/* Specification.  */
#include "progname.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


/* String containing name the program is called with.  To be
   initialized by |main()|.  */
const char *program_name = NULL;

/* Set |program_name|, based on |argv[0]|.  |argv0| must be a string
   allocated with indefinite extent, and must not be modified after
   this call.  */
void
set_program_name(const char *argv0) {
    /* libtool creates a temporary executable whose name is sometimes
       prefixed with "lt-" (depends on the platform).  It also makes
       |argv[0]| absolute.  But the name of the temporary executable
       is a detail that should not be visible to the end user and to
       the test suite.  Remove this |"<dirname>/.libs/"| or
       |"<dirname>/.libs/lt-"| prefix here.  */
    const char *slash;
    const char *base;

    /* Sanity check.  POSIX requires the invoking process to pass a
       non-|NULL| |argv[0]|.  */
    if (argv0 == NULL) {
        /* It's a bug in the invoking program.  Help diagnosing
           it.  */
        fputs("A NULL argv[0] was passed through an exec system call.\n",
              stderr);
        abort();
    }

    slash = strrchr(argv0, '/');
    base = (slash != NULL ? slash + 1 : argv0);
    if (base - argv0 >= 7 && strncmp(base - 7, "/.libs/", 7) == 0) {
        argv0 = base;
        if (strncmp(base, "lt-", 3) == 0) {
            argv0 = base + 3;
            /* On glibc systems, remove the "lt-" prefix from the
               variable |program_invocation_short_name|.  */
#if HAVE_DECL_PROGRAM_INVOCATION_SHORT_NAME
            program_invocation_short_name = (char *) argv0;
#endif
        }
    }

    /* But don't strip off a leading |<dirname>/| in general, because
       when the user runs

           |/some/hidden/place/bin/cp foo foo|

       he should get the error message

           |/some/hidden/place/bin/cp: `foo' and `foo' are the same file|

       not

          | cp: `foo' and `foo' are the same file|
     */

    program_name = argv0;

    /* On glibc systems, the |error()| function comes from libc and
       uses the variable |program_invocation_name|, not
       |program_name|.  So set this variable as well.  */
#if HAVE_DECL_PROGRAM_INVOCATION_NAME
    program_invocation_name = (char *) argv0;
#endif
}

const char *
get_program_name(void) {
    return program_name;
}