SigInfo.hxx File Reference

#include <optional>
#include <cosmos/error/errno.hxx>
#include <cosmos/fs/types.hxx>
#include <cosmos/io/types.hxx>
#include <cosmos/memory.hxx>
#include <cosmos/proc/ptrace.hxx>
#include <cosmos/proc/signal.hxx>
#include <cosmos/proc/types.hxx>
#include <cosmos/time/types.hxx>
#include <cosmos/utils.hxx>

Go to the source code of this file.

Classes
class	cosmos::SigInfo
	Signal information struct used when receiving signals. More...
struct	cosmos::SigInfo::ProcessCtx
	Information about the process a signal is from or about. More...
struct	cosmos::SigInfo::CustomData
	Additional custom SigInfo data. More...
struct	cosmos::SigInfo::UserSigData
	Additional data found in SigInfo with Source::USER. More...
struct	cosmos::SigInfo::QueueSigData
	Additional data found in SigInfo with Source::QUEUE. More...
struct	cosmos::SigInfo::MsgQueueData
	Additional data found in SigInfo with Source::MESGQ. More...
struct	cosmos::SigInfo::TimerData
	Additional data found in SigInfo with Source::TIMER. More...
struct	cosmos::SigInfo::FaultData
	Additional data found in SigInfo for one of the memory fault / trap signals. More...
struct	cosmos::SigInfo::IllData
	Additional data delivered with SIGILL signals. More...
struct	cosmos::SigInfo::FPEData
	Extra data delivered with SIGFPE signals. More...
struct	cosmos::SigInfo::SegfaultData
	Additional data delivered with SIGSEGV signals. More...
struct	cosmos::SigInfo::SegfaultData::Bound
struct	cosmos::SigInfo::BusData
	Additional data delivered with SIGBUS signals. More...
struct	cosmos::SigInfo::ChildData
	Additional data found in SigInfo with SIGCHILD. More...
struct	cosmos::SigInfo::SysData
	Additional data found in SigInfo delivered with SIGSYS. More...
struct	cosmos::SigInfo::PollData
	Additional data found in SigInfo with SIGPOLL. More...

Macros
#define	SYS_SECCOMP   1

Detailed Description

Wrapper around the siginfo_t type.

Providing a type safe, clear and efficient API for siginfo_t is a difficult task. The struct is big (~150 bytes), contains some union fields, many fields are only valid in specific contexts and some fields have conflicting meanings depending on context.

The structure is typically only filled in by the kernel or glibc, not by applications. It is possible to use it in custom ways via the low level system call rt_sigqueueinfo(), though. The latter is also problematic in terms of trusting the siginfo_t data received from the kernel. If the signal source is another userspace process then the structure could contain rather arbitrary data, breaking the interface contract as documented in the sigaction(2) man page.

The libcosmos API focuses on interpreting data from siginfo_t received from the kernel and conforming to the API contract. For special use cases applications can access the raw data structure.

Depending on the signal number and signal source different interfaces need to be provided to siginfo_t. We wouldn't want to copy the full ~150 bytes all the time just for accessing the data using the proper types. This can be addressed by either always keeping siginfo_t on the heap and using a shared_ptr to manage the lifetime of all representations of the data. This limits the way in which siginfo_t related APIs can be used, though. Application might not want to involve the heap for this. An alternative is to provide types that only carry the relevant data, not the full siginfo_t anymore. This way not the fully blown data structure needs to be copied and the overhead remains low, since most signal contexts only use a few fields from siginfo_t. This is what libcosmos currently does.

For getting a better idea of the union structure you can have a look at the union __sifields in the system headers.

Definition in file SigInfo.hxx.

Macro Definition Documentation

SYS_SECCOMP

#define SYS_SECCOMP   1

Definition at line 25 of file SigInfo.hxx.