获取当前进程堆的起始地址？
我正在探索系统的较低级别工作原理，并且想知道 malloc 如何确定堆的起始地址。堆的偏移量是否恒定，或者是否有某种调用来获取起始地址？栈会影响堆的起始地址吗？
I am exploring the lower level workings of the system, and was wondering how malloc determines the start address of the heap. Is the heap at a constant offset or is there a call of some sort to get the start address? Does the stack affect the start address of the heap?
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sbrk 返回它添加（或删除）的字节的起始地址。在尚未分配堆的新进程中，对 sbrk 的第一次调用应返回堆的“break”部分的起始地址。如果我必须打赌，这就是使用 brk/sbrk 的 malloc 实现在第一次运行时可能会做的事情。
sbrk returns the start address of the bytes it adds (or removes). In a fresh process with no heap allocated yet, the first call to sbrk should then return the start address of the "break" section of the heap. If I had to bet, that's what malloc implementations which use brk/sbrk probably do on their first run.
传统上，堆从文本部分上方开始并逐渐增大。堆栈帧根本不影响起始地址，因为它们会向下增长到未映射的 0 页。然而，现在更常见的是
malloc()通常只是调用mmap()获取虚拟地址空间中任意位置的地址Traditionally, the heap started just above the text section and grew up; stack frames didn't affect start address at all as they grow down towards the unmapped 0 page. However, it's more common these days for
malloc()usually just callsmmap()to get an address anywhere in the virtual address space