2.196 Pragma Unreserve_All_Interrupts

Syntax:

pragma Unreserve_All_Interrupts;

Normally certain interrupts are reserved to the implementation. Any attempt to attach an interrupt causes Program_Error to be raised, as described in RM C.3.2(22). A typical example is the SIGINT interrupt used in many systems for a Ctrl-C interrupt. Normally this interrupt is reserved to the implementation, so that Ctrl-C can be used to interrupt execution.

If the pragma Unreserve_All_Interrupts appears anywhere in any unit in a program, then all such interrupts are unreserved. This allows the program to handle these interrupts, but disables their standard functions. For example, if this pragma is used, then pressing Ctrl-C will not automatically interrupt execution. However, a program can then handle the SIGINT interrupt as it chooses.

For a full list of the interrupts handled in a specific implementation, see the source code for the spec of Ada.Interrupts.Names in file a-intnam.ads. This is a target dependent file that contains the list of interrupts recognized for a given target. The documentation in this file also specifies what interrupts are affected by the use of the Unreserve_All_Interrupts pragma.

For a more general facility for controlling what interrupts can be handled, see pragma Interrupt_State, which subsumes the functionality of the Unreserve_All_Interrupts pragma.