/*=========================================================================

  Program:   KWSys - Kitware System Library
  Module:    SharedForward.h.in

  Copyright (c) Kitware, Inc., Insight Consortium.  All rights reserved.
  See Copyright.txt or http://www.kitware.com/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef @KWSYS_NAMESPACE@_SharedForward_h
#define @KWSYS_NAMESPACE@_SharedForward_h

/*
  This header is used to create a forwarding executable sets up the
  shared library search path and replaces itself with a real
  executable.  This is useful when creating installations on UNIX with
  shared libraries that will run from any install directory.  Typical
  usage:

  #define @KWSYS_NAMESPACE@_SHARED_FORWARD_DIR_BUILD "/path/to/foo-build/bin"
  #define @KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_BUILD "."
  #define @KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_INSTALL "../lib/foo-1.2"
  #define @KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_BUILD "foo-real"
  #define @KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_INSTALL "../lib/foo-1.2/foo-real"
  #include <@KWSYS_NAMESPACE@/SharedForward.h>
  int main(int argc, char** argv)
  {
    return @KWSYS_NAMESPACE@_shared_forward_to_real(argc, argv);
  }
 */

/*--------------------------------------------------------------------------*/
/* Configuration for this executable.  Specify search and executable
   paths relative to the forwarding executable location or as full
   paths.  Include no trailing slash.  */

/* This is not useful on Windows.  */
#if defined(_WIN32)
# error "@KWSYS_NAMESPACE@/SharedForward.h is useless on Windows."
#endif

/* Full path to the directory in which this executable is built.  Do
   not include a trailing slash.  */
#if !defined(@KWSYS_NAMESPACE@_SHARED_FORWARD_DIR_BUILD)
# error "Must define @KWSYS_NAMESPACE@_SHARED_FORWARD_DIR_BUILD"
#endif
#if !defined(KWSYS_SHARED_FORWARD_DIR_BUILD)
# define KWSYS_SHARED_FORWARD_DIR_BUILD @KWSYS_NAMESPACE@_SHARED_FORWARD_DIR_BUILD
#endif

/* Library search path for build tree.  */
#if !defined(@KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_BUILD)
# error "Must define @KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_BUILD"
#endif
#if !defined(KWSYS_SHARED_FORWARD_PATH_BUILD)
# define KWSYS_SHARED_FORWARD_PATH_BUILD @KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_BUILD
#endif

/* Library search path for install tree.  */
#if !defined(@KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_INSTALL)
# error "Must define @KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_INSTALL"
#endif
#if !defined(KWSYS_SHARED_FORWARD_PATH_INSTALL)
# define KWSYS_SHARED_FORWARD_PATH_INSTALL @KWSYS_NAMESPACE@_SHARED_FORWARD_PATH_INSTALL
#endif

/* The real executable to which to forward in the build tree.  */
#if !defined(@KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_BUILD)
# error "Must define @KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_BUILD"
#endif
#if !defined(KWSYS_SHARED_FORWARD_EXE_BUILD)
# define KWSYS_SHARED_FORWARD_EXE_BUILD @KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_BUILD
#endif

/* The real executable to which to forward in the install tree.  */
#if !defined(@KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_INSTALL)
# error "Must define @KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_INSTALL"
#endif
#if !defined(KWSYS_SHARED_FORWARD_EXE_INSTALL)
# define KWSYS_SHARED_FORWARD_EXE_INSTALL @KWSYS_NAMESPACE@_SHARED_FORWARD_EXE_INSTALL
#endif

/* Create command line option to print environment setting and exit.  */
#if defined(@KWSYS_NAMESPACE@_SHARED_FORWARD_OPTION_PRINT)
# if !defined(KWSYS_SHARED_FORWARD_OPTION_PRINT)
#  define KWSYS_SHARED_FORWARD_OPTION_PRINT @KWSYS_NAMESPACE@_SHARED_FORWARD_OPTION_PRINT
# endif
#else
# undef KWSYS_SHARED_FORWARD_OPTION_PRINT
#endif

/* Create command line option to run ldd or equivalent.  */
#if defined(@KWSYS_NAMESPACE@_SHARED_FORWARD_OPTION_LDD)
# if !defined(KWSYS_SHARED_FORWARD_OPTION_LDD)
#  define KWSYS_SHARED_FORWARD_OPTION_LDD @KWSYS_NAMESPACE@_SHARED_FORWARD_OPTION_LDD
# endif
#else
# undef KWSYS_SHARED_FORWARD_OPTION_LDD
#endif

/*--------------------------------------------------------------------------*/
/* Include needed system headers.  */

#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdio.h>

/*--------------------------------------------------------------------------*/
/* Configuration for this platform.  */

/* The path separator for this platform.  */
#define KWSYS_SHARED_FORWARD_PATH_SEP ':'
static const char kwsys_shared_forward_path_sep[2] = {KWSYS_SHARED_FORWARD_PATH_SEP, 0};

/* The maximum length of a file name.  */
#if defined(PATH_MAX)
# define KWSYS_SHARED_FORWARD_MAXPATH PATH_MAX
#elif defined(MAXPATHLEN)
# define KWSYS_SHARED_FORWARD_MAXPATH MAXPATHLEN
#else
# define KWSYS_SHARED_FORWARD_MAXPATH 16384
#endif

/* Select the environment variable holding the shared library runtime
   search path for this platform and build configuration.  Also select
   ldd command equivalent.  */

/* Linux */
#if defined(__linux)
# define KWSYS_SHARED_FORWARD_LDD "ldd"
# define KWSYS_SHARED_FORWARD_LDD_N 1
# define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY_PATH"
#endif

/* FreeBSD */
#if defined(__FreeBSD__)
# define KWSYS_SHARED_FORWARD_LDD "ldd"
# define KWSYS_SHARED_FORWARD_LDD_N 1
# define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY_PATH"
#endif

/* OSX */
#if defined(__APPLE__)
# define KWSYS_SHARED_FORWARD_LDD "otool", "-L"
# define KWSYS_SHARED_FORWARD_LDD_N 2
# define KWSYS_SHARED_FORWARD_LDPATH "DYLD_LIBRARY_PATH"
#endif

/* AIX */
#if defined(_AIX)
# define KWSYS_SHARED_FORWARD_LDD "dump", "-H"
# define KWSYS_SHARED_FORWARD_LDD_N 2
# define KWSYS_SHARED_FORWARD_LDPATH "LIBPATH"
#endif

/* SUN */
#if defined(__sparc)
# define KWSYS_SHARED_FORWARD_LDD "ldd"
# define KWSYS_SHARED_FORWARD_LDD_N 1
# include <sys/isa_defs.h>
# if defined(_ILP32)
#  define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY_PATH"
# elif defined(_LP64)
#  define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY_PATH_64"
# endif
#endif

/* HP-UX */
#if defined(__hpux)
# define KWSYS_SHARED_FORWARD_LDD "chatr"
# define KWSYS_SHARED_FORWARD_LDD_N 1
# if defined(__LP64__)
#  define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY_PATH"
# else
#  define KWSYS_SHARED_FORWARD_LDPATH "SHLIB_PATH"
# endif
#endif

/* SGI MIPS */
#if defined(__sgi) && defined(_MIPS_SIM)
# define KWSYS_SHARED_FORWARD_LDD "ldd"
# define KWSYS_SHARED_FORWARD_LDD_N 1
# if _MIPS_SIM == _ABIO32
#  define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY_PATH"
# elif _MIPS_SIM == _ABIN32
#  define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARYN32_PATH"
# elif _MIPS_SIM == _ABI64
#  define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY64_PATH"
# endif
#endif

/* Guess on this unknown system.  */
#if !defined(KWSYS_SHARED_FORWARD_LDPATH)
# define KWSYS_SHARED_FORWARD_LDD "ldd"
# define KWSYS_SHARED_FORWARD_LDD_N 1
# define KWSYS_SHARED_FORWARD_LDPATH "LD_LIBRARY_PATH"
#endif

/*--------------------------------------------------------------------------*/
/* Function to get the directory containing the given file or directory.  */
static void kwsys_shared_forward_dirname(const char* begin, char* result)
{
  /* Find the location of the last slash.  */
  int last_slash_index = -1;
  const char* end = begin + strlen(begin);
  for(;begin <= end && last_slash_index < 0; --end)
    {
    if(*end == '/')
      {
      last_slash_index = end-begin;
      }
    }

  /* Handle each case of the index of the last slash.  */
  if(last_slash_index < 0)
    {
    /* No slashes.  */
    strcpy(result, ".");
    }
  else if(last_slash_index == 0)
    {
    /* Only one leading slash.  */
    strcpy(result, "/");
    }
  else
    {
    /* A non-leading slash.  */
    strncpy(result, begin, last_slash_index);
    result[last_slash_index] = 0;
    }
}

/*--------------------------------------------------------------------------*/
/* Function to locate the executable currently running.  */
static int kwsys_shared_forward_self_path(const char* argv0, char* result)
{
  /* Check whether argv0 has a slash.  */
  int has_slash = 0;
  const char* p = argv0;
  for(;*p && !has_slash; ++p)
    {
    if(*p == '/')
      {
      has_slash = 1;
      }
    }

  if(has_slash)
    {
    /* There is a slash.  Use the dirname of the given location.  */
    kwsys_shared_forward_dirname(argv0, result);
    return 1;
    }
  else
    {
    /* There is no slash.  Search the PATH for the executable.  */
    const char* path = getenv("PATH");
    const char* begin = path;
    const char* end = begin + (begin?strlen(begin):0);
    const char* first = begin;
    while(first != end)
      {
      /* Store the end of this path entry.  */
      const char* last;

      /* Skip all path separators.  */
      for(;*first && *first == KWSYS_SHARED_FORWARD_PATH_SEP; ++first);

      /* Find the next separator.  */
      for(last = first;*last && *last != KWSYS_SHARED_FORWARD_PATH_SEP; ++last);

      /* If we got a non-empty directory, look for the executable there.  */
      if(first < last)
        {
        /* Determine the length without trailing slash.  */
        int length = last-first;
        if(*(last-1) == '/')
          {
          --length;
          }

        /* Construct the name of the executable in this location.  */
        strncpy(result, first, length);
        result[length] = '/';
        strcpy(result+(length)+1, argv0);

        /* Check if it exists.  */
        if(access(result, X_OK) == 0)
          {
          /* Found it.  */
          result[length] = 0;
          return 1;
          }
        }

      /* Move to the next directory in the path.  */
      first = last;
      }
    }

  /* We could not find the executable.  */
  return 0;
}

/*--------------------------------------------------------------------------*/
/* Function to convert a specified path to a full path.  If it is not
   already full, it is taken relative to the self path.  */
static int kwsys_shared_forward_fullpath(const char* self_path,
                                         const char* in_path,
                                         char* result,
                                         const char* desc)
{
  /* Check the specified path type.  */
  if(in_path[0] == '/')
    {
    /* Already a full path.  */
    strcpy(result, in_path);
    }
  else
    {
    /* Relative to self path.  */
    char temp_path[KWSYS_SHARED_FORWARD_MAXPATH];
    strcpy(temp_path, self_path);
    strcat(temp_path, "/");
    strcat(temp_path, in_path);
    if(!realpath(temp_path, result))
      {
      if(desc)
        {
        fprintf(stderr, "Error converting %s \"%s\" to real path: %s\n",
                desc, temp_path, strerror(errno));
        }
      return 0;
      }
    }
  return 1;
}

/*--------------------------------------------------------------------------*/
/* Function to compute the library search path and executable name
   based on the self path.  */
static int kwsys_shared_forward_get_settings(const char* self_path,
                                             char* ldpath, char* exe)
{
  /* Possible search paths.  */
  static const char* search_path_build[] = {KWSYS_SHARED_FORWARD_PATH_BUILD, 0};
  static const char* search_path_install[] = {KWSYS_SHARED_FORWARD_PATH_INSTALL, 0};

  /* Chosen paths.  */
  const char** search_path;
  const char* exe_path;

  /* Get the real name of the build and self paths.  */
  char build_path[KWSYS_SHARED_FORWARD_MAXPATH];
  char self_path_real[KWSYS_SHARED_FORWARD_MAXPATH];
  if(!realpath(self_path, self_path_real))
    {
    fprintf(stderr, "Error converting self path \"%s\" to real path: %s\n",
            self_path, strerror(errno));
    return 0;
    }

  /* Check whether we are running in the build tree or an install tree.  */
  if(realpath(KWSYS_SHARED_FORWARD_DIR_BUILD, build_path) &&
     strcmp(self_path_real, build_path) == 0)
    {
    /* Running in build tree.  Use the build path and exe.  */
    search_path = search_path_build;
    exe_path = KWSYS_SHARED_FORWARD_EXE_BUILD;
    }
  else
    {
    /* Running in install tree.  Use the install path and exe.  */
    search_path = search_path_install;
    exe_path = KWSYS_SHARED_FORWARD_EXE_INSTALL;
    }

  /* Construct the runtime search path.  */
  {
  const char** dir;
  for(dir = search_path; *dir; ++dir)
    {
    /* Add seperator between path components.  */
    if(dir != search_path)
      {
      strcat(ldpath, kwsys_shared_forward_path_sep);
      }

    /* Add this path component.  */
    if(!kwsys_shared_forward_fullpath(self_path, *dir,
                                      ldpath+strlen(ldpath),
                                      "runtime path entry"))
      {
      return 0;
      }
    }
  }

  /* Construct the executable location.  */
  if(!kwsys_shared_forward_fullpath(self_path, exe_path, exe,
                                    "executable file"))
    {
    return 0;
    }
  return 1;
}

/*--------------------------------------------------------------------------*/
/* Function to print why execution of a command line failed.  */
static void kwsys_shared_forward_print_failure(char** argv, const char* msg)
{
  char** arg = argv;
  fprintf(stderr, "Error running");
  for(; *arg; ++arg)
    {
    fprintf(stderr, " \"%s\"", *arg);
    }
  fprintf(stderr, ": %s\n", msg);
}

/* Static storage space to store the updated environment variable.  */
static char kwsys_shared_forward_ldpath[KWSYS_SHARED_FORWARD_MAXPATH*16] = KWSYS_SHARED_FORWARD_LDPATH "=";

/*--------------------------------------------------------------------------*/
/* Main driver function to be called from main.  */
static int @KWSYS_NAMESPACE@_shared_forward_to_real(int argc, char** argv)
{
  /* Get the directory containing this executable.  */
  char self_path[KWSYS_SHARED_FORWARD_MAXPATH];
  if(kwsys_shared_forward_self_path(argv[0], self_path))
    {
    /* Found this executable.  Use it to get the library directory.  */
    char exe[KWSYS_SHARED_FORWARD_MAXPATH];
    if(kwsys_shared_forward_get_settings(self_path,
                                         kwsys_shared_forward_ldpath, exe))
      {
      /* Append the old runtime search path.  */
      const char* old_ldpath = getenv(KWSYS_SHARED_FORWARD_LDPATH);
      if(old_ldpath)
        {
        strcat(kwsys_shared_forward_ldpath, kwsys_shared_forward_path_sep);
        strcat(kwsys_shared_forward_ldpath, old_ldpath);
        }

      /* Store the environment variable.  */
      putenv(kwsys_shared_forward_ldpath);

#if defined(KWSYS_SHARED_FORWARD_OPTION_PRINT)
      /* Look for the print command line option.  */
      if(argc > 1 && strcmp(argv[1], KWSYS_SHARED_FORWARD_OPTION_PRINT) == 0)
        {
        fprintf(stdout, "%s\n", kwsys_shared_forward_ldpath);
        fprintf(stdout, "%s\n", exe);
        return 0;
        }
#endif

#if defined(KWSYS_SHARED_FORWARD_OPTION_LDD)
      /* Look for the ldd command line option.  */
      if(argc > 1 && strcmp(argv[1], KWSYS_SHARED_FORWARD_OPTION_LDD) == 0)
        {
        char* ldd_argv[] = {KWSYS_SHARED_FORWARD_LDD, 0, 0};
        ldd_argv[KWSYS_SHARED_FORWARD_LDD_N] = exe;
        execvp(ldd_argv[0], ldd_argv);

        /* Report why execution failed.  */
        kwsys_shared_forward_print_failure(ldd_argv, strerror(errno));
        return 1;
        }
#endif

      /* Replace this process with the real executable.  */
      argv[0] = exe;
      execv(argv[0], argv);

      /* Report why execution failed.  */
      kwsys_shared_forward_print_failure(argv, strerror(errno));
      }
    else
      {
      /* Could not convert self path to the library directory.  */
      }
    }
  else
    {
    /* Could not find this executable.  */
    fprintf(stderr, "Error locating executable \"%s\".", argv[0]);
    }

  /* Avoid unused argument warning.  */
  (void)argc;

  /* Exit with failure.  */
  return 1;
}

#else
# error "@KWSYS_NAMESPACE@/SharedForward.h should be included only once."
#endif
