shmat
Partial in Antinomie 0.7.0 · Syscall list
Synopsis
Section titled “Synopsis”long shmat(int shmid, char *shmaddr, int shmflg);| Number (x86-64) | 30 |
| ABI | common |
| Kernel entry point | sys_shmat |
This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.
Description
Section titled “Description”Attaches a System V shared memory segment to the address space.
Arguments
Section titled “Arguments”| Name | Type | Meaning |
|---|---|---|
shmid (arg0) |
int |
System V shared memory segment id. |
shmaddr (arg1) |
char * |
Address at which to attach the segment, or 0. |
shmflg (arg2) |
int |
Shared memory flags. |
Return value
Section titled “Return value”On success: the address where the segment is attached.
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
Section titled “Common errors”| Raw return | Name | Meaning |
|---|---|---|
-13 |
EACCES |
Permission denied. |
-22 |
EINVAL |
An argument is invalid. |
Man page
Section titled “Man page”Captured by Antinomie
Section titled “Captured by Antinomie”Coverage mark: Partial. The attach address (shmaddr) is recorded as a bare address with the “address only” status; the attached memory itself is not read.
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
Section titled “Arguments”| Argument | When | How | Recorded field key | Condition |
|---|---|---|---|---|
shmid (arg0) |
Entry | raw scalar word | args.0, args.shmid |
|
shmaddr (arg1) |
Entry | the pointer itself, as a raw word | args.1, args.raw[1] |
|
| ↳ pointee | Entry | the requested address, 0 bytes, status “address only” | shm.mapping_address |
always |
shmflg (arg2) |
Entry | raw scalar word; Syscall Trace also decodes it into flag names (shmat group), listing unknown bits separately |
args.2, args.shmflg |
Filter fields
Section titled “Filter fields”- Result:
ret,syscall.errno,syscall.success,syscall.duration_ns. - Argument words:
args.shmid(arg0),args.shmaddr(arg1),args.shmflg(arg2);args.0toargs.5by position.
See Syscall Trace filter for the full syntax.
Known gaps
Section titled “Known gaps”- See the coverage mark above for the code paths that record a gap.
For what the capture statuses mean, see Capture statuses. For what is never recorded, see Known gaps.