path: root/lib/relocatable.c

/* Provide relocatable packages.
   Copyright (C) 2003-2006, 2008-2016 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 either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.
   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 Lesser General Public License for more details.

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


/* Tell glibc's <stdio.h> to provide a prototype for getline().
   This must come before <config.h> because <config.h> may include
   <features.h>, and once <features.h> has been included, it's too late.  */
#ifndef _GNU_SOURCE
# define _GNU_SOURCE 1
#endif

#define _GL_USE_STDLIB_ALLOC 1
#include <config.h>

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

#if ENABLE_RELOCATABLE

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

#ifdef NO_XMALLOC
# define xmalloc malloc
#else
# include "xalloc.h"
#endif

#if (defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__
# define WIN32_LEAN_AND_MEAN
# include <windows.h>
#endif

#ifdef __EMX__
# define INCL_DOS
# include <os2.h>

# define strcmp  stricmp
# define strncmp strnicmp
#endif

#if DEPENDS_ON_LIBCHARSET
# include <libcharset.h>
#endif
#if DEPENDS_ON_LIBICONV && HAVE_ICONV
# include <iconv.h>
#endif
#if DEPENDS_ON_LIBINTL && ENABLE_NLS
# include <libintl.h>
#endif

/* Faked cheap 'bool'.  */
#undef bool
#undef false
#undef true
#define bool int
#define false 0
#define true 1

/* Pathname support.
   ISSLASH(C)           tests whether C is a directory separator character.
   IS_PATH_WITH_DIR(P)  tests whether P contains a directory specification.
 */
#if ((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__) || defined __EMX__ || defined __DJGPP__
  /* Native Windows, OS/2, DOS */
# define ISSLASH(C) ((C) == '/' || (C) == '\\')
# define HAS_DEVICE(P) \
    ((((P)[0] >= 'A' && (P)[0] <= 'Z') || ((P)[0] >= 'a' && (P)[0] <= 'z')) \
     && (P)[1] == ':')
# define IS_PATH_WITH_DIR(P) \
    (strchr (P, '/') != NULL || strchr (P, '\\') != NULL || HAS_DEVICE (P))
# define FILE_SYSTEM_PREFIX_LEN(P) (HAS_DEVICE (P) ? 2 : 0)
#else
  /* Unix */
# define ISSLASH(C) ((C) == '/')
# define IS_PATH_WITH_DIR(P) (strchr (P, '/') != NULL)
# define FILE_SYSTEM_PREFIX_LEN(P) 0
#endif

/* Whether to enable the more costly support for relocatable libraries.
   It allows libraries to be have been installed with a different original
   prefix than the program.  But it is quite costly, especially on Cygwin
   platforms, see below.  Therefore we enable it by default only on native
   Windows platforms.  */
#ifndef ENABLE_COSTLY_RELOCATABLE
# if (defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__
#  define ENABLE_COSTLY_RELOCATABLE 1
# else
#  define ENABLE_COSTLY_RELOCATABLE 0
# endif
#endif

/* Original installation prefix.  */
static char *orig_prefix;
static size_t orig_prefix_len;
/* Current installation prefix.  */
static char *curr_prefix;
static size_t curr_prefix_len;
/* These prefixes do not end in a slash.  Anything that will be concatenated
   to them must start with a slash.  */

/* Sets the original and the current installation prefix of this module.
   Relocation simply replaces a pathname starting with the original prefix
   by the corresponding pathname with the current prefix instead.  Both
   prefixes should be directory names without trailing slash (i.e. use ""
   instead of "/").  */
static void
set_this_relocation_prefix (const char *orig_prefix_arg,
                            const char *curr_prefix_arg)
{
  if (orig_prefix_arg != NULL && curr_prefix_arg != NULL
      /* Optimization: if orig_prefix and curr_prefix are equal, the
         relocation is a nop.  */
      && strcmp (orig_prefix_arg, curr_prefix_arg) != 0)
    {
      /* Duplicate the argument strings.  */
      char *memory;

      orig_prefix_len = strlen (orig_prefix_arg);
      curr_prefix_len = strlen (curr_prefix_arg);
      memory = (char *) xmalloc (orig_prefix_len + 1 + curr_prefix_len + 1);
#ifdef NO_XMALLOC
      if (memory != NULL)
#endif
        {
          memcpy (memory, orig_prefix_arg, orig_prefix_len + 1);
          orig_prefix = memory;
          memory += orig_prefix_len + 1;
          memcpy (memory, curr_prefix_arg, curr_prefix_len + 1);
          curr_prefix = memory;
          return;
        }
    }
  orig_prefix = NULL;
  curr_prefix = NULL;
  /* Don't worry about wasted memory here - this function is usually only
     called once.  */
}

/* Sets the original and the current installation prefix of the package.
   Relocation simply replaces a pathname starting with the original prefix
   by the corresponding pathname with the current prefix instead.  Both
   prefixes should be directory names without trailing slash (i.e. use ""
   instead of "/").  */
void
set_relocation_prefix (const char *orig_prefix_arg, const char *curr_prefix_arg)
{
  set_this_relocation_prefix (orig_prefix_arg, curr_prefix_arg);

  /* Now notify all dependent libraries.  */
#if DEPENDS_ON_LIBCHARSET
  libcharset_set_relocation_prefix (orig_prefix_arg, curr_prefix_arg);
#endif
#if DEPENDS_ON_LIBICONV && HAVE_ICONV && _LIBICONV_VERSION >= 0x0109
  libiconv_set_relocation_prefix (orig_prefix_arg, curr_prefix_arg);
#endif
#if DEPENDS_ON_LIBINTL && ENABLE_NLS && defined libintl_set_relocation_prefix
  libintl_set_relocation_prefix (orig_prefix_arg, curr_prefix_arg);
#endif
}

#if !defined IN_LIBRARY || (defined PIC && defined INSTALLDIR && ENABLE_COSTLY_RELOCATABLE)

/* Convenience function:
   Computes the current installation prefix, based on the original
   installation prefix, the original installation directory of a particular
   file, and the current pathname of this file.
   Returns it, freshly allocated.  Returns NULL upon failure.  */
#ifdef IN_LIBRARY
#define compute_curr_prefix local_compute_curr_prefix
static
#endif
char *
compute_curr_prefix (const char *orig_installprefix,
                     const char *orig_installdir,
                     const char *curr_pathname)
{
  char *curr_installdir;
  const char *rel_installdir;

  if (curr_pathname == NULL)
    return NULL;

  /* Determine the relative installation directory, relative to the prefix.
     This is simply the difference between orig_installprefix and
     orig_installdir.  */
  if (strncmp (orig_installprefix, orig_installdir, strlen (orig_installprefix))
      != 0)
    /* Shouldn't happen - nothing should be installed outside $(prefix).  */
    return NULL;
  rel_installdir = orig_installdir + strlen (orig_installprefix);

  /* Determine the current installation directory.  */
  {
    const char *p_base = curr_pathname + FILE_SYSTEM_PREFIX_LEN (curr_pathname);
    const char *p = curr_pathname + strlen (curr_pathname);
    char *q;

    while (p > p_base)
      {
        p--;
        if (ISSLASH (*p))
          break;
      }

    q = (char *) xmalloc (p - curr_pathname + 1);
#ifdef NO_XMALLOC
    if (q == NULL)
      return NULL;
#endif
    memcpy (q, curr_pathname, p - curr_pathname);
    q[p - curr_pathname] = '\0';
    curr_installdir = q;
  }

  /* Compute the current installation prefix by removing the trailing
     rel_installdir from it.  */
  {
    const char *rp = rel_installdir + strlen (rel_installdir);
    const char *cp = curr_installdir + strlen (curr_installdir);
    const char *cp_base =
      curr_installdir + FILE_SYSTEM_PREFIX_LEN (curr_installdir);

    while (rp > rel_installdir && cp > cp_base)
      {
        bool same = false;
        const char *rpi = rp;
        const char *cpi = cp;

        while (rpi > rel_installdir && cpi > cp_base)
          {
            rpi--;
            cpi--;
            if (ISSLASH (*rpi) || ISSLASH (*cpi))
              {
                if (ISSLASH (*rpi) && ISSLASH (*cpi))
                  same = true;
                break;
              }
            /* Do case-insensitive comparison if the file system is always or
               often case-insensitive.  It's better to accept the comparison
               if the difference is only in case, rather than to fail.  */
#if defined _WIN32 || defined __WIN32__ || defined __CYGWIN__ || defined __EMX__ || defined __DJGPP__
            /* Native Windows, Cygwin, OS/2, DOS - case insignificant file system */
            if ((*rpi >= 'a' && *rpi <= 'z' ? *rpi - 'a' + 'A' : *rpi)
                != (*cpi >= 'a' && *cpi <= 'z' ? *cpi - 'a' + 'A' : *cpi))
              break;
#else
            if (*rpi != *cpi)
              break;
#endif
          }
        if (!same)
          break;
        /* The last pathname component was the same.  opi and cpi now point
           to the slash before it.  */
        rp = rpi;
        cp = cpi;
      }

    if (rp > rel_installdir)
      {
        /* Unexpected: The curr_installdir does not end with rel_installdir.  */
        free (curr_installdir);
        return NULL;
      }

    {
      size_t curr_prefix_len = cp - curr_installdir;
      char *curr_prefix;

      curr_prefix = (char *) xmalloc (curr_prefix_len + 1);
#ifdef NO_XMALLOC
      if (curr_prefix == NULL)
        {
          free (curr_installdir);
          return NULL;
        }
#endif
      memcpy (curr_prefix, curr_installdir, curr_prefix_len);
      curr_prefix[curr_prefix_len] = '\0';

      free (curr_installdir);

      return curr_prefix;
    }
  }
}

#endif /* !IN_LIBRARY || PIC */

#if defined PIC && defined INSTALLDIR && ENABLE_COSTLY_RELOCATABLE

/* Full pathname of shared library, or NULL.  */
static char *shared_library_fullname;

#if (defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__
/* Native Windows only.
   On Cygwin, it is better to use the Cygwin provided /proc interface, than
   to use native Windows API and cygwin_conv_to_posix_path, because it
   supports longer file names
   (see <http://cygwin.com/ml/cygwin/2011-01/msg00410.html>).  */

/* Determine the full pathname of the shared library when it is loaded.  */

BOOL WINAPI
DllMain (HINSTANCE module_handle, DWORD event, LPVOID reserved)
{
  (void) reserved;

  if (event == DLL_PROCESS_ATTACH)
    {
      /* The DLL is being loaded into an application's address range.  */
      static char location[MAX_PATH];

      if (!GetModuleFileName (module_handle, location, sizeof (location)))
        /* Shouldn't happen.  */
        return FALSE;

      if (!IS_PATH_WITH_DIR (location))
        /* Shouldn't happen.  */
        return FALSE;

      shared_library_fullname = strdup (location);
    }

  return TRUE;
}

#elif defined __EMX__

extern int  _CRT_init (void);
extern void _CRT_term (void);
extern void __ctordtorInit (void);
extern void __ctordtorTerm (void);

unsigned long _System
_DLL_InitTerm (unsigned long hModule, unsigned long ulFlag)
{
  static char location[CCHMAXPATH];

  switch (ulFlag)
    {
      case 0:
        if (_CRT_init () == -1)
          return 0;

        __ctordtorInit();

        /* See http://cyberkinetica.homeunix.net/os2tk45/cp1/1247_L2H_DosQueryModuleNameSy.html
           for specification of DosQueryModuleName(). */
        if (DosQueryModuleName (hModule, sizeof (location), location))
          return 0;

        _fnslashify (location);
        shared_library_fullname = strdup (location);
        break;

      case 1:
        __ctordtorTerm();

        _CRT_term ();
        break;
    }

  return 1;
}

#else /* Unix */

static void
find_shared_library_fullname ()
{
#if (defined __linux__ && (__GLIBC__ >= 2 || defined __UCLIBC__)) || defined __CYGWIN__
  /* Linux has /proc/self/maps. glibc 2 and uClibc have the getline()
     function.
     Cygwin >= 1.5 has /proc/self/maps and the getline() function too.
     But it is costly: ca. 0.3 ms on Linux, 3 ms on Cygwin 1.5, and 5 ms on
     Cygwin 1.7.  */
  FILE *fp;

  /* Open the current process' maps file.  It describes one VMA per line.  */
  fp = fopen ("/proc/self/maps", "r");
  if (fp)
    {
      unsigned long address = (unsigned long) &find_shared_library_fullname;
      for (;;)
        {
          unsigned long start, end;
          int c;

          if (fscanf (fp, "%lx-%lx", &start, &end) != 2)
            break;
          if (address >= start && address <= end - 1)
            {
              /* Found it.  Now see if this line contains a filename.  */
              while (c = getc (fp), c != EOF && c != '\n' && c != '/')
                continue;
              if (c == '/')
                {
                  size_t size;
                  int len;

                  ungetc (c, fp);
                  shared_library_fullname = NULL; size = 0;
                  len = getline (&shared_library_fullname, &size, fp);
                  if (len >= 0)
                    {
                      /* Success: filled shared_library_fullname.  */
                      if (len > 0 && shared_library_fullname[len - 1] == '\n')
                        shared_library_fullname[len - 1] = '\0';
                    }
                }
              break;
            }
          while (c = getc (fp), c != EOF && c != '\n')
            continue;
        }
      fclose (fp);
    }
#endif
}

#endif /* Native Windows / EMX / Unix */

/* Return the full pathname of the current shared library.
   Return NULL if unknown.
   Guaranteed to work only on Linux, EMX, Cygwin, and native Windows.  */
static char *
get_shared_library_fullname ()
{
#if (!((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__) \
     && !defined __EMX__)
  static bool tried_find_shared_library_fullname;
  if (!tried_find_shared_library_fullname)
    {
      find_shared_library_fullname ();
      tried_find_shared_library_fullname = true;
    }
#endif
  return shared_library_fullname;
}

#endif /* PIC */

/* Returns the pathname, relocated according to the current installation
   directory.
   The returned string is either PATHNAME unmodified or a freshly allocated
   string that you can free with free() after casting it to 'char *'.  */
const char *
relocate (const char *pathname)
{
#if defined PIC && defined INSTALLDIR && ENABLE_COSTLY_RELOCATABLE
  static int initialized;

  /* Initialization code for a shared library.  */
  if (!initialized)
    {
      /* At this point, orig_prefix and curr_prefix likely have already been
         set through the main program's set_program_name_and_installdir
         function.  This is sufficient in the case that the library has
         initially been installed in the same orig_prefix.  But we can do
         better, to also cover the cases that 1. it has been installed
         in a different prefix before being moved to orig_prefix and (later)
         to curr_prefix, 2. unlike the program, it has not moved away from
         orig_prefix.  */
      const char *orig_installprefix = INSTALLPREFIX;
      const char *orig_installdir = INSTALLDIR;
      char *curr_prefix_better;

      curr_prefix_better =
        compute_curr_prefix (orig_installprefix, orig_installdir,
                             get_shared_library_fullname ());

      set_relocation_prefix (orig_installprefix,
                             curr_prefix_better != NULL
                             ? curr_prefix_better
                             : curr_prefix);

      if (curr_prefix_better != NULL)
        free (curr_prefix_better);

      initialized = 1;
    }
#endif

  /* Note: It is not necessary to perform case insensitive comparison here,
     even for DOS-like file systems, because the pathname argument was
     typically created from the same Makefile variable as orig_prefix came
     from.  */
  if (orig_prefix != NULL && curr_prefix != NULL
      && strncmp (pathname, orig_prefix, orig_prefix_len) == 0)
    {
      if (pathname[orig_prefix_len] == '\0')
        {
          /* pathname equals orig_prefix.  */
          char *result = (char *) xmalloc (strlen (curr_prefix) + 1);

#ifdef NO_XMALLOC
          if (result != NULL)
#endif
            {
              strcpy (result, curr_prefix);
              return result;
            }
        }
      else if (ISSLASH (pathname[orig_prefix_len]))
        {
          /* pathname starts with orig_prefix.  */
          const char *pathname_tail = &pathname[orig_prefix_len];
          char *result =
            (char *) xmalloc (curr_prefix_len + strlen (pathname_tail) + 1);

#ifdef NO_XMALLOC
          if (result != NULL)
#endif
            {
              memcpy (result, curr_prefix, curr_prefix_len);
              strcpy (result + curr_prefix_len, pathname_tail);
              return result;
            }
        }
    }

#ifdef __EMX__
# ifdef __KLIBC__
#  undef strncmp

  if (pathname && strncmp (pathname, "/@unixroot", 10) == 0
      && (pathname[10] == '\0' || pathname[10] == '/' || pathname[10] == '\\'))
    {
      /* kLIBC itself processes /@unixroot prefix */

      return pathname;
    }
  else
# endif
  if (pathname && ISSLASH (pathname[0]))
    {
      const char *unixroot = getenv ("UNIXROOT");

      if (unixroot && HAS_DEVICE (unixroot) && !unixroot[2])
        {
          char *result = (char *) xmalloc (2 + strlen (pathname) + 1);
#ifdef NO_XMALLOC
          if (result != NULL)
#endif
            {
              strcpy (result, unixroot);
              strcpy (result + 2, pathname);
              return result;
            }
        }
    }
#endif

  /* Nothing to relocate.  */
  return pathname;
}

#endif