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/*
* LD_PRELOAD trick to make c3pldrv handle the absolute path to /usr/{bin,lib,share)}.
* As c3pldrv is a 32 bit executable, /lib will be rewritten to /lib32.
*
* Usage:
* gcc -shared -fPIC -DOUT="$out" preload.c -o preload.so -ldl
* LD_PRELOAD=$PWD/preload.so ./c3pldrv
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <dlfcn.h>
#include <limits.h>
#ifndef OUT
#error Missing OUT define - path to the installation directory.
#endif
typedef void *(*dlopen_func_t)(const char *filename, int flag);
typedef int (*open_func_t)(const char *pathname, int flags, ...);
typedef int (*execv_func_t)(const char *path, char *const argv[]);
void *dlopen(const char *filename, int flag)
{
dlopen_func_t orig_dlopen;
const char *new_filename;
char buffer[PATH_MAX];
orig_dlopen = (dlopen_func_t)dlsym(RTLD_NEXT, "dlopen");
new_filename = filename;
if (strncmp("/usr/lib", filename, 8) == 0) {
snprintf(buffer, PATH_MAX, OUT "/lib32%s", filename+8);
buffer[PATH_MAX-1] = '\0';
new_filename = buffer;
}
return orig_dlopen(new_filename, flag);
}
int open(const char *pathname, int flags, ...)
{
open_func_t orig_open;
const char *new_pathname;
char buffer[PATH_MAX];
orig_open = (open_func_t)dlsym(RTLD_NEXT, "open");
new_pathname = pathname;
if (strncmp("/usr/share", pathname, 10) == 0) {
snprintf(buffer, PATH_MAX, OUT "%s", pathname+4);
buffer[PATH_MAX-1] = '\0';
new_pathname = buffer;
}
return orig_open(new_pathname, flags);
}
int execv(const char *path, char *const argv[])
{
execv_func_t orig_execv;
const char *new_path;
char buffer[PATH_MAX];
orig_execv = (execv_func_t)dlsym(RTLD_NEXT, "execv");
new_path = path;
if (strncmp("/usr/bin", path, 8) == 0) {
snprintf(buffer, PATH_MAX, OUT "%s", path+4);
buffer[PATH_MAX-1] = '\0';
new_path = buffer;
}
return orig_execv(new_path, argv);
}
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