c-file to mex-file pnet.c in OS 10.9.5 MATLAB 2012a

System:

OS 10.9.5

MATLAB R2012a

terminal request: gcc --version

Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix
llvm-gcc --version Apple LLVM version 6.0 (clang-600.0.57) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin13.4.0;

I would like to convert the pnet.c file into a mex-file, see below:

>> mex pnet.c

/Applications/MATLAB_R2012a.app/bin/mex: line 305: gcc-4.2: command not found

    mex:  pnet.c  not a normal file or does not exist.

I'm a beginner and I tried for too long already to find some answer by myself... can anyone help me please?

thanks in advance!

Answer 1

[Walter Roberson]

The message is fairly clear: you need to install gcc 4.2 to use that configuration. If it already is installed then you need to create a symbolic link from "gcc-4.2" to the actual software.

[florian schertenleib]

Thanks for your answer, finally I made it! I installed a newer version of xcode (5.0) and run mex -setup again. besides that, i still get warnings. should i care ?

pnet.c:857:2: warning: add explicit braces to avoid dangling else [-Wdangling-else]
        else
        ^
pnet.c:
879:55: warning: passing 'int *' to parameter of type 'socklen_t *'
      (aka 'unsigned int *') converts between pointers to integer types with different sign
      [-Wpointer-sign]
                                readlen,MSG_NOSIGNAL,(struct sockaddr *)&my_addr, &fromlen);
                                                                                  ^~~~~~~~
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk//usr/include/sys/socket.h:622:25: note: 
      passing argument to parameter here
                socklen_t * __restrict) __DARWIN_ALIAS_C(recvfrom);

                             ^
  pnet.c:990:83: warning: passing 'int *' to parameter of type 'socklen_t *'
        (aka 'unsigned int *') converts between pointers to integer types with different sign
        [-Wpointer-sign]
    ...= accept(sock_fd, (struct sockaddr *)&con[con_index].remote_addr,&sin_size)) > -1)
                                                                        ^~~~~~~~~
  /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.8.sdk//usr/include/sys/socket.h:610:69: note: 
        passing argument to parameter here
  int     accept(int, struct sockaddr * __restrict, socklen_t * __restrict)
                                                                          ^
  3 warnings generated.

[Walter Roberson]

The second and third warnings are applicable to cases where you might have more than 2^31-1 bytes (2 gigabyte) being transferred. If you were working with something that was intended to need to be secure then I would say you need to fix them, but if you are just using the code for your own purposes with no distribution then do not bother.

The warning about the dangling else might indicate a bug in the code. The difficulty is that if you have

if (condition1)
if (condition2)
     ...
else
    ...

then it is not immediately clear in C whether the "else" belongs to the first "if" or to the second "if". C does have rules to resolve it, but it is something that programmers get confused about, so the compiler warns you in case you did not notice that it was happening. It is better to avoid the problem by putting in explicit blocks, either

if (condition1) {
  if (condition2)
    ...
  else
    ...
}

or

if (condition1) {
  if (condition2)
    ...
} else
   ...

The first of those associates the else with the second if, and the second of those associates the else with the first if.

[芝 赵]

How to solve this probelm when I use mex pnet.c

Tip: the first four red words are 'Error use mex'

blem

[Walter Roberson]

It looks to me as if you should possibly use

mex pnet.c -lws2_32