/* Guessing the program name.  */

/* 3 ways to call a program:
   $ foo                            - search in PATH
   $ ./foo                          - relative filename
   $ /bin/foo                       - absolute filename
 */

/* See also these discussions:
   http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/5080/focus=5082
   http://fixunix.com/unix/542990-getting-mains-argv-0-a.html
 */

/* ============================= glibc systems ============================= */
#if !1

/* Reference: glibc manual
   http://www.gnu.org/software/libc/manual/html_node/Error-Messages.html
 */

#define _GNU_SOURCE 1
#include <errno.h>

/* The value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "./foo"
   $ /bin/foo                       -> "/bin/foo"
 */
static const char *
get_program_invocation_name ()
{
  return program_invocation_name;
}

/* The part after the last slash (if any) of the value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static const char *
get_program_invocation_short_name ()
{
  return program_invocation_short_name;
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_invocation_name() = %s\n", get_program_invocation_name ());
  printf ("get_program_invocation_short_name() = %s\n", get_program_invocation_short_name ());
  return 0;
}

#endif

/* ============================ uClibc systems ============================ */

/* Depending on the configuration, libc may or may not contain the variables
   'program_invocation_name' and 'program_invocation_short_name', like glibc.
 */

/* ============================= Linux systems ============================= */
#if !1

/* The executable is accessible as /proc/<pid>/exe.  In newer Linux
   versions, also as /proc/self/exe.  Linux >= 2.1 provides a symlink
   to the true pathname; older Linux versions give only device and ino,
   enclosed in brackets, which we cannot use here.  */

#define _GNU_SOURCE 1
#include <limits.h>
#include <string.h>
#include <unistd.h>

/* The canonicalized file name of the program.
   $ foo                            -> "/opt/gnu/bin/foo"
   $ ./foo                          -> "/opt/gnu/bin/foo"
   $ /bin/foo                       -> "/opt/gnu/bin/foo"
 */
static char *
get_program_canonicalized_name ()
{
  char buf[PATH_MAX];
  int ret;

  ret = readlink ("/proc/self/exe", buf, sizeof (buf));
  if (ret < 0 || buf[0] == '[')
    return NULL;
  return strndup (buf, PATH_MAX);
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_canonicalized_name() = %s\n", get_program_canonicalized_name ());
  return 0;
}

#endif

/* ============================ MacOS X systems ============================ */
#if !1

#include <mach-o/dyld.h>
#include <string.h>

/* On MacOS X 10.2 or newer, the function
     int _NSGetExecutablePath (char *buf, uint32_t *bufsize);
   can be used to retrieve the executable's full path.
   Reference:
   <http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man3/dyld.3.html>
 */

/* The absolute name (but not canonicalized) of the value of argv[0].
   $ foo                            -> /found_dir/foo
   $ ./foo                          -> /currdir/./foo
   $ symlink/foo                    -> /currdir/symlink/foo
   $ /bin/foo                       -> /bin/foo
 */
static char *
get_program_absolute_name ()
{
  char location[4096];
  unsigned int length = sizeof (location);
  if (_NSGetExecutablePath (location, &length) == 0)
    return strdup (location);
  else
    return NULL;
}

#include <stdlib.h>

/* The part after the last slash (if any) of the value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static const char *
get_program_invocation_short_name ()
{
  return getprogname ();
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_absolute_name() = %s\n", get_program_absolute_name ());
  printf ("get_program_invocation_short_name() = %s\n", get_program_invocation_short_name ());
  return 0;
}

#endif

/* ============================ FreeBSD systems ============================ */
#if !1

/* Reference:
   <http://www.freebsd.org/cgi/man.cgi?query=getprogname&sektion=3>
 */

#include <stdlib.h>

/* The part after the last slash (if any) of the value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static const char *
get_program_invocation_short_name ()
{
  return getprogname ();
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_invocation_short_name() = %s\n", get_program_invocation_short_name ());
  return 0;
}

#endif

/* ============================ NetBSD systems ============================ */
#if !1

#include <stdlib.h>

/* The part after the last slash (if any) of the value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static const char *
get_program_invocation_short_name ()
{
  return getprogname ();
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_invocation_short_name() = %s\n", get_program_invocation_short_name ());
  return 0;
}

#endif

/* ============================ OpenBSD systems ============================ */
#if !1

/* The variable __progname is defined in /usr/lib/crt0.o.  */

/* The part after the last slash (if any) of the value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static const char *
get_program_invocation_short_name ()
{
  extern const char *__progname;
  return __progname;
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_invocation_short_name() = %s\n", get_program_invocation_short_name ());
  return 0;
}

#endif

/* ============================== AIX systems ============================== */
#if !1

/* Idea by Bastien ROUCARIÈS <address@hidden>.  */
/* <http://lists.gnu.org/archive/html/bug-gnulib/2010-12/msg00095.html> */

/* Reference:
   <http://publib.boulder.ibm.com/infocenter/aix/v6r1/index.jsp?topic=/com.ibm.aix.basetechref/doc/basetrf1/getprocs.htm>
 */

#include <unistd.h>
#include <procinfo.h>
#include <string.h>

/* The part after the last slash (if any) of the value of argv[0],
   truncated to at most 32 bytes.
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static char *
get_program_invocation_short_name_truncated ()
{
  extern int getprocs64 (struct procentry64 *, int, struct fdsinfo64 *, int,
                         pid_t *, int);
  pid_t pid = getpid ();
  struct procentry64 procs;
  if (getprocs64 (&procs, sizeof (procs), NULL, 0, &pid, 1) > 0)
    return strdup (procs.pi_comm);
  return NULL;
}

/* The value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "./foo"
   $ /bin/foo                       -> "/bin/foo"
 */
static char *
get_program_invocation_name ()
{
  extern int getargs (void *, int, char *, int);
  char arg0[PATH_MAX + 1];
  struct procentry64 procs;
  procs.pi_pid = getpid ();
  if (getargs (&procs, sizeof (procs), arg0, sizeof (arg0)) == 0)
    /* arg0 is always NUL terminated.  */
    return strdup (arg0);
  return NULL;
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_invocation_short_name_truncated() = %s\n", get_program_invocation_short_name_truncated ());
  printf ("get_program_invocation_name() = %s\n", get_program_invocation_name ());
  return 0;
}

#endif

/* ============================= HP-UX systems ============================= */
#if !1

/* Idea by Bastien ROUCARIÈS <address@hidden>.  */
/* <http://lists.gnu.org/archive/html/bug-gnulib/2010-11/msg00203.html> */

/* Reference: <http://docs.hp.com/en/B2355-90682/pstat.2.html> */

#include <unistd.h>
#include <sys/pstat.h>
#include <string.h>

/* The part after the last slash (if any) of the value of argv[0],
   truncated to at most 14 bytes.
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static char *
get_program_invocation_short_name_truncated ()
{
  int pid = getpid ();
  struct pst_status buf;

  if (pstat_getproc (&buf, sizeof (buf), 0, pid) > 0)
    return strdup (buf.pst_ucomm);
  return NULL;
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_invocation_short_name_truncated() = %s\n", get_program_invocation_short_name_truncated ());
  return 0;
}

#endif

/* ============================= IRIX systems ============================= */
#if !1

/* Idea by Bastien ROUCARIÈS <address@hidden>.  */
/* <http://lists.gnu.org/archive/html/bug-gnulib/2010-12/msg00096.html> */

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/procfs.h>

static size_t
strnlen (const char *string, size_t maxlen)
{
  const char *end = memchr (string, '\0', maxlen);
  return end ? (size_t) (end - string) : maxlen;
}

static char *
strndup (char const *s, size_t n)
{
  size_t len = strnlen (s, n);
  char *new = malloc (len + 1);

  if (new == NULL)
    return NULL;

  new[len] = '\0';
  return memcpy (new, s, len);
}

/* The part after the last slash (if any) of the value of argv[0],
   truncated to at most 32 bytes.
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static char *
get_program_invocation_short_name_truncated ()
{
  char filename[50];
  int fd;

  sprintf (filename, "/proc/pinfo/%d", (int) getpid ());
  fd = open (filename, O_RDONLY);
  if (fd >= 0)
    {
      prpsinfo_t buf;

      if (ioctl (fd, PIOCPSINFO, &buf) >= 0)
        {
          close (fd);
          return strndup (buf.pr_fname, sizeof (buf.pr_fname));
        }
      close (fd);
    }
  return NULL;
}

int
main ()
{
  printf ("get_program_invocation_short_name_truncated() = %s\n", get_program_invocation_short_name_truncated ());
  return 0;
}

#endif

/* ============================= OSF/1 systems ============================= */
#if !1

#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/procfs.h>

static size_t
strnlen (const char *string, size_t maxlen)
{
  const char *end = memchr (string, '\0', maxlen);
  return end ? (size_t) (end - string) : maxlen;
}

static char *
strndup (char const *s, size_t n)
{
  size_t len = strnlen (s, n);
  char *new = malloc (len + 1);

  if (new == NULL)
    return NULL;

  new[len] = '\0';
  return memcpy (new, s, len);
}

/* The part after the last slash (if any) of the value of argv[0],
   truncated to at most 16 bytes.
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static char *
get_program_invocation_short_name_truncated ()
{
  char filename[50];
  int fd;

  sprintf (filename, "/proc/%d", (int) getpid ());
  fd = open (filename, O_RDONLY);
  if (fd >= 0)
    {
      prpsinfo_t buf;

      if (ioctl (fd, PIOCPSINFO, &buf) >= 0)
        {
          close (fd);
          return strndup (buf.pr_fname, sizeof (buf.pr_fname));
        }
      close (fd);
    }
  return NULL;
}

int
main ()
{
  printf ("get_program_invocation_short_name_truncated() = %s\n", get_program_invocation_short_name_truncated ());
  return 0;
}

#endif

/* ============================ Solaris systems ============================ */
#if !1

/* Reference for getexecname:
   <http://docs.sun.com/app/docs/doc/816-5168/getexecname-3c?l=en&a=view>
 */

#include <stdlib.h>

/* The value of argv[0], looked up in PATH, with symlinks resolved and
   "." components removed.
   $ foo                            -> "foo" or "subdir/foo" or "/bin/foo"
   $ ./foo                          -> "foo"
   $ subdir/foo                     -> "subdir/foo"
   $ symlink/foo                    -> "subdir/foo"
   $ /bin/foo                       -> "/bin/foo"
 */
static const char *
get_resolved_program_invocation_name ()
{
  return getexecname ();
}

#if HAVE_GETPROGNAME /* Solaris 11 2010-11 */

/* The part after the last slash (if any) of the value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ /bin/foo                       -> "foo"
 */
static const char *
get_program_invocation_short_name ()
{
  return getprogname ();
}

#else

static const char *
get_program_invocation_short_name ()
{
  return NULL;
}

#endif

#include <stdio.h>

int
main ()
{
  printf ("get_resolved_program_invocation_name() = %s\n", get_resolved_program_invocation_name () != NULL ? get_resolved_program_invocation_name () : "(null)");
  printf ("get_program_invocation_short_name() = %s\n", get_program_invocation_short_name () != NULL ? get_program_invocation_short_name () : "(null)");
  return 0;
}

#endif

/* ============================ Cygwin systems ============================ */
#if !1

/* References:
   <http://www.cygwin.com/cygwin-api/std-bsd.html>
   <http://msdn.microsoft.com/en-us/library/ms683197(v=vs.85).aspx>
 */

#include <stdlib.h>

/* The part after the last slash (if any) of the value of argv[0].
   $ foo                            -> "foo"
   $ ./foo                          -> "foo"
   $ ./foo.exe                      -> "foo"
   $ /bin/foo                       -> "foo"
 */
static const char *
get_program_invocation_short_name ()
{
  return getprogname ();
}

#define WIN32_LEAN_AND_MEAN  /* avoid including junk */
#include <windows.h>

#include <string.h>

/* The canonicalized file name of the program.
   $ foo                            -> "/cygdrive/c/gnu/bin/foo.exe"
   $ ./foo                          -> "/cygdrive/c/gnu/bin/foo.exe"
   $ /bin/foo                       -> "/cygdrive/c/bin/foo.exe"
 */
static char *
get_program_canonicalized_name1 ()
{
  char location[MAX_PATH + 1];
  char location_as_posix_path[2 * MAX_PATH];
  int length = GetModuleFileName (NULL, location, sizeof (location) - 1);
  if (length < 0)
    return NULL;
  if (length == sizeof (location) - 1)
    location[length] = '\0';
  /* On Cygwin, we need to convert paths coming from Win32 system calls
     to the Unix-like slashified notation.  */
  /* There's no error return defined for cygwin_conv_to_posix_path.
     See cygwin-api/func-cygwin-conv-to-posix-path.html.
     Does it overflow the buffer of expected size MAX_PATH or does it
     truncate the path?  I don't know.  Let's catch both.  */
  cygwin_conv_to_posix_path (location, location_as_posix_path);
  location_as_posix_path[MAX_PATH - 1] = '\0';
  if (strlen (location_as_posix_path) >= MAX_PATH - 1)
    /* A sign of buffer overflow or path truncation.  */
    return NULL;
  return strdup (location_as_posix_path);
}

/* An alternative implementation, that works with cygwin-1.5.13 (2005-03-01)
   or newer.  */

#include <limits.h>
#include <string.h>
#include <unistd.h>

/* The canonicalized file name of the program.
   $ foo                            -> "/opt/gnu/bin/foo"
   $ ./foo                          -> "/opt/gnu/bin/foo"
   $ /bin/foo                       -> "/opt/gnu/bin/foo"
 */
static char *
get_program_canonicalized_name2 ()
{
  char buf[PATH_MAX];
  int ret;

  ret = readlink ("/proc/self/exe", buf, sizeof (buf));
  if (ret < 0)
    return NULL;
  return strndup (buf, ret);
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_invocation_short_name() = %s\n", get_program_invocation_short_name ());
  printf ("get_program_canonicalized_name1() = %s\n", get_program_canonicalized_name1 ());
  printf ("get_program_canonicalized_name2() = %s\n", get_program_canonicalized_name2 ());
  return 0;
}

#endif

/* ============================= mingw systems ============================= */
#if !1

/* Reference:
   <http://msdn.microsoft.com/en-us/library/ms683197(v=vs.85).aspx>
 */

#define WIN32_LEAN_AND_MEAN  /* avoid including junk */
#include <windows.h>

#include <string.h>

/* The canonicalized file name of the program.
   $ foo                            -> "C:\\gnu\\bin\\foo.exe"
   $ ./foo                          -> "C:\\gnu\\bin\\foo.exe"
   $ /bin/foo                       -> "C:\\bin\\foo.exe"
 */
static char *
get_program_canonicalized_name ()
{
  char location[MAX_PATH + 1];
  int length = GetModuleFileName (NULL, location, sizeof (location) - 1);
  if (length < 0)
    return NULL;
  if (length == sizeof (location) - 1)
    location[length] = '\0';
  return strdup (location);
}

#include <stdio.h>

int
main ()
{
  printf ("get_program_canonicalized_name() = %s\n", get_program_canonicalized_name ());
  return 0;
}

#endif

/* ============================ Interix systems ============================ */

/* ============================= BeOS systems ============================= */