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2022-06-09lib/printbuf: Unit specifiersKent Overstreet
This adds options to printbuf for specifying whether units should be printed raw (default) or with human readable units, and for controlling whether human-readable units should be base 2 (default), or base 10. This also adds new helpers that obey these options: - pr_human_readable_u64 - pr_human_readable_s64 These obey printbuf->si_units - pr_units_u64 - pr_units_s64 These obey both printbuf-human_readable_units and printbuf->si_units Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
2022-06-09lib/printbuf: Tabstops, indentingKent Overstreet
This patch adds two new features to printbuf for structured formatting: - Indent level: the indent level, as a number of spaces, may be increased with pr_indent_add() and decreased with pr_indent_sub(). Subsequent lines, when started with pr_newline() (not "\n", although that may change) will then be intended according to the current indent level. This helps with pretty-printers that structure a large amonut of data across multiple lines and multiple functions. - Tabstops: Tabstops may be set by assigning to the printbuf->tabstops array. Then, pr_tab() may be used to advance to the next tabstop, printing as many spaces as required - leaving previous output left justified to the previous tabstop. pr_tab_rjust() advances to the next tabstop but inserts the spaces just after the previous tabstop - right justifying the previously-outputted text to the next tabstop. Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
2022-06-09lib/printbuf: Heap allocationKent Overstreet
This makes printbufs optionally heap allocated: a printbuf initialized with the PRINTBUF initializer will automatically heap allocate and resize as needed. Allocations are done with GFP_KERNEL: code should use e.g. memalloc_nofs_save()/restore() as needed. Since we do not currently have memalloc_nowait_save()/restore(), in contexts where it is not safe to block we provide the helpers printbuf_atomic_inc() printbuf_atomic_dec() When the atomic count is nonzero, memory allocations will be done with GFP_NOWAIT. On memory allocation failure, output will be truncated. Code that wishes to check for memory allocation failure (in contexts where we should return -ENOMEM) should check if printbuf->allocation_failure is set. Since printbufs are expected to be typically used for log messages and on a best effort basis, we don't return errors directly. Other helpers provided by this patch: - printbuf_make_room(buf, extra) Reallocates if necessary to make room for @extra bytes (not including terminating null). - printbuf_str(buf) Returns a null terminated string equivalent to the contents of @buf. If @buf was never allocated (or allocation failed), returns a constant empty string. - printbuf_exit(buf) Releases memory allocated by a printbuf. Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>