tools lib traceevent: Man pages for trace sequences APIs

Create man pages for trace sequences libtraceevent APIs:

  trace_seq_init(),
  trace_seq_destroy(),
  trace_seq_reset(),
  trace_seq_terminate(),
  trace_seq_putc(),
  trace_seq_puts(),
  trace_seq_printf(),
  trace_seq_vprintf(),
  trace_seq_do_fprintf(),
  trace_seq_do_printf()

Signed-off-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-trace-devel@vger.kernel.org
Link: http://lore.kernel.org/linux-trace-devel/20190503091119.23399-27-tstoyanov@vmware.com
Link: http://lkml.kernel.org/r/20190510200110.462646052@goodmis.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/traceevent/Documentation/libtraceevent-tseq.txt

@@ -0,0 +1,158 @@
+libtraceevent(3)
+================
+
+NAME
+----
+trace_seq_init, trace_seq_destroy, trace_seq_reset, trace_seq_terminate,
+trace_seq_putc, trace_seq_puts, trace_seq_printf, trace_seq_vprintf,
+trace_seq_do_fprintf, trace_seq_do_printf -
+Initialize / destroy a trace sequence.
+
+SYNOPSIS
+--------
+[verse]
+--
+*#include <event-parse.h>*
+*#include <trace-seq.h>*
+
+void *trace_seq_init*(struct trace_seq pass:[*]_s_);
+void *trace_seq_destroy*(struct trace_seq pass:[*]_s_);
+void *trace_seq_reset*(struct trace_seq pass:[*]_s_);
+void *trace_seq_terminate*(struct trace_seq pass:[*]_s_);
+int *trace_seq_putc*(struct trace_seq pass:[*]_s_, unsigned char _c_);
+int *trace_seq_puts*(struct trace_seq pass:[*]_s_, const char pass:[*]_str_);
+int *trace_seq_printf*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, _..._);
+int *trace_seq_vprintf*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, va_list _args_);
+int *trace_seq_do_printf*(struct trace_seq pass:[*]_s_);
+int *trace_seq_do_fprintf*(struct trace_seq pass:[*]_s_, FILE pass:[*]_fp_);
+--
+
+DESCRIPTION
+-----------
+Trace sequences are used to allow a function to call several other functions
+to create a string of data to use.
+
+The _trace_seq_init()_ function initializes the trace sequence _s_.
+
+The _trace_seq_destroy()_ function destroys the trace sequence _s_ and frees
+all its resources that it had used.
+
+The _trace_seq_reset()_ function re-initializes the trace sequence _s_. All
+characters already written in _s_ will be deleted.
+
+The _trace_seq_terminate()_ function terminates the trace sequence _s_. It puts
+the null character pass:['\0'] at the end of the buffer.
+
+The _trace_seq_putc()_ function puts a single character _c_ in the trace
+sequence _s_.
+
+The _trace_seq_puts()_ function puts a NULL terminated string _str_ in the
+trace sequence _s_.
+
+The _trace_seq_printf()_ function puts a formated string _fmt _with
+variable arguments _..._ in the trace sequence _s_.
+
+The _trace_seq_vprintf()_ function puts a formated string _fmt _with
+list of arguments _args_ in the trace sequence _s_.
+
+The _trace_seq_do_printf()_ function prints the buffer of trace sequence _s_ to
+the standard output stdout.
+
+The _trace_seq_do_fprintf()_ function prints the buffer of trace sequence _s_
+to the given file _fp_.
+
+RETURN VALUE
+------------
+Both _trace_seq_putc()_ and _trace_seq_puts()_ functions return the number of
+characters put in the trace sequence, or 0 in case of an error
+
+Both _trace_seq_printf()_ and _trace_seq_vprintf()_ functions return 0 if the
+trace oversizes the buffer's free space, the number of characters printed, or
+a negative value in case of an error.
+
+Both _trace_seq_do_printf()_ and _trace_seq_do_fprintf()_ functions return the
+number of printed characters, or -1 in case of an error.
+
+EXAMPLE
+-------
+[source,c]
+--
+#include <event-parse.h>
+#include <trace-seq.h>
+...
+struct trace_seq seq;
+trace_seq_init(&seq);
+...
+void foo_seq_print(struct trace_seq *tseq, char *format, ...)
+{
+	va_list ap;
+	va_start(ap, format);
+	if (trace_seq_vprintf(tseq, format, ap) <= 0) {
+		/* Failed to print in the trace sequence */
+	}
+	va_end(ap);
+}
+
+trace_seq_reset(&seq);
+
+char *str = " MAN page example";
+if (trace_seq_puts(&seq, str) != strlen(str)) {
+	/* Failed to put str in the trace sequence */
+}
+if (trace_seq_putc(&seq, ':') != 1) {
+	/* Failed to put ':' in the trace sequence */
+}
+if (trace_seq_printf(&seq, " trace sequence: %d", 1) <= 0) {
+	/* Failed to print in the trace sequence */
+}
+foo_seq_print( &seq, "  %d\n", 2);
+
+trace_seq_terminate(&seq);
+...
+
+if (trace_seq_do_printf(&seq) < 0 ) {
+	/* Failed to print the sequence buffer to the standard output */
+}
+FILE *fp = fopen("trace.txt", "w");
+if (trace_seq_do_fprintf(&seq, fp) < 0 ) [
+	/* Failed to print the sequence buffer to the trace.txt file */
+}
+
+trace_seq_destroy(&seq);
+...
+--
+
+FILES
+-----
+[verse]
+--
+*event-parse.h*
+	Header file to include in order to have access to the library APIs.
+*trace-seq.h*
+	Header file to include in order to have access to trace sequences related APIs.
+*-ltraceevent*
+	Linker switch to add when building a program that uses the library.
+--
+
+SEE ALSO
+--------
+_libtraceevent(3)_, _trace-cmd(1)_
+
+AUTHOR
+------
+[verse]
+--
+*Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*.
+*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page.
+--
+REPORTING BUGS
+--------------
+Report bugs to  <linux-trace-devel@vger.kernel.org>
+
+LICENSE
+-------
+libtraceevent is Free Software licensed under the GNU LGPL 2.1
+
+RESOURCES
+---------
+https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git