52 lines
1.1 KiB
C
52 lines
1.1 KiB
C
/*
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* gcc link_failure.c -o link_failure.so -shared -ldl
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* LD_PRELOAD=./link_failure.so FAILURE_PATH=/etc/shadow ./test /etc/shadow
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*/
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#define _GNU_SOURCE
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#include <dlfcn.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <stdarg.h>
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#include <fcntl.h>
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#include <string.h>
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#include <errno.h>
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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typedef int (*link_type) (const char *oldpath, const char *newpath);
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static link_type next_link;
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static const char *failure_path = NULL;
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int link (const char *oldpath, const char *newpath)
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{
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if (NULL == next_link)
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{
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next_link = dlsym (RTLD_NEXT, "link");
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assert (NULL != next_link);
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}
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if (NULL == failure_path) {
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failure_path = getenv ("FAILURE_PATH");
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if (NULL == failure_path) {
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fputs ("No FAILURE_PATH defined\n", stderr);
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}
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}
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if ( (NULL != newpath)
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&& (NULL != failure_path)
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&& (strcmp (newpath, failure_path) == 0))
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{
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fprintf (stderr, "link FAILURE %s %s\n", oldpath, newpath);
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errno = EIO;
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return -1;
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}
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return next_link (oldpath, newpath);
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}
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