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| -rw-r--r-- | Documentation/libtracefs-files.txt | 131 |
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diff --git a/Documentation/libtracefs-files.txt b/Documentation/libtracefs-files.txt new file mode 100644 index 0000000..d22e759 --- /dev/null +++ b/Documentation/libtracefs-files.txt @@ -0,0 +1,131 @@ +libtracefs(3) +============= + +NAME +---- +tracefs_get_tracing_file, tracefs_put_tracing_file, tracefs_tracing_dir, tracefs_debug_dir, tracefs_set_tracing_dir, +tracefs_tracing_dir_is_mounted - Find and set locations of trace directory and files. + +SYNOPSIS +-------- +[verse] +-- +*#include <tracefs.h>* + +char pass:[*]*tracefs_get_tracing_file*(const char pass:[*]_name_); +void *tracefs_put_tracing_file*(char pass:[*]_name_); +const char pass:[*]*tracefs_tracing_dir*(void); +const char pass:[*]*tracefs_debug_dir*(void); +int *tracefs_set_tracing_dir*(char pass:[*]_tracing_dir_) +int *tracefs_tracing_dir_is_mounted*(bool _mount_, const char pass:[**]_path_); +-- + +DESCRIPTION +----------- +This set of APIs can be used to find the full path of the trace file +system mount point and trace files in it. + +The *tracefs_set_tracing_dir()* function sets a custom location of the +system's tracing directory mount point. Usually, the library auto detects +it using the information from the /proc/mounts file. Use this API only if the +mount point is not standard and cannot be detected by the library. The _tracing_dir_ +argument can be NULL, in that case the custom location is deleted and the library +auto detection logic is used. + +The *tracefs_get_tracing_file()* function returns the full path of the +file with given _name_ in the trace file system. The function works +only with files in the tracefs main directory, it is not trace instance +aware. It is recommended to use *tracefs_instance_get_file()* and +*tracefs_instance_get_dir()* instead. The returned string must be freed +with *tracefs_put_tracing_file()*. + +The *tracefs_put_tracing_file()* function frees trace file name, +returned by *tracefs_get_tracing_file()*. + +The *tracefs_tracing_dir()* function returns the full path to the +trace file system. In the first function call, the mount point of the +tracing file system is located, cached and returned. It will mount it, +if it is not mounted. On any subsequent call the cached path is returned. +The return string must _not_ be freed. + +The *tracefs_debug_dir()* is similar to *tracefs_tracing_dir()* except +that it will return where the debugfs file system is mounted. If it +is not mounted it will try to mount it. The return string must _not_ +be freed. + +*tracefs_tracing_dir_is_mounted()* returns 1 if the tracing directory is +already mounted and 0 if it is not. If _mount_ is true, it will try to +mount it if it is not, and returns 0 if it succesfully mounted it and -1 +if it did not. If _path_ is set, it will be assigned to the path where it +mounted it. _path_ is internal and should not be freed. + +RETURN VALUE +------------ +The *tracefs_set_tracing_dir()* function returns 0 on success, -1 otherwise. + +The *tracefs_get_tracing_file()* function returns a string or NULL in case +of an error. The returned string must be freed with *tracefs_put_tracing_file()*. + +The *tracefs_tracing_dir()* function returns a constant string or NULL +in case of an error. The returned string must _not_ be freed. + +The *tracefs_debug_dir()* function returns a constant string or NULL +in case of an error. The returned string must _not_ be freed. + +The *tracefs_tracing_dir_is_mounted()* returns 1 if the tracing directory +is already mounted, 0 if it is not, and -1 on error. + +EXAMPLE +------- +[source,c] +-- +#include <tracefs.h> +... +char *trace_on = tracefs_get_tracing_file("tracing_on"); + if (trace_on) { + ... + tracefs_put_tracing_file(trace_on); + } +... +const char *trace_dir = tracefs_tracing_dir(); + +-- +FILES +----- +[verse] +-- +*tracefs.h* + Header file to include in order to have access to the library APIs. +*-ltracefs* + Linker switch to add when building a program that uses the library. +-- + +SEE ALSO +-------- +*libtracefs*(3), +*libtraceevent*(3), +*trace-cmd*(1) + +AUTHOR +------ +[verse] +-- +*Steven Rostedt* <rostedt@goodmis.org> +*Tzvetomir Stoyanov* <tz.stoyanov@gmail.com> +-- +REPORTING BUGS +-------------- +Report bugs to <linux-trace-devel@vger.kernel.org> + +LICENSE +------- +libtracefs is Free Software licensed under the GNU LGPL 2.1 + +RESOURCES +--------- +https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ + +COPYING +------- +Copyright \(C) 2020 VMware, Inc. Free use of this software is granted under +the terms of the GNU Public License (GPL). |