The sbrksystem call moves the “border” of the data segment. This means it moves a border of an area in which a program may read/write data (letting it grow or shrink, although AFAIK no malloc really gives memory segments back to the kernel with that method). Aside from that, there’s also mmap which is used … Read more
When your signal handler returns (assuming it doesn’t call exit or longjmp or something that prevents it from actually returning), the code will continue at the point the signal occurred, reexecuting the same instruction. Since at this point, the memory protection has not been changed, it will just throw the signal again, and you’ll be … Read more
A question about syscalls needs to be in the context of a particular implementation (OS/kernel), since the very concept of syscalls is not universal but implementation-specific, and many operating systems do not even have them as a stable public interface you can use from applications. I’m going to assume you’re asking about Linux where the … Read more