POSIX_TRACE_CLOSE(3P)

💖 POSIX_TRACE_CLOSE(3P) — the girlies' guide to trace log management 💖

okay bestie, so this is a page from the POSIX Programmer's Manual, and it's giving very specific energy. Before we even start:

⚠️ PROLOG — this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (so like, go check the corresponding Linux manual page for the actual Linux behavior), or the interface may not even be implemented on Linux at all. 🙈 no cap.

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✨ NAME ✨

posix_trace_close, posix_trace_open, and posix_trace_rewind — trace log management (TRACING). 🦋

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🌸 SYNOPSIS 🌸

#include <trace.h>

int posix_trace_close(trace_id_t trid);
int posix_trace_open(int file_desc, trace_id_t *trid);
int posix_trace_rewind(trace_id_t trid);

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💅 DESCRIPTION 💅

okay so here's the tea on all three of these functions, one at a time:

posix_trace_close()

It shall deallocate the trace log identifier indicated by trid, and all of its associated resources. like, everything. gone. ✨ And if there's no valid trace log pointed to by the trid? Then this function shall fail. periodt. 💀

posix_trace_open()

It shall allocate the necessary resources and establish the connection between a trace log identified by the file_desc argument and a trace stream identifier identified by the object pointed to by the trid argument.

The file_desc argument should be a valid open file descriptor that corresponds to a trace log. And it shall be open for reading — no writing, bestie, reading only. 📖

The current trace event timestamp — which is the timestamp of the trace event that will be read by the next call to posix_trace_getnext_event() — shall be set to the timestamp of the oldest trace event recorded in the trace log identified by trid. so we start from the very beginning, iconic. 🎀

the trace stream identifier it hands you? it can ONLY be used by these functions:

• posix_trace_close()
• posix_trace_eventid_equal()
• posix_trace_eventid_get_name()
• posix_trace_eventtypelist_getnext_id()
• posix_trace_eventtypelist_rewind()
• posix_trace_get_attr()
• posix_trace_get_status()
• posix_trace_getnext_event()
• posix_trace_rewind()

🚨 In particular, notice that the operations normally used by a trace controller process — like posix_trace_start(), posix_trace_stop(), or posix_trace_shutdown() — cannot be invoked using the trace stream identifier returned by posix_trace_open(). like, not allowed. the vibe check says no. 🙅‍♀️

posix_trace_rewind()

It shall reset the current trace event timestamp — which, again, specifies the timestamp of the trace event that will be read by the next call to posix_trace_getnext_event() — to the timestamp of the oldest trace event recorded in the trace log identified by trid. it's the rewind button, we love a do-over. ⏪

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🔥 RETURN VALUE 🔥

Upon successful completion, these functions shall return a value of zero. 🫶 Otherwise, they shall return the corresponding error number. (so, zero = slay, nonzero = uh oh.)

If successful, the posix_trace_open() function stores the trace stream identifier value in the object pointed to by trid.

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💀 ERRORS 💀

posix_trace_open() shall fail if:

• EINTR — The operation was interrupted by a signal and thus no trace log was opened. rude, honestly. 😭
• EINVAL — The object pointed to by file_desc does not correspond to a valid trace log.

posix_trace_close() and posix_trace_rewind() may fail if:

• EINVAL — The object pointed to by trid does not correspond to a valid trace log.

✨ note the difference bestie: one says shall fail, the other says may fail. that's not a typo, that's the spec being precise. 👑

The following sections are informative.

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🦋 EXAMPLES 🦋

None. (yes, really. empty. nothing. the void. 💀)

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🎀 APPLICATION USAGE 🎀

None. (again! iconic of them.)

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🌈 RATIONALE 🌈

None.

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⭐ FUTURE DIRECTIONS ⭐

The posix_trace_close(), posix_trace_open(), and posix_trace_rewind() functions may be removed in a future version. so like, enjoy them while they last, babe. 🥲

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👑 SEE ALSO 👑

• posix_trace_get_attr()
• posix_trace_get_filter()
• posix_trace_getnext_event()

The Base Definitions volume of POSIX.1‐2017, <trace.h>

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💜 COPYRIGHT 💜

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group.

In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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and that's the whole page, bestie! 💖 this one came from the IEEE/The Open Group, dated 2017, and it lives under the name POSIX_TRACE_CLOSE(3P). go forth and trace responsibly. mwah. 💅✨