linux-kernel - Re: [PATCH v3 1/7] lib: string: add functions to case-convert strings

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Message-ID: <CAGt4E5vYzkqgiiQXXjnX7az-KzCVSYthEW5Df03U=Y1qhEJdRQ@mail.gmail.com>
Date:	Sat, 9 Jul 2016 08:30:19 -0700
From:	Markus Mayer <markus.mayer@...adcom.com>
To:	Luis de Bethencourt <luisbg@....samsung.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Al Viro <viro@...iv.linux.org.uk>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	Chris Metcalf <cmetcalf@...hip.com>,
	Kees Cook <keescook@...omium.org>, devel@...verdev.osuosl.org,
	linux-scsi@...r.kernel.org, linux-pm@...r.kernel.org,
	nouveau@...ts.freedesktop.org, speakup@...ux-speakup.org,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	dri-devel@...ts.freedesktop.org, linux-acpi@...r.kernel.org,
	target-devel@...r.kernel.org
Subject: Re: [PATCH v3 1/7] lib: string: add functions to case-convert strings

On 9 July 2016 at 05:04, Luis de Bethencourt <luisbg@....samsung.com> wrote:
> On 08/07/16 23:43, Markus Mayer wrote:
>> Add a collection of generic functions to convert strings to lowercase
>> or uppercase.
>>
>> Changing the case of a string (with or without copying it first) seems
>> to be a recurring requirement in the kernel that is currently being
>> solved by several duplicated implementations doing the same thing. This
>> change aims at reducing this code duplication.
>>
>> The new functions are
>>     void strlcpytoupper(char *dst, const char *src, size_t len);
>>     void strlcpytolower(char *dst, const char *src, size_t len);
>>     void strcpytoupper(char *dst, const char *src);
>>     void strcpytolower(char *dst, const char *src);
>>     void strtoupper(char *s);
>>     void strtolower(char *s);
>>
>> The "str[l]cpyto*" versions of the function take a destination string
>> and a source string as arguments. The "strlcpyto*" versions additionally
>> take a length argument like strlcpy() itself. Lastly, the strto*
>> functions take a single string argument and modify the passed-in string.
>>
>> Like strlcpy(), and unlike strncpy(), the functions guarantee NULL
>> termination of the destination string.
>>
>> Signed-off-by: Markus Mayer <mmayer@...adcom.com>
>> ---
>>  include/linux/string.h | 40 ++++++++++++++++++++++++++++++++++++++++
>>  lib/string.c           | 38 ++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 78 insertions(+)
>>
>> diff --git a/include/linux/string.h b/include/linux/string.h
>> index 26b6f6a..36c9d14 100644
>> --- a/include/linux/string.h
>> +++ b/include/linux/string.h
>> @@ -116,6 +116,8 @@ extern void * memchr(const void *,int,__kernel_size_t);
>>  #endif
>>  void *memchr_inv(const void *s, int c, size_t n);
>>  char *strreplace(char *s, char old, char new);
>> +extern void strlcpytoupper(char *dst, const char *src, size_t len);
>> +extern void strlcpytolower(char *dst, const char *src, size_t len);
>>
>>  extern void kfree_const(const void *x);
>>
>> @@ -169,4 +171,42 @@ static inline const char *kbasename(const char *path)
>>       return tail ? tail + 1 : path;
>>  }
>>
>> +/**
>> + * strcpytoupper - Copy string and convert to uppercase.
>> + * @dst: The buffer to store the result.
>> + * @src: The string to convert to uppercase.
>> + */
>> +static inline void strcpytoupper(char *dst, const char *src)
>> +{
>> +     strlcpytoupper(dst, src, -1);
>> +}
>> +
>
> Why not use SIZE_MAX instead of -1?

Sure. I'll change all four of them. Thanks.

>> +/**
>> + * strcpytolower - Copy string and convert to lowercase.
>> + * @dst: The buffer to store the result.
>> + * @src: The string to convert to lowercase.
>> + */
>> +static inline void strcpytolower(char *dst, const char *src)
>> +{
>> +     strlcpytolower(dst, src, -1);
>> +}
>> +
>
> Same here, and the 2 below :)
>
> Thanks Markus,
> Luis
>
>> +/**
>> + * strtoupper - Convert string to uppercase.
>> + * @s: The string to operate on.
>> + */
>> +static inline void strtoupper(char *s)
>> +{
>> +     strlcpytoupper(s, s, -1);
>> +}
>> +
>> +/**
>> + * strtolower - Convert string to lowercase.
>> + * @s: The string to operate on.
>> + */
>> +static inline void strtolower(char *s)
>> +{
>> +     strlcpytolower(s, s, -1);
>> +}
>> +
>>  #endif /* _LINUX_STRING_H_ */
>> diff --git a/lib/string.c b/lib/string.c
>> index ed83562..fd8c427 100644
>> --- a/lib/string.c
>> +++ b/lib/string.c
>> @@ -952,3 +952,41 @@ char *strreplace(char *s, char old, char new)
>>       return s;
>>  }
>>  EXPORT_SYMBOL(strreplace);
>> +
>> +/**
>> + * strlcpytoupper - Copy a length-limited string and convert to uppercase.
>> + * @dst: The buffer to store the result.
>> + * @src: The string to convert to uppercase.
>> + * @len: Maximum string length. May be SIZE_MAX (-1) to set no limit.
>> + */
>> +void strlcpytoupper(char *dst, const char *src, size_t len)
>> +{
>> +     size_t i;
>> +
>> +     if (!len)
>> +             return;
>> +
>> +     for (i = 0; i < len && src[i]; ++i)
>> +             dst[i] = toupper(src[i]);
>> +     dst[i < len ? i : i - 1] = '\0';
>> +}
>> +EXPORT_SYMBOL(strlcpytoupper);
>> +
>> +/**
>> + * strlcpytolower - Copy a length-limited string and convert to lowercase.
>> + * @dst: The buffer to store the result.
>> + * @src: The string to convert to lowercase.
>> + * @len: Maximum string length. May be SIZE_MAX (-1) to set no limit.
>> + */
>> +void strlcpytolower(char *dst, const char *src, size_t len)
>> +{
>> +     size_t i;
>> +
>> +     if (!len)
>> +             return;
>> +
>> +     for (i = 0; i < len && src[i]; ++i)
>> +             dst[i] = tolower(src[i]);
>> +     dst[i < len ? i : i - 1] = '\0';
>> +}
>> +EXPORT_SYMBOL(strlcpytolower);
>>
>