段故障：在Ubuntu中C程序堆栈分配时bufffer＆GT; 4M [英] Segmentation fault: Stack allocation in a C program in Ubuntu when bufffer>4M
问题描述
下面是一个小程序，一个大学的任务：
Here's a small program to a college's task:
#include <unistd.h>
#ifndef BUFFERSIZE
#define BUFFERSIZE 1
#endif
main()
{
char buffer[BUFFERSIZE];
int i;
int j = BUFFERSIZE;
i = read(0, buffer, BUFFERSIZE);
while (i>0)
{
write(1, buffer, i);
i = read(0, buffer, BUFFERSIZE);
}
return 0;
}
有是用stdio.h中的fread和fwrite函数，而不是替代。
There is a alternative using the stdio.h fread and fwrite functions instead.
嘛。我编译的程序这两个版本的缓冲区大小25个不同的值：1，2，4，...，2 ^ I其中i = 0..30
Well. I compiled this both versions of program with 25 different values of Buffer Size: 1, 2, 4, ..., 2^i with i=0..30
这是我如何编译一个例子：
GCC -DBUFFERSIZE = 8388608 prog_sys.c -o斌/ psys.8M
This is a example of how I compile it: gcc -DBUFFERSIZE=8388608 prog_sys.c -o bin/psys.8M
问题：在我的机器（Ubuntu的precise 64，到底有详细介绍）程序的所有版本的正常工作：
./psys.1M＆LT;数据
The question: In my machine (Ubuntu Precise 64, more details in the end) all versions of the program works fine: ./psys.1M < data
（数据是一个小文件有3行ASCII文本。）
(data is a small file with 3 line ascii text.)
的问题是：当缓冲区大小是8MB或更大。这两个版本（使用系统调用或CLIB功能）崩溃与这些缓冲区大小（段错误）。
The problem is: When the buffer size is 8MB or greater. Both versions (using system call or clib functions) crashes with these buffer sizes (Segmentation Fault).
我测试了很多东西。在code的第一个版本是这样的：
（......）
主要（）
{
字符缓冲区[BUFFERSIZE]
INT I;
I tested many things. The first version of the code was like this: (...) main() { char buffer[BUFFERSIZE]; int i;
i = read(0, buffer, BUFFERSIZE);
(...)
这crashs当我打电话的读取功能。但随着这些版本：
This crashs when I call the read function. But with these versions:
main()
{
char buffer[BUFFERSIZE]; // SEGMENTATION FAULT HERE
int i;
int j = BUFFERSIZE;
i = read(0, buffer, BUFFERSIZE);
main()
{
int j = BUFFERSIZE; // SEGMENTATION FAULT HERE
char buffer[BUFFERSIZE];
int i;
i = read(0, buffer, BUFFERSIZE);
他们两个crashs（段错误）在主要的第一行。但是，如果我移动缓冲出主让全球范围内（因此，在堆而不是堆栈分配），这工作得很好：
Both them crashs (SEGFAULT) in the first line of main. However, if I move the buffer out of main to the global scope (thus, allocation in the heap instead the stack), this works fine:
char buffer[BUFFERSIZE]; //NOW GLOBAL AND WORKING FINE
main()
{
int j = BUFFERSIZE;
int i;
i = read(0, buffer, BUFFERSIZE);
我用的是Ubuntu的$ P $ 12.04 pcise 64位和英特尔酷睿i5 480中号的第一代。
I use a Ubuntu Precise 12.04 64bits and Intel i5 M 480 1st generation.
#uname -a
Linux hostname 3.2.0-34-generic #53-Ubuntu SMP Thu Nov 15 10:48:16 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
不知有关堆栈操作系统的限制。是否有某种方式来分配堆栈大数据，即使这不是一个很好的初步实践？
I don't know the OS limitations about the stack. Is there some way to allocate big data in stack, even if this is not a good pratice?
推荐答案
栈的大小经常在Linux中的限制。命令的ulimit -s 会给当前值，以KB为单位。您可以更改（通常）文件 /etc/security/limits.conf文件默认值。您也可以根据权限，改就通过code每个进程的基础上：
The stack size is quite often limited in Linux. The command ulimit -s will give the current value, in Kbytes. You can change the default in (usually) the file /etc/security/limits.conf. You can also, depending on privileges, change it on a per-process basis via the code:
#include <sys/resource.h>
// ...
struct rlimit x;
if (getrlimit(RLIMIT_STACK, &x) < 0)
perror("getrlimit");
x.rlim_cur = RLIM_INFINITY;
if (setrlimit(RLIMIT_STACK, &x) < 0)
perror("setrlimit");
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