56 lines
1.0 KiB
TeX
56 lines
1.0 KiB
TeX
\chapter{Debug}\index{Debug}
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\label{chap:debug}
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Quand plus rien ne marche, il existe encore un espoir...
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\section{strace}\index{strace}
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\section{LD\_PRELOAD}\index{LD\_PRELOAD}
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\begin{lstlisting}[language=C]
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/*
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spy_getenv.so: spy_getenv.c Makefile
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gcc -Wall -shared -fPIC $< -ldl -o $@
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*/
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#define __USE_GNU
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#include <dlfcn.h>
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typedef char * (*original_getenv)(const char *envname);
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char *getenv(char *envname)
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{
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static char *arrow = "--getenv--> ";
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static char *wtf = " --> WTF ?";
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char *content;
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original_getenv orig_getenv;
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orig_getenv = (original_getenv)dlsym(RTLD_NEXT, "getenv");
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write(STDERR_FILENO, arrow, strlen(arrow));
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write(STDERR_FILENO, envname, strlen(envname));
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content = orig_getenv(envname);
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if (NULL != content) {
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write(STDERR_FILENO, "=", 1);
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write(STDERR_FILENO, content, strlen(content));
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}
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else {
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write(STDERR_FILENO, wtf, strlen(wtf));
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}
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write(STDERR_FILENO, "\n", 1);
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return content;
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}
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\end{lstlisting}
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