1POSIX_TRACE_EVENT(3P) POSIX Programmer's Manual POSIX_TRACE_EVENT(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 posix_trace_event, posix_trace_eventid_open — trace functions for
13 instrumenting application code (TRACING)
14
16 #include <sys/types.h>
17 #include <trace.h>
18 void posix_trace_event(trace_event_id_t event_id,
20 const void *restrict data_ptr, size_t data_len);
21 int posix_trace_eventid_open(const char *restrict event_name,
22 trace_event_id_t *restrict event_id);
23
25 The posix_trace_event() function shall record the event_id and the user
26 data pointed to by data_ptr in the trace stream into which the calling
27 process is being traced and in which event_id is not filtered out. If
28 the total size of the user trace event data represented by data_len is
29 not greater than the declared maximum size for user trace event data,
30 then the truncation-status attribute of the trace event recorded is
31 POSIX_TRACE_NOT_TRUNCATED. Otherwise, the user trace event data is
32 truncated to this declared maximum size and the truncation-status
33 attribute of the trace event recorded is POSIX_TRACE_TRUNCATED_RECORD.
34 If there is no trace stream created for the process or if the created
36 trace stream is not running, or if the trace event specified by
37 event_id is filtered out in the trace stream, the posix_trace_event()
38 function shall have no effect.
39 The posix_trace_eventid_open() function shall associate a user trace
41 event name with a trace event type identifier for the calling process.
42 The trace event name is the string pointed to by the argument
43 event_name. It shall have a maximum of {TRACE_EVENT_NAME_MAX} charac‐
44 ters (which has the minimum value {_POSIX_TRACE_EVENT_NAME_MAX}). The
45 number of user trace event type identifiers that can be defined for any
46 given process is limited by the maximum value {TRACE_USER_EVENT_MAX},
47 which has the minimum value {POSIX_TRACE_USER_EVENT_MAX}.
48 If the Trace Inherit option is not supported, the posix_trace_even‐
50 tid_open() function shall associate the user trace event name pointed
51 to by the event_name argument with a trace event type identifier that
52 is unique for the traced process, and is returned in the variable
53 pointed to by the event_id argument. If the user trace event name has
54 already been mapped for the traced process, then the previously
55 assigned trace event type identifier shall be returned. If the per-
56 process user trace event name limit represented by
57 {TRACE_USER_EVENT_MAX} has been reached, the pre-defined
58 POSIX_TRACE_UNNAMED_USEREVENT (see Table 2-7, Trace Option: User Trace
59 Event) user trace event shall be returned.
60 If the Trace Inherit option is supported, the posix_trace_even‐
62 tid_open() function shall associate the user trace event name pointed
63 to by the event_name argument with a trace event type identifier that
64 is unique for all the processes being traced in this same trace stream,
65 and is returned in the variable pointed to by the event_id argument. If
66 the user trace event name has already been mapped for the traced pro‐
67 cesses, then the previously assigned trace event type identifier shall
68 be returned. If the per-process user trace event name limit represented
69 by {TRACE_USER_EVENT_MAX} has been reached, the pre-defined
70 POSIX_TRACE_UNNAMED_USEREVENT (Table 2-7, Trace Option: User Trace
71 Event) user trace event shall be returned.
72 Note: The above procedure, together with the fact that multiple
74 processes can only be traced into the same trace stream by
75 inheritance, ensure that all the processes that are traced
76 into a trace stream have the same mapping of trace event
77 names to trace event type identifiers.
78 If there is no trace stream created, the posix_trace_eventid_open()
80 function shall store this information for future trace streams created
81 for this process.
82
84 No return value is defined for the posix_trace_event() function.
85 Upon successful completion, the posix_trace_eventid_open() function
87 shall return a value of zero. Otherwise, it shall return the corre‐
88 sponding error number. The posix_trace_eventid_open() function stores
89 the trace event type identifier value in the object pointed to by
90 event_id, if successful.
91
93 The posix_trace_eventid_open() function shall fail if:
94 ENAMETOOLONG
96 The size of the name pointed to by the event_name argument was
97 longer than the implementation-defined value
98 {TRACE_EVENT_NAME_MAX}.
99 The following sections are informative.
101
103 None.
104
106 None.
107
109 None.
110
112 The posix_trace_event() and posix_trace_eventid_open() functions may be
113 removed in a future version.
114
116 Table 2-7, Trace Option: User Trace Event, exec, posix_trace_even‐
117 tid_equal(), posix_trace_start()
118 The Base Definitions volume of POSIX.1‐2017, <sys_types.h>, <trace.h>
120
122 Portions of this text are reprinted and reproduced in electronic form
123 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
124 table Operating System Interface (POSIX), The Open Group Base Specifi‐
125 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
126 Electrical and Electronics Engineers, Inc and The Open Group. In the
127 event of any discrepancy between this version and the original IEEE and
128 The Open Group Standard, the original IEEE and The Open Group Standard
129 is the referee document. The original Standard can be obtained online
130 at http://www.opengroup.org/unix/online.html .
131 Any typographical or formatting errors that appear in this page are
133 most likely to have been introduced during the conversion of the source
134 files to man page format. To report such errors, see https://www.ker‐
135 nel.org/doc/man-pages/reporting_bugs.html .
136IEEE/The Open Group 2017 POSIX_TRACE_EVENT(3P)