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153 lines
5.4 KiB
153 lines
5.4 KiB
libtraceevent(3) |
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================ |
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NAME |
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---- |
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tep_register_comm, tep_override_comm, tep_pid_is_registered, |
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tep_data_comm_from_pid, tep_data_pid_from_comm, tep_cmdline_pid - |
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Manage pid to process name mappings. |
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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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int *tep_register_comm*(struct tep_handle pass:[*]_tep_, const char pass:[*]_comm_, int _pid_); |
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int *tep_override_comm*(struct tep_handle pass:[*]_tep_, const char pass:[*]_comm_, int _pid_); |
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bool *tep_is_pid_registered*(struct tep_handle pass:[*]_tep_, int _pid_); |
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const char pass:[*]*tep_data_comm_from_pid*(struct tep_handle pass:[*]_pevent_, int _pid_); |
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struct cmdline pass:[*]*tep_data_pid_from_comm*(struct tep_handle pass:[*]_pevent_, const char pass:[*]_comm_, struct cmdline pass:[*]_next_); |
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int *tep_cmdline_pid*(struct tep_handle pass:[*]_pevent_, struct cmdline pass:[*]_cmdline_); |
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-- |
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DESCRIPTION |
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----------- |
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These functions can be used to handle the mapping between pid and process name. |
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The library builds a cache of these mappings, which is used to display the name |
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of the process, instead of its pid. This information can be retrieved from |
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tracefs/saved_cmdlines file. |
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The _tep_register_comm()_ function registers a _pid_ / process name mapping. |
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If a command with the same _pid_ is already registered, an error is returned. |
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The _pid_ argument is the process ID, the _comm_ argument is the process name, |
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_tep_ is the event context. The _comm_ is duplicated internally. |
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The _tep_override_comm()_ function registers a _pid_ / process name mapping. |
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If a process with the same pid is already registered, the process name string is |
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udapted with the new one. The _pid_ argument is the process ID, the _comm_ |
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argument is the process name, _tep_ is the event context. The _comm_ is |
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duplicated internally. |
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The _tep_is_pid_registered()_ function checks if a pid has a process name |
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mapping registered. The _pid_ argument is the process ID, _tep_ is the event |
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context. |
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The _tep_data_comm_from_pid()_ function returns the process name for a given |
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pid. The _pid_ argument is the process ID, _tep_ is the event context. |
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The returned string should not be freed, but will be freed when the _tep_ |
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handler is closed. |
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The _tep_data_pid_from_comm()_ function returns a pid for a given process name. |
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The _comm_ argument is the process name, _tep_ is the event context. |
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The argument _next_ is the cmdline structure to search for the next pid. |
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As there may be more than one pid for a given process, the result of this call |
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can be passed back into a recurring call in the _next_ parameter, to search for |
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the next pid. If _next_ is NULL, it will return the first pid associated with |
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the _comm_. The function performs a linear search, so it may be slow. |
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The _tep_cmdline_pid()_ function returns the pid associated with a given |
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_cmdline_. The _tep_ argument is the event context. |
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RETURN VALUE |
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------------ |
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_tep_register_comm()_ function returns 0 on success. In case of an error -1 is |
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returned and errno is set to indicate the cause of the problem: ENOMEM, if there |
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is not enough memory to duplicate the _comm_ or EEXIST if a mapping for this |
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_pid_ is already registered. |
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_tep_override_comm()_ function returns 0 on success. In case of an error -1 is |
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returned and errno is set to indicate the cause of the problem: ENOMEM, if there |
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is not enough memory to duplicate the _comm_. |
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_tep_is_pid_registered()_ function returns true if the _pid_ has a process name |
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mapped to it, false otherwise. |
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_tep_data_comm_from_pid()_ function returns the process name as string, or the |
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string "<...>" if there is no mapping for the given pid. |
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_tep_data_pid_from_comm()_ function returns a pointer to a struct cmdline, that |
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holds a pid for a given process, or NULL if none is found. This result can be |
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passed back into a recurring call as the _next_ parameter of the function. |
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_tep_cmdline_pid()_ functions returns the pid for the give cmdline. If _cmdline_ |
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is NULL, then -1 is returned. |
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EXAMPLE |
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------- |
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The following example registers pid for command "ls", in context of event _tep_ |
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and performs various searches for pid / process name mappings: |
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[source,c] |
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-- |
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#include <event-parse.h> |
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... |
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int ret; |
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int ls_pid = 1021; |
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struct tep_handle *tep = tep_alloc(); |
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... |
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ret = tep_register_comm(tep, "ls", ls_pid); |
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if (ret != 0 && errno == EEXIST) |
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ret = tep_override_comm(tep, "ls", ls_pid); |
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if (ret != 0) { |
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/* Failed to register pid / command mapping */ |
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} |
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... |
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if (tep_is_pid_registered(tep, ls_pid) == 0) { |
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/* Command mapping for ls_pid is not registered */ |
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} |
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... |
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const char *comm = tep_data_comm_from_pid(tep, ls_pid); |
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if (comm) { |
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/* Found process name for ls_pid */ |
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} |
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... |
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int pid; |
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struct cmdline *cmd = tep_data_pid_from_comm(tep, "ls", NULL); |
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while (cmd) { |
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pid = tep_cmdline_pid(tep, cmd); |
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/* Found pid for process "ls" */ |
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cmd = tep_data_pid_from_comm(tep, "ls", cmd); |
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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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*-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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