Content-type: text/html Man page of libc_db

libc_db

Section: Interface Libraries (3LIB)
Updated: 24 Mar 2004
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NAME

libc_db - threads debugging library  

SYNOPSIS

cc [ flag ... ] file ... -lc_db [ library ... ]
#include <proc_service.h>
#include <thread_db.h>
 

DESCRIPTION

The libc_db library provides support for monitoring and manipulating threads-related aspects of a multithreaded program. There are at least two processes involved, the controlling process and one or more target processes. The controlling process is the libc_db client, which links with libc_db and uses libc_db to inspect or modify threads-related aspects of one or more target processes. The target processes must be multithreaded processes that use libc. The controlling process mignt or might not be multithreaded itself.

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:

• Look up symbols in a target process.

• Stop and continue individual lightweight processes ( LWPs) within a target process.

• Stop and continue an entire target process.

• Read and write memory and registers in a target process.

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.  

INTERFACES

The shared object libc_db.so.1 provides the public interfaces defined below. See intro(3) for additional information on shared object interfaces.

td_inittd_log
td_sync_get_infotd_sync_get_stats
td_sync_setstatetd_sync_waiters
td_ta_clear_eventtd_ta_delete
td_ta_enable_statstd_ta_event_addr
td_ta_event_getmsgtd_ta_get_nthreads
td_ta_get_phtd_ta_get_stats
td_ta_map_addr2synctd_ta_map_id2thr
td_ta_map_lwp2thrtd_ta_new
td_ta_reset_statstd_ta_set_event
td_ta_setconcurrencytd_ta_sync_iter
td_ta_sync_tracking_enabletd_ta_thr_iter
td_ta_tsd_itertd_thr_clear_event
td_thr_dbresumetd_thr_dbsuspend
td_thr_event_enabletd_thr_event_getmsg
td_thr_get_infotd_thr_getfpregs
td_thr_getgregstd_thr_getxregs
td_thr_getxregsizetd_thr_lockowner
td_thr_set_eventtd_thr_setfpregs
td_thr_setgregstd_thr_setprio
td_thr_setsigpendingtd_thr_setxregs
td_thr_sigsetmasktd_thr_sleepinfo
td_thr_tsdtd_thr_validate

 

FILES

/lib/libc_db.so.1 shared object

/lib/64/libc_db.so.1 64-bit shared object

 

ATTRIBUTES

See attributes(5) for description of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
AvailabilitySUNWcsl (32-bit)
SUNWcslx (64-bit)
MT-LevelSafe

 

SEE ALSO

intro(3), td_ta_new(3C_DB), attributes(5), threads(5)


 

Index

NAME
SYNOPSIS
DESCRIPTION
INTERFACES
FILES
ATTRIBUTES
SEE ALSO

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Time: 02:38:41 GMT, October 02, 2010