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   6 .TH LIBC_DB 3LIB "Aug 19, 2019"
   7 .SH NAME
   8 libc_db \- threads debugging library
  10 .nf
  11 cc [ \fIflag\fR... ] \fIfile\fR... \fB-lc_db\fR [ \fIlibrary\fR... ]
  12 #include <\fBproc_service.h\fR>
  13 #include <\fBthread_db.h\fR>
  14 .fi
  17 The \fBlibc_db\fR library provides support for monitoring and manipulating
  18 threads-related aspects of a multithreaded program. There are at least two
  19 processes involved,  the controlling process and one or more target processes.
  20 The controlling process is the \fBlibc_db\fR client, which links with
  21 \fBlibc_db\fR and uses \fBlibc_db\fR to inspect or modify threads-related
  22 aspects of one or more target processes. The target processes must be
  23 multithreaded processes that use \fBlibc\fR. The controlling process might or
  24 might not be multithreaded itself.
  25 .sp
  26 .LP
  27 The most commonly anticipated use for \fBlibc_db\fR is that the controlling
  28 process will be a debugger for a multithreaded program, hence the "db" in
  29 \fBlibc_db\fR.
  30 .sp
  31 .LP
  32 The \fBlibc_db\fR library is dependent on the internal implementation details
  33 of \fBlibc\fR. It is a "friend" of \fBlibc\fR in the C++ sense, which is
  34 precisely the "value added" by \fBlibc_db\fR. It encapsulates the knowledge of
  35 \fBlibc\fR internals that a debugger needs to manipulate the threads-related
  36 state of a target process.
  37 .sp
  38 .LP
  39 To be able to inspect and manipulate target processes, \fBlibc_db\fR makes use
  40 of certain process control primitives that must be  provided by the process
  41 using \fBlibc_db\fR. The imported interfaces are defined in
  42 \fBproc_service\fR(3PROC). In other words, the controlling process is linked
  43 with \fBlibc_db\fR and calls routines in \fBlibc_db\fR. In turn, \fBlibc_db\fR
  44 calls certain routines that it expects the controlling process to provide.
  45 These process control  primitives allow \fBlibc_db\fR to:
  46 .RS +4
  47 .TP
  48 .ie t \(bu
  49 .el o
  50 Look up symbols in a target process.
  51 .RE
  52 .RS +4
  53 .TP
  54 .ie t \(bu
  55 .el o
  56 Stop and continue individual lightweight processes ( LWPs) within a target
  57 process.
  58 .RE
  59 .RS +4
  60 .TP
  61 .ie t \(bu
  62 .el o
  63 Stop and continue an entire target process.
  64 .RE
  65 .RS +4
  66 .TP
  67 .ie t \(bu
  68 .el o
  69 Read and write memory and registers in a target process.
  70 .RE
  71 .sp
  72 .LP
  73 Initially, a controlling process obtains a handle for a target process. Through
  74 that handle it can then obtain handles for the component objects of the target
  75 process, its threads, its synchronization objects, and its thread-specific-data
  76 keys.
  77 .sp
  78 .LP
  79 When \fBlibc_db\fR needs to return sets of handles to the controlling process,
  80 for example, when returning handles for all the threads in a target process, it
  81 uses an iterator function. An iterator function calls back a client-specified
  82 function once for each handle to be returned, passing one handle back on each
  83 call to the callback function.  The calling function also passes another
  84 parameter to the iterator function,  which the iterator function passes on to
  85 the callback function.  This makes it easy to build a linked list of thread
  86 handles for a particular target process. The additional parameter is the head
  87 of the linked list, and the callback function simply inserts the current handle
  88 into the linked list.
  89 .sp
  90 .LP
  91 Callback functions are expected to return an integer.  Iteration terminates
  92 early if a callback function returns a non-zero value. Otherwise, iteration
  93 terminates when there are no more handles to pass back.
  95 The shared object \fBlibc_db.so.1\fR provides the public interfaces defined
  96 below. See \fBIntro\fR(3) for additional information on shared object
  97 interfaces.
  98 .sp
 100 .sp
 101 .TS
 102 l l
 103 l l .
 104 \fBtd_init\fR   \fBtd_log\fR
 105 \fBtd_sync_get_info\fR  \fBtd_sync_get_stats\fR
 106 \fBtd_sync_setstate\fR  \fBtd_sync_waiters\fR
 107 \fBtd_ta_clear_event\fR \fBtd_ta_delete\fR
 108 \fBtd_ta_enable_stats\fR        \fBtd_ta_event_addr\fR
 109 \fBtd_ta_event_getmsg\fR        \fBtd_ta_get_nthreads\fR
 110 \fBtd_ta_get_ph\fR      \fBtd_ta_get_stats\fR
 111 \fBtd_ta_map_addr2sync\fR       \fBtd_ta_map_id2thr\fR
 112 \fBtd_ta_map_lwp2thr\fR \fBtd_ta_new\fR
 113 \fBtd_ta_reset_stats\fR \fBtd_ta_set_event\fR
 114 \fBtd_ta_setconcurrency\fR      \fBtd_ta_sync_iter\fR
 115 \fBtd_ta_sync_tracking_enable\fR        \fBtd_ta_thr_iter\fR
 116 \fBtd_ta_tsd_iter\fR    \fBtd_thr_clear_event\fR
 117 \fBtd_thr_dbresume\fR   \fBtd_thr_dbsuspend\fR
 118 \fBtd_thr_event_enable\fR       \fBtd_thr_event_getmsg\fR
 119 \fBtd_thr_get_info\fR   \fBtd_thr_getfpregs\fR
 120 \fBtd_thr_getgregs\fR   \fBtd_thr_getxregs\fR
 121 \fBtd_thr_getxregsize\fR        \fBtd_thr_lockowner\fR
 122 \fBtd_thr_set_event\fR  \fBtd_thr_setfpregs\fR
 123 \fBtd_thr_setgregs\fR   \fBtd_thr_setprio\fR
 124 \fBtd_thr_setsigpending\fR      \fBtd_thr_setxregs\fR
 125 \fBtd_thr_sigsetmask\fR \fBtd_thr_sleepinfo\fR
 126 \fBtd_thr_tsd\fR        \fBtd_thr_validate\fR
 127 .TE
 129 .SH FILES
 130 .ne 2
 131 .na
 132 \fB/lib/libc_db.so.1\fR
 133 .ad
 134 .RS 24n
 135 shared object
 136 .RE
 138 .sp
 139 .ne 2
 140 .na
 141 \fB/lib/64/libc_db.so.1\fR
 142 .ad
 143 .RS 24n
 144 64-bit shared object
 145 .RE
 148 See \fBattributes\fR(5) for description of the following attributes:
 149 .sp
 151 .sp
 152 .TS
 153 box;
 154 c | c
 155 l | l .
 157 MT-Level        Safe
 158 .TE
 161 \fBIntro\fR(3), \fBtd_ta_new\fR(3C_DB), \fBattributes\fR(5), \fBthreads\fR(5)