What do Segmentation violation, `Bus error, and General protection fault mean? What is a core dump?

Q

What do Segmentation violation, `Bus error, and General protection fault mean? What is a core dump?

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A

These symptoms (and any similar messages having to do with memory access violations or protection faults) generally mean that your program tried to access memory it shouldn't have, invariably as a result of stack corruption or improper pointer use. Likely causes are:
* overflow of local (``automatic,'' stack-allocated) arrays * inadvertent use of null pointers
* uninitialized, misaligned, or otherwise improperly allocated pointers
* stale aliases to memory that has been relocated
* corruption of the malloc arena
* attempts to modify read-only values (those declared const, and string literals
* mismatched function arguments, especially involving pointers; two possibilities are scanf and fprintf (make sure it receives its first FILE * argument)
Under Unix, any of these problems almost invariably leads to a ``core dump'': a file named core, created in the current directory, containing a memory image of the crashed process, for debugging.
The distinction between ``Bus error'' and ``Segmentation Violation'' may or may not be significant; different versions of Unix generate these signals under different sets of circumstances. Roughly speaking, a segmentation violation indicates an attempt to access memory which doesn't even exist, and a bus error indicates an attempt to access memory in an illegal way

2015-05-20, 1023👍, 0💬