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158 lines
4.5 KiB
158 lines
4.5 KiB
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* <[email protected]>, author of *libtraceevent*. |
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*Tzvetomir Stoyanov* <[email protected]>, 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 <[email protected]> |
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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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