mirror of
https://github.com/ioacademy-jikim/debugging
synced 2025-06-08 00:16:11 +00:00
41 lines
1.0 KiB
C
41 lines
1.0 KiB
C
#include <assert.h>
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#include <stdio.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <unistd.h>
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// kernel brk() and libc brk() act quite differently...
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int main(void)
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{
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int i;
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void* orig_ds = sbrk(0);
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void* ds = orig_ds;
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void* vals[10];
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void* res __attribute__((unused));
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#define EOL ((void*)( ~(long)0 ))
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vals[0] = (void*)0;
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vals[1] = (void*)1;
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vals[2] = ds - 0x1; // small shrink
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vals[3] = ds;
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vals[4] = ds + 0x1000; // small growth
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vals[5] = ds + 0x40000000; // too-big growth
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vals[6] = ds + 0x500; // shrink a little, but still above start size
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vals[7] = ds - 0x1; // shrink below start size
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// vals[8] = ds - 0x1000; // shrink a lot below start size (into text)
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// vals[9] = EOL;
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vals[8] = EOL;
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for (i = 0; EOL != vals[i]; i++) {
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res = (void*)syscall(__NR_brk, vals[i]);
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}
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assert( 0 == brk(orig_ds) ); // libc brk()
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for (i = 0; EOL != vals[i]; i++) {
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res = (void*)(long)brk(vals[i]);
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}
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return 0;
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}
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