defines. To be sure your code doesn't crash or access OOB memory, you should check the appropriate mspack_version() before relying on using something that only exists in V2, V3 of a specific API. A version number in a header can't give you this assurance, because header files can't control what version of library is linked or what .DLL is put in the same directory as the executable.
The only reason I can think of for including the packaging version number in libmspack is to provide it to end users as assurance, e.g. sysadmins wanting to know their libmspack-consuming-program isn't using a vulnerable version of libmspack, so they could run command --help and hope to see command v1.0, using libmspack v0.9.1
Even then, I don't think it should be in a header, because it could bear false witness. It would have to be a function in the public API, to be assured it came from the library/DLL whose code will really run.
Are there other uses of version numbers in library headers that I'm not considering?
libmspack/mspack/mspack.h
Outdated
| * @param int An MSPACK_ERR code. | ||
| * @return a constant string with an appropriate error message. | ||
| */ | ||
| static inline const char *mspack_error_msg(int error) { |
There was a problem hiding this comment.
While I do think this looks very convenient, there are a few problems with it, which is why I haven't added something like this in the past:
Firstly, libmspack should be able to compile without any standard C library functions when MSPACK_NO_DEFAULT_SYSTEM is defined. I understand that static inline means that technically this code is not in the library, but I would prefer to see no <stdio.h> in mspack.h at all.
Secondly, I am secretly trying to avoid any user-readable text available from the library API or header, because if it exists, it should really be internationalisable / localisable, therefore that would mean the library and/or header need to support every environment's localisation processes. I'd like to keep localisation exclusively to clients, so that e.g. clients depend on libmspack and gettext, not that libmspack depends on gettext, and definitely not that you need gettext installed in order to #include <mspack.h>
Thirdly, it reduces the quality of cabextract. cabextract.c intentionally uses its own mspack_system implementation, and knows it uses C stdio functions, so its error_msg() function is not the same as error.h, it intentionally uses errno and strerror() to print a more useful error message that includes the reason why there was a file opening/read/write error.
There was a problem hiding this comment.
Reviewing the code in light of these comments:
Firstly, libmspack should be able to compile without any standard C library functions when
MSPACK_NO_DEFAULT_SYSTEMis defined. I understand thatstatic inlinemeans that technically this code is not in the library, but I would prefer to see no<stdio.h>in mspack.h at all.
... I've found that memcmp, memset and strlen calls have crept into libmspack, so I've introduced replacement functions in system.h and avoid including <string.h> at all, if MSPACK_NO_DEFAULT_SYSTEM is set, so libmspack still meets its std-C-library independence goals.
However, this makes it hard to include system.h with code outside libmspack when MSPACK_NO_DEFAULT_SYSTEM is set, so I moved the convenient macros that outside code was using system.h for into a new file, macros.h.
On reflection, I'd probably be happy with the error text function in mspack.h, if it simply returned "unknown error" rather than return a snprintf() buffer, and thus mspack.h did not need stdio.h
Secondly, I am secretly trying to avoid any user-readable text available from the library API or header, because if it exists, it should really be internationalisable / localisable, therefore that would mean the library and/or header need to support every environment's localisation processes. I'd like to keep localisation exclusively to clients, so that e.g. clients depend on libmspack and gettext, not that libmspack depends on gettext, and definitely not that you need gettext installed in order to
#include <mspack.h>
While I am trying to avoid it, it's clearly not working because there are several english-only warning messages emitted by libmspack. So this is still an issue to consider, but this new macro doesn't introduce a new problem.
Thirdly, it reduces the quality of cabextract.
cabextract.cintentionally uses its own mspack_system implementation, and knows it uses C stdio functions, so itserror_msg()function is not the same aserror.h, it intentionally useserrnoandstrerror()to print a more useful error message that includes the reason why there was a file opening/read/write error.
cabextract.c should still revert to its original implementation.
There was a problem hiding this comment.
Roger I'd be happy to revert cabextract to it's original error message implementation. I'll do this as I rebase the PR and fix merge conflicts.
Regarding mspack/macros.h, I see that it's been used in one of the example programs. Would you mind me removing the #include from cabrip.c and copypasting the code to define LD? This way, the example program only depends on header(s) provided by the mspack library build target.
In the "modern" CMake method, a build is a collection of build targets to include objects, static or shared libraries, and executables. Each may have "private", "public", and "interface" sources.
- Private sources are required to build the given target.
- Public sources are required to build the given target and are provided as a part of the API for downstream targets.
- Interface sources aren't used in the current target and provide an API for downstream targets (particularly useful when providing a header for pre-built sources, like a proprietary library.
I've set up the examples as executable targets that link with the mspack shared library target. As the mspack shared library doesn't include mspack/macros.h in it's public sources, the example programs don't have access to it, just like a real user application. We could definitely cheat with the target_include_directories(), but it seems an appropriate test of the library to build the example executables the same way your library users would.
As a side note, this also affects the tests targets, but for unit tests I think it makes sense to "cheat" and give unit tests access to library internals.
There was a problem hiding this comment.
The issue of only using exported headers is also the reason providing MSPACK_ERROR() and mspack_error_msg() in mspack.h made sense to me. It makes these available for use in your examples.
The alternatives are to:
(A) duplicate error.h in the examples directory.
(B) merely print error codes instead of error messages in the examples.
Which would you prefer? I lean towards duplicating error.h so users are guided towards the approach cabextract uses. Since it's late and I want to push up updates before the work week, I'll make that change. Let me know if you'd prefer something different.
There was a problem hiding this comment.
I think I would rather have error.h in the examples directory.
But in general, what I'd like to have with macros.h doesn't fit cleanly with CMake's way of thinking; a header file that is used both internally by a project, and internally by its examples, but simply because it helps define the coding conventions of that project, it's not part of that project's external interface, nor is it recommended for other project users.
Perhaps instead of copy-paste, would creating a symlink work? This is how cabextract consumes its internal copy of libmspack, and it also uses files "private" to libmspack in cabinfo, simply because it does not make sense (to me) to define the structure offsets of cabinet files more than once, even if this breaks the theoretical encapsulation.
So, to cover this better, I've removed the various largefile define checks that just guess if off_t is 64-bit or not, and now rely only on SIZEOF_OFF_T, so this should be simpler. If SIZEOF_OFF_T < 8, libmspack will assume off_t is at least 32-bit, and will apply overflow error checking if cab search offsets or CHM offsets go beyond a 2GB barrier. Build systems should apply any flags needed to enable 64-bit off_t (and fseeko/ftello) if they want 64-bit I/O support. |
|
Sorry about the delay on this! I never saw a notification from github, and thought you hadn't looked at it yet. I'll try to review your comments asap and update accordingly. |
micahsnyder
force-pushed
the
cmake-tooling
branch
from
3e0c377 to
8989019
Compare
|
After rebasing to include your changes and fix up a the mspack error message stuff, and add additional improvements to the autogen.sh script, I have found that 2/3 tests pass now. The chmd test still fails, because off_t is 32bits on Windows. Output below: |
You should want 64-bit I/O on Windows, given it is capable of it. config.h needs to have something like this on Windows / Visual C: However, this is just papering over a bug in the test suite which is visible when any system, not just Windows, runs with 32-bit I/O.
The purpose of
I've changed these offsets in the test files so both 32-bit I/O mode and 64-bit I/O mode get to the same code path and test the files properly. See commit 7e63519 |
micahsnyder
force-pushed
the
cmake-tooling
branch
from
8989019 to
f4e0217
Compare
I rebased the PR and fixed a minor issue w/ defining aliases for the static and shared libraries while I was at it. I'm now seeing a test passes on Windows!
I just tried playing around with your suggestion to I'm not sure what to do about that. Any ideas? Anyhow, With libmspack building and passing all unit tests (at least with 32bit I/O), I reckon it's time for me to implement the CMake tooling for cabextract. I'll hop on it. Best, |
|
Okay! I have cabextract building on mac & Windows. The tests will run on posix systems, but not on Windows because they're all shell scripts. That said, I haven't really tested out if cabextract.exe works properly on Windows. I did have to use a Win32 API since Windows doesn't have The tests all pass except the Please try it out and let me know what you think. |
|
@kyz Have you had a chance to give this a try? I've been meaning to figure out the reason for the encoding test failure. Will try to figure that out soon. |
Adds CMake tooling for libmspack to the project. This attempts to replicate every feature available in the autotools tooling and includes support for building on Windows. Adds a mspack-version.h header file, generated from mspack-version.h.in. mspack-version.h is to be installed alongside mspack.h so that application developers can use the version numbers and strings in the event that the API is modified and the application must maintain backwards compatibility. Adds error handling to autogen.sh. Reformats libmspack's README as Markdown. Adds mspack_error_msg() and MSPACK_ERROR() macro to mspack.h API. The new API is a cross between the cab_error() function previously found in cabextract and error_msg() found in test/error.h. This removes the need the examples to depend on test/error.h, a header not exported by any build target, and removes the code duplication with cabextract. Fixes __func__ macro for Windows.
On Windows, the tests should write to "NUL" instead of "/dev/null". Resolved an issue where a large unsigned int cast to an off_t resulted in a negative value, because off_t is 32-bits instead of 64.
micahsnyder
force-pushed
the
cmake-tooling
branch
from
190b899 to
faabe48
Compare
Adds CMake tooling for cabextract to the project. Converts cabextract README to Markdown (.md) so it will look pretty on Github, and adds build instructions to cabextract README.md.
The current implementations check for iconv.h and set HAVE_ICONV_H but don't set HAVE_ICONV, which is the macro we actually depend on. In the autotools build system, HAVE_ICONV is set by the `AM_ICONV` macro, if you have gettext-devel installed (note, this will cause an autoreconf warning if you don't have gettext-devel installed). Anyways... to fix this in CMake, I've added FindICONV.cmake module which is a slightly modified variant of the official CMake iconv detection module. This one has some additional features including setting the ICONV_CONST macro as needed. This commit fixes the cabextract "encoding" test, which was the final outstanding issue with CMake support, excluding the fact that there are no cabextract feature tests for Windows. I think this is acceptable for now, since it's not like there were any before switching to CMake.
micahsnyder
force-pushed
the
cmake-tooling
branch
3 times, most recently
from
37a5a38 to
e4bb594
Compare
Add CMake build for cabextract and libmspack on GitHub Actions. Will test on Ubuntu, macOS, Windows. Added build badges to the readme for each project.
|
@kyz Ok I fixed the encoding test. It was an iconv detection issue. Speaking of which, I noticed that iconv detection will fail for autotools if gettext-devel isn't installed, but I didn't know if I should try to fix it (or how). I also rebased this with master and since then the Windows tests for libmspack are passing. 🎉 Anyways, I also just added github actions build tests for Mac, Linux, and Windows for cabextract and libmspack. For them to run on this PR, I think you'll have to approve them. I tested them on my fork and they seem to run nicely: https://github.com/micahsnyder/libmspack/actions/workflows/cmake-cabextract.yml I was also able to use vcpkg to bring in libiconv support with cabextract on Windows! You can see libiconv detection working on Windows here: https://github.com/micahsnyder/libmspack/runs/2484761769?check_suite_focus=true Anyways, I think this work is basically done? Personally I'd advocate for removing the autotools build system at this point. If you like that, I can help. Please give this a try and let me know what you think. |
|
I strongly advise against removing the autotools stuff. I had to create or restore autotools projects to be able to properly cross compile a few apps. With autotools I can easily cross compile cabextract for 20 linux processor architectures and win32/win64, it needs a couple of tweaks for libiconv and only include the local getopt when the system getopt is missing, for better compatibility with MinGW. Setting CMake mininum version to 3.20 and remove all the extra cmake files is a good idea. CMake for modern systems, autotools for older systems and for cross compiling like there's no tomorrow. |
|
Cross-compiling should be possible with CMake as well, though I don't have any experience with it: https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html
Can you elaborate? |
|
I think it got easier in recent versions, but for many years only the old autotools could handle cross-compiling properly. My scripts use autotools, this is crucial for mingw at least, Windows binaries magically appear. And autotools works with barebones toolchains, with basically gcc and nothing else, simple C apps like this one compile in a lot of architectures without issues. If anybody is interested I can provide static binaries for releases. I mean all those cmake modules or something that got added to cmake in recent years, I see a lot of them in this PR. But it's just an idea. Anyway if autotools gets removed I'll restore it for my cross-builds. CMake is good for testing stuff in native installations in Travis CI and the like. Anyway I think this PR is good and it was a lot of work, I hope it gets merged. |
|
Porting autotools configs to cmake is a bit problematic, it requires knowledge of both build systems. Testing unshield in several OS's until Travis CI cancelled my ability to trigger builds, I have some ideas. A better md5.c that is endian-independent, a header-only getopt.h and fnmatch.h only used if system headers are not found, but this should be merged first. autotools: something like this, cabextract.c should have something like this: #ifdef HAVE_GETOPT_H
# include <getopt.h>
#else
# include "../compat/getopt.h"
#endifMSVC and ancient Solaris versions lack getopt.h, only MSVC is worth considering. Now with CMake: and so on |
|
But here's the thing, one may have many ideas and the ability to perform big changes, but that's not enough for stuff to be merged. Once the momentum is lost, everything is back to normal and the code lays dormant. I'm seeing the same history in basically all repos. |
Update: This PR is complete.
Best,
Micah
Adds CMake tooling for libmspack to the project.
This attempts to replicate every feature available in the autotools
tooling and includes support for building on Windows.
Adds a mspack-version.h header file, generated from mspack-version.h.in.
mspack-version.h is to be installed alongside mspack.h so that application
developers can use the version numbers and strings in the event that the API
is modified and the application must maintain backwards compatibility.
Adds error handling to autogen.sh.
Reformats libmspack's README as Markdown.
Adds mspack_error_msg() and MSPACK_ERROR() macro to mspack.h API.
The new API is a cross between the cab_error() function previously found
in cabextract and error_msg() found in test/error.h. This removes the
need the examples to depend on test/error.h, a header not exported by
any build target, and removes the code duplication with cabextract.