data / bss / heap和stack中的内存分配

我有以下代码：

#include  int global_var; int global_initialized_var=5; void function(){ int stack_var; printf("The function's stack_var is at address 0x%08x\n", &stack_var); } int main(){ int stack_var; static int static_initialized_var = 5; static int static_var; int *heap_var_ptr; heap_var_ptr = (int *) malloc(4); // Next variables will be at data segment printf("global_initialized_var is at address 0x%08x\n", &global_initialized_var); printf("static_initialized_var is at address 0x%08x\n\n", &static_initialized_var); // These will be in the bss segment printf("static_var is at address 0x%08x\n", &static_var); printf("global_var is at address 0x%08x\n", &global_var); // This will be in heap segment printf("heap_var is at address 0x%08x\n\n", heap_var_ptr); // These will be in stack segment printf("stack_var is at address 0x%08x\n", &stack_var); function(); } 

我回过头来看：

 # ./memory_segments global_initialized_var is at address 0x0804a018 static_initialized_var is at address 0x0804a01c static_var is at address 0x0804a028 global_var is at address 0x0804a02c heap_var is at address 0x09285008 stack_var is at address 0xbf809fbc The function's stack_var is at address 0xbf809f8c 

假设前两个变量因为它们被初始化为static和global应该在.data段中，其中2个static_var和global_var应该在.bss段中。 我认为我得到的地址暗示它们都在同一个内存区域。 我会盲目猜测，我会说这是.bss段。

无论如何，问题是以下，我是对的？ 如果我是如何找到这些区域的“限制”（bss，数据等）或从哪里开始等等。

Answer 1

假设您正在编译类似gcc memaddr.c -g -o memaddr ，您可以使用objdump -h来显示您的部分的大小和地址：

 $ objdump -h memaddr |  grep -e'尺寸'-e'\ .data'-e'\ .bss'
 Idx名称大小VMA LMA文件关闭Algn
  23。数据00000018 0000000000601018 0000000000601018 00001018 2 ** 3
  24 .bss 00000018 0000000000601030 0000000000601030 00001030 2 ** 3
 $

您还可以使用objdump -t显示符号所属的地址和部分：

 $ objdump -t memaddr |  grep“_var”
 000000000060102c l O .data 0000000000000004 static_initialized_var.2049
 0000000000601040 l O .bss 0000000000000004 static_var.2050
 0000000000601044 g O .bss 0000000000000004 global_var
 0000000000601028 g O .data 0000000000000004 global_initialized_var
 $

所以我们可以看到.data和.bss部分相当小，碰巧彼此相邻，所以.data和.bss地址非常接近就不足为奇了。