[PATCH v2] perf tools: New function to parse string representing size in bytes

[Hitoshi Mitake]

This patch modifies util/string.[ch] to add new function: bytesexp2int()
to parse string representing size in bytes.

This is version 2. Acording to Frederic and Ingo's advice,
I removed static function digit() and rewrote to use
isdigit() macro of util.h.

Below is the description of bytesexp2int().

Parse (\d+)(b|B|kb|KB|mb|MB|gb|GB) (e.g. "256MB")
and return its numeric value. (e.g. 268435456)

The parameter str is not changed before and after calling,
but it changed temporally and internally for atoi().
So type of str is char *, not const char *.

Signed-off-by: Hitoshi Mitake <mitake@xxxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
---
 tools/perf/util/string.c |   82 ++++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/string.h |    1 +
 2 files changed, 83 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/string.c b/tools/perf/util/string.c
index 04743d3..1ee7b17 100644
--- a/tools/perf/util/string.c
+++ b/tools/perf/util/string.c
@@ -1,4 +1,5 @@
 #include <string.h>
+#include <stdlib.h>
 #include "string.h"
 
 static int hex(char ch)
@@ -43,3 +44,84 @@ char *strxfrchar(char *s, char from, char to)
 
 	return s;
 }
+
+#define K 1024
+/*
+ * bytesexp2int()
+ * Parse (\d+)(b|B|kb|KB|mb|MB|gb|GB) (e.g. "256MB")
+ * and return its numeric value
+ *
+ * The parameter str is not changed before and after calling,
+ * but it changed temporally and internally for atoi().
+ * So type of str is char *, not const char *.
+ */
+int bytesexp2int(char *str)
+{
+	int i, unit = 1;
+	char shelter = '\0';
+	size_t length = -1;
+
+	if (!isdigit(str[0]))
+		goto err;
+	
+	for (i = 1; i < (int)strlen(str); i++) {
+		switch (str[i]) {
+		case 'B':
+		case 'b':
+			break;
+		case 'K':
+			if (str[i + 1] != 'B')
+				goto err;
+			else
+				goto kilo;
+		case 'k':
+			if (str[i + 1] != 'b')
+				goto err;
+kilo:
+			unit = K;
+			break;
+		case 'M':
+			if (str[i + 1] != 'B')
+				goto err;
+			else
+				goto mega;
+		case 'm':
+			if (str[i + 1] != 'b')
+				goto err;
+mega:
+			unit = K * K;
+			break;
+		case 'G':
+			if (str[i + 1] != 'B')
+				goto err;
+			else
+				goto giga;
+		case 'g':
+			if (str[i + 1] != 'b')
+				goto err;
+giga:
+			unit = K * K * K;
+			break;
+		case '\0':	/* only specified figures */
+			unit = 1;
+			break;
+		default:
+			if (!isdigit(str[i]))
+				goto err;
+			break;
+		}
+	}
+
+	shelter = str[i];
+	str[i] = (char)'\0';
+	length = atoi(str) * unit;
+	if (shelter != '\0')
+		str[i] = shelter;
+
+	goto end;
+
+err:
+	length = -1;
+end:
+	return length;
+}
diff --git a/tools/perf/util/string.h b/tools/perf/util/string.h
index 2c84bf6..adbf077 100644
--- a/tools/perf/util/string.h
+++ b/tools/perf/util/string.h
@@ -5,6 +5,7 @@
 
 int hex2u64(const char *ptr, u64 *val);
 char *strxfrchar(char *s, char from, char to);
+int bytesexp2int(char *str);
 
 #define _STR(x) #x
 #define STR(x) _STR(x)
-- 
1.6.5.2

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