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lseek

Implemented in Antinomie 0.7.0 · Syscall list

long lseek(unsigned int fd, off_t offset, unsigned int whence);
Number (x86-64) 8
ABI common
Kernel entry point sys_lseek

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

Moves the read/write offset of an open file to an absolute or relative position.

Name Type Meaning
fd (arg0) unsigned int File descriptor to operate on.
offset (arg1) off_t Offset, interpreted according to whence.
whence (arg2) unsigned int Reference point for the offset: SEEK_SET, SEEK_CUR or SEEK_END.

On success: the new file offset.

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.

Raw return Name Meaning
-9 EBADF A file descriptor is not valid for this operation.
-22 EINVAL An argument is invalid.
-29 ESPIPE The descriptor is not seekable, for example a pipe.

lseek(2) on man7.org

Coverage mark: Implemented. All arguments are plain values, recorded as the raw argument words at entry. There is no pointee to copy and no known gap.

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).

Argument When How Recorded field key Condition
fd (arg0) Entry raw scalar word args.0, args.fd
offset (arg1) Entry raw scalar word args.1, args.offset
whence (arg2) Entry raw scalar word args.2, args.whence
  • Result: ret, syscall.errno, syscall.success, syscall.duration_ns.
  • Argument words: args.fd (arg0), args.offset (arg1), args.whence (arg2); args.0 to args.5 by 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.