C alloca函数-当试图分配太多内存时会发生什么

Question

在C语言中，alloca（）函数在alloca（）调用方的stackframe上分配内存。

当您试图分配大量它无法分配的字节时，会发生什么？

null

有人有更多关于这方面的信息吗？

Answer 1

在windows上，您可以从中恢复。使用GCC测试：

/*
 * Show how get memory from stack without crash
 * Currently, compiles ok with mingw, and the latest version of tiny c (from git)
 * Last Version: 29/june/2014
 * Programmed by Carlos Montiers
 */

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <malloc.h>
#include <setjmp.h>

int _resetstkoflw(void);

static jmp_buf alloca_jmp_buf;

LONG WINAPI AllocaExceptionFilter(EXCEPTION_POINTERS * ExceptionInfo)
{

    switch (ExceptionInfo->ExceptionRecord->ExceptionCode) {
    case STATUS_STACK_OVERFLOW:

    // reset the stack
    if (0 == _resetstkoflw()) {
        printf("Could not reset the stack!\n");
        _exit(1);
    }

    longjmp(alloca_jmp_buf, 1);

    break;
    }

    return EXCEPTION_EXECUTE_HANDLER;
}

int main()
{
    void *m;
    int alloca_jmp_res;
    LPTOP_LEVEL_EXCEPTION_FILTER prev;

    //replace the exception filter function saving the previous
    prev = SetUnhandledExceptionFilter(AllocaExceptionFilter);

    alloca_jmp_res = setjmp(alloca_jmp_buf);
    if ((0 == alloca_jmp_res)) {
    m = alloca(INT_MAX);

    } else if ((1 == alloca_jmp_res)) {
    m = NULL;

    }
    //restore exception filter function
    SetUnhandledExceptionFilter(prev);

    if (!m) {
    printf("alloca Failed\n");
    }

    printf("Bye\n");
    return 1;

}