159 lines
4.5 KiB
Plaintext
159 lines
4.5 KiB
Plaintext
libtraceevent(3)
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================
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NAME
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----
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trace_seq_init, trace_seq_destroy, trace_seq_reset, trace_seq_terminate,
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trace_seq_putc, trace_seq_puts, trace_seq_printf, trace_seq_vprintf,
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trace_seq_do_fprintf, trace_seq_do_printf -
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Initialize / destroy a trace sequence.
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SYNOPSIS
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--------
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[verse]
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--
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*#include <event-parse.h>*
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*#include <trace-seq.h>*
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void *trace_seq_init*(struct trace_seq pass:[*]_s_);
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void *trace_seq_destroy*(struct trace_seq pass:[*]_s_);
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void *trace_seq_reset*(struct trace_seq pass:[*]_s_);
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void *trace_seq_terminate*(struct trace_seq pass:[*]_s_);
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int *trace_seq_putc*(struct trace_seq pass:[*]_s_, unsigned char _c_);
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int *trace_seq_puts*(struct trace_seq pass:[*]_s_, const char pass:[*]_str_);
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int *trace_seq_printf*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, _..._);
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int *trace_seq_vprintf*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, va_list _args_);
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int *trace_seq_do_printf*(struct trace_seq pass:[*]_s_);
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int *trace_seq_do_fprintf*(struct trace_seq pass:[*]_s_, FILE pass:[*]_fp_);
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--
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DESCRIPTION
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-----------
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Trace sequences are used to allow a function to call several other functions
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to create a string of data to use.
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The _trace_seq_init()_ function initializes the trace sequence _s_.
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The _trace_seq_destroy()_ function destroys the trace sequence _s_ and frees
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all its resources that it had used.
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The _trace_seq_reset()_ function re-initializes the trace sequence _s_. All
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characters already written in _s_ will be deleted.
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The _trace_seq_terminate()_ function terminates the trace sequence _s_. It puts
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the null character pass:['\0'] at the end of the buffer.
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The _trace_seq_putc()_ function puts a single character _c_ in the trace
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sequence _s_.
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The _trace_seq_puts()_ function puts a NULL terminated string _str_ in the
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trace sequence _s_.
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The _trace_seq_printf()_ function puts a formated string _fmt _with
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variable arguments _..._ in the trace sequence _s_.
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The _trace_seq_vprintf()_ function puts a formated string _fmt _with
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list of arguments _args_ in the trace sequence _s_.
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The _trace_seq_do_printf()_ function prints the buffer of trace sequence _s_ to
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the standard output stdout.
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The _trace_seq_do_fprintf()_ function prints the buffer of trace sequence _s_
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to the given file _fp_.
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RETURN VALUE
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------------
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Both _trace_seq_putc()_ and _trace_seq_puts()_ functions return the number of
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characters put in the trace sequence, or 0 in case of an error
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Both _trace_seq_printf()_ and _trace_seq_vprintf()_ functions return 0 if the
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trace oversizes the buffer's free space, the number of characters printed, or
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a negative value in case of an error.
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Both _trace_seq_do_printf()_ and _trace_seq_do_fprintf()_ functions return the
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number of printed characters, or -1 in case of an error.
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EXAMPLE
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-------
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[source,c]
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--
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#include <event-parse.h>
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#include <trace-seq.h>
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...
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struct trace_seq seq;
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trace_seq_init(&seq);
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...
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void foo_seq_print(struct trace_seq *tseq, char *format, ...)
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{
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va_list ap;
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va_start(ap, format);
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if (trace_seq_vprintf(tseq, format, ap) <= 0) {
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/* Failed to print in the trace sequence */
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}
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va_end(ap);
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}
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trace_seq_reset(&seq);
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char *str = " MAN page example";
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if (trace_seq_puts(&seq, str) != strlen(str)) {
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/* Failed to put str in the trace sequence */
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}
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if (trace_seq_putc(&seq, ':') != 1) {
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/* Failed to put ':' in the trace sequence */
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}
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if (trace_seq_printf(&seq, " trace sequence: %d", 1) <= 0) {
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/* Failed to print in the trace sequence */
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}
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foo_seq_print( &seq, " %d\n", 2);
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trace_seq_terminate(&seq);
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...
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if (trace_seq_do_printf(&seq) < 0 ) {
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/* Failed to print the sequence buffer to the standard output */
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}
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FILE *fp = fopen("trace.txt", "w");
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if (trace_seq_do_fprintf(&seq, fp) < 0 ) [
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/* Failed to print the sequence buffer to the trace.txt file */
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}
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trace_seq_destroy(&seq);
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...
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--
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FILES
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-----
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[verse]
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--
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*event-parse.h*
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Header file to include in order to have access to the library APIs.
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*trace-seq.h*
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Header file to include in order to have access to trace sequences related APIs.
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*-ltraceevent*
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Linker switch to add when building a program that uses the library.
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--
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SEE ALSO
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--------
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_libtraceevent(3)_, _trace-cmd(1)_
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AUTHOR
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------
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[verse]
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--
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*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
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*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
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--
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REPORTING BUGS
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--------------
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Report bugs to <linux-trace-devel@vger.kernel.org>
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LICENSE
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-------
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libtraceevent is Free Software licensed under the GNU LGPL 2.1
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RESOURCES
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---------
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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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