copyinstr
Copies a null-terminated C string from the specified user address to a DTrace buffer and returns the address of the buffer.
string copyinstr(uintptr_t addr [, size_t size])
The copyinstr
function copies a null-terminated C string from the
specified user address into a DTrace scratch buffer and returns the address of this buffer.
The user address is interpreted as an address in the space of the process that's associated
with the current thread. An optional maximum length parameter sets a limit on the number of
bytes that are examined beyond the address. The resulting string is always null-terminated
and the string's length is limited to the value set by the compiler and runtime
strsize
option. As with the copyin
function, the specified address must correspond
to a faulted-in page in the current process. If the address doesn't correspond to a
faulted-in page, or if insufficient scratch memory is available, NULL is returned, and an
error is generated.
Example 7-8 How to use copyinstr to copy a string from an address space for a process to the DTrace buffer
In this example, a probe is set for the entry point on write system calls. A predicate is
set to filter for when the process execname matches the passwd
application.
The copyinstr
function is used to copy the first argument,
arg1
, of the write call to a string which is printed by
printf
. This script prints the arguments for the system write calls when
somebody uses the passwd
application to reset a password.
syscall::write:entry
/execname=="passwd"/
{
printf("%s", copyinstr(arg1));
}