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

[Markus Mayer]

On 13 July 2016 at 15:53, Luis de Bethencourt  wrote:
>
> Hi Markus,
>
> Thank you very much for the thorough testing and solution searching.
>
> Earlier today I sent a patch that removes dynamic_debug.h from
> include/linux/kernel.h, since it isn't really needed. Sorry about this
> since it changes what you were testing just a few hours later.

I did see at least some of the changes you posted. I was mostly
curious to see where the problem was coming from in the first place.

> I am starting to think that getting access to SIZE_MAX isn't worth the
> trouble, specially considering that moving an include out of the top
> of the file makes the code less readable. The Linux kernel is growing
> in complexity and trying to keep it readable for newcomers is very
> important IMHO.

I've been thinking the same thing. It seems to be turning into a huge
effort to make this simple constant available.

> The maintainers have the last word on this, but for now I remove my
> question about why use -1 instead of SIZE_MAX.
>
> Apologies for that, the silver lining was that at least for me it was
> interesting to explore this area of the code and its inclusions. I hope
> it was for you as well.

No need to apologize. It seemed like a no-brainer to use SIZE_MAX. :-)
And I am sure all the digging will come handy in some way.

> PD: just a small comment, in case you end up sending a new version of
> your patches. In the following documentation of your functions.
> * @len: Maximum string length. May be SIZE_MAX (-1) to set no limit.
>
> What do you think about "SIZE_MAX or -1" instead of "SIZE_MAX (-1)" to
> avoid confusing any readers who might think SIZE_MAX is a function? As
> I think you intend to mean your code accepts both -1 or SIZE_MAX, which
> is ~0.
>
> Just an idea, feel free to ignore it :)

I think I might use ~(size_t)0 directly instead of -1 (or SIZE_MAX).

Thanks,
-Markus
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Re: [PATCH v3 1/7] lib: string: add functions to case-convert strings

[Luis de Bethencourt]

On 13/07/16 23:26, Markus Mayer wrote:
> On 13 July 2016 at 10:19, Luis de Bethencourt  wrote:
>> On 11/07/16 23:46, Markus Mayer wrote:
>>
>> Hi Markus,
>>
>> Amazing. I see this happening as well, but I know it shouldn't.
>>
>> The reason the #ifndef guards in headers are there is precisely to allow
>> circular dependencies.
>>
>> The problem in your output reads as:
>> strstr() is in string.h
>> #include string.h -> that includes kernel.h -> that includes string.h
>>
>> The third should do nothing based on _LINUX_STRING_H_ being defined already
>> and all code inside the #ifndef in string.h not being executed.
>> Yet it shouldn't block the first include above since that macro isn't 
>> defined,
>> which is what the error suggests since it doesn't have strstr()
>> If _LINUX_STRING_H is defined, strstr() should be available.
>>
>> Investigating this issue, it only happens when CONFIG_DYNAMIC_DEBUG is not
>> set and line 170 of dynamic_debug.h runs, but just above we have an
>> include of string.h.
>>
>> Very strange that #include  isn't doing its job.
>>
>> The first thing I tried is to understand where dynamic_debug.h is used and
>> removed the unneeded ones:
>> --
>> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
>> --- a/include/linux/kernel.h
>> +++ b/include/linux/kernel.h
>> @@ -11,7 +11,6 @@
>>  #include 
>>  #include 
>>  #include 
>> -#include 
>>  #include 
>>  #include 
>>
>> diff --git a/include/linux/printk.h b/include/linux/printk.h
>> --- a/include/linux/printk.h
>> +++ b/include/linux/printk.h
>> @@ -307,10 +307,11 @@ asmlinkage __printf(1, 2) __cold void __pr_info(const 
>> char *fmt, ...);
>> no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
>>  #endif
>>
>> -#include 
>>
>>  /* If you are writing a driver, please use dev_dbg instead */
>>  #if defined(CONFIG_DYNAMIC_DEBUG)
>> +#include 
>> +
>>  /* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
>>  #define pr_debug(fmt, ...) \
>> dynamic_pr_debug(fmt, ##__VA_ARGS__)
>> diff --git a/kernel/module.c b/kernel/module.c
>> index beaebea..e70a2fa 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -60,6 +60,7 @@
>>  #include 
>>  #include 
>>  #include 
>> +#include 
>>  #include 
>>  #include "module-internal.h"
>> --
>>
>> This diff [0] fixes the issue but it is a workaround for the original
>> issue about string.h not being properly included in dynamic_debug.h
>>
>> Puzzled by this and can't figure out what is happening wrong.
>>
>> The second thing I tried was adding
>> #warning "Linking to string header"
>> in include/linux/string.h, and I don't see any include path mentioning
>> kernel.h, where do you see the circular dependency? I might be missing
>> something.
> 
> I did some more poking around and this is what I found.
> 
> For starters, the problem happens with kernel/bounds.c. Without
> worrying about SIZE_MAX or making any other changes, I added a
> #warning line to kernel.h and string.h to see the include sequence.
> 
> $ aarch64-linux-gcc -Wp,-MD,kernel/.bounds.s.d  -nostdinc -isystem
> /opt/toolchain/stbgcc-4.8-1.5/bin/../lib/gcc/aarch64-linux-gnu/4.8.5/include
> -I./arch/arm64/include -Iarch/arm64/include/generated/uapi
> -Iarch/arm64/include/generated  -Iinclude -I./arch/arm64/include/uapi
> -Iarch/arm64/include/generated/uapi -I./include/uapi
> -Iinclude/generated/uapi -include ./include/linux/kconfig.h
> -D__KERNEL__ -mlittle-endian -Wall -Wundef -Wstrict-prototypes
> -Wno-trigraphs -fno-strict-aliasing -fno-common
> -Werror-implicit-function-declaration -Wno-format-security -std=gnu89
> -mgeneral-regs-only -fno-asynchronous-unwind-tables
> -fno-delete-null-pointer-checks -O2 --param=allow-store-data-races=0
> -Wframe-larger-than=2048 -fno-stack-protector
> -Wno-unused-but-set-variable -fno-omit-frame-pointer
> -fno-optimize-sibling-calls -fno-var-tracking-assignments -g
> -Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow
> -fconserve-stack -Werror=implicit-int -Werror=strict-prototypes
> -DKBUILD_BASENAME='"bounds"'  -DKBUILD_MODNAME='"bounds"'
> -fverbose-asm -E -o kernel/bounds.i kernel/bounds.c
> In file included from include/asm-generic/bug.h:13:0,
>  from ./arch/arm64/include/asm/bug.h:62,
>  from include/linux/bug.h:4,
>  from include/linux/page-flags.h:9,
>  from kernel/bounds.c:9:
> include/linux/kernel.h:4:2: warning: #warning In kernel.h [-Wcpp]
>  #warning In kernel.h
>   ^
> In file included from include/linux/dynamic_debug.h:111:0,
>  from include/linux/printk.h:289,
>  from include/linux/kernel.h:14,
>  from include/asm-generic/bug.h:13,
>  from ./arch/arm64/include/asm/bug.h:62,
>  from include/linux/bug.h:4,
> 

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

[Markus Mayer]

On 13 July 2016 at 10:19, Luis de Bethencourt  wrote:
> On 11/07/16 23:46, Markus Mayer wrote:
>
> Hi Markus,
>
> Amazing. I see this happening as well, but I know it shouldn't.
>
> The reason the #ifndef guards in headers are there is precisely to allow
> circular dependencies.
>
> The problem in your output reads as:
> strstr() is in string.h
> #include string.h -> that includes kernel.h -> that includes string.h
>
> The third should do nothing based on _LINUX_STRING_H_ being defined already
> and all code inside the #ifndef in string.h not being executed.
> Yet it shouldn't block the first include above since that macro isn't defined,
> which is what the error suggests since it doesn't have strstr()
> If _LINUX_STRING_H is defined, strstr() should be available.
>
> Investigating this issue, it only happens when CONFIG_DYNAMIC_DEBUG is not
> set and line 170 of dynamic_debug.h runs, but just above we have an
> include of string.h.
>
> Very strange that #include  isn't doing its job.
>
> The first thing I tried is to understand where dynamic_debug.h is used and
> removed the unneeded ones:
> --
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -11,7 +11,6 @@
>  #include 
>  #include 
>  #include 
> -#include 
>  #include 
>  #include 
>
> diff --git a/include/linux/printk.h b/include/linux/printk.h
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -307,10 +307,11 @@ asmlinkage __printf(1, 2) __cold void __pr_info(const 
> char *fmt, ...);
> no_printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__)
>  #endif
>
> -#include 
>
>  /* If you are writing a driver, please use dev_dbg instead */
>  #if defined(CONFIG_DYNAMIC_DEBUG)
> +#include 
> +
>  /* dynamic_pr_debug() uses pr_fmt() internally so we don't need it here */
>  #define pr_debug(fmt, ...) \
> dynamic_pr_debug(fmt, ##__VA_ARGS__)
> diff --git a/kernel/module.c b/kernel/module.c
> index beaebea..e70a2fa 100644
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -60,6 +60,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  #include 
>  #include "module-internal.h"
> --
>
> This diff [0] fixes the issue but it is a workaround for the original
> issue about string.h not being properly included in dynamic_debug.h
>
> Puzzled by this and can't figure out what is happening wrong.
>
> The second thing I tried was adding
> #warning "Linking to string header"
> in include/linux/string.h, and I don't see any include path mentioning
> kernel.h, where do you see the circular dependency? I might be missing
> something.

I did some more poking around and this is what I found.

For starters, the problem happens with kernel/bounds.c. Without
worrying about SIZE_MAX or making any other changes, I added a
#warning line to kernel.h and string.h to see the include sequence.

$ aarch64-linux-gcc -Wp,-MD,kernel/.bounds.s.d  -nostdinc -isystem
/opt/toolchain/stbgcc-4.8-1.5/bin/../lib/gcc/aarch64-linux-gnu/4.8.5/include
-I./arch/arm64/include -Iarch/arm64/include/generated/uapi
-Iarch/arm64/include/generated  -Iinclude -I./arch/arm64/include/uapi
-Iarch/arm64/include/generated/uapi -I./include/uapi
-Iinclude/generated/uapi -include ./include/linux/kconfig.h
-D__KERNEL__ -mlittle-endian -Wall -Wundef -Wstrict-prototypes
-Wno-trigraphs -fno-strict-aliasing -fno-common
-Werror-implicit-function-declaration -Wno-format-security -std=gnu89
-mgeneral-regs-only -fno-asynchronous-unwind-tables
-fno-delete-null-pointer-checks -O2 --param=allow-store-data-races=0
-Wframe-larger-than=2048 -fno-stack-protector
-Wno-unused-but-set-variable -fno-omit-frame-pointer
-fno-optimize-sibling-calls -fno-var-tracking-assignments -g
-Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow
-fconserve-stack -Werror=implicit-int -Werror=strict-prototypes
-DKBUILD_BASENAME='"bounds"'  -DKBUILD_MODNAME='"bounds"'
-fverbose-asm -E -o kernel/bounds.i kernel/bounds.c
In file included from include/asm-generic/bug.h:13:0,
 from ./arch/arm64/include/asm/bug.h:62,
 from include/linux/bug.h:4,
 from include/linux/page-flags.h:9,
 from kernel/bounds.c:9:
include/linux/kernel.h:4:2: warning: #warning In kernel.h [-Wcpp]
 #warning In kernel.h
  ^
In file included from include/linux/dynamic_debug.h:111:0,
 from include/linux/printk.h:289,
 from include/linux/kernel.h:14,
 from include/asm-generic/bug.h:13,
 from ./arch/arm64/include/asm/bug.h:62,
 from include/linux/bug.h:4,
 from include/linux/page-flags.h:9,
 from kernel/bounds.c:9:
include/linux/string.h:4:2: warning: #warning In string.h [-Wcpp]
 #warning In string.h
  ^

So, kernel.h gets pulled 

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

[Luis de Bethencourt]

On 11/07/16 23:46, Markus Mayer wrote:
> On 9 July 2016 at 08:30, Markus Mayer  wrote:
>> On 9 July 2016 at 05:04, Luis de Bethencourt  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 
 ---
  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.
> 
> Turns out there's actually a circular dependency here. SIZE_MAX is
> defined in linux/kernel.h. So, string.h would need to include
> kernel.h. But kernel.h, by way of several other headers, includes
> string.h.
> 
> Attempting to include kernel.h in string.h then leads to something like this:
> 
>   CHK include/config/kernel.release
>   CHK include/generated/uapi/linux/version.h
>   CHK include/generated/utsrelease.h
>   CC  scripts/mod/devicetable-offsets.s
>   CHK include/generated/timeconst.h
> In file included from include/linux/printk.h:289:0,
>  from include/linux/kernel.h:13,
>  from include/linux/string.h:11,
>  from include/uapi/linux/uuid.h:21,
>  from include/linux/uuid.h:19,
>  from include/linux/mod_devicetable.h:12,
>  from scripts/mod/devicetable-offsets.c:2:
> include/linux/dynamic_debug.h: In function ‘ddebug_dyndbg_module_param_cb’:
> include/linux/dynamic_debug.h:122:2: error: implicit declaration of
> function ‘strstr’ [-Werror=implicit-function-declaration]
>   if (strstr(param, "dyndbg")) {
>   ^
> include/linux/dynamic_debug.h:122:6: warning: incompatible implicit
> declaration of built-in function ‘strstr’ [enabled by default]
>   if (strstr(param, "dyndbg")) {
>   ^
> Since kernel.h is referencing string.h (which is needed, but not
> included a second time due to the include guards), this leads to
> undeclared string functions, because we are still in the early stages
> of including string.h itself and haven't gotten to the function
> declarations yet.
> 

Hi Markus,

Amazing. I see this happening as well, but I know it shouldn't.

The reason the #ifndef guards in headers are there is precisely to allow
circular dependencies.

The problem in your output reads as:
strstr() is in string.h
#include string.h -> that includes kernel.h -> that includes string.h

The third should do nothing based on _LINUX_STRING_H_ being defined already
and all code inside the #ifndef in string.h not being executed.
Yet it shouldn't block the first include above since that macro isn't defined,
which is what the error suggests since it doesn't have strstr()
If 

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

[Markus Mayer]

On 9 July 2016 at 08:30, Markus Mayer  wrote:
> On 9 July 2016 at 05:04, Luis de Bethencourt  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 
>>> ---
>>>  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.

Turns out there's actually a circular dependency here. SIZE_MAX is
defined in linux/kernel.h. So, string.h would need to include
kernel.h. But kernel.h, by way of several other headers, includes
string.h.

Attempting to include kernel.h in string.h then leads to something like this:

  CHK include/config/kernel.release
  CHK include/generated/uapi/linux/version.h
  CHK include/generated/utsrelease.h
  CC  scripts/mod/devicetable-offsets.s
  CHK include/generated/timeconst.h
In file included from include/linux/printk.h:289:0,
 from include/linux/kernel.h:13,
 from include/linux/string.h:11,
 from include/uapi/linux/uuid.h:21,
 from include/linux/uuid.h:19,
 from include/linux/mod_devicetable.h:12,
 from scripts/mod/devicetable-offsets.c:2:
include/linux/dynamic_debug.h: In function ‘ddebug_dyndbg_module_param_cb’:
include/linux/dynamic_debug.h:122:2: error: implicit declaration of
function ‘strstr’ [-Werror=implicit-function-declaration]
  if (strstr(param, "dyndbg")) {
  ^
include/linux/dynamic_debug.h:122:6: warning: incompatible implicit
declaration of built-in function ‘strstr’ [enabled by default]
  if (strstr(param, "dyndbg")) {
  ^
Since kernel.h is referencing string.h (which is needed, but not
included a second time due to the include guards), this leads to
undeclared string functions, because we are still in the early stages
of including string.h itself and haven't gotten to the function
declarations yet.

>>> +/**
>>> + * 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, 

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

[Markus Mayer]

On 9 July 2016 at 05:04, Luis de Bethencourt  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 
>> ---
>>  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);
>>
>
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Re: [PATCH v3 1/7] lib: string: add functions to case-convert strings

[Luis de Bethencourt]

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 
> ---
>  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?

> +/**
> + * 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);
> 

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

[Markus Mayer]

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 
---
 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);
+}
+
+/**
+ * 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);
+}
+
+/**
+ * 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);
-- 
2.7.4

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