I'm looking for a cross platform library to detect when files in a directory are added or modified.
I know there are OS specific way to do this (inotify for Linux, FindFirstChangeNotification for windows, etc...).
But is there a platform independent library that works specifically in C? (Like the QFileSystemWatcher in C++)
inotify is Linux specific, if you want some UNIX portable features you are pobably looking for something like libfam. it is name of library. Full package name is fileschanged.
fileschanged is a GNU/Linux command-line utility that reports when files have been altered.
It's now 2021 so maybe septag/dmon is your cup of tea.
From the description:
Single header C99 portable library for monitoring directory changes
... or maybe the more beefy fswatch ?
Sounds like a good use case for golang.
Simply change $GOOS and/or $GOARCH and run go build.
Boom - trivial cross-platform development.
Related
So, I have a large C project that was built entirely on Unix (SPARC Solaris). me and several others have begun to revisit it because their was some interest in a windows build.
none of us have done this with a project of such size, so for starters, has anyone ported something from unix to windows and could maybe give me some pointers or how they did it.
our first step on our plan was to decide on a compiler/dev environment.
it seems that our options are MS Visual Studio, Cygwin, mingw/gcc, and Windows Services for UNIX (SFU).
we are on a fairly short timetable so we want to rewrite as little code as possible.
so, Deciding on a compiler.
Another issue is that the code does use POSIX thread commands (pthread, etc)
we would prefer to compile natively, not using some sort of layer between the executable and the OS. unfortunatly with the pthread calls in our code, this may not be possible.
I believe both Cygwin and SFU do just that. Cygwin has a .dll that must be included in compiled code to work. I am not sure about SFU, any information about that would be greatly appreciated. It seems like it would be a good option but was developed to allow for UNIX compiled software to run on a windows machine with SFU, not any old windows box.
mingw does have the ability to create native exes, but lacks the POSIX support.
So, can anyone give me any more information, suggestions, knowledge on any of these compilers in this context. or any experience they have with this sort of thing, it is greatly appreciated.
Short timetable? CygWin, plain and simple.
Despite your preference to not use a layer, that's going to provide the fastest path and you don't seem to indicate that the timeframe requirement is flexible.
We've ported both command-line and X-based UNIX programs to Windows using CygWin with minimal hassle.
Cygwin is likely the fastest path to a working executable. However it will leave you with some interesting distribution choices. Most obviously, cygwin.dll becomes a dependency. Its licensed GPL, unless you pay money to buy commercial use rights.
Cygwin is not particularly friendly to an ordinary Windows user. Its goal is to provide a full POSIX experience on Windows, supplying a shell, all the familiar *nix utilities, and even a port of X. However, it also remaps the Windows disk drive naming into a POSIX-like file system. I've never attempted to distribute an application built for Cygwin to machines that don't already have a full Cygwin installation. I will note that to my knowledge none of the big well-known open-source applications with Windows ports are based on Cygwin.
If the only hard POSIX dependency you have is pthreads, then that is solvable. There is a pthreads port built on native Windows threads that works well with MinGW. IIRC, it is even distributed along with MinGW, or at least is one of their core supported packages.
If the rest of your handling of file names is largely as opaque strings, you may not even need to care about changing / to \. The Windows API is generally happy to treat either character as a path separator, even mixed in the same name. It is the CMD.EXE and early DOS convention of using / for command line options that prevents the use of / for pathnames at the command prompt, not the underlying Windows API.
For tools that might make porting your build process easier, check out the MSYS component of MinGW. It provides a lightweigh fork from the Cygwin environment in which enough *nix utilities are available to generally run ./configure and similar processes.
In addition, the GnuWin32 project has ports of a large number of utilities and libraries that are all built to run as native Windows applications without unusual dependencies.
If the code is (at least mostly) portable and the only major issue is the use of pthreads, you might want to use the Pthreads Win32 library. While incomplete, it's sufficiently complete and accurate to deal with most pthreads code I've tried it with. While normally built as a DLL, this can also be built as a static library to avoid creating an extra dependencies in your executable.
That, of course, leaves everything else to port -- but you haven't said enough to even guess whether porting the rest within your timeframe is at all reasonable.
I'm attempting to utilize the socket.h functions within Windows. Essentially, I'm currently looking at the sample code at https://beej.us/guide/bgnet/html/multi/clientserver.html#datagram. I understand that socket.h is a Unix function -- is there anyway I can easily emulate that environment while compiling this sample code? Does a different IDE / compiler change anything?
Otherwise, I imagine that I need to utilize a virtualized Linux environment, which may be best anyways as the code will most likely be running in a UNIX environment.
Thanks.
You have two options:
Use Cygwin (Unix emulation library).
Port to Winsock (Windows standard library).
Cygwin: lets you compile your Unix sources mostly untouched, but ties you to the Cygwin emulation library. This have two implications: general performance -no only network- will probably be less than optimal; and the target environment must have (at run time) the Cygwin DLL installed.
Winsock: this requires you to replace sys/socket.h (BSD sockets library, UNIX standard for the TCP/IP stack) with winsock2.h, and rewrite some parts of the code - not much, but some.
Some related questions with valuable info:
Differences between winsock and BSD socket implementations
Some Issues About Cygwin[Linux in Windows] (socket,thread,other programming and shell issues)
Examples for Winsock?
I think you are looking for Winsock library.
Writing cross platform network applications is not easy with what the BSD standard provides you. Sure it will work but you'll have to make some replacements like replacing ioctl (if needed) with ioctlsocket (on windows). More differences here.
My advice is to use a library that hides these ugly differences and provides a unified way of communicating. I personally use ACE. You have plenty of examples that show you how to create a server and a client. Copy from the samples and see how they do it there. Their mailing lists are of great help also (don't forget to use the PRF - see the source tree for the Problem-Report-Form). You can borrow the books for more information. Important note: by using ace you can use ACE wrapper functions like socket, setsockopt, ioctl etc. without worry that they will not work. Unfortunately this adds a library dependency which is not always an option. But ACE has more powerfull features which I'm sure you'll like once you discover them. Hints: Reactor, Proactor.
I would like to port a few applications that I use on Linux to Windows. In particular I have been working on wdiff. A program that compares the differences word by word of two files.
Currently I have been able to successfully compile the program on windows through Cygwin. However, I would like to run the program natively on Windows similar to the Project: UnixUtils.
How would I go about porting unix utilities on a windows environment?
My possible guess it to manually create the ./configure file so that I can create a proper makefile. Am I on the right track? Has anyone had experience porting GNU software to windows?
Update:
I've compiled it on Code::Blocks and I get two errors:
wdiff.c|226|error: `SIGPIPE'
undeclared (first use in this
function)
readpipe.c:71: undefined reference to `_pipe'
readpipe.c:74: undefined reference to `_fork
This is a linux signal that is not supported by windows... equvilancy?
wdiff.c|1198|error: `PRODUCT'
undeclared (first use in this
function)|
this is in the configure.in file... hardcode would probably be the fastest solution...
Outcome:
MSYS took care of the configure problems, however MinGW couldnt solve the posix issues. I attempt to utilize pthreads as recommended by mrjoltcola. However, after several hours I couldnt get it to compile nor link using the provided libraries. I think if this had worked it would have been the solution I was after.
Special mention to Michael Madsen for MSYS.
Yes. If you stick to the standard C library, and POSIX functions, most is available on Windows. You may just have to find the implementations. There are implementations of things that do not require Cywgin or MinGW (such as a pthreads package, etc.)
Also, there is a great book that is written in the style of W. Richard Steven's Advanced Proramming in the UNIX Environment, and the book is Windows System Programming, author Johnson Hart. He has a 4th edition. It focuses on System Programming, there is no GUI treatment whatsoever.
http://www.amazon.com/Windows-Programming-Addison-Wesley-Microsoft-Technology/dp/0321657748
It is the best book I know of for a UNIX programming moving to Windows.
You can have a look at MinGW (and MSYS), which are similar to cygwin, but gcc produce native Windows executables. However, since the Unix emulation is not as good as cygwin, you may have to adjust your code.
Always try to following standarts even when porting applications. POSIX compliant compilers exist on windows/Linux. You can try mingw. It has full toolchain required to build standart POSIX application (GNU Linux as well). Check out Dev-Cpp it eases the work.
MinGW is about the easiest way to get gcc and associated binary utilities (including gdb) on a Windows PC. It includes header files and import libraries so that you can call native Windows APIs. If you want more of an integrated IDE development environment you could download Microsoft's free Visual Studio Express C++.
Either way you'll likely have to convert some of the function calls to use Windows specific APIs (if you want a book I'd also recommend the Hart book mentioned in mrjoltcola's answer). For simple command line tools this conversion is usually not a huge deal, the big porting nightmares tend to involve tools with GUIs which have deep embedded dependencies on the GUI framework provided by the OS.
I am in a big problem ..i have compiled my c files using linux make file in Linux OS.
I want to compile the same files in Windows using the same make file by command prompt. For that i have nmake utility and Cygwin utility too.
I have done that successfully with simple programs with simple make file ..
But it is not possible to compile when i was using the complex C files with complex make file.
I have changed the '/' in linux make file to '\' in windows? Anyother changes?
I want to know 'Is there any special make file formats in windows?'
also the difference between them..
I am really in need of that...
Unfortunately, nmake was only loosly inspired by make, and they didn't get many important things right. By far the easiest thing to do is to start by having the same flavor of make on both platforms.
On linux, Gnu make is the default and best option.
On Windows, there are several sources for Gnu make, with some quirks to choose among. Personally, I mostly use the native win32 build of Gnu make from the GnuWin32 project. You might want to poke around at the rest of the project's packages because some of the others will be useful to have as well.
Alternative sources are Cygwin and MinGW32/MSYS.
Cygwin is a credible attempt at providing a *nix compatibility environment on top of the Windows kernel. It consists of a DLL that exports a huge percentage of *nix (especially POSIX) system calls implemented via the Windows API. That DLL also has its own idea about disk mounts and prefers *nix-style path names. The DLL itself is licensed GPL (although a commercial-use license is available for a fee), and programs built in the Cygwin environment require it by default, so that can be a factor to consider. Another factor is that Cygwin is not friendly to normal Windows users, so development projects based on it usually end up difficult for non-unix users to deal with. For a cross-platform developer, however, Cygwin can be really useful as it gets you all of the usual suspect utility programs required by your Makefile, and it includes the MinGW32 native Windows targeted GCC as well as a GCC targeting the Cygwin environment.
MinGW32 is a porting project that did a really good job of porting the GCC compilers to run as native Windows executables. If used along with the header files they supply, it is possible to use nearly all of the Windows API via a C runtime DLL that ships with modern Windows installations.
MSYS is a lightweight fork of Cygwin that contains a minimal set of utilities (starting with a *nix shell) that are usually assumed to exist by a typical *nix Makefile. Unlike Cygwin, MSYS is configured such that the default target is the native Windows API.
What I'm trying to hint at here, and probably should just state flat out, is that your compatibility issues don't end with the dialect of make you use.
The Makefile language itself is highly dependent on the command shell available, and most serious project Makefiles end up using many of the *nix the core utilities such as cp and rm.
I would strongly recommend starting with the GnuWin32 build of make, and also installing MinGW32 and MSYS. It is then relatively easy to write a Makefile that works under both MSYS and linux, and needs only a small amount of platform-specific logic.
You should consider CMake for cross-platform make but your real problem is you shouldn't have to change the '/' to '\'. If you run under cygwin or msys (recommended) this should be handled for you.
NMake is a windows tool and will parse only windows-style paths, i.e. paths with drive letters and backslashes. Therefore you should use GNU Make installed with cygwin.
nmake should read your makefiles okay, the differences are generally between versions of make rather than OSs.
The big question is what your target platform actually is, are you trying to make this code operate in Windows natively or are you looking to run it under Cygwin?
Use gnumake on both platforms. I do. I haven't touched Visual C in years.
nmake got it's own format rather than windows itself, so makefile format is related to make tool rather than os. For simple things format is similar for g(nu)make and nmake, as people suggested before consider using gmake only.
What things should be kept most in mind when writing cross-platform applications in C? Targeted platforms: 32-bit Intel based PC, Mac, and Linux. I'm especially looking for the type of versatility that Jungle Disk has in their USB desktop edition ( http://www.jungledisk.com/desktop/download.aspx )
What are tips and "gotchas" for this type of development?
I maintained for a number of years an ANSI C networking library that was ported to close to 30 different OS's and compilers. The library didn't have any GUI components, which made it easier. We ended up abstracting out into dedicated source files any routine that was not consistent across platforms, and used #defines where appropriate in those source files. This kept the code that was adjusted per platform isolated away from the main business logic of the library. We also made extensive use of typedefs and our own dedicated types so that we could easily change them per platform if needed. This made the port to 64-bit platforms fairly easy.
If you are looking to have GUI components, I would suggest looking at GUI toolkits such as WxWindows or Qt (which are both C++ libraries).
Try to avoid platform-dependent #ifdefs, as they tend to grow exponentially when you add new platforms. Instead, try to organize your source files as a tree with platform-independent code at the root, and platform-dependent code on the "leaves". There is a nice book on the subject, Multi-Platform Code Management. Sample code in it may look obsolete, but ideas described in the book are still brilliantly vital.
Further to Kyle's answer, I would strongly recommend against trying to use the Posix subsystem in Windows. It's implemented to an absolute bare minimum level such that Microsoft can claim "Posix support" on a feature sheet tick box. Perhaps somebody out there actually uses it, but I've never encountered it in real life.
One can certainly write cross-platform C code, you just have to be aware of the differences between platforms, and test, test, test. Unit tests and a CI (continuous integration) solution will go a long way toward making sure your program works across all your target platforms.
A good approach is to isolate the system-dependent stuff in one or a few modules at most. Provide a system-independent interface from that module. Then build everything else on top of that module, so it doesn't depend on the system you're compiling for.
XVT have a cross platform GUI C API which is mature 15+ years and sits on top of the native windowing toollkits. See WWW.XVT.COM.
They support at least LINUX, Windows, and MAC.
Try to write as much as you can with POSIX. Mac and Linux support POSIX natively and Windows has a system that can run it (as far as I know - I've never actually used it). If your app is graphical, both Mac and Linux support X11 libraries (Linux natively, Mac through X11.app) and there are numerous ways of getting X11 apps to run on Windows.
However, if you're looking for true multi-platform deployment, you should probably switch to a language like Java or Python that's capable of running the same program on multiple systems with little or no change.
Edit: I just downloaded the application and looked at the files. It does appear to have binaries for all 3 platforms in one directory. If your concern is in how to write apps that can be moved from machine to machine without losing settings, you should probably write all your configuration to a file in the same directory as the executable and not touch the Windows registry or create any dot directories in the home folder of the user that's running the program on Linux or Mac. And as far as creating a cross-distribution Linux binary, 32-bit POSIX/X11 would probably be the safest bet. I'm not sure what JungleDisk uses as I'm currently on a Mac.
There do exist quite few portable libraries just examples I've worked within the past
1) glib and gtk+
2) libcurl
3) libapr
Those cover nearly every platform and so they are extremly useful tool.
Posix is fine on Unices but well I doubt it's that great on windows, besides we do not have any stuff for portable GUIs there.
I also second the recommendation to separate code for different platforms into different modules/trees instead of ifdefs.
Also I recommend to check beforehand what are the differences in you platforms and how you could abstract them. E.g. this is some OS related stuff (e.g. the annoying CR,CRLF,LF in text files), or hardware stuff. E.g. the previous mentioned posix compability doesnt stop you from
int c;
fread(&c, sizeof(int), 1, file);
But on different hardware platforms the internal memory layout can be complete different (endianess), forcing you to use conversion functions on some of the target platforms.
You can use NAppGUI for both console and desktop apps. The SDK uses ANSI-C and your code will work on Windows/macOS/Linux.
https://www.nappgui.com
It's free and OpenSource.