- allocate or deallocate a buffer for trace data
cc [ flag ... ] file ... -ltnfctl [ library ... ] #include <tnf/tnfctl.h> tnfctl_errcode_t tnfctl_buffer_alloc(tnfctl_handle_t *hndl, const char *trace_file_name, size_t trace_buffer_size);
tnfctl_buffer_alloc() allocates a buffer to which trace events are logged. When tracing a process using a tnfctl handle returned by tnfctl_pid_open(3TNF), tnfctl_exec_open(3TNF), tnfctl_indirect_open(3TNF), and tnfctl_internal_open(3TNF)), trace_file_name is the name of the trace file to which trace events should be logged. It can be an absolute path specification or a relative path specification. If it is relative, the current working directory of the process that is calling tnfctl_buffer_alloc() is prefixed to trace_file_name. If the named trace file already exists, it is overwritten. For kernel tracing, that is, for a tnfctl handle returned by tnfctl_kernel_open(3TNF), trace events are logged to a trace buffer in memory; therefore, trace_file_name is ignored. Use tnfxtract(1) to extract a kernel buffer into a file.
trace_buffer_size is the size in bytes of the trace buffer that should be allocated. An error is returned if an attempt is made to allocate a buffer when one already exists. tnfctl_buffer_alloc() affects the trace attributes; use tnfctl_trace_attrs_get(3TNF) to get the latest trace attributes after a buffer is allocated.
tnfctl_buffer_dealloc() is used to deallocate a kernel trace buffer that is no longer needed. hndl must be a kernel handle, returned by tnfctl_kernel_open(3TNF). A process's trace file cannot be deallocated using tnfctl_buffer_dealloc(). Instead, once the trace file is no longer needed for analysis and after the process being traced exits, use rm(1) to remove the trace file. Do not remove the trace file while the process being traced is still alive. tnfctl_buffer_dealloc() affects the trace attributes; use tnfctl_trace_attrs_get(3TNF) to get the latest trace attributes after a buffer is deallocated.
For a complete discussion of tnf tracing, see tracing(3TNF).
tnfctl_buffer_alloc() and tnfctl_buffer_dealloc() return TNFCTL_ERR_NONE upon success.
The following error codes apply to tnfctl_buffer_alloc():
A buffer already exists.
Permission denied; could not create a trace file.
The trace_buffer_size requested is smaller than the minimum trace buffer size needed. Use trace_min_size of trace attributes in tnfctl_trace_attrs_get(3TNF) to determine the minimum size of the buffer.
The requested trace file size is too big.
trace_file_name is NULL or the absolute path name is longer than MAXPATHLEN.
A memory allocation failure occurred.
An internal error occurred.
The following error codes apply to tnfctl_buffer_dealloc():
hndl is not a kernel handle.
No buffer exists to deallocate.
Cannot deallocate a trace buffer unless tracing is stopped. Use tnfctl_trace_state_set(3TNF) to stop tracing.
An internal error occurred.
See attributes(5) for descriptions of the following attributes:
prex(1), rm(1), tnfxtract(1), TNF_PROBE(3TNF), libtnfctl(3TNF), tnfctl_exec_open(3TNF), tnfctl_indirect_open(3TNF), tnfctl_internal_open(3TNF), tnfctl_kernel_open(3TNF), tnfctl_pid_open(3TNF), tnfctl_trace_attrs_get(3TNF), tracing(3TNF), attributes(5)