siginfo

The siginfo structure is a common component in Unix-like operating systems, used to convey detailed information about a signal that has been delivered to a process. When a signal is generated, the operating system typically provides a siginfo structure to the signal handler. This structure contains fields that describe the cause of the signal, the process or user that sent it, and other relevant data.

The contents of siginfo vary depending on the type of signal. For instance, for real-time signals, the siginfo structure might include the sender's process ID and user ID. For segmentation fault signals (SIGSEGV), it can specify the memory address that caused the fault. Other signals, like SIGCHLD, might provide information about the child process that terminated.

The siginfo structure is usually passed to a signal handler function as a pointer. The handler can then inspect the contents of siginfo to determine the specific circumstances of the signal and take appropriate action. This allows for more sophisticated signal handling than simply knowing that a signal occurred. The presence and exact layout of siginfo are typically defined in system headers like `<signal.h>`. Understanding siginfo is crucial for developing robust and responsive applications that interact with the operating system's signal mechanism.