msgrcv
Implemented in Antinomie 0.7.0 · Syscall list
Synopsis
Section titled “Synopsis”long msgrcv(int msqid, struct msgbuf *msgp, size_t msgsz, long msgtyp, int msgflg);| Number (x86-64) | 70 |
| ABI | common |
| Kernel entry point | sys_msgrcv |
This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.
Description
Section titled “Description”Receives a message from a System V message queue and returns its length.
Arguments
Section titled “Arguments”| Name | Type | Meaning |
|---|---|---|
msqid (arg0) |
int |
System V message queue id. |
msgp (arg1) |
struct msgbuf * |
Pointer to a message buffer. |
msgsz (arg2) |
size_t |
Size of the message text in bytes. |
msgtyp (arg3) |
long |
Message type to receive. |
msgflg (arg4) |
int |
Message queue flags. |
Return value
Section titled “Return value”On success: The number of bytes transferred (see the description for what 0 means).
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 |
|---|---|---|
-7 |
E2BIG |
An argument list or structure is too large. |
-42 |
ENOMSG |
No message of the requested type. |
-4 |
EINTR |
The call was interrupted by a signal. |
Man page
Section titled “Man page”Captured by Antinomie
Section titled “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
Section titled “Arguments”| Argument | When | How | Recorded field key | Condition |
|---|---|---|---|---|
msqid (arg0) |
Entry | raw scalar word | args.0, args.msqid |
|
msgp (arg1) |
Entry | the pointer itself, as a raw word | args.1, args.raw[1] |
|
| ↳ pointee | Exit | message buffer (msgbuf): type word plus min(msgsz, result) bytes |
arg1.message |
result is 0 or greater |
msgsz (arg2) |
Entry | raw scalar word | args.2, args.msgsz |
|
msgtyp (arg3) |
Entry | raw scalar word | args.3, args.msgtyp |
|
msgflg (arg4) |
Entry | raw scalar word; Syscall Trace also decodes it into flag names (msgrcv group), listing unknown bits separately |
args.4, args.msgflg |
Filter fields
Section titled “Filter fields”- Result:
ret,syscall.errno,syscall.success,syscall.duration_ns. - Argument words:
args.msqid(arg0),args.msgp(arg1),args.msgsz(arg2),args.msgtyp(arg3),args.msgflg(arg4);args.0toargs.5by position.
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.