libopenredir.c.in

#include<stdarg.h>
#include<dlfcn.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<limits.h>
#include<unistd.h>

#include<lua.h>
#include<lualib.h>
#include<lauxlib.h>

{% set functions = [
    ['open', [['const char*', 'file'], ['int', 'flags'], ['mode_t', 'mode']]],
    ['open64', [['const char*', 'file'], ['int', 'flags'], ['mode_t', 'mode']]],
    ['creat', [['const char*', 'file'], ['mode_t', 'mode']]],
    ['readlink', [['const char*', 'file'], ['char*', 'buf'], ['size_t', 'bufsiz']], 'ssize_t'],
    ['__open_2', [['const char*', 'file'], ['int', 'flags']]],
    ['__open64_2', [['const char*', 'file'], ['int', 'flags']]],
    ['stat', [['const char*', 'file'], ['void*', 'buf']]],
    ['statx', [['int', 'fd'], ['const char*', 'file'], ['int', 'flags'], ['unsigned int', 'mask'], ['void*', 'buf']]],
    ['__lxstat', [['int', 'vers'], ['const char*', 'file'], ['void*', 'buf']]],
    ['__lxstat64', [['int', 'vers'], ['const char*', 'file'], ['void*', 'buf']]],
    ['execve', [['const char*', 'file'], ['char *const*', 'argv'], ['char *const*', 'envp']]],
    ['opendir', [['const char*', 'file']], 'void*'],
    ['getxattr', [['const char*', 'file'], ['const char*', 'name'], ['void*', 'value'], ['size_t', 'size']], 'ssize_t'],
    ['lgetxattr', [['const char*', 'file'], ['const char*', 'name'], ['void*', 'value'], ['size_t', 'size']], 'ssize_t'],
  ] %}
{% autoescape None %}

static int lib_initialized = 0;
{% for func, args, *rest in functions %}static {{rest[0] if rest else 'int'}} (*orig_{{func}})({{', '.join(x[0] for x in args)}}) = 0;
{% end %}
static lua_State *L = NULL;
void lib_init();

void die(char *fmt, ...) {
  va_list args;
  va_start(args, fmt);
  vfprintf(stderr, fmt, args);
  va_end(args);
  fprintf(stderr, "\n");
  fflush(stderr);
  exit(-1);
}

static char* redirect(const char* func, const char* file){
  int ret;
  const char *new;
  lua_getglobal(L, "redirect");
  lua_pushstring(L, func);
  lua_pushstring(L, file);
  ret = lua_pcall(L, 2, 1, 0);
  if(ret){
    fprintf(stderr, "取得重定向文件路径时出错了： %s\n", lua_tostring(L, -1));
    lua_pop(L, 1); /* 错误信息 */
    return (char*)file;
  }else{
    new = lua_tostring(L, -1);
    lua_pop(L, 1); /* 返回值 */
  }
  return (char*)new;
}

{% for func, args, *rest in functions %}
{{rest[0] if rest else 'int'}} {{func}}({{', '.join(' '.join(x) for x in args)}}) {
  lib_init();
  file = redirect({{'"' + func.replace('"', r'\"') + '"'}}, file);
  return orig_{{func}}({{', '.join(x[1] for x in args)}});
}
{% end %}

void lib_init() {
  void *libhdl;
  char *dlerr;

  if (lib_initialized) return;

  if (!(libhdl=dlopen("libc.so.6", RTLD_LAZY)))
    die("Failed to patch library calls: %s", dlerror());

  {% for func, args, *rest in functions %}
  orig_{{func}} = dlsym(libhdl, "{{func}}");
  if ((dlerr=dlerror()) != NULL)
    die("Failed to patch {{func}}() library call: %s", dlerr);
  {% end %}

  int ret;
  L = luaL_newstate();
  luaL_openlibs(L);
  char config[PATH_MAX];
  if (getenv("OPENREDIR_CONFDIR"))
    strncpy(config, getenv("OPENREDIR_CONFDIR"), PATH_MAX);
  else
    strncpy(config, getenv("HOME"), PATH_MAX);

  strcat(config, "/.openredir.lua");
  ret = luaL_dofile(L, config);
  if(ret){
    die("Error run ~/.openredir.lua");
  }
  lua_getglobal(L, "redirect");
  if(!lua_isfunction(L,-1)){
    die("Error run 'redirect' function in openredir.lua");
  }
  lua_pop(L, 1);

  lib_initialized = 1;
}

/* vim: set syntax=c.tornadotmpl: */