lib/relocwrapper.c

/* Relocating wrapper program.
   Copyright (C) 2003, 2005-2007, 2009-2026 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2003.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Dependencies:
   relocwrapper
    -> progname
    -> progreloc
       -> stat
          -> filename
          -> pathmax
          -> stat-time
          -> verify
       -> areadlink
          -> careadlinkat
             -> allocator
          -> readlink
             -> stat
       -> canonicalize-lgpl
          -> c-bool
          -> libc-config
          -> errno
          -> fcntl-h
          -> sys_stat
          -> unistd
          -> eloop-threshold
          -> filename
          -> idx
          -> intprops
          -> scratch_buffer
             -> malloc-posix
             -> realloc-posix
             -> free-posix
          -> pathmax
          -> mempcpy
          -> rawmemchr
          -> readlink
          -> stat
          -> double-slash-root
    -> relocatable
    -> setenv
       -> malloca
    -> fprintf-posix [ignore, cut dependency tree here]
    -> strerror [ignore, cut dependency tree here]
    -> c-ctype

   Macros that need to be set while compiling this file:
     - ENABLE_RELOCATABLE 1
     - INSTALLPREFIX the base installation directory
     - INSTALLDIR the directory into which this program is installed
     - LIBPATHVAR the platform dependent runtime library path variable
     - LIBDIRS a comma-terminated list of strings representing the list of
       directories that contain the libraries at installation time

   We don't want to internationalize this wrapper because then it would
   depend on libintl and therefore need relocation itself.  So use only
   libc functions, no gettext(), no error(), no xmalloc(), no xsetenv().
 */

#define _GL_USE_STDLIB_ALLOC 1
#include <config.h>

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

#include "progname.h"
#include "relocatable.h"
#include "c-ctype.h"

/* Use the system functions, not the gnulib overrides in this file.  */
#undef fprintf
#undef strerror

/* Return a copy of the filename, with an extra ".bin" at the end.
   More generally, it replaces "${EXEEXT}" at the end with ".bin${EXEEXT}".  */
static char *
add_dotbin (const char *filename)
{
  size_t filename_len = strlen (filename);
  char *result = (char *) malloc (filename_len + 4 + 1);

  if (result != NULL)
    {
      if (sizeof (EXEEXT) > sizeof (""))
        {
          /* EXEEXT handling.  */
          const size_t exeext_len = sizeof (EXEEXT) - sizeof ("");
          static const char exeext[] = EXEEXT;
          if (filename_len > exeext_len)
            {
              /* Compare using an inlined copy of c_strncasecmp(), because
                 the filenames may have undergone a case conversion since
                 they were packaged.  In other words, EXEEXT may be ".exe"
                 on one system and ".EXE" on another.  */
              const char *s1 = filename + filename_len - exeext_len;
              const char *s2 = exeext;
              for (; *s1 != '\0'; s1++, s2++)
                {
                  unsigned char c1 = *s1;
                  unsigned char c2 = *s2;
                  if (c_tolower (c1) != c_tolower (c2))
                    goto simple_append;
                }
              /* Insert ".bin" before EXEEXT or its equivalent.  */
              memcpy (result, filename, filename_len - exeext_len);
              memcpy (result + filename_len - exeext_len, ".bin", 4);
              memcpy (result + filename_len - exeext_len + 4,
                      filename + filename_len - exeext_len,
                      exeext_len + 1);
              return result;
            }
        }
     simple_append:
      /* Simply append ".bin".  */
      memcpy (result, filename, filename_len);
      memcpy (result + filename_len, ".bin", 4 + 1);
      return result;
    }
  else
    {
      fprintf (stderr, "%s: %s\n", program_name, "memory exhausted");
      exit (1);
    }
}

/* List of directories that contain the libraries.  */
static const char *libdirs[] = { LIBDIRS NULL };
/* Verify that at least one directory is given.  */
static_assert (sizeof (libdirs) / sizeof (libdirs[0]) > 1);

/* Relocate the list of directories that contain the libraries.  */
static void
relocate_libdirs ()
{
  for (size_t i = 0; i < sizeof (libdirs) / sizeof (libdirs[0]) - 1; i++)
    libdirs[i] = relocate (libdirs[i]);
}

/* Activate the list of directories in the LIBPATHVAR.  */
static void
activate_libdirs ()
{
  const char *old_value = getenv (LIBPATHVAR);
  if (old_value == NULL)
    old_value = "";

  size_t total = 0;
  for (size_t i = 0; i < sizeof (libdirs) / sizeof (libdirs[0]) - 1; i++)
    total += strlen (libdirs[i]) + 1;
  total += strlen (old_value) + 1;

  char *value = (char *) malloc (total);
  if (value == NULL)
    {
      fprintf (stderr, "%s: %s\n", program_name, "memory exhausted");
      exit (1);
    }
  {
    char *p = value;
    for (size_t i = 0; i < sizeof (libdirs) / sizeof (libdirs[0]) - 1; i++)
      {
        size_t len = strlen (libdirs[i]);
        memcpy (p, libdirs[i], len);
        p += len;
        *p++ = ':';
      }
    if (old_value[0] != '\0')
      strcpy (p, old_value);
    else
      p[-1] = '\0';
  }
  if (setenv (LIBPATHVAR, value, 1) < 0)
    {
      fprintf (stderr, "%s: %s\n", program_name, "memory exhausted");
      exit (1);
    }
}

int
main (int argc, char *argv[])
{
  /* Set the program name and perform preparations for
     get_full_program_name() and relocate().  */
  set_program_name_and_installdir (argv[0], INSTALLPREFIX, INSTALLDIR);

  /* Get the full program path.  (Important if accessed through a symlink.)  */
  char *full_program_name = get_full_program_name ();
  if (full_program_name == NULL)
    full_program_name = argv[0];

  /* Invoke the real program, with suffix ".bin".  */
  argv[0] = add_dotbin (full_program_name);
  relocate_libdirs ();
  activate_libdirs ();
  execv (argv[0], argv);
  fprintf (stderr, "%s: could not execute %s: %s\n",
           program_name, argv[0], strerror (errno));
  exit (127);
}