fchmodat2
Implemented in Antinomie 0.7.0 · Syscall list
Synopsis
Section titled “Synopsis”long fchmodat2(int dfd, const char *filename, umode_t mode, unsigned int flags);| Number (x86-64) | 452 |
| ABI | common |
| Kernel entry point | sys_fchmodat2 |
This is the raw kernel prototype from the pinned Linux 6.12.94 schema, not the libc wrapper.
Description
Section titled “Description”Like fchmodat with flags, such as not following symbolic links.
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. |
filename (arg1) |
const char * |
Path of the file, as a NUL-terminated string in user memory. |
mode (arg2) |
umode_t |
Permission bits (and, for some calls, the file type) for a file or directory being created or changed. |
flags (arg3) |
unsigned int |
Option flags that change 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 |
|---|---|---|
-2 |
ENOENT |
A path component or the named object does not exist. |
-1 |
EPERM |
The operation is not permitted for this process. |
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 |
|---|---|---|---|---|
dfd (arg0) |
Entry | raw scalar word | args.0, args.dfd |
|
filename (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 |
mode (arg2) |
Entry | raw scalar word | args.2, args.mode |
|
flags (arg3) |
Entry | raw scalar word; Syscall Trace also decodes it into flag names (nofollow_empty group), listing unknown bits separately |
args.3, args.flags |
Filter fields
Section titled “Filter fields”- Result:
ret,syscall.errno,syscall.success,syscall.duration_ns. - Argument words:
args.dfd(arg0),args.filename(arg1),args.mode(arg2),args.flags(arg3);args.0toargs.5by position. - Captured strings: the
args.<name>field of a path argument, andargs.path, give the captured text instead of the pointer.
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.