/*

 * BinReloc - a library for creating relocatable executables

 * Written by: Hongli Lai <[email protected]>

 * http://autopackage.org/

 *

 * This source code is public domain. You can relicense this code

 * under whatever license you want.

 *

 * See http://autopackage.org/docs/binreloc/ for

 * more information and how to use this.

 */

#ifndef __BINRELOC_C__

#define __BINRELOC_C__

#ifdef ENABLE_BINRELOC

	#include <sys/types.h>

	#include <sys/stat.h>

	#include <unistd.h>

#endif /* ENABLE_BINRELOC */

#include <stdio.h>

#include <stdlib.h>

#include <limits.h>

#include <string.h>

#include "binreloc.h"

#ifdef __cplusplus

extern "C" {

#endif /* __cplusplus */

/** @internal

 * Find the canonical filename of the executable. Returns the filename

 * (which must be freed) or NULL on error. If the parameter 'error' is

 * not NULL, the error code will be stored there, if an error occured.

 */

static char *

_br_find_exe (BrInitError *error)

{

#ifndef ENABLE_BINRELOC

	if (error)

		*error = BR_INIT_ERROR_DISABLED;

	return NULL;

#else

	char *path, *path2, *line, *result;

	size_t buf_size;

	ssize_t size;

	struct stat stat_buf;

	FILE *f;

	/* Read from /proc/self/exe (symlink) */

	if (sizeof (path) > SSIZE_MAX)

		buf_size = SSIZE_MAX - 1;

	else

		buf_size = PATH_MAX - 1;

	path = (char *) malloc (buf_size);

	if (path == NULL) {

		/* Cannot allocate memory. */

		if (error)

			*error = BR_INIT_ERROR_NOMEM;

		return NULL;

	}

	path2 = (char *) malloc (buf_size);

	if (path2 == NULL) {

		/* Cannot allocate memory. */

		if (error)

			*error = BR_INIT_ERROR_NOMEM;

		free (path);

		return NULL;

	}

	strncpy (path2, "/proc/self/exe", buf_size - 1);

	while (1) {

		int i;

		size = readlink (path2, path, buf_size - 1);

		if (size == -1) {

			/* Error. */

			free (path2);

			break;

		}

		/* readlink() success. */

		path[size] = '\0';

		/* Check whether the symlink's target is also a symlink.

		 * We want to get the final target. */

		i = stat (path, &stat_buf);

		if (i == -1) {

			/* Error. */

			free (path2);

			break;

		}

		/* stat() success. */

		if (!S_ISLNK (stat_buf.st_mode)) {

			/* path is not a symlink. Done. */

			free (path2);

			return path;

		}

		/* path is a symlink. Continue loop and resolve this. */

		strncpy (path, path2, buf_size - 1);

	}

	/* readlink() or stat() failed; this can happen when the program is

	 * running in Valgrind 2.2. Read from /proc/self/maps as fallback. */

	buf_size = PATH_MAX + 128;

	line = (char *) realloc (path, buf_size);

	if (line == NULL) {

		/* Cannot allocate memory. */

		free (path);

		if (error)

			*error = BR_INIT_ERROR_NOMEM;

		return NULL;

	}

	f = fopen ("/proc/self/maps", "r");

	if (f == NULL) {

		free (line);

		if (error)

			*error = BR_INIT_ERROR_OPEN_MAPS;

		return NULL;

	}

	/* The first entry should be the executable name. */

	result = fgets (line, (int) buf_size, f);

	if (result == NULL) {

		fclose (f);

		free (line);

		if (error)

			*error = BR_INIT_ERROR_READ_MAPS;

		return NULL;

	}

	/* Get rid of newline character. */

	buf_size = strlen (line);

	if (buf_size <= 0) {

		/* Huh? An empty string? */

		fclose (f);

		free (line);

		if (error)

			*error = BR_INIT_ERROR_INVALID_MAPS;

		return NULL;

	}

	if (line[buf_size - 1] == 10)

		line[buf_size - 1] = 0;

	/* Extract the filename; it is always an absolute path. */

	path = strchr (line, '/');

	/* Sanity check. */

	if (strstr (line, " r-xp ") == NULL || path == NULL) {

		fclose (f);

		free (line);

		if (error)

			*error = BR_INIT_ERROR_INVALID_MAPS;

		return NULL;

	}

	path = strdup (path);

	free (line);

	fclose (f);

	return path;

#endif /* ENABLE_BINRELOC */

}

/** @internal

 * Find the canonical filename of the executable which owns symbol.

 * Returns a filename which must be freed, or NULL on error.

 */

static char *

_br_find_exe_for_symbol (const void *symbol, BrInitError *error)

{

#ifndef ENABLE_BINRELOC

	if (error)

		*error = BR_INIT_ERROR_DISABLED;

	return (char *) NULL;

#else

	#define SIZE PATH_MAX + 100

	FILE *f;

	size_t address_string_len;

	char *address_string, line[SIZE], *found;

	if (symbol == NULL)

		return (char *) NULL;

	f = fopen ("/proc/self/maps", "r");

	if (f == NULL)

		return (char *) NULL;

	address_string_len = 4;

	address_string = (char *) malloc (address_string_len);

	found = (char *) NULL;

	while (!feof (f)) {

		char *start_addr, *end_addr, *end_addr_end, *file;

		void *start_addr_p, *end_addr_p;

		size_t len;

		if (fgets (line, SIZE, f) == NULL)

			break;

		/* Sanity check. */

		if (strstr (line, " r-xp ") == NULL || strchr (line, '/') == NULL)

			continue;

		/* Parse line. */

		start_addr = line;

		end_addr = strchr (line, '-');

		file = strchr (line, '/');

		/* More sanity check. */

		if (!(file > end_addr && end_addr != NULL && end_addr[0] == '-'))

			continue;

		end_addr[0] = '\0';

		end_addr++;

		end_addr_end = strchr (end_addr, ' ');

		if (end_addr_end == NULL)

			continue;

		end_addr_end[0] = '\0';

		len = strlen (file);

		if (len == 0)

			continue;

		if (file[len - 1] == '\n')

			file[len - 1] = '\0';

		/* Get rid of "(deleted)" from the filename. */

		len = strlen (file);

		if (len > 10 && strcmp (file + len - 10, " (deleted)") == 0)

			file[len - 10] = '\0';

		/* I don't know whether this can happen but better safe than sorry. */

		len = strlen (start_addr);

		if (len != strlen (end_addr))

			continue;

		/* Transform the addresses into a string in the form of 0xdeadbeef,

		 * then transform that into a pointer. */

		if (address_string_len < len + 3) {

			address_string_len = len + 3;

			address_string = (char *) realloc (address_string, address_string_len);

		}

		memcpy (address_string, "0x", 2);

		memcpy (address_string + 2, start_addr, len);

		address_string[2 + len] = '\0';

		sscanf (address_string, "%p", &start_addr_p);

		memcpy (address_string, "0x", 2);

		memcpy (address_string + 2, end_addr, len);

		address_string[2 + len] = '\0';

		sscanf (address_string, "%p", &end_addr_p);

		if (symbol >= start_addr_p && symbol < end_addr_p) {

			found = file;

			break;

		}

	}

	free (address_string);

	fclose (f);

	if (found == NULL)

		return (char *) NULL;

	else

		return strdup (found);

#endif /* ENABLE_BINRELOC */

}

#ifndef BINRELOC_RUNNING_DOXYGEN

	#undef NULL

	#define NULL ((void *) 0) /* typecasted as char* for C++ type safeness */

#endif

static char *exe = (char *) NULL;

/** Initialize the BinReloc library (for applications).

 *

 * This function must be called before using any other BinReloc functions.

 * It attempts to locate the application's canonical filename.

 *

 * @note If you want to use BinReloc for a library, then you should call

 *       br_init_lib() instead.

 *

 * @param error  If BinReloc failed to initialize, then the error code will

 *               be stored in this variable. Set to NULL if you want to

 *               ignore this. See #BrInitError for a list of error codes.

 *

 * @returns 1 on success, 0 if BinReloc failed to initialize.

 */

int

br_init (BrInitError *error)

{

	exe = _br_find_exe (error);

	return exe != NULL;

}

/** Initialize the BinReloc library (for libraries).

 *

 * This function must be called before using any other BinReloc functions.

 * It attempts to locate the calling library's canonical filename.

 *

 * @note The BinReloc source code MUST be included in your library, or this

 *       function won't work correctly.

 *

 * @param error  If BinReloc failed to initialize, then the error code will

 *               be stored in this variable. Set to NULL if you want to

 *               ignore this. See #BrInitError for a list of error codes.

 *

 * @returns 1 on success, 0 if a filename cannot be found.

 */

int

br_init_lib (BrInitError *error)

{

	exe = _br_find_exe_for_symbol ((const void *) "", error);

	return exe != NULL;

}

/** Find the canonical filename of the current application.

 *

 * @param default_exe  A default filename which will be used as fallback.

 * @returns A string containing the application's canonical filename,

 *          which must be freed when no longer necessary. If BinReloc is

 *          not initialized, or if br_init() failed, then a copy of

 *          default_exe will be returned. If default_exe is NULL, then

 *          NULL will be returned.

 */

char *

br_find_exe (const char *default_exe)

{

	if (exe == (char *) NULL) {

		/* BinReloc is not initialized. */

		if (default_exe != (const char *) NULL)

			return strdup (default_exe);

		else

			return (char *) NULL;

	}

	return strdup (exe);

}

/** Locate the directory in which the current application is installed.

 *

 * The prefix is generated by the following pseudo-code evaluation:

 * \code

 * dirname(exename)

 * \endcode

 *

 * @param default_dir  A default directory which will used as fallback.

 * @return A string containing the directory, which must be freed when no

 *         longer necessary. If BinReloc is not initialized, or if the

 *         initialization function failed, then a copy of default_dir

 *         will be returned. If default_dir is NULL, then NULL will be

 *         returned.

 */

char *

br_find_exe_dir (const char *default_dir)

{

	if (exe == NULL) {

		/* BinReloc not initialized. */

		if (default_dir != NULL)

			return strdup (default_dir);

		else

			return NULL;

	}

	return br_dirname (exe);

}

/** Locate the prefix in which the current application is installed.

 *

 * The prefix is generated by the following pseudo-code evaluation:

 * \code

 * dirname(dirname(exename))

 * \endcode

 *

 * @param default_prefix  A default prefix which will used as fallback.

 * @return A string containing the prefix, which must be freed when no

 *         longer necessary. If BinReloc is not initialized, or if

 *         the initialization function failed, then a copy of default_prefix

 *         will be returned. If default_prefix is NULL, then NULL will be returned.

 */

char *

br_find_prefix (const char *default_prefix)

{

	char *dir1, *dir2;

	if (exe == (char *) NULL) {

		/* BinReloc not initialized. */

		if (default_prefix != (const char *) NULL)

			return strdup (default_prefix);

		else

			return (char *) NULL;

	}

	dir1 = br_dirname (exe);

	dir2 = br_dirname (dir1);

	free (dir1);

	return dir2;

}

/** Locate the application's binary folder.

 *

 * The path is generated by the following pseudo-code evaluation:

 * \code

 * prefix + "/bin"

 * \endcode

 *

 * @param default_bin_dir  A default path which will used as fallback.

 * @return A string containing the bin folder's path, which must be freed when

 *         no longer necessary. If BinReloc is not initialized, or if

 *         the initialization function failed, then a copy of default_bin_dir will

 *         be returned. If default_bin_dir is NULL, then NULL will be returned.

 */

char *

br_find_bin_dir (const char *default_bin_dir)

{

	char *prefix, *dir;

	prefix = br_find_prefix ((const char *) NULL);

	if (prefix == (char *) NULL) {

		/* BinReloc not initialized. */

		if (default_bin_dir != (const char *) NULL)

			return strdup (default_bin_dir);

		else

			return (char *) NULL;

	}

	dir = br_build_path (prefix, "bin");

	free (prefix);

	return dir;

}

/** Locate the application's superuser binary folder.

 *

 * The path is generated by the following pseudo-code evaluation:

 * \code

 * prefix + "/sbin"

 * \endcode

 *

 * @param default_sbin_dir  A default path which will used as fallback.

 * @return A string containing the sbin folder's path, which must be freed when

 *         no longer necessary. If BinReloc is not initialized, or if the

 *         initialization function failed, then a copy of default_sbin_dir will

 *         be returned. If default_bin_dir is NULL, then NULL will be returned.

 */

char *

br_find_sbin_dir (const char *default_sbin_dir)

{

	char *prefix, *dir;

	prefix = br_find_prefix ((const char *) NULL);

	if (prefix == (char *) NULL) {

		/* BinReloc not initialized. */

		if (default_sbin_dir != (const char *) NULL)

			return strdup (default_sbin_dir);

		else

			return (char *) NULL;

	}

	dir = br_build_path (prefix, "sbin");

	free (prefix);

	return dir;

}

/** Locate the application's data folder.

 *

 * The path is generated by the following pseudo-code evaluation:

 * \code

 * prefix + "/share"

 * \endcode

 *

 * @param default_data_dir  A default path which will used as fallback.

 * @return A string containing the data folder's path, which must be freed when

 *         no longer necessary. If BinReloc is not initialized, or if the

 *         initialization function failed, then a copy of default_data_dir

 *         will be returned. If default_data_dir is NULL, then NULL will be

 *         returned.

 */

char *

br_find_data_dir (const char *default_data_dir)

{

	char *prefix, *dir;

	prefix = br_find_prefix ((const char *) NULL);

	if (prefix == (char *) NULL) {

		/* BinReloc not initialized. */

		if (default_data_dir != (const char *) NULL)

			return strdup (default_data_dir);

		else

			return (char *) NULL;

	}

	dir = br_build_path (prefix, "share");

	free (prefix);

	return dir;

}

/** Locate the application's localization folder.

 *

 * The path is generated by the following pseudo-code evaluation:

 * \code

 * prefix + "/share/locale"

 * \endcode

 *

 * @param default_locale_dir  A default path which will used as fallback.

 * @return A string containing the localization folder's path, which must be freed when

 *         no longer necessary. If BinReloc is not initialized, or if the

 *         initialization function failed, then a copy of default_locale_dir will be returned.

 *         If default_locale_dir is NULL, then NULL will be returned.

 */

char *

br_find_locale_dir (const char *default_locale_dir)

{

	char *data_dir, *dir;

	data_dir = br_find_data_dir ((const char *) NULL);

	if (data_dir == (char *) NULL) {

		/* BinReloc not initialized. */

		if (default_locale_dir != (const char *) NULL)

			return strdup (default_locale_dir);

		else

			return (char *) NULL;

	}

	dir = br_build_path (data_dir, "locale");

	free (data_dir);

	return dir;

}

/** Locate the application's library folder.

 *

 * The path is generated by the following pseudo-code evaluation:

 * \code

 * prefix + "/lib"

 * \endcode

 *

 * @param default_lib_dir  A default path which will used as fallback.

 * @return A string containing the library folder's path, which must be freed when

 *         no longer necessary. If BinReloc is not initialized, or if the initialization

 *         function failed, then a copy of default_lib_dir will be returned.

 *         If default_lib_dir is NULL, then NULL will be returned.

 */

char *

br_find_lib_dir (const char *default_lib_dir)

{

	char *prefix, *dir;

	prefix = br_find_prefix ((const char *) NULL);

	if (prefix == (char *) NULL) {

		/* BinReloc not initialized. */

		if (default_lib_dir != (const char *) NULL)

			return strdup (default_lib_dir);

		else

			return (char *) NULL;

	}

	dir = br_build_path (prefix, "lib");

	free (prefix);

	return dir;

}

/** Locate the application's libexec folder.

 *

 * The path is generated by the following pseudo-code evaluation:

 * \code

 * prefix + "/libexec"

 * \endcode

 *

 * @param default_libexec_dir  A default path which will used as fallback.

 * @return A string containing the libexec folder's path, which must be freed when

 *         no longer necessary. If BinReloc is not initialized, or if the initialization

 *         function failed, then a copy of default_libexec_dir will be returned.

 *         If default_libexec_dir is NULL, then NULL will be returned.

 */

char *

br_find_libexec_dir (const char *default_libexec_dir)

{

	char *prefix, *dir;

	prefix = br_find_prefix ((const char *) NULL);

	if (prefix == (char *) NULL) {

		/* BinReloc not initialized. */

		if (default_libexec_dir != (const char *) NULL)

			return strdup (default_libexec_dir);

		else

			return (char *) NULL;

	}

	dir = br_build_path (prefix, "libexec");

	free (prefix);

	return dir;

}

/** Locate the application's configuration files folder.

 *

 * The path is generated by the following pseudo-code evaluation:

 * \code

 * prefix + "/etc"

 * \endcode

 *

 * @param default_etc_dir  A default path which will used as fallback.

 * @return A string containing the etc folder's path, which must be freed when

 *         no longer necessary. If BinReloc is not initialized, or if the initialization

 *         function failed, then a copy of default_etc_dir will be returned.

 *         If default_etc_dir is NULL, then NULL will be returned.

 */

char *