{"id":320,"date":"2021-11-08T23:18:15","date_gmt":"2021-11-08T15:18:15","guid":{"rendered":"http:\/\/pareto.fun\/?p=320"},"modified":"2021-12-01T14:22:55","modified_gmt":"2021-12-01T06:22:55","slug":"elf%e6%96%87%e4%bb%b6%e5%8a%a0%e5%af%86","status":"publish","type":"post","link":"http:\/\/pareto.fun\/?p=320","title":{"rendered":"elf\u6587\u4ef6\u52a0\u5bc6"},"content":{"rendered":"\n

\u76ee\u7684<\/h2>\n\n\n\n

elf\u6587\u4ef6\u9759\u6001\u5206\u6790\u7684\u5bf9\u6297\u3002<\/p>\n\n\n\n

\u6784\u60f3<\/h2>\n\n\n\n

\u6211\u4eec\u60f3\u8981\u7684\u6548\u679c\uff1a<\/p>\n\n\n\n

\u76ee\u6807\u7a0b\u5e8f\u88ab\u83b7\u53d6\u5230\u65f6\u662f\u88ab\u52a0\u5bc6\u7684\uff0c\u5728\u8fd0\u884c\u65f6\u5b8c\u6210\u6587\u4ef6\u7684\u89e3\u5bc6\uff0c\u518d\u5c06\u7a0b\u5e8f\u6d41\u4ea4\u8fd8\u7ed9\u76ee\u6807\u7a0b\u5e8f\u3002<\/p>\n\n\n\n

\u5982\u4f55\u8fbe\u5230\u8fd9\u4e2a\u6548\u679c\uff0c\u5c31\u8981\u501f\u52a9ELF\u6587\u4ef6\u7ed3\u6784\u4e2d\u4e24\u4e2a\u7279\u6b8a\u8282INIT \uff0c INIT_ARRAY \u3002<\/p>\n\n\n\n

INIT , INIT_ARRAY \u90fd\u662f\u4f1a\u5728elf\u6587\u4ef6\u88ab\u52a0\u8f7d\u65f6\u6700\u5148\u88ab\u8c03\u7528\u7684\u51fd\u6570\u3002<\/p>\n\n\n\n

\u5047\u5982\u6211\u4eec\u5728elf\u505a\u52a0\u5bc6\u7684\u65f6\u5019\uff0c\u907f\u5f00\u5bf9init\u548cinit_array \u9020\u6210\u5f71\u54cd\u7684\u90e8\u5206\uff0c\u5c31\u53ef\u4ee5\u5b9e\u73b0elf\u52a0\u8f7d\u5b8c\u6210\u540e\u8c03\u7528init\u6216\u8005init_array \u5b8c\u6210elf\u6587\u4ef6\u7684\u89e3\u5bc6\u5de5\u4f5c\u3002<\/p>\n\n\n\n

\u4f46\u662f\u6bcf\u4e00\u4e2a\u76ee\u6807\u6587\u4ef6\uff0c\u90fd\u88ab\u63d2\u5165\u89e3\u5bc6\u51fd\u6570\u7684\u8bdd\uff0c\u5b9e\u73b0\u8d77\u6765\u7b80\u5355\uff0c\u4f46\u662f\u8fd8\u4e0d\u591f\u4f18\u96c5\u3002<\/p>\n\n\n\n

\u6240\u4ee5\u6211\u4eec\u5c06\u89e3\u5bc6\u51fd\u6570\u63d0\u53d6\u6210\u4e00\u4e2a\u5171\u4eab\u5e93\uff0c\u6bcf\u4e00\u4e2a\u76ee\u6807\u6587\u4ef6\u7684init\u6bb5\u4ee3\u7801\u4ec5\u9700\u8981\u8c03\u7528\u5171\u4eab\u5e93\u7684\u89e3\u5bc6\u51fd\u6570\u5373\u53ef\uff0c\u8282\u7ea6\u4e86\u4f53\u79ef\u53c8\u589e\u52a0\u4e86\u53ef\u7ef4\u62a4\u6027\u3002<\/p>\n\n\n\n

\u4f46\u662f\u53c8\u9700\u8981\u4fdd\u8bc1\u8fd9\u4e2a\u5171\u4eab\u5e93\u4f1a\u88ab\u76ee\u6807elf\u6587\u4ef6\u524d\u88ab\u52a0\u8f7d\uff0c<\/p>\n\n\n\n

\u53ea\u9700\u8981\u5728dynamic\u4e2d\u6dfb\u52a0\u4e00\u6761neededso\u7684\u8bb0\u5f55\u5373\u53ef\u3002<\/p>\n\n\n\n

\u5b9e\u73b0\u6d41\u7a0b<\/h2>\n\n\n\n
\"\"<\/figure>\n\n\n\n

\u5176\u4f59\u90e8\u5206\u90fd\u5f88\u597d\u5b9e\u73b0\uff0c\u8fd8\u6709\u4e2a\u5c0f\u95ee\u9898\u5728init \u8c03\u7528\u5916\u90e8\u89e3\u5bc6\u51fd\u6570\u3002<\/p>\n\n\n\n

\u8c03\u7528\u5916\u90e8\u51fd\u6570\u6709\u4e24\u79cd\u65b9\u5f0f<\/p>\n\n\n\n

  1. \u9690\u5f0f\u8c03\u7528\uff0clinker\u89e3\u6790\u5916\u90e8\u51fd\u6570\u3002<\/li>
  2. \u663e\u5f0f\u8c03\u7528\uff0c\u8d70dlopen \u3001dlsym\u4e3b\u52a8\u8c03\u7528\u5916\u90e8\u51fd\u6570\u3002<\/li><\/ol>\n\n\n\n

    \u9690\u5f0f\u8c03\u7528<\/h3>\n\n\n\n
    #include \"library.h\"
    \u200b
    #include <iostream>
    void func();
    void hello() {
        func();
        std::cout << \"Hello, World!\" << std::endl;
    }<\/pre>\n\n\n\n
    \u5c06\u8fd9\u6bb5\u4ee3\u7801\u7f16\u8bd1\u6210\u5171\u4eab\u5e93\u7f16\u8bd1\u80fd\u901a\u8fc7\u5417\uff1f\u90a3\u7f16\u8bd1\u6210\u53ef\u6267\u884c\u7a0b\u5e8f\u5462\uff1f<\/p>\n\n\n\n
    why ?<\/p>\n\n\n\n
     \u5171\u4eab\u5e93 \u80fd\u901a\u8fc7\uff0c \u53ef\u6267\u884c\u7a0b\u5e8f \u4e0d\u80fd\u901a\u8fc7\u3002\u4e00\u822c\u4eba\u90fd\u4f1a\u8bf4func\u6ca1\u6709\u88ab\u5b9e\u73b0\uff0c\u7b54\u6848\u6b63\u786e\u4f46\u662f\u4e0d\u591f\u7ec6\u8282\uff0c\u51c6\u786e\u70b9\u8bf4\uff0c\u5305\u542b\u8be5\u5171\u4eab\u5e93\u548c\u5176\u4ed6\u8fd0\u884c\u65f6\u5e93\u90fd\u672a\u5bfc\u51fa\u8be5\u51fd\u6570\u6240\u4ee5\u5bfc\u81f4\u7684\u4e0d\u901a\u8fc7\u3002<\/p>\n\n\n\n
    \u518d\u770b\u4e00\u6bb5<\/p>\n\n\n\n
    \u5171\u4eab\u5e93\u4ee3\u7801<\/p>\n\n\n\n
    \u5934\u6587\u4ef6<\/p>\n\n\n\n
    #ifndef UNTITLED4_LIBRARY_H
    #define UNTITLED4_LIBRARY_H
    # define __nonnull(params) __attribute__ ((__nonnull__ params))
    extern void hello();
    extern void *dlsym (void *__restrict __handle,
                        const char *__restrict __name)  __nonnull ((2));
    \u200b
    #endif \/\/UNTITLED4_LIBRARY_H<\/pre>\n\n\n\n
    .c<\/p>\n\n\n\n
    #include \"library.h\"
    \u200b
    #include <stdio.h>
    \u200b
    \u200b
    void hello() {
        dlsym(-1 , \"printf\");
         printf(\"Hello, World!\");
    }<\/pre>\n\n\n\n
    \u53ef\u6267\u884c\u7a0b\u5e8f<\/p>\n\n\n\n
    #include <stdio.h>
    #include \"lib\/library.h\"
    int main() {
        printf(\"HelloWorld\");
        hello();
        return 0;
    }<\/pre>\n\n\n\n
    \u53ef\u6b63\u5e38\u8fd0\u884c\u3002libraray \u88ab\u7f16\u8bd1\u5668\u7f16\u8bd1\u6210so \u65f6\uff0cdlsym \u7531\u4e8e\u6ca1\u6709\u88ab\u5b9e\u73b0\u4f1a\u88ab\u6807\u8bb0\u4e3aUND(undefine)\uff0c\u8868\u793a\u51fd\u6570\u7684\u5b9e\u73b0\u6ca1\u6709\u5728\u8fd9\u4e2aelf\u6587\u4ef6\u5b9e\u73b0\u3002linker\u5728\u52a0\u8f7dso\u65f6\uff0c\u4f1a\u5c06\u5c1d\u8bd5\u5728\u5f53\u524dELF\u6587\u4ef6\u548c\u4f9d\u8d56\u7684\u8fd0\u884c\u65f6\u5e93\u53bb\u627e\u8be5\u7b26\u53f7\u7684\u5b9e\u73b0\uff08\u8fd9\u4e2a\u8fc7\u7a0b\u4e5f\u53eb\u91cd\u5b9a\u4f4d\uff0c\u4f46\u662f\u8fd9\u4e2a\u529f\u80fd\u53ea\u662f\u91cd\u5b9a\u4f4d\u4e4b\u4e00\uff09\u3002\u4f46\u662f\u548c\u6267\u884c\u7a0b\u5e8f\u4e00\u8d77\u8fd0\u884c\u65f6\uff0c\u53ef\u6267\u884c\u7a0b\u5e8f\u4f9d\u8d56libdl \uff0c\u5176\u4e2d\u53c8\u6709dlsym\u7684\u5b9e\u73b0\uff0clinker\u904d\u5386\u8fd0\u884c\u65f6\u5e93\u65f6\uff0c\u5c06library \u7684dlsym\u6307\u5411\u4e86libdl\u4e2d\u7684dlsym\uff0c\u6240\u4ee5\u53ef\u6b63\u5e38\u8fd0\u884c\u3002<\/p>\n\n\n\n
    \u90a3\u4e48\u8981\u60f3\u5b8c\u6210\u9690\u5f0f\u8c03\u7528\u9700\u8981\u54ea\u4e9b\u4e1c\u897f\uff0c\u6700\u91cd\u8981\u7684\u4e1c\u897f\u641e\u5b9a\u91cd\u5b9a\u4f4d\u8868\uff0c\u7136\u540e\u4f7f\u7528\u91cd\u5b9a\u4f4d\u4fee\u590d\u540e\u7684\u5730\u5740(\u8fd9\u91cc\u8fd9\u4e2a\u5730\u5740\u4e5f\u53ebGOT)\u5373\u53ef\u3002<\/p>\n\n\n\n
    \u6700\u5c0f\u7684\u6dfb\u52a0\u5355\u5143\uff1a<\/p>\n\n\n\n
    1. \u65b0\u589egot \u8868\u3002<\/li>
    2. \u65b0\u589e\u91cd\u5b9a\u4f4d\u8868\u548c\u5bf9\u5e94\u7684\u7b26\u53f7\u8868\u3002<\/li><\/ol>\n\n\n\n
      \u663e\u5f0f\u8c03\u7528<\/h3>\n\n\n\n
      \u901a\u8fc7dlopen \uff0cdlsym \u53bb\u8c03\u7528\u67d0\u4e2aelf\u6587\u4ef6\u7684\u5bfc\u51fa\u51fd\u6570\u3002<\/p>\n\n\n\n
      \u8fd9\u5c31\u5f88\u7b80\u5355\uff0c\u5f88\u591a\u60c5\u51b5\u4e0b\u8fd9\u4e24\u4e2a\u51fd\u6570\u90fd\u4f1a\u88ab\u5bfc\u5165\uff0c\u53ef\u4ee5\u9009\u62e9\u5199\u4ee3\u7801\u8c03\u7528\u5230\u5bf9\u5e94\u7684plt \u6216\u8005got\u8868\u5373\u53ef\u3002<\/p>\n\n\n\n
      <\/p>\n\n\n\n
      <\/p>\n","protected":false},"excerpt":{"rendered":"
      \u76ee\u7684 elf\u6587\u4ef6\u9759\u6001\u5206\u6790\u7684\u5bf9\u6297\u3002 \u6784\u60f3 \u6211\u4eec\u60f3\u8981\u7684\u6548\u679c\uff1a \u76ee\u6807\u7a0b\u5e8f\u88ab\u83b7\u53d6\u5230\u65f6\u662f\u88ab\u52a0\u5bc6\u7684\uff0c\u5728\u8fd0\u884c\u65f6\u5b8c\u6210 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[19],"tags":[28],"_links":{"self":[{"href":"http:\/\/pareto.fun\/index.php?rest_route=\/wp\/v2\/posts\/320"}],"collection":[{"href":"http:\/\/pareto.fun\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/pareto.fun\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/pareto.fun\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/pareto.fun\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=320"}],"version-history":[{"count":8,"href":"http:\/\/pareto.fun\/index.php?rest_route=\/wp\/v2\/posts\/320\/revisions"}],"predecessor-version":[{"id":366,"href":"http:\/\/pareto.fun\/index.php?rest_route=\/wp\/v2\/posts\/320\/revisions\/366"}],"wp:attachment":[{"href":"http:\/\/pareto.fun\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=320"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/pareto.fun\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=320"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/pareto.fun\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=320"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}