[PATCH v2 08/11] lib/vsprintf: allow range of prefix for %pl[From[To]]

[Andy Shevchenko]

The user may supply the range of desired prefixes in a format %pl[From[To]],
where 'From' is letter of minimum allowed prefix, and 'To' is a maximum
correspondently.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 Documentation/printk-formats.txt |  4 ++++
 lib/test_printf.c                | 35 ++++++++++++++++++++++++++++++++---
 lib/vsprintf.c                   | 18 +++++++++++++++++-
 3 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/Documentation/printk-formats.txt b/Documentation/printk-formats.txt
index 8e8b4c0..3b41899 100644
--- a/Documentation/printk-formats.txt
+++ b/Documentation/printk-formats.txt
@@ -289,9 +289,13 @@ struct clk:
 
 unsigned long long value in human-readable form (with IEC binary prefix):
 
+	%pl[From[To]]
+
 	%pl		1023 KiB	(1047552)
 	%pl		1048575 B	(1048575)
+	%plKM		1023 KiB	(1048575)
 	%pl		1 MiB		(1048576)
+	%plG		2 TiB		(2199023255552)
 
 	For printing given unsigned long long value in human-readable form with
 	automatically choosen IEC binary prefix.
diff --git a/lib/test_printf.c b/lib/test_printf.c
index 1e078c2..ae35885 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -420,10 +420,39 @@ human_readable(void)
 		{ .v = 1048575ULL,		.r = "1048575 B" },
 		{ .v = 1047552ULL,		.r = "1023 KiB" },
 	};
-	unsigned int i;
+	struct hr_test_data htdplM[] = {
+		{ .v = 1097364144128ULL,	.r = "1022 GiB" },
+		{ .v = 1097364144125ULL,	.r = "1046527 MiB" },
+		{ .v = 1048576ULL,		.r = "1 MiB" },
+		{ .v = 1048575ULL,		.r = "0 MiB" },
+		{ .v = 1047552ULL,		.r = "0 MiB" },
+	};
+	struct hr_test_data htdplKM[] = {
+		{ .v = 1097364144128ULL,	.r = "1046528 MiB" },
+		{ .v = 1097364144125ULL,	.r = "1071644671 KiB" },
+		{ .v = 1048578ULL,		.r = "1024 KiB" },
+		{ .v = 1048576ULL,		.r = "1 MiB" },
+		{ .v = 1048575ULL,		.r = "1023 KiB" },
+		{ .v = 1047552ULL,		.r = "1023 KiB" },
+	};
+	struct hr_test_array {
+		const char *fmt;
+		struct hr_test_data *data;
+		size_t sz;
+	};
+	struct hr_test_array hta[] = {
+		{ "%pl",	htdpl,		ARRAY_SIZE(htdpl) },
+		{ "%plM",	htdplM,		ARRAY_SIZE(htdplM) },
+		{ "%plKM",	htdplKM,	ARRAY_SIZE(htdplKM) },
+		/* No reversed %pl[To[From]] order */
+		{ "%plMK",	htdplM,		ARRAY_SIZE(htdplM) },
+	};
+	unsigned int i, j;
 
-	for (i = 0; i < ARRAY_SIZE(htdpl); i++)
-		test(htdpl[i].r, "%pl", &htdpl[i].v);
+	for (j = 0; j < ARRAY_SIZE(hta); j++) {
+		for (i = 0; i < hta[j].sz; i++)
+			test(hta[j].data[i].r, hta[j].fmt, &hta[j].data[i].v);
+	}
 }
 
 static void __init
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 8288470..fbcb221 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1310,12 +1310,28 @@ char *human_readable(char *buf, char *end, const void *addr,
 		     struct printf_spec spec, const char *fmt)
 {
 	unsigned long long value = *(unsigned long long *)addr;
+	unsigned short from = 0, to = STRING_UNITS_2_NUM - 1;
 	unsigned long index;
+	unsigned int i;
+
+	/* Parse %pl[From[To]] */
+	for (i = 0; i < STRING_UNITS_2_NUM; i++)
+		if (fmt[1] == string_units_2[i][0])
+			break;
+	if (i < STRING_UNITS_2_NUM) {
+		from = i;
+		for (i = 0; i < STRING_UNITS_2_NUM; i++)
+			if (fmt[2] == string_units_2[i][0])
+				break;
+		if (i < STRING_UNITS_2_NUM && i >= from)
+			to = i;
+	}
 
 	if (value)
 		index = __ffs64(value) / 10;
 	else
 		index = 0;
+	index = clamp_t(unsigned long, index, from, to);
 
 	/* Print numeric part */
 	buf = number(buf, end, value >> (index * 10), default_dec_spec);
@@ -1459,7 +1475,7 @@ int kptr_restrict __read_mostly;
  *       Do not use this feature without some mechanism to verify the
  *       correctness of the format string and va_list arguments.
  * - 'K' For a kernel pointer that should be hidden from unprivileged users
- * - 'l' For a value in human-readable form (with IEC binary prefix)
+ * - 'l[from[to]]' For a value in human-readable form (with IEC binary prefix)
  * - 'NF' For a netdev_features_t
  * - 'h[CDN]' For a variable-length buffer, it prints it as a hex string with
  *            a certain separator (' ' by default):
-- 
2.6.4