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[PATCH v3] add u64 number parser

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  [PATCH v3] add u64 number parser james.smart@broadcom.com (James Smart) - 2016-09-24 17:40 +0200
    Re: [PATCH v3] add u64 number parser Linus Torvalds <torvalds@linux-foundation.org> - 2016-09-24 20:40 +0200

#1490667 — [PATCH v3] add u64 number parser

add u64 number parser

Prior patch revised to use kasprintf.
Modified match_number to use kasprintf as well

Signed-off-by: James Smart <james.smart@broadcom.com>
---
 include/linux/parser.h |  1 +
 lib/parser.c           | 51 ++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/include/linux/parser.h b/include/linux/parser.h
index 39d5b79..884c1e6 100644
--- a/include/linux/parser.h
+++ b/include/linux/parser.h
@@ -27,6 +27,7 @@ typedef struct {
 
 int match_token(char *, const match_table_t table, substring_t args[]);
 int match_int(substring_t *, int *result);
+int match_u64(substring_t *, u64 *result);
 int match_octal(substring_t *, int *result);
 int match_hex(substring_t *, int *result);
 bool match_wildcard(const char *pattern, const char *str);
diff --git a/lib/parser.c b/lib/parser.c
index b6d1163..7e9d23f 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -131,13 +131,11 @@ static int match_number(substring_t *s, int *result, int base)
 	char *buf;
 	int ret;
 	long val;
-	size_t len = s->to - s->from;
+	int len = s->to - s->from;
 
-	buf = kmalloc(len + 1, GFP_KERNEL);
+	buf = kasprintf(GFP_KERNEL, "%.*s", len, s->from);
 	if (!buf)
 		return -ENOMEM;
-	memcpy(buf, s->from, len);
-	buf[len] = '\0';
 
 	ret = 0;
 	val = simple_strtol(buf, &endp, base);
@@ -152,6 +150,34 @@ static int match_number(substring_t *s, int *result, int base)
 }
 
 /**
+ * match_u64int: scan a number in the given base from a substring_t
+ * @s: substring to be scanned
+ * @result: resulting u64 on success
+ * @base: base to use when converting string
+ *
+ * Description: Given a &substring_t and a base, attempts to parse the substring
+ * as a number in that base. On success, sets @result to the integer represented
+ * by the string and returns 0. Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
+ */
+static int match_u64int(substring_t *s, u64 *result, int base)
+{
+	char *buf;
+	int ret;
+	u64 val;
+	int len = s->to - s->from;
+
+	buf = kasprintf(GFP_KERNEL, "%.*s", len, s->from);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = kstrtoull(buf, base, &val);
+	if (!ret)
+		*result = val;
+	kfree(buf);
+	return ret;
+}
+
+/**
  * match_int: - scan a decimal representation of an integer from a substring_t
  * @s: substring_t to be scanned
  * @result: resulting integer on success
@@ -167,6 +193,23 @@ int match_int(substring_t *s, int *result)
 EXPORT_SYMBOL(match_int);
 
 /**
+ * match_u64: - scan a decimal representation of a u64 from
+ *                  a substring_t
+ * @s: substring_t to be scanned
+ * @result: resulting unsigned long long on success
+ *
+ * Description: Attempts to parse the &substring_t @s as a long decimal
+ * integer. On success, sets @result to the integer represented by the
+ * string and returns 0.
+ * Returns -ENOMEM, -EINVAL, or -ERANGE on failure.
+ */
+int match_u64(substring_t *s, u64 *result)
+{
+	return match_u64int(s, result, 0);
+}
+EXPORT_SYMBOL(match_u64);
+
+/**
  * match_octal: - scan an octal representation of an integer from a substring_t
  * @s: substring_t to be scanned
  * @result: resulting integer on success
-- 
2.5.0

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#1490712

On Sat, Sep 24, 2016 at 8:27 AM, James Smart <james.smart@broadcom.com> wrote:
>
> add u64 number parser
>
> Prior patch revised to use kasprintf.
> Modified match_number to use kasprintf as well

Why would you do this? It's insane. kasprintf() is not the right thing
at all to use for anything like this. It appears that you want to use
strncpy() or something. Or you could just avoid the extra copy
entirely in 99% of all cases and just use simple_strtol() and check
that the end didn't overflow the substring, which it presumably never
does anyway.

Yes, the stupid code is already disgustingly bad. But let's not make
it *worse*, for chrissake!

               Linus

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