1 files changed, 509 insertions, 0 deletions
diff --git a/fs/bcachefs/printbuf.c b/fs/bcachefs/printbuf.c
new file mode 100644
index 000000000000..4cf5a2af1e6f
--- /dev/null
+++ b/fs/bcachefs/printbuf.c
@@ -0,0 +1,509 @@
+// SPDX-License-Identifier: LGPL-2.1+
+/* Copyright (C) 2022 Kent Overstreet */
+
+#include <linux/bitmap.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string_helpers.h>
+
+#include "printbuf.h"
+
+static inline unsigned __printbuf_linelen(struct printbuf *buf, unsigned pos)
+{
+	return pos - buf->last_newline;
+}
+
+static inline unsigned printbuf_linelen(struct printbuf *buf)
+{
+	return __printbuf_linelen(buf, buf->pos);
+}
+
+/*
+ * Returns spaces from start of line, if set, or 0 if unset:
+ */
+static inline unsigned cur_tabstop(struct printbuf *buf)
+{
+	return buf->cur_tabstop < buf->nr_tabstops
+		? buf->_tabstops[buf->cur_tabstop]
+		: 0;
+}
+
+int bch2_printbuf_make_room(struct printbuf *out, unsigned extra)
+{
+	/* Reserved space for terminating nul: */
+	extra += 1;
+
+	if (out->pos + extra <= out->size)
+		return 0;
+
+	if (!out->heap_allocated) {
+		out->overflow = true;
+		return 0;
+	}
+
+	unsigned new_size = roundup_pow_of_two(out->size + extra);
+
+	/* Sanity check... */
+	if (new_size > PAGE_SIZE << MAX_PAGE_ORDER) {
+		out->allocation_failure = true;
+		out->overflow = true;
+		return -ENOMEM;
+	}
+
+	/*
+	 * Note: output buffer must be freeable with kfree(), it's not required
+	 * that the user use printbuf_exit().
+	 */
+	char *buf = krealloc(out->buf, new_size, !out->atomic ? GFP_KERNEL : GFP_NOWAIT);
+
+	if (!buf) {
+		out->allocation_failure = true;
+		out->overflow = true;
+		return -ENOMEM;
+	}
+
+	out->buf	= buf;
+	out->size	= new_size;
+	return 0;
+}
+
+static void printbuf_advance_pos(struct printbuf *out, unsigned len)
+{
+	out->pos += min(len, printbuf_remaining(out));
+}
+
+static void printbuf_insert_spaces(struct printbuf *out, unsigned pos, unsigned nr)
+{
+	unsigned move = out->pos - pos;
+
+	bch2_printbuf_make_room(out, nr);
+
+	if (pos + nr < out->size)
+		memmove(out->buf + pos + nr,
+			out->buf + pos,
+			min(move, out->size - 1 - pos - nr));
+
+	if (pos < out->size)
+		memset(out->buf + pos, ' ', min(nr, out->size - pos));
+
+	printbuf_advance_pos(out, nr);
+	printbuf_nul_terminate_reserved(out);
+}
+
+static void __printbuf_do_indent(struct printbuf *out, unsigned pos)
+{
+	while (true) {
+		int pad;
+		unsigned len = out->pos - pos;
+		char *p = out->buf + pos;
+		char *n = memscan(p, '\n', len);
+		if (cur_tabstop(out)) {
+			n = min(n, (char *) memscan(p, '\r', len));
+			n = min(n, (char *) memscan(p, '\t', len));
+		}
+
+		pos = n - out->buf;
+		if (pos == out->pos)
+			break;
+
+		switch (*n) {
+		case '\n':
+			pos++;
+			out->last_newline = pos;
+
+			printbuf_insert_spaces(out, pos, out->indent);
+
+			pos = min(pos + out->indent, out->pos);
+			out->last_field = pos;
+			out->cur_tabstop = 0;
+			break;
+		case '\r':
+			memmove(n, n + 1, out->pos - pos);
+			--out->pos;
+			pad = (int) cur_tabstop(out) - (int) __printbuf_linelen(out, pos);
+			if (pad > 0) {
+				printbuf_insert_spaces(out, out->last_field, pad);
+				pos += pad;
+			}
+
+			out->last_field = pos;
+			out->cur_tabstop++;
+			break;
+		case '\t':
+			pad = (int) cur_tabstop(out) - (int) __printbuf_linelen(out, pos) - 1;
+			if (pad > 0) {
+				*n = ' ';
+				printbuf_insert_spaces(out, pos, pad - 1);
+				pos += pad;
+			} else {
+				memmove(n, n + 1, out->pos - pos);
+				--out->pos;
+			}
+
+			out->last_field = pos;
+			out->cur_tabstop++;
+			break;
+		}
+	}
+}
+
+static inline void printbuf_do_indent(struct printbuf *out, unsigned pos)
+{
+	if (out->has_indent_or_tabstops && !out->suppress_indent_tabstop_handling)
+		__printbuf_do_indent(out, pos);
+}
+
+void bch2_prt_vprintf(struct printbuf *out, const char *fmt, va_list args)
+{
+	int len;
+
+	do {
+		va_list args2;
+
+		va_copy(args2, args);
+		len = vsnprintf(out->buf + out->pos, printbuf_remaining_size(out), fmt, args2);
+		va_end(args2);
+	} while (len > printbuf_remaining(out) &&
+		 !bch2_printbuf_make_room(out, len));
+
+	unsigned indent_pos = out->pos;
+	printbuf_advance_pos(out, len);
+	printbuf_do_indent(out, indent_pos);
+}
+
+void bch2_prt_printf(struct printbuf *out, const char *fmt, ...)
+{
+	va_list args;
+	int len;
+
+	do {
+		va_start(args, fmt);
+		len = vsnprintf(out->buf + out->pos, printbuf_remaining_size(out), fmt, args);
+		va_end(args);
+	} while (len > printbuf_remaining(out) &&
+		 !bch2_printbuf_make_room(out, len));
+
+	unsigned indent_pos = out->pos;
+	printbuf_advance_pos(out, len);
+	printbuf_do_indent(out, indent_pos);
+}
+
+/**
+ * bch2_printbuf_str() - returns printbuf's buf as a C string, guaranteed to be
+ * null terminated
+ * @buf:	printbuf to terminate
+ * Returns:	Printbuf contents, as a nul terminated C string
+ */
+const char *bch2_printbuf_str(const struct printbuf *buf)
+{
+	/*
+	 * If we've written to a printbuf then it's guaranteed to be a null
+	 * terminated string - but if we haven't, then we might not have
+	 * allocated a buffer at all:
+	 */
+	return buf->pos
+		? buf->buf
+		: "";
+}
+
+/**
+ * bch2_printbuf_exit() - exit a printbuf, freeing memory it owns and poisoning it
+ * against accidental use.
+ * @buf:	printbuf to exit
+ */
+void bch2_printbuf_exit(struct printbuf *buf)
+{
+	if (buf->heap_allocated) {
+		kfree(buf->buf);
+		buf->buf = ERR_PTR(-EINTR); /* poison value */
+	}
+}
+
+void bch2_printbuf_tabstops_reset(struct printbuf *buf)
+{
+	buf->nr_tabstops = 0;
+}
+
+void bch2_printbuf_tabstop_pop(struct printbuf *buf)
+{
+	if (buf->nr_tabstops)
+		--buf->nr_tabstops;
+}
+
+/*
+ * bch2_printbuf_tabstop_set() - add a tabstop, n spaces from the previous tabstop
+ *
+ * @buf: printbuf to control
+ * @spaces: number of spaces from previous tabpstop
+ *
+ * In the future this function may allocate memory if setting more than
+ * PRINTBUF_INLINE_TABSTOPS or setting tabstops more than 255 spaces from start
+ * of line.
+ */
+int bch2_printbuf_tabstop_push(struct printbuf *buf, unsigned spaces)
+{
+	unsigned prev_tabstop = buf->nr_tabstops
+		? buf->_tabstops[buf->nr_tabstops - 1]
+		: 0;
+
+	if (WARN_ON(buf->nr_tabstops >= ARRAY_SIZE(buf->_tabstops)))
+		return -EINVAL;
+
+	buf->_tabstops[buf->nr_tabstops++] = prev_tabstop + spaces;
+	buf->has_indent_or_tabstops = true;
+	return 0;
+}
+
+/**
+ * bch2_printbuf_indent_add() - add to the current indent level
+ *
+ * @buf: printbuf to control
+ * @spaces: number of spaces to add to the current indent level
+ *
+ * Subsequent lines, and the current line if the output position is at the start
+ * of the current line, will be indented by @spaces more spaces.
+ */
+void bch2_printbuf_indent_add(struct printbuf *buf, unsigned spaces)
+{
+	if (WARN_ON_ONCE(buf->indent + spaces < buf->indent))
+		spaces = 0;
+
+	buf->indent += spaces;
+	prt_chars(buf, ' ', spaces);
+
+	buf->has_indent_or_tabstops = true;
+}
+
+/**
+ * bch2_printbuf_indent_sub() - subtract from the current indent level
+ *
+ * @buf: printbuf to control
+ * @spaces: number of spaces to subtract from the current indent level
+ *
+ * Subsequent lines, and the current line if the output position is at the start
+ * of the current line, will be indented by @spaces less spaces.
+ */
+void bch2_printbuf_indent_sub(struct printbuf *buf, unsigned spaces)
+{
+	if (WARN_ON_ONCE(spaces > buf->indent))
+		spaces = buf->indent;
+
+	if (buf->last_newline + buf->indent == buf->pos) {
+		buf->pos -= spaces;
+		printbuf_nul_terminate(buf);
+	}
+	buf->indent -= spaces;
+
+	if (!buf->indent && !buf->nr_tabstops)
+		buf->has_indent_or_tabstops = false;
+}
+
+void bch2_prt_newline(struct printbuf *buf)
+{
+	bch2_printbuf_make_room(buf, 1 + buf->indent);
+
+	__prt_char_reserved(buf, '\n');
+
+	buf->last_newline	= buf->pos;
+
+	__prt_chars_reserved(buf, ' ', buf->indent);
+
+	printbuf_nul_terminate_reserved(buf);
+
+	buf->last_field		= buf->pos;
+	buf->cur_tabstop	= 0;
+}
+
+void bch2_printbuf_strip_trailing_newline(struct printbuf *out)
+{
+	for (int p = out->pos - 1; p >= 0; --p) {
+		if (out->buf[p] == '\n') {
+			out->pos = p;
+			break;
+		}
+		if (out->buf[p] != ' ')
+			break;
+	}
+
+	printbuf_nul_terminate_reserved(out);
+}
+
+static void __prt_tab(struct printbuf *out)
+{
+	int spaces = max_t(int, 0, cur_tabstop(out) - printbuf_linelen(out));
+
+	prt_chars(out, ' ', spaces);
+
+	out->last_field = out->pos;
+	out->cur_tabstop++;
+}
+
+/**
+ * bch2_prt_tab() - Advance printbuf to the next tabstop
+ * @out:	printbuf to control
+ *
+ * Advance output to the next tabstop by printing spaces.
+ */
+void bch2_prt_tab(struct printbuf *out)
+{
+	if (WARN_ON(!cur_tabstop(out)))
+		return;
+
+	__prt_tab(out);
+}
+
+static void __prt_tab_rjust(struct printbuf *buf)
+{
+	int pad = (int) cur_tabstop(buf) - (int) printbuf_linelen(buf);
+	if (pad > 0)
+		printbuf_insert_spaces(buf, buf->last_field, pad);
+
+	buf->last_field = buf->pos;
+	buf->cur_tabstop++;
+}
+
+/**
+ * bch2_prt_tab_rjust - Advance printbuf to the next tabstop, right justifying
+ * previous output
+ *
+ * @buf: printbuf to control
+ *
+ * Advance output to the next tabstop by inserting spaces immediately after the
+ * previous tabstop, right justifying previously outputted text.
+ */
+void bch2_prt_tab_rjust(struct printbuf *buf)
+{
+	if (WARN_ON(!cur_tabstop(buf)))
+		return;
+
+	__prt_tab_rjust(buf);
+}
+
+/**
+ * bch2_prt_bytes_indented() - Print an array of chars, handling embedded control characters
+ *
+ * @out:	output printbuf
+ * @str:	string to print
+ * @count:	number of bytes to print
+ *
+ * The following contol characters are handled as so:
+ *   \n: prt_newline	newline that obeys current indent level
+ *   \t: prt_tab	advance to next tabstop
+ *   \r: prt_tab_rjust	advance to next tabstop, with right justification
+ */
+void bch2_prt_bytes_indented(struct printbuf *out, const char *str, unsigned count)
+{
+	unsigned indent_pos = out->pos;
+	prt_bytes(out, str, count);
+	printbuf_do_indent(out, indent_pos);
+}
+
+/**
+ * bch2_prt_human_readable_u64() - Print out a u64 in human readable units
+ * @out:	output printbuf
+ * @v:		integer to print
+ *
+ * Units of 2^10 (default) or 10^3 are controlled via @out->si_units
+ */
+void bch2_prt_human_readable_u64(struct printbuf *out, u64 v)
+{
+	bch2_printbuf_make_room(out, 10);
+	unsigned len = string_get_size(v, 1, !out->si_units,
+				       out->buf + out->pos,
+				       printbuf_remaining_size(out));
+	printbuf_advance_pos(out, len);
+}
+
+/**
+ * bch2_prt_human_readable_s64() - Print out a s64 in human readable units
+ * @out:	output printbuf
+ * @v:		integer to print
+ *
+ * Units of 2^10 (default) or 10^3 are controlled via @out->si_units
+ */
+void bch2_prt_human_readable_s64(struct printbuf *out, s64 v)
+{
+	if (v < 0)
+		prt_char(out, '-');
+	bch2_prt_human_readable_u64(out, abs(v));
+}
+
+/**
+ * bch2_prt_units_u64() - Print out a u64 according to printbuf unit options
+ * @out:	output printbuf
+ * @v:		integer to print
+ *
+ * Units are either raw (default), or human reabable units (controlled via
+ * @buf->human_readable_units)
+ */
+void bch2_prt_units_u64(struct printbuf *out, u64 v)
+{
+	if (out->human_readable_units)
+		bch2_prt_human_readable_u64(out, v);
+	else
+		bch2_prt_printf(out, "%llu", v);
+}
+
+/**
+ * bch2_prt_units_s64() - Print out a s64 according to printbuf unit options
+ * @out:	output printbuf
+ * @v:		integer to print
+ *
+ * Units are either raw (default), or human reabable units (controlled via
+ * @buf->human_readable_units)
+ */
+void bch2_prt_units_s64(struct printbuf *out, s64 v)
+{
+	if (v < 0)
+		prt_char(out, '-');
+	bch2_prt_units_u64(out, abs(v));
+}
+
+void bch2_prt_string_option(struct printbuf *out,
+			    const char * const list[],
+			    size_t selected)
+{
+	for (size_t i = 0; list[i]; i++)
+		bch2_prt_printf(out, i == selected ? "[%s] " : "%s ", list[i]);
+}
+
+void bch2_prt_bitflags(struct printbuf *out,
+		       const char * const list[], u64 flags)
+{
+	unsigned bit, nr = 0;
+	bool first = true;
+
+	while (list[nr])
+		nr++;
+
+	while (flags && (bit = __ffs64(flags)) < nr) {
+		if (!first)
+			bch2_prt_printf(out, ",");
+		first = false;
+		bch2_prt_printf(out, "%s", list[bit]);
+		flags ^= BIT_ULL(bit);
+	}
+}
+
+void bch2_prt_bitflags_vector(struct printbuf *out,
+			      const char * const list[],
+			      unsigned long *v, unsigned nr)
+{
+	bool first = true;
+	unsigned i;
+
+	for (i = 0; i < nr; i++)
+		if (!list[i]) {
+			nr = i - 1;
+			break;
+		}
+
+	for_each_set_bit(i, v, nr) {
+		if (!first)
+			bch2_prt_printf(out, ",");
+		first = false;
+		bch2_prt_printf(out, "%s", list[i]);
+	}
+}