name_to_handle_at
Implemented in Antinomie 0.7.0 · Syscall list
Synopsis
Section titled “Synopsis”long name_to_handle_at(int dfd, const char *name, struct file_handle *handle, void *mnt_id, int flag);| Number (x86-64) | 303 |
| ABI | common |
| Kernel entry point | sys_name_to_handle_at |
This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.
Description
Section titled “Description”Converts a path to an opaque, persistent file handle and a mount id.
Arguments
Section titled “Arguments”| Name | Type | Meaning |
|---|---|---|
dfd (arg0) |
int |
Directory file descriptor that a relative path is resolved against, or AT_FDCWD (-100) for the current directory. |
name (arg1) |
const char * |
Name string (a path, queue name, module name or attribute name depending on the call). |
handle (arg2) |
struct file_handle * |
Pointer to a file_handle structure. |
mnt_id (arg3) |
void * |
Where the mount id is stored. |
flag (arg4) |
int |
Option flag that changes the behavior of the call. |
Return value
Section titled “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
Section titled “Common errors”| Raw return | Name | Meaning |
|---|---|---|
-75 |
EOVERFLOW |
A value does not fit in the result type. |
-95 |
ENOTSUP |
The operation is not supported (same value as EOPNOTSUPP). |
Man page
Section titled “Man page”name_to_handle_at(2) on man7.org
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 |
|---|---|---|---|---|
dfd (arg0) |
Entry | raw scalar word | args.0, args.dfd |
|
name (arg1) |
Entry | the pointer itself, as a raw word | args.1, args.raw[1] |
|
| ↳ pointee | Entry | NUL-terminated string, up to 4,096 bytes (PATH_MAX) | arg1.path |
always |
handle (arg2) |
Entry | the pointer itself, as a raw word | args.2, args.raw[2] |
|
| ↳ pointee | Entry | structure file_handle header |
handle.header |
at exit again when the result is 0 or -EOVERFLOW |
| ↳ pointee | Exit | the handle bytes, length from the header’s handle_bytes up to 128 |
handle.bytes |
result is 0 |
mnt_id (arg3) |
Entry | the pointer itself, as a raw word | args.3, args.raw[3] |
|
| ↳ pointee | Exit | int (or u64 with AT_HANDLE_MNT_ID_UNIQUE) |
arg3.mount_id |
result is 0 or -EOVERFLOW |
flag (arg4) |
Entry | raw scalar word; Syscall Trace also decodes it into flag names (handle_at group), listing unknown bits separately |
args.4, args.flag |
Filter fields
Section titled “Filter fields”- Result:
ret,syscall.errno,syscall.success,syscall.duration_ns. - Argument words:
args.dfd(arg0),args.name(arg1),args.handle(arg2),args.mnt_id(arg3),args.flag(arg4);args.0toargs.5by position. - Captured strings: the
args.<name>field of a path argument, andargs.path, give the captured text instead of the pointer. - Structure
u64behindmnt_id(arg3):args.mnt_id.<member>forvalue.
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.