src/thirdparty/binreloc/prefix.c

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/*
 * BinReloc - a library for creating relocatable executables
 * Written by: Mike Hearn <mike@theoretic.com>
 *             Hongli Lai <h.lai@chello.nl>
 * http://autopackage.org/
 * 
 * This source code is public domain. You can relicense this code
 * under whatever license you want.
 *
 * NOTE: if you're using C++ and are getting "undefined reference
 * to br_*", try renaming prefix.c to prefix.cpp
 */

/* WARNING, BEFORE YOU MODIFY PREFIX.C:
 *
 * If you make changes to any of the functions in prefix.c, you MUST
 * change the BR_NAMESPACE macro (in prefix.h).
 * This way you can avoid symbol table conflicts with other libraries
 * that also happen to use BinReloc.
 *
 * Example:
 * #define BR_NAMESPACE(funcName) foobar_ ## funcName
 * --> expands br_locate to foobar_br_locate
 */

#ifndef _PREFIX_C_
#define _PREFIX_C_

#ifdef HAVE_CONFIG_H
        #include "aa_config.h"
#endif

#ifndef BR_PTHREADS
        /* Change 1 to 0 if you don't want pthread support */
        #define BR_PTHREADS 1
#endif /* BR_PTHREADS */

#include <stdlib.h>
#include <stdio.h>
#include <limits.h>
#include <string.h>
#include "prefix.h"

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */


#undef NULL
#define NULL ((void *) 0)

#ifdef __GNUC__
        #define br_return_val_if_fail(expr,val) if (!(expr)) {fprintf (stderr, "** BinReloc (%s): assertion %s failed\n", __PRETTY_FUNCTION__, #expr); return val;}
#else
        #define br_return_val_if_fail(expr,val) if (!(expr)) return val
#endif /* __GNUC__ */


static br_locate_fallback_func fallback_func = (br_locate_fallback_func) NULL;
static void *fallback_data = NULL;


#ifdef ENABLE_BINRELOC
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <unistd.h>


char *
br_locate (void *symbol)
{
        char line[5000];
        FILE *f;
        char *path;

        br_return_val_if_fail (symbol != NULL, NULL);

        f = fopen ("/proc/self/maps", "r");
        if (!f) {
                if (fallback_func)
                        return fallback_func(symbol, fallback_data);
                else
                        return NULL;
        }

        while (!feof (f))
        {
                unsigned long start, end;

                if (!fgets (line, sizeof (line), f))
                        continue;
                if (!strstr (line, " r-xp ") || !strchr (line, '/'))
                        continue;

                sscanf (line, "%lx-%lx ", &start, &end);
                if (symbol >= (void *) start && symbol < (void *) end)
                {
                        char *tmp;
                        size_t len;

                        /* Extract the filename; it is always an absolute path */
                        path = strchr (line, '/');

                        /* Get rid of the newline */
                        tmp = strrchr (path, '\n');
                        if (tmp) *tmp = 0;

                        /* Get rid of "(deleted)" */
                        len = strlen (path);
                        if (len > 10 && strcmp (path + len - 10, " (deleted)") == 0)
                        {
                                tmp = path + len - 10;
                                *tmp = 0;
                        }

                        fclose(f);
                        return strdup (path);
                }
        }

        fclose (f);
        return NULL;
}


char *
br_locate_prefix (void *symbol)
{
        char *path, *prefix;

        br_return_val_if_fail (symbol != NULL, NULL);

        path = br_locate (symbol);
        if (!path) return NULL;

        prefix = br_extract_prefix (path);
        free (path);
        return prefix;
}


char *
br_prepend_prefix (void *symbol, char *path)
{
        char *tmp, *newpath;

        br_return_val_if_fail (symbol != NULL, NULL);
        br_return_val_if_fail (path != NULL, NULL);

        tmp = br_locate_prefix (symbol);
        if (!tmp) return NULL;

        if (strcmp (tmp, "/") == 0)
                newpath = strdup (path);
        else
                newpath = br_strcat (tmp, path);

        /* Get rid of compiler warning ("br_prepend_prefix never used") */
        if (0) br_prepend_prefix (NULL, NULL);

        free (tmp);
        return newpath;
}

#endif /* ENABLE_BINRELOC */


/* Pthread stuff for thread safetiness */
#if BR_PTHREADS && defined(ENABLE_BINRELOC)

#include <pthread.h>

static pthread_key_t br_thread_key;
static pthread_once_t br_thread_key_once = PTHREAD_ONCE_INIT;


static void
br_thread_local_store_fini ()
{
        char *specific;

        specific = (char *) pthread_getspecific (br_thread_key);
        if (specific)
        {
                free (specific);
                pthread_setspecific (br_thread_key, NULL);
        }
        pthread_key_delete (br_thread_key);
        br_thread_key = 0;
}


static void
br_str_free (void *str)
{
        if (str)
                free (str);
}


static void
br_thread_local_store_init ()
{
        if (pthread_key_create (&br_thread_key, br_str_free) == 0)
                atexit (br_thread_local_store_fini);
}

#else /* BR_PTHREADS */
#ifdef ENABLE_BINRELOC

static char *br_last_value = (char *) NULL;

static void
br_free_last_value ()
{
        if (br_last_value)
                free (br_last_value);
}

#endif /* ENABLE_BINRELOC */
#endif /* BR_PTHREADS */


#ifdef ENABLE_BINRELOC

const char *
br_thread_local_store (char *str)
{
        #if BR_PTHREADS
                char *specific;

                pthread_once (&br_thread_key_once, br_thread_local_store_init);

                specific = (char *) pthread_getspecific (br_thread_key);
                br_str_free (specific);
                pthread_setspecific (br_thread_key, str);

        #else /* BR_PTHREADS */
                static int initialized = 0;

                if (!initialized)
                {
                        atexit (br_free_last_value);
                        initialized = 1;
                }

                if (br_last_value)
                        free (br_last_value);
                br_last_value = str;
        #endif /* BR_PTHREADS */

        return (const char *) str;
}

#endif /* ENABLE_BINRELOC */


char *
br_strcat (const char *str1, const char *str2)
{
        char *result;
        size_t len1, len2;

        if (!str1) str1 = "";
        if (!str2) str2 = "";

        len1 = strlen (str1);
        len2 = strlen (str2);

        result = (char *) malloc (len1 + len2 + 1);
        memcpy (result, str1, len1);
        memcpy (result + len1, str2, len2);
        result[len1 + len2] = '\0';

        return result;
}


/* Emulates glibc's strndup() */
static char *
br_strndup (char *str, size_t size)
{
        char *result = (char *) NULL;
        size_t len;

        br_return_val_if_fail (str != (char *) NULL, (char *) NULL);

        len = strlen (str);
        if (!len) return strdup ("");
        if (size > len) size = len;

        result = (char *) calloc (sizeof (char), len + 1);
        memcpy (result, str, size);
        return result;
}


char *
br_extract_dir (const char *path)
{
        char *end, *result;

        br_return_val_if_fail (path != (char *) NULL, (char *) NULL);

        end = strrchr (path, '/');
        if (!end) return strdup (".");

        while (end > path && *end == '/')
                end--;
        result = br_strndup ((char *) path, end - path + 1);
        if (!*result)
        {
                free (result);
                return strdup ("/");
        } else
                return result;
}


char *
br_extract_prefix (const char *path)
{
        char *end, *tmp, *result;

        br_return_val_if_fail (path != (char *) NULL, (char *) NULL);

        if (!*path) return strdup ("/");
        end = strrchr (path, '/');
        if (!end) return strdup (path);

        tmp = br_strndup ((char *) path, end - path);
        if (!*tmp)
        {
                free (tmp);
                return strdup ("/");
        }
        end = strrchr (tmp, '/');
        if (!end) return tmp;

        result = br_strndup (tmp, end - tmp);
        free (tmp);

        if (!*result)
        {
                free (result);
                result = strdup ("/");
        }

        return result;
}


void
br_set_locate_fallback_func (br_locate_fallback_func func, void *data)
{
        fallback_func = func;
        fallback_data = data;
}


#ifdef __cplusplus
}
#endif /* __cplusplus */

#endif /* _PREFIX_C */

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