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