不能直接写stdout

user1 于 2023-02-01 20:05:14 发表,最后修改于 2023-02-02 06:23:35


#include <stdio.h>
int a;
#define P 0x408000
int main() { 
    printf("%p\n", &a);
    *((char*)0x4081a0) = '?';
    for (int i=0; i<100; ++i) printf("%p %p", (char**)P+i, *((char**)P+i)), printf(" %p\n", *((char**)P+i));
 //*((char**)0x408048) = (char*)0x4081b9;
}

明明stdout就在那,改不了

#include <stdio.h>
int a;
#define P 0x408180
int main() { 
    printf("%p\n", &a);
    //*((char*)0x4081a0) = '?';
    for (int i=0; i<100; ++i) printf("%p %p", (char**)P+i, *((char**)P+i)), printf(" %p\n", *((char**)P+i));
    //*((char**)0x408048) = (char*)0x4081b9;
}

EDIT: 好了

    #include <sys/syscall.h>
#include <stdio.h>
#define uint64_t unsigned long long
struct DuckInfo_t {
    uint64_t abi_version;

    const char *stdin_ptr;   // stdin pointer (read-only contents)
    uint64_t stdin_size;     // stdin size

    char *stdout_ptr;        // stdout pointer
    uint64_t stdout_limit;   // [IN] stdout maximum size
    uint64_t stdout_size;    // [OUT] stdout actual size

    char *stderr_ptr;        // stderr pointer
    uint64_t stderr_limit;   // [IN] stderr maximum size
    uint64_t stderr_size;    // [OUT] stderr actual size

    const char *IB_ptr;      // IB (Input Buffer) pointer
    uint64_t IB_limit;       // IB limit

    char *OB_ptr;            // OB (Output Buffer) pointer
    uint64_t OB_limit;       // OB limit

    uint64_t tsc_frequency;  // TSC (Time Stamp Counter) frequency
} __attribute__((packed));

int main() {
    struct DuckInfo_t *duckinfo = (struct DuckInfo_t *) getauxval(0x6b637564);
    printf ("%p", duckinfo);
    fprintf (stderr, "吃鸭肉");
    duckinfo->stderr_ptr = duckinfo->stdout_ptr;
    duckinfo->stderr_size = 4;
}

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