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path: root/include/linux/printbuf.h
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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>
2022-06-09lib/printbuf: New data structure for printing stringsKent Overstreet
This adds printbufs: a printbuf points to a char * buffer and knows the size of the output buffer as well as the current output position. Future patches will be adding more features to printbuf, but initially printbufs are targeted at refactoring and improving our existing code in lib/vsprintf.c - so this initial printbuf patch has the features required for that. Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>