470 lines
13 KiB
C
470 lines
13 KiB
C
/*
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* BinReloc - a library for creating relocatable executables
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* Written by: Hongli Lai <h.lai@chello.nl>
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* http://autopackage.org/
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*
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* This source code is public domain. You can relicense this code
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* under whatever license you want.
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*
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* See http://autopackage.org/docs/binreloc/ for
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* more information and how to use this.
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*/
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#include "config.h"
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#include <stdlib.h>
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#include <limits.h>
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#include <string.h>
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#if defined(ENABLE_RELOCATABLE_RESOURCES) && ! defined(G_OS_WIN32)
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#endif /* ENABLE_RELOCATABLE_RESOURCES && ! G_OS_WIN32 */
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#include <gio/gio.h>
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#include <glib.h>
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#include <glib/gstdio.h>
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#include "pikareloc.h"
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/*
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* Find the canonical filename of the executable. Returns the filename
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* (which must be freed) or NULL on error. If the parameter 'error' is
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* not NULL, the error code will be stored there, if an error occurred.
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*/
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static char *
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_br_find_exe (PikaBinrelocInitError *error)
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{
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#if ! defined(ENABLE_RELOCATABLE_RESOURCES) || defined(G_OS_WIN32) || defined(__APPLE__)
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if (error)
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*error = PIKA_RELOC_INIT_ERROR_DISABLED;
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return NULL;
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#else
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GDataInputStream *data_input;
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GInputStream *input;
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GFile *file;
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GError *gerror = NULL;
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gchar *path;
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gchar *sym_path;
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gchar *maps_line;
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sym_path = g_strdup ("/proc/self/exe");
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while (1)
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{
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struct stat stat_buf;
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int i;
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/* Do not use readlink() with a buffer of size PATH_MAX because
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* some systems actually allow paths of bigger size. Thus this
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* macro is kind of bogus. Some systems like Hurd will not even
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* define it (see MR !424).
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* g_file_read_link() on the other hand will return a size of
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* appropriate size, with newline removed and NUL terminator
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* added.
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*/
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path = g_file_read_link (sym_path, &gerror);
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g_free (sym_path);
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if (! path)
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{
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/* Read link fails but we can try reading /proc/self/maps as
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* an alternate method.
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*/
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g_printerr ("%s: %s\n", G_STRFUNC, gerror->message);
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g_clear_error (&gerror);
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break;
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}
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/* Check whether the symlink's target is also a symlink.
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* We want to get the final target. */
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i = stat (path, &stat_buf);
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if (i == -1)
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{
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/* Error. */
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break;
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}
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/* stat() success. */
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if (! S_ISLNK (stat_buf.st_mode))
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{
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/* path is not a symlink. Done. */
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return path;
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}
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/* path is a symlink. Continue loop and resolve this. */
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sym_path = path;
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}
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/* readlink() or stat() failed; this can happen when the program is
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* running in Valgrind 2.2. Read from /proc/self/maps as fallback. */
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file = g_file_new_for_path ("/proc/self/maps");
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input = G_INPUT_STREAM (g_file_read (file, NULL, &gerror));
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g_object_unref (file);
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if (! input)
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{
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g_printerr ("%s: %s", G_STRFUNC, gerror->message);
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g_clear_error (&gerror);
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if (error)
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*error = PIKA_RELOC_INIT_ERROR_OPEN_MAPS;
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return NULL;
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}
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data_input = g_data_input_stream_new (input);
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g_object_unref (input);
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/* The first entry with r-xp permission should be the executable name. */
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while ((maps_line = g_data_input_stream_read_line (data_input, NULL, NULL, &gerror)))
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{
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if (maps_line == NULL)
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{
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if (gerror)
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{
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g_printerr ("%s: %s\n", G_STRFUNC, gerror->message);
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g_error_free (gerror);
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}
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g_object_unref (data_input);
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if (error)
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*error = PIKA_RELOC_INIT_ERROR_READ_MAPS;
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return NULL;
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}
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/* Extract the filename; it is always an absolute path. */
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path = strchr (maps_line, '/');
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/* Sanity check. */
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if (path && strstr (maps_line, " r-xp "))
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{
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/* We found the executable name. */
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path = g_strdup (path);
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break;
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}
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g_free (maps_line);
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maps_line = NULL;
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path = NULL;
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}
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if (path == NULL && error)
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*error = PIKA_RELOC_INIT_ERROR_INVALID_MAPS;
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g_object_unref (data_input);
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g_free (maps_line);
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return path;
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#endif /* ! ENABLE_RELOCATABLE_RESOURCES || G_OS_WIN32 */
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}
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/*
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* Find the canonical filename of the executable which owns symbol.
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* Returns a filename which must be freed, or NULL on error.
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*/
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static char *
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_br_find_exe_for_symbol (const void *symbol, PikaBinrelocInitError *error)
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{
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#if ! defined(ENABLE_RELOCATABLE_RESOURCES) || defined(G_OS_WIN32) || defined(__APPLE__)
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if (error)
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*error = PIKA_RELOC_INIT_ERROR_DISABLED;
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return (char *) NULL;
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#else
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GDataInputStream *data_input;
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GInputStream *input;
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GFile *file;
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GError *gerror = NULL;
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gchar *maps_line;
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char *found = NULL;
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char *address_string;
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size_t address_string_len;
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if (symbol == NULL)
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return (char *) NULL;
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file = g_file_new_for_path ("/proc/self/maps");
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input = G_INPUT_STREAM (g_file_read (file, NULL, &gerror));
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g_object_unref (file);
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if (! input)
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{
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g_printerr ("%s: %s", G_STRFUNC, gerror->message);
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g_error_free (gerror);
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if (error)
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*error = PIKA_RELOC_INIT_ERROR_OPEN_MAPS;
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return NULL;
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}
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data_input = g_data_input_stream_new (input);
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g_object_unref (input);
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address_string_len = 4;
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address_string = g_try_new (char, address_string_len);
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while ((maps_line = g_data_input_stream_read_line (data_input, NULL, NULL, &gerror)))
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{
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char *start_addr, *end_addr, *end_addr_end;
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char *path;
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void *start_addr_p, *end_addr_p;
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size_t len;
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if (maps_line == NULL)
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{
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if (gerror)
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{
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g_printerr ("%s: %s\n", G_STRFUNC, gerror->message);
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g_error_free (gerror);
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}
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if (error)
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*error = PIKA_RELOC_INIT_ERROR_READ_MAPS;
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break;
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}
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/* Sanity check. */
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/* XXX Early versions of this code would check that the mapped
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* region was with r-xp permission. It might have been true at
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* some point in time, but last I tested, the searched pointer was
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* in a r--p region for libpikabase. Thus _br_find_exe_for_symbol()
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* would fail to find the executable's path.
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* So now we don't test the region's permission anymore.
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*/
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if (strchr (maps_line, '/') == NULL)
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{
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g_free (maps_line);
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continue;
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}
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/* Parse line. */
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start_addr = maps_line;
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end_addr = strchr (maps_line, '-');
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path = strchr (maps_line, '/');
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/* More sanity check. */
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if (!(path > end_addr && end_addr != NULL && end_addr[0] == '-'))
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{
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g_free (maps_line);
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continue;
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}
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end_addr[0] = '\0';
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end_addr++;
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end_addr_end = strchr (end_addr, ' ');
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if (end_addr_end == NULL)
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{
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g_free (maps_line);
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continue;
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}
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end_addr_end[0] = '\0';
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len = strlen (path);
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if (len == 0)
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{
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g_free (maps_line);
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continue;
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}
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if (path[len - 1] == '\n')
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path[len - 1] = '\0';
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/* Get rid of "(deleted)" from the filename. */
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len = strlen (path);
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if (len > 10 && strcmp (path + len - 10, " (deleted)") == 0)
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path[len - 10] = '\0';
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/* I don't know whether this can happen but better safe than sorry. */
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len = strlen (start_addr);
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if (len != strlen (end_addr))
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{
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g_free (maps_line);
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continue;
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}
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/* Transform the addresses into a string in the form of 0xdeadbeef,
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* then transform that into a pointer. */
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if (address_string_len < len + 3)
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{
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address_string_len = len + 3;
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address_string = (char *) g_try_realloc (address_string, address_string_len);
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}
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memcpy (address_string, "0x", 2);
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memcpy (address_string + 2, start_addr, len);
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address_string[2 + len] = '\0';
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sscanf (address_string, "%p", &start_addr_p);
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memcpy (address_string, "0x", 2);
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memcpy (address_string + 2, end_addr, len);
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address_string[2 + len] = '\0';
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sscanf (address_string, "%p", &end_addr_p);
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if (symbol >= start_addr_p && symbol < end_addr_p)
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{
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found = g_strdup (path);
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g_free (maps_line);
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break;
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}
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g_free (maps_line);
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}
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g_free (address_string);
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g_object_unref (data_input);
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return found;
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#endif /* ! ENABLE_RELOCATABLE_RESOURCES || G_OS_WIN32 */
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}
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static gchar *exe = NULL;
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static void set_gerror (GError **error, PikaBinrelocInitError errcode);
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/* Initialize the BinReloc library (for applications).
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*
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* This function must be called before using any other BinReloc functions.
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* It attempts to locate the application's canonical filename.
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*
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* @note If you want to use BinReloc for a library, then you should call
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* _pika_reloc_init_lib() instead.
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* @note Initialization failure is not fatal. BinReloc functions will just
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* fallback to the supplied default path.
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*
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* @param error If BinReloc failed to initialize, then the error report will
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* be stored in this variable. Set to NULL if you don't want an
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* error report. See the #PikaBinrelocInitError for a list of error
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* codes.
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*
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* @returns TRUE on success, FALSE if BinReloc failed to initialize.
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*/
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gboolean
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_pika_reloc_init (GError **error)
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{
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PikaBinrelocInitError errcode;
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/* Shut up compiler warning about uninitialized variable. */
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errcode = PIKA_RELOC_INIT_ERROR_NOMEM;
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/* Locate the application's filename. */
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exe = _br_find_exe (&errcode);
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if (exe != NULL)
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/* Success! */
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return TRUE;
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else
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{
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/* Failed :-( */
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set_gerror (error, errcode);
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return FALSE;
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}
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}
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/* Initialize the BinReloc library (for libraries).
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*
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* This function must be called before using any other BinReloc functions.
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* It attempts to locate the calling library's canonical filename.
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*
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* @note The BinReloc source code MUST be included in your library, or this
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* function won't work correctly.
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* @note Initialization failure is not fatal. BinReloc functions will just
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* fallback to the supplied default path.
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*
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* @returns TRUE on success, FALSE if a filename cannot be found.
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*/
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gboolean
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_pika_reloc_init_lib (GError **error)
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{
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PikaBinrelocInitError errcode;
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/* Shut up compiler warning about uninitialized variable. */
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errcode = PIKA_RELOC_INIT_ERROR_NOMEM;
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exe = _br_find_exe_for_symbol ((const void *) "", &errcode);
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if (exe != NULL)
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{
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/* Success! */
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return TRUE;
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}
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else
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{
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/* Failed :-( */
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set_gerror (error, errcode);
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return exe != NULL;
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}
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}
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static void
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set_gerror (GError **error, PikaBinrelocInitError errcode)
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{
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const gchar *error_message;
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if (error == NULL)
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return;
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switch (errcode)
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{
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case PIKA_RELOC_INIT_ERROR_NOMEM:
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error_message = "Cannot allocate memory.";
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break;
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case PIKA_RELOC_INIT_ERROR_OPEN_MAPS:
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error_message = "Unable to open /proc/self/maps for reading.";
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break;
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case PIKA_RELOC_INIT_ERROR_READ_MAPS:
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error_message = "Unable to read from /proc/self/maps.";
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break;
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case PIKA_RELOC_INIT_ERROR_INVALID_MAPS:
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error_message = "The file format of /proc/self/maps is invalid.";
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break;
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case PIKA_RELOC_INIT_ERROR_DISABLED:
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error_message = "Binary relocation support is disabled.";
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break;
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default:
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error_message = "Unknown error.";
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break;
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};
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g_set_error (error, g_quark_from_static_string ("GBinReloc"),
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errcode, "%s", error_message);
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}
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/* Locate the prefix in which the current application is installed.
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*
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* The prefix is generated by the following pseudo-code evaluation:
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* \code
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* dirname(dirname(exename))
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* \endcode
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*
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* @param default_prefix A default prefix which will used as fallback.
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* @return A string containing the prefix, which must be freed when no
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* longer necessary. If BinReloc is not initialized, or if the
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* initialization function failed, then a copy of default_prefix
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* will be returned. If default_prefix is NULL, then NULL will be
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* returned.
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*/
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gchar *
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_pika_reloc_find_prefix (const gchar *default_prefix)
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{
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gchar *dir1, *dir2;
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if (exe == NULL)
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{
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/* BinReloc not initialized. */
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if (default_prefix != NULL)
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return g_strdup (default_prefix);
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else
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return NULL;
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}
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dir1 = g_path_get_dirname (exe);
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dir2 = g_path_get_dirname (dir1);
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g_free (dir1);
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return dir2;
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}
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