UTRACE(2) BSD System Calls Manual UTRACE(2)
utrace -- insert user record in ktrace log
utrace(const char *label, void *addr, size_t len);
Adds a record to the process trace with information supplied by the user.
The record is identified by label and contains len bytes from memory
pointed to by addr. This call only has an effect if the calling process
is being traced.
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
[ENOSYS] The currently running kernel was compiled without
ktrace(2) support (option KTRACE).
[ENAMETOOLONG] The length of the label string was longer than
[EINVAL] The specified data length len was bigger than
kdump(1), ktrace(1), ktrace(2), options(4)
The utrace() system call first appeared in FreeBSD 2.2. It was added to
OpenBSD in OpenBSD 5.4. The label argument is an extension.
BSD June 1, 2013 BSD