semop

Implemented in Antinomie 0.7.0 · Syscall list

Synopsis

long semop(int semid, struct sembuf *sops, unsigned int nsops);

Number (x86-64)	65
ABI	common
Kernel entry point	sys_semop

This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.

Description

Performs a list of operations on a System V semaphore set atomically.

Arguments

Name	Type	Meaning
semid (arg0)	int	System V semaphore set id.
sops (arg1)	struct sembuf *	Pointer to an array of sembuf operations.
nsops (arg2)	unsigned int	Number of operations.

Return value

On success: 0.

In an Antinomie trace the Return column and the ret filter field show the raw kernel return value. On failure that is the negative errno, for example -2 for ENOENT, not the -1 plus errno that the libc wrapper gives. syscall.errno holds the positive errno and syscall.success is false.

Common errors

Raw return	Name	Meaning
-7	E2BIG	An argument list or structure is too large.
-11	EAGAIN	The call would block, or a resource is temporarily unavailable.
-4	EINTR	The call was interrupted by a signal.

Man page

semop(2) on man7.org

Captured by Antinomie

Coverage mark: Implemented. Every pointer argument has a capture rule in the pinned kernel patch and none of them records a “no decoder”, “address only” or “not observed” gap on any code path. Individual values can still be incomplete on a particular call; see the capture statuses.

Every call is recorded as an Entry record (the six argument words and the pointees copied at entry) and an Exit record (the return value and the pointees copied at exit).

Arguments

Argument	When	How	Recorded field key	Condition
semid (arg0)	Entry	raw scalar word	args.0, args.semid
sops (arg1)	Entry	the pointer itself, as a raw word	args.1, args.raw[1]
↳ pointee	Entry	array of sembuf, count from nsops (arg2), “invalid extent” above the IPC limit	arg1.semops	always
nsops (arg2)	Entry	raw scalar word	args.2, args.nsops

Filter fields

• Result: ret, syscall.errno, syscall.success, syscall.duration_ns.
• Argument words: args.semid (arg0), args.sops (arg1), args.nsops (arg2); args.0 to args.5 by position.
• Structure sembuf[] behind sops (arg1): args.sops.<member> for sem_flg, sem_num, sem_op.

See Syscall Trace filter for the full syntax.

For what the capture statuses mean, see Capture statuses. For what is never recorded, see Known gaps.