Either you are doing something wrong or the library is. A number of implementations of either the runtime library or your OS may detect this situation in some conditions and terminate the program. This is stack smashing, and undefined behavior. If a process receives SIGTERM, some other process sent that signal. Because the buffer can only contain 16 characters, the remaining characters will be written past its end. And there are a few signals that are sent due to a key press in a terminal, mainly SIGINT for Ctrl+ C, SIGQUIT for Ctrl+ \ and SIGTSTP for Ctrl+ Z, but SIGTERM is not one of those.
Youre not allowed to insert or remove objects in the middle, you can only operate on the top of the stack. When you push, youre putting a new object on top of the stack when you pop youre taking an object from the top of the stack. Stack uses an encapsulated object of either vector or deque (by default) or list (sequential container class) as its underlying container, providing a. There are a few signals that are sent automatically like SIGHUP when a terminal goes away, SIGSEGV/SIGBUS/SIGILL when a process does things it shouldn't be doing, SIGPIPE when it writes to a broken pipe/socket, etc. A stack is a last-in-first-out structure, like a stack of books. Stacks are a type of container adaptors with LIFO (Last In First Out) type of working, where a new element is added at one end (top) and an element is removed from that end only.
To answer the question in your title, SIGTERM is never sent automatically by the system. Note that this includes the case of a process that receives SIGTERM, but has a signal handler for it, and eventually exits normally (perhaps as an indirect consequence of the SIGTERM signal, perhaps not). In particular, if $? is 0, your program exited normally.
In the shell, a command's exit status (saved in $?) conflates the actual exit status of the program and the signal value: if a program is killed by a signal, $? is set to a value greater than 128 (with most shells, this value is 128 plus the signal number ATT ksh uses 256 + signal number and yash uses 384 + signal number, which avoids the ambiguity, but the other shells haven't followed suit). Values 126 and above are used by the shell to report special conditions, so it's best to avoid them.Īt the C API level, programs report a 16-bit status¹ that encodes both the program's exit status and the signal that killed it, if any. Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals.
'Stack shielding' software have been developed on the promise of preventing exploitation of buffer overflow vulnerabilities that make use of the stack smashing techniques.
Conventionally, programs use small values. Technologies to detect and prevent 'stack smashing' exploit code were presented thereafter, notably at the 1998 USENIX Security conference 4. An exiting program can choose any integer between 0 and 255 as its exit status. I'll post this as an answer so that there's some kind of resolution if this turns out to be the issue.Īn exit status of 0 means a normal exit from a successful program.