/* Provide relocatable packages.

   Copyright (C) 2003 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 Library General Public License as published

   by the Free Software Foundation; either version 2, 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

   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public

   License along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301,

   USA.  */

/* 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

#ifdef HAVE_CONFIG_H

# include "config.h"

#endif

/* 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 "xmalloc.h"

#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 __EMX__ || defined __DJGPP__

  /* Win32, 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 FILESYSTEM_PREFIX_LEN(P) (HAS_DEVICE (P) ? 2 : 0)

#else

  /* Unix */

# define ISSLASH(C) ((C) == '/')

# define IS_PATH_WITH_DIR(P) (strchr (P, '/') != NULL)

# define FILESYSTEM_PREFIX_LEN(P) 0

#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

}

/* 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 NULL upon failure.  */

#ifdef IN_LIBRARY

#define compute_curr_prefix local_compute_curr_prefix

static

#endif

const char *

compute_curr_prefix (const char *orig_installprefix,

		     const char *orig_installdir,

		     const char *curr_pathname)

{

  const 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 + FILESYSTEM_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 + FILESYSTEM_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;

	      }

#if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__

	    /* Win32, OS/2, DOS - case insignificant filesystem */

	    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.  */

      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)

	return NULL;

#endif

      memcpy (curr_prefix, curr_installdir, curr_prefix_len);

      curr_prefix[curr_prefix_len] = '\0';

      return curr_prefix;

    }

  }

}

#if defined PIC && defined INSTALLDIR

/* Full pathname of shared library, or NULL.  */

static char *shared_library_fullname;

#if defined _WIN32 || defined __WIN32__

/* 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;

}

#else /* Unix */

static void

find_shared_library_fullname ()

{

#ifdef __linux__

  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 /* WIN32 / Unix */

/* Return the full pathname of the current shared library.

   Return NULL if unknown.

   Guaranteed to work only on Linux and Woe32.  */

static char *

get_shared_library_fullname ()

{

#if !(defined _WIN32 || defined __WIN32__)

  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.  */

const char *

relocate (const char *pathname)

{

#if defined PIC && defined INSTALLDIR

  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;

      const char *curr_prefix_better;

      curr_prefix_better =

	compute_curr_prefix (orig_installprefix, orig_installdir,

			     get_shared_library_fullname ());

      if (curr_prefix_better == NULL)

	curr_prefix_better = curr_prefix;

      set_relocation_prefix (orig_installprefix, curr_prefix_better);

      initialized = 1;

    }

#endif

  /* Note: It is not necessary to perform case insensitive comparison here,

     even for DOS-like filesystems, 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.  */

	return curr_prefix;

      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;

	    }

	}

    }

  /* Nothing to relocate.  */

  return pathname;

}

#endif