10.12. Creating a Multiarch Wrapper

10.12.1. Installation de The Multiarch Wrapper

Create the source file:

cat > multiarch_wrapper.c << "EOF"
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

#ifndef USE_ARCH
#define USE_ARCH "64"
#endif

int main(int argc, char **argv)
{
  char *filename;
  char *use_arch;

  if(!(use_arch = getenv("USE_ARCH")))
    use_arch = USE_ARCH;

  filename = (char *) malloc(strlen(argv[0]) + strlen(use_arch) + 2);
  strcpy(filename, argv[0]);
  strcat(filename, "-");
  strcat(filename, use_arch);

  execvp(filename, argv);
  perror(argv[0]);
  free(filename);
}
EOF

Compile and Install the Multiarch Wrapper:

gcc ${BUILD64} multiarch_wrapper.c -o /usr/bin/multiarch_wrapper

This multiarch wrapper is going to be used later on in the book with Perl. It will also be very useful outside of the base CLFS system.

Create a testcase:

echo 'echo "32bit Version"' > test-32
echo 'echo "64bit Version"' > test-64
chmod 755 test-32 test-64
ln -sv /usr/bin/multiarch_wrapper test

Test the wrapper:

USE_ARCH=32 ./test
USE_ARCH=64 ./test

The output of the above command should be:

32bit Version
64bit Version