| LIBC_DB(3LIB) | Interface Libraries | LIBC_DB(3LIB) |
cc [ flag... ] file... -lc_db [ library... ] #include <proc_service.h> #include <thread_db.h>
The most commonly anticipated use for libc_db is that the controlling process will be a debugger for a multithreaded program, hence the "db" in libc_db.
The libc_db library is dependent on the internal implementation details of libc. It is a "friend" of libc in the C++ sense, which is precisely the "value added" by libc_db. It encapsulates the knowledge of libc internals that a debugger needs to manipulate the threads-related state of a target process.
To be able to inspect and manipulate target processes, libc_db makes use of certain process control primitives that must be provided by the process using libc_db. The imported interfaces are defined in proc_service(3PROC). In other words, the controlling process is linked with libc_db and calls routines in libc_db. In turn, libc_db calls certain routines that it expects the controlling process to provide. These process control primitives allow libc_db to:
Initially, a controlling process obtains a handle for a target process. Through that handle it can then obtain handles for the component objects of the target process, its threads, its synchronization objects, and its thread-specific-data keys.
When libc_db needs to return sets of handles to the controlling process, for example, when returning handles for all the threads in a target process, it uses an iterator function. An iterator function calls back a client-specified function once for each handle to be returned, passing one handle back on each call to the callback function. The calling function also passes another parameter to the iterator function, which the iterator function passes on to the callback function. This makes it easy to build a linked list of thread handles for a particular target process. The additional parameter is the head of the linked list, and the callback function simply inserts the current handle into the linked list.
Callback functions are expected to return an integer. Iteration terminates early if a callback function returns a non-zero value. Otherwise, iteration terminates when there are no more handles to pass back.
| td_init | td_log |
| td_sync_get_info | td_sync_get_stats |
| td_sync_setstate | td_sync_waiters |
| td_ta_clear_event | td_ta_delete |
| td_ta_enable_stats | td_ta_event_addr |
| td_ta_event_getmsg | td_ta_get_nthreads |
| td_ta_get_ph | td_ta_get_stats |
| td_ta_map_addr2sync | td_ta_map_id2thr |
| td_ta_map_lwp2thr | td_ta_new |
| td_ta_reset_stats | td_ta_set_event |
| td_ta_setconcurrency | td_ta_sync_iter |
| td_ta_sync_tracking_enable | td_ta_thr_iter |
| td_ta_tsd_iter | td_thr_clear_event |
| td_thr_dbresume | td_thr_dbsuspend |
| td_thr_event_enable | td_thr_event_getmsg |
| td_thr_get_info | td_thr_getfpregs |
| td_thr_getgregs | td_thr_getxregs |
| td_thr_getxregsize | td_thr_lockowner |
| td_thr_set_event | td_thr_setfpregs |
| td_thr_setgregs | td_thr_setprio |
| td_thr_setsigpending | td_thr_setxregs |
| td_thr_sigsetmask | td_thr_sleepinfo |
| td_thr_tsd | td_thr_validate |
/lib/64/libc_db.so.1
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | Safe |
| August 19, 2019 |