Home | History | Annotate | Download | only in libdl 
      1 /*
      2  * Copyright (C) 2008 The Android Open Source Project
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *  * Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  *  * Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in
     12  *    the documentation and/or other materials provided with the
     13  *    distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
     22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #include <stdio.h>
     30 #include <unistd.h>
     31 #include <stdlib.h>
     32 #include <getopt.h>
     33 #include <string.h>
     34 #include <dlfcn.h>
     35 
     36 extern char *optarg;
     37 extern int optind, opterr, optopt;
     38 
     39 static struct option long_options[] = {
     40     {"library", required_argument, 0, 'l'},
     41     {"symbol",  required_argument, 0, 's'},
     42     {"help",    no_argument,       0, 'h'},
     43     {0, 0, 0, 0},
     44 };
     45 
     46 /* This array must parallel long_options[] */
     47 static const char *descriptions[] = {
     48     "specify a library path to look up symbol",
     49     "specify symbol to look up",
     50     "print this help screen",
     51 };
     52 
     53 void print_help(const char *name) {
     54     fprintf(stdout,
     55             "invokation:\n"
     56             "\t%s [-l <libname>] -s <symbol name>\n"
     57             "\t%s -h\n\n", name, name);
     58     fprintf(stdout, "options:\n");
     59     struct option *opt = long_options;
     60     const char **desc = descriptions;
     61     while (opt->name) {
     62         fprintf(stdout, "\t-%c/--%s%s: %s\n",
     63                 opt->val,
     64                 opt->name,
     65                 (opt->has_arg ? " (argument)" : ""),
     66                 *desc);
     67         opt++;
     68         desc++;
     69     }
     70 }
     71 
     72 int get_options(int argc, char **argv, char **lib, char **sym)
     73 {
     74     int c;
     75 
     76     *lib = 0;
     77     *sym = 0;
     78 
     79     while (1) {
     80         /* getopt_long stores the option index here. */
     81         int option_index = 0;
     82 
     83         c = getopt_long (argc, argv,
     84                          "l:s:h",
     85                          long_options,
     86                          &option_index);
     87         /* Detect the end of the options. */
     88         if (c == -1) break;
     89 
     90         switch (c) {
     91 		case 'l':
     92             *lib = strdup(optarg);
     93 			break;
     94         case 's':
     95             *sym = strdup(optarg);
     96             break;
     97         case 'h': print_help(argv[0]); exit(EXIT_FAILURE); break;
     98         case '?':
     99             /* getopt_long already printed an error message. */
    100             break;
    101         default:
    102             fprintf(stderr, "Unknown option");
    103             exit(EXIT_FAILURE);
    104         }
    105     }
    106 
    107     return optind;
    108 }
    109 
    110 int main(int argc, char **argv)
    111 {
    112     char *libname, *symname, *prog = *argv;
    113 
    114     get_options(argc, argv, &libname, &symname);
    115 
    116     if (symname == NULL) {
    117         fprintf(stderr, "You must specify a symbol!\n");
    118         print_help(prog);
    119         exit(EXIT_FAILURE);
    120     }
    121 
    122     {
    123         const char *dlerr;
    124         void *handle, *symbol;
    125 
    126         printf("opening library [%s]\n", libname);
    127         dlerr = dlerror();
    128         handle = libname ? dlopen(libname, RTLD_NOW) : RTLD_DEFAULT;
    129         dlerr = dlerror();
    130         if (dlerr != NULL) fprintf(stderr, "dlopen() error: %s\n", dlerr);
    131 
    132         printf("opening symbol [%s]\n", symname);
    133         symbol = dlsym(handle, symname);
    134         dlerr = dlerror();
    135         if (dlerr != NULL) fprintf(stderr, "dlsym() error: %s\n", dlerr);
    136 
    137         printf("closing library [%s]\n", libname);
    138         dlclose(handle);
    139         dlerr = dlerror();
    140         if (dlerr != NULL) fprintf(stderr, "dlclose() error: %s\n", dlerr);
    141         else printf("successfully opened symbol\n");
    142     }
    143 
    144     if (libname != NULL) free(libname);
    145     if (symname != NULL) free(symname);
    146     return 0;
    147 }
    148