I want to compile some OCaml bytecode and have it run on Windows and Unix-type systems. My source code works fine if I recompile it on each platform, but the bytecode isn't portable.
Sample code:
open Unix
let on_windows = Filename.dir_sep <> "/";;
Printf.printf "On windows: %b\n" on_windows;;
let child = create_process "gpg" (Array.of_list ["gpg"; "--version"]) stdin stdout stderr;;
Printf.printf "Child %d\n" child;;
Build command:
ocamlbuild -use-ocamlfind -pkg unix test.byte
If I compile on Windows and run on Linux, I get
Fatal error: unknown C primitive `win_waitpid'
If I compile on Linux and run on Windows I get:
Fatal error: unknown C primitive `unix_waitpid'
How can I make the bytecode work everywhere?
Obviously, the reason is that ocaml unix library has different names for C stubs depending on the platform, and this hinders bytecode portability. I do not see the way out except for patching stub names..
Merely renaming the C symbols doesn't work because there are two completely different versions of the unix.ml module (though with the same interface). If you link your code statically, you'll get the one for the build platform and it won't work on the other platform.
The solution is to create and distribute a .cma archive (with the Unix module not linked in) rather than an executable. Then use ocaml to link dynamically on the target platform:
http://roscidus.com/blog/blog/2013/07/07/ocaml-binary-compatibility/#windows--linux-compatibility
Update: This isn't safe. When you do ocaml /path/to/script.ml, it adds the current directory (not the directory containing the script) to the start of the search path. Thus:
$ cd /tmp
$ /usr/bin/myprog
will first try to load myprog's libraries (e.g. unix.cma) from /tmp.
Should be fixed in 4.03: http://caml.inria.fr/mantis/view.php?id=6081
Related
Main question:
In Ubuntu trying to debug an embedded application running in QNX, I am getting the following error message from gdb:
warning: Shared object "$SOLIB_PATH/libc.so.4" could not be validated and will be ignored.,
Q: What is the "validation" operation going on ?
After some research I found that the information reported by readelf -n libfoo.so contains a build-id and that this is compared against something and there could be a mismatch causing gdb to refuse to load the library. If that's the case what ELF file's build-id is the shared object's build-id compared against ? Can I find this information parsing the executable file ?
More context:
I have a .core file for this executable. I am using a version of gdb provided by QNX and making sure I use set sysroot and set solib-search-path to where I installed the QNX toolchain.
My full command to launch gdb in Ubuntu is :
$QNX_TOOLCHAIN_PATH/ntox86_64-gdb --init-eval-command 'set sysroot $SYSROOT_PATH' --init-eval-command 'set solib-search-path $SOLIB_PATH --init-eval-command 'python sys.path.append("/usr/share/gcc-8/python");' -c path-to-exe.core path-to-executable-bin
Gdb is complaining that it cannot load shared objects :
warning: Shared object "$SOLIB_PATH/libc.so.4" could not be validated and will be ignored.
The big thing here is to make sure you're using the exact same binary that is on the target (that the program runs over). This is often quite difficult with libc, especially because libc/ldqnx are sometimes "the same thing" and it confuses gdb.
The easiest way to do this is to log your mkifs output (on the linux host):
make 2>&1 | tee build-out.txt
and read through that, search for libc.so.4, and copy the binary that's being pulled onto the target into . (wherever you're running gdb) so you don't need to mess with SOLIB paths (the lazy solution).
Alternatively, scp/ftp a new libc (one that you want to use, and ideally one that you have associated symbols for) into /tmp and use LD_LIBRARY_PATH to pull that one (and DL_DEBUG=libs to confirm, if you need). Use that same libc to debug
source: I work at QNX and even we struggle with gdb + libc sometimes
I have created a simple hello world (hello.lisp) ,code:
(defun main ()
(format t "Hello,World"))
, program to test CCL's native executable compilation. I proceed to compile and load buffer from the CCL GUI (using version Clozure Common Lisp Version 1.10-store-r16266 (DarwinX8664)).
When i test it:
? (main)
Hello,World
NIL
?
It finds the main function. When i proceed to compile it with: (save-application "/tmp/h" :toplevel-function #'main :prepend-kernel t), it proceeds with the operation and CCL exits.
The file is created and is arround ~56MB. When i try to run it though I get the following output:
Error: There is no applicable method for the generic function:
#
when called with arguments:
(# :NOTE-CURRENT-PACKAGE #)
While executing: #, in process toplevel(6).
Error: There is no applicable method for the generic function:
#
when called with arguments:
(# :BREAK-OPTIONS-STRING T)
While executing: #, in process toplevel(6).
Error: There is no applicable method for the generic function:
#
when called with arguments:
(# :BREAK-OPTIONS-STRING T)
While executing: #, in process toplevel(6).
Error: There is no applicable method for the generic function:
#
when called with arguments:
And the errors proceed. What do I do wrong? Is it a bug?
Thank you
I found the keywords :note-current-package and :break-options-string in the cocoa-ide of the sources. Since prepend-kernel t prepends the kernel that was used in the current session, it seems that you would include the cocoa-ide startup in your application. However, the methods dispatching on those keywords only dispatch on ´ns-application`s, which your new application seems not to be.
The solution might be to prepend a kernel without cocoa-ide, either by loading your code into a non-GUI image, or by using the pathname of such a kernel for the :prepend-kernel argument.
To create executables of Clozure CL on Mac OS X:
for non-GUI applications, you need to install Clozure CL from the repository: Installing Clozure CL. You need to download CCL from there. This version comes with an executable Lisp (kernel + image), which hasn't the GUI loaded.
for GUI applications you need to use the Application Builder. The corresponding function is ccl::build-application. GUI applications on Mac OS X need some infrastructure, which is created then. Note that CCL comes with a example application in ccl/examples/cocoa/currency-converter/. Personally I would also prefer to use CCL from the repository - it's usually a bit newer than the version in the Mac Application store.
Is there a way to compile with MingW with CodeBlocks in Windows so they can be used in Ubuntu or Centos distros?
I've tried compiling with GNU GCC option then got the output file with .o extensions under obj/Release/ folder.
When I run I get this error under my Vagrant Ubuntu machine:
-bash: ./main.o: cannot execute binary file
How can I compile it so it runs on my Linux machines?
The technical term for what you're trying to accomplish is cross-compilation. For that, you need to build a specific cross-compiler using GCC sources. If you still want to keep MinGW, there is a page explaining the steps needed to create a ARM cross-compiler : http://www.mingw.org/wiki/HostedCrossCompilerHOWTO. (you'll have to modify the target)
List of targets supported by GCC :
armv5te-android-gcc armv5te-linux-rvct armv5te-linux-gcc
armv5te-none-rvct
armv6-darwin-gcc armv6-linux-rvct armv6-linux-gcc
armv6-none-rvct
armv7-android-gcc armv7-darwin-gcc armv7-linux-rvct
armv7-linux-gcc armv7-none-rvct
mips32-linux-gcc
ppc32-darwin8-gcc ppc32-darwin9-gcc ppc32-linux-gcc
ppc64-darwin8-gcc ppc64-darwin9-gcc ppc64-linux-gcc
sparc-solaris-gcc
x86-android-gcc x86-darwin8-gcc x86-darwin8-icc
x86-darwin9-gcc x86-darwin9-icc x86-darwin10-gcc
x86-darwin11-gcc x86-darwin12-gcc x86-linux-gcc
x86-linux-icc x86-os2-gcc x86-solaris-gcc
x86-win32-gcc x86-win32-vs7 x86-win32-vs8
x86-win32-vs9
x86_64-darwin9-gcc x86_64-darwin10-gcc x86_64-darwin11-gcc
x86_64-darwin12-gcc x86_64-linux-gcc x86_64-linux-icc
x86_64-solaris-gcc x86_64-win64-gcc x86_64-win64-vs8
x86_64-win64-vs9
universal-darwin8-gcc universal-darwin9-gcc universal-darwin10-gcc
universal-darwin11-gcc universal-darwin12-gcc
generic-gnu
There is only one big caveat : since Windows is not POSIX compliant, I don't think you can use signals or pthreads.
Finally, brace yourself because it's a tedious task to build a cx-compiler (lots of obscure bugs). That's why profesionnal devs pays $$$ for "plug'n'play" solutions.
EDIT : this MXE project can be useful to you
Currently I'm trying to start programming on my new Mac. I installed TextWrangler, and chose C++ as my language of choice; since I have some prior knowledge of it, from when I used Windows.
So, I wrote the ever so common "Hello World" program. Although, when I tried to run it, I got an error:
"This file doesn’t appear to contain a valid ‘shebang’ line (application error code: 13304)"
I tried searching the error code to find out how to fix this, but I couldn't find anything.. I have no idea what a 'shebang' line is... Can someone help me out?
You need to compile it with a compiler first. I assume you tried to run the source file like ./source but C++ doesn't work this way.
With some compilers however, you can provide a shebang-line as the first line of the source file (the #! is known as shebang or crunchbang, hence the name), like so:
#!/path/to/compiler
So that the shell knows what application is used to run that sort of file, and when you attempt to run the source file by itself, the compiler will compile and run it for you. That's a compiler-dependent feature though, so I recommend just plain compiling with G++ or whatever Macs use to get an executable, then run that.
While I wouldn't recommend it for regular C++ development, I'm using a simple shell script wrapper for small C++ utilities. Here is a Hello World example:
#if 0 // -- build and run wrapper script for C++ ------------------------------
TMP=$(mktemp -d)
c++ -o ${TMP}/a.out ${0} && ${TMP}/a.out ${#:1} ; RV=${?}
rm -rf ${TMP}
exit ${RV}
#endif // ----------------------------------------------------------------------
#include <iostream>
int main(int argc, char *argv[])
{
std::cout << "Hello world" << std::endl;
return 0;
}
It does appear that you are trying to run the source file directly, however you will need to compile using a C++ compiler, such as that included in the gcc (GNU Compiler Collection) which contains the C++ compiler g++ for the Mac. It is not included with the Mac, you have to download it first:
from http://www.tech-recipes.com/rx/726/mac-os-x-install-gcc-compiler/ : "To install the gcc compiler, download the xcode package from http://connect.apple.com/. You’ll need to register for an Apple Developer Connection account. Once you’ve registered, login and click Download Software and then Developer Tools. Find the Download link next to Xcode Tools (version) – CD Image and click it!"
Once it's installed, if you are going for a quick Hello World, then, from a terminal window in the directory of your source file, you can execute the command g++ HelloWorld.cpp -o HelloWorld. Then you should be able to run it as ./HelloWorld.
Also, if you're coming from a Visual Studio world, you might want to give Mono and MonoDevelop a try. Mono is a free implementation of C# (and other languages), and MonoDevelop is an IDE which is very similar to Visual Studio. MonoDevelop supports C# and other .NET languages, including Visual Basic .NET, as well as C/C++ development. I have not used it extensively, but it does seem to be very similar to VS, so you won't have to learn new everything all in a day. I also have used KDevelop, which I liked a lot while I was using it, although that's been a while now. It has a lot of support for GNU-style development in C/C++, and was very powerful as I recall.
Good luck with your endeavors!
Links:
Mono: http://mono-project.com/Main_Page
MonoDevelop: http://monodevelop.com/
KDevelop: http://kdevelop.org/
shebang is http://en.wikipedia.org/wiki/Shebang_%28Unix%29.
not sure why your program is not running. you will need to compile and link to make an executable.
What I find confusing (/interesting) is C++ program giving "Shebang line" error. Shebang line is a way for the Unix like operating system to specify which program should be used to interpret the rest of the file. The shebang line usually points to the path of the interpreter. C++ is a compiled language and does not have interpreter for it.
To get the real technical details of how shebang lines work, do a man execve and get that man page online here - man execve.
If you're on a mac then doing something like this on the commandline:
g++ -o program program.cpp
Will compile and link your program into an executable called program. Then you can run it like:
./program
The reason you got the 'shebang' error is probably because you tried to run the cpp file like:
./program.cpp
And the shell tries to find an interpreter to run the code in the file. Because this is C++ there is no relevant interpreter but if your file contains Python or Bash then having a line like this
#!/usr/bin/python
at the 1st line in your source file will tell the shell to use the python interpreter
The lines that start with a pattern like this: #!/.../.../.. is called a shebang line. In other words, a shebang is the character sequence consisting of the characters number sign and exclamation mark (#!).In Unix-like operating systems, when a text file with a shebang is used as if it is an executable, the program loader mechanism parses the rest of the file's initial line as an interpreter directive. The loader executes the specified interpreter program, passing to it as an argument the path that was initially used when attempting to run the script, so that the program may use the file as input data.
I have a batch file that tries to compile a static library using Borland C++ Builder 6.0
It is called from Borland make (makefile created with bpr2mak) which is called from a .bat file (used to compile the whole project with Visual Studio and some Borland C++ Builder legacy projects), which is called from a bash shell script running inside Cygwin.
When I run the .bat file directly from a Cygwin shell, it runs OK, but when its being run from a Program calling cygwin with Boost::Process::launcher I'm getting this error:
C:\ARQUIV~1\Borland\CBUILD~1\Bin\..\BIN\TLib /u bclibs.lib #MAKE0000.###
DOS-reported error: Bad file number
TLIB 4.5 Copyright (c) 1987, 1999 Inprise Corporation
opening 'MAKE0000.###'
** error 1 ** deleting bclibs.lib
It's a complicated scenario, but this Program which calls cygwin is run whenever we need to build our software package which needs to be build for various Linux distos and Windows 32 and 64-bit.
Note: It's the only Borland Project failing, the other compile just fine (it's the only static library using borland also, so it can be some problem with the TLib tool.
The problem was that TLib does not like to have his output redirected (seen here) without having an input pipe as well. Solved by creating an input pipe to in the Boost::Process::launcher using set_stdin_behavior
I'm just guessing here, but this may have to do with long filenames and/or spaces in paths.
1) Modify your makefile so it would save current environment to a file, immediately before executing the failing command (set > d:\env.txt & echo CD=%CD% >> d:\env.txt). Then run it both ways (directly and via program) and compare the environments of good run and bad run.
2) Using filemon from Sysinternals, capture logs of disk access in both cases (these logs are going to be huge, though you can uncheck everything except Open in the filter to reduce the size). Again, compare and check for clues...
3) Try instaling everything involved to paths conforming to 8.3 scheme.
This error is not related to C++ itself. It happens when your build script opens too much files (more than defined in DOS command processor environment). To resolve this issue try to set value of files variable to 253. For Windows XP this variable defined in the file %WINDIR%\system32\config.nt.
files=253
Seems it is known bug in Borland C++ tools. Here is description and possible workaround for this issue:
Problem: Some static Lib projects will
not link correctly when compiled. You might see something
like this :
J:\Borland\CBUILD~1\bin\..\BIN\TLib /u debug\jpegD.lib #MAKE0000.###
DOS-reported error: Bad file number
TLIB 4.5 Copyright (c) 1987, 1999 Inprise Corporation
opening 'MAKE0000.###'
** error 1 ** deleting debug\jpegD.lib
MAKE failed, returned : 1
Workaround : In some cases (where the "Bad file number" error is seen) it may be possible to work around this by specifying -tDEFLIB.BMK in the BPR2MAKE Options field, and Turning off the "Capture Make Output" option.
I have not tested it, but I hope that helps.