[PATCH] Implement kasprintf

[PATCH] Implement kasprintf

[Jeremy Fitzhardinge]

From: Jeremy Fitzhardinge <jeremy@xensource.com>

Implement kasprintf, a kernel version of asprintf.  This allocates the
memory required for the formatted string, including the trailing '\0'.
Returns NULL on allocation failure.

Requires vsnprintf to accept a NULL buffer when the buffer size is 0.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

---
 include/linux/kernel.h |    2 +
 lib/Makefile           |    2 -
 lib/kasprintf.c        |   54 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)


diff -r c175fd50e604 include/linux/kernel.h
--- a/include/linux/kernel.h	Tue Jun 20 16:47:53 2006 -0700
+++ b/include/linux/kernel.h	Tue Jun 20 16:53:19 2006 -0700
@@ -114,6 +114,8 @@ extern int scnprintf(char * buf, size_t 
 	__attribute__ ((format (printf, 3, 4)));
 extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 	__attribute__ ((format (printf, 3, 0)));
+extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
+	__attribute__ ((format (printf, 2, 3)));
 
 extern int sscanf(const char *, const char *, ...)
 	__attribute__ ((format (scanf, 2, 3)));
diff -r c175fd50e604 lib/Makefile
--- a/lib/Makefile	Tue Jun 20 16:47:53 2006 -0700
+++ b/lib/Makefile	Tue Jun 20 16:53:19 2006 -0700
@@ -5,7 +5,7 @@ lib-y := errno.o ctype.o string.o vsprin
 lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
 	 bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \
 	 idr.o div64.o int_sqrt.o bitmap.o extable.o prio_tree.o \
-	 sha1.o
+	 sha1.o kasprintf.o
 
 lib-$(CONFIG_SMP) += cpumask.o
 
diff -r c175fd50e604 lib/kasprintf.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/kasprintf.c	Tue Jun 20 16:53:19 2006 -0700
@@ -0,0 +1,54 @@
+/******************************************************************************
+ * Simplified asprintf.
+ *
+ * Copyright (C) 2006 XenSource Ltd
+ * 
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/* Simplified asprintf. */
+char *kasprintf(gfp_t gfp, const char *fmt, ...)
+{
+	va_list ap;
+	unsigned int len;
+	char *p;
+
+	va_start(ap, fmt);
+	len = vsnprintf(NULL, 0, fmt, ap);
+	va_end(ap);
+
+	p = kmalloc(len+1, gfp);
+	if (!p)
+		return NULL;
+	va_start(ap, fmt);
+	vsnprintf(p, len+1, fmt, ap);
+	va_end(ap);
+	return p;
+}
+EXPORT_SYMBOL(kasprintf);

Re: [PATCH] Implement kasprintf

[Randy.Dunlap]

On Tue, 20 Jun 2006 16:57:16 -0700 Jeremy Fitzhardinge wrote:

> From: Jeremy Fitzhardinge <jeremy@xensource.com>
> 
> Implement kasprintf, a kernel version of asprintf.  This allocates the
> memory required for the formatted string, including the trailing '\0'.
> Returns NULL on allocation failure.
> 
> Requires vsnprintf to accept a NULL buffer when the buffer size is 0.
> 
> Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
> 
> ---
>  include/linux/kernel.h |    2 +
>  lib/Makefile           |    2 -
>  lib/kasprintf.c        |   54 ++++++++++++++++++++++++++++++++++++++++++++++++

Hi,
<nit>

Why do we want a separate source file for this one function?


>  3 files changed, 57 insertions(+), 1 deletion(-)
> 
> 
> diff -r c175fd50e604 include/linux/kernel.h
> --- a/include/linux/kernel.h	Tue Jun 20 16:47:53 2006 -0700
> +++ b/include/linux/kernel.h	Tue Jun 20 16:53:19 2006 -0700
> @@ -114,6 +114,8 @@ extern int scnprintf(char * buf, size_t 
>  	__attribute__ ((format (printf, 3, 4)));
>  extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
>  	__attribute__ ((format (printf, 3, 0)));
> +extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
> +	__attribute__ ((format (printf, 2, 3)));
>  
>  extern int sscanf(const char *, const char *, ...)
>  	__attribute__ ((format (scanf, 2, 3)));
> diff -r c175fd50e604 lib/Makefile
> --- a/lib/Makefile	Tue Jun 20 16:47:53 2006 -0700
> +++ b/lib/Makefile	Tue Jun 20 16:53:19 2006 -0700
> @@ -5,7 +5,7 @@ lib-y := errno.o ctype.o string.o vsprin
>  lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
>  	 bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \
>  	 idr.o div64.o int_sqrt.o bitmap.o extable.o prio_tree.o \
> -	 sha1.o
> +	 sha1.o kasprintf.o
>  
>  lib-$(CONFIG_SMP) += cpumask.o
>  
> diff -r c175fd50e604 lib/kasprintf.c
> --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
> +++ b/lib/kasprintf.c	Tue Jun 20 16:53:19 2006 -0700
> @@ -0,0 +1,54 @@
> +/******************************************************************************
> + * Simplified asprintf.
> + *
> + * Copyright (C) 2006 XenSource Ltd
> + * 
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License version 2
> + * as published by the Free Software Foundation; or, when distributed
> + * separately from the Linux kernel or incorporated into other
> + * software packages, subject to the following license:
> + * 
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this source file (the "Software"), to deal in the Software without
> + * restriction, including without limitation the rights to use, copy, modify,
> + * merge, publish, distribute, sublicense, and/or sell copies of the Software,
> + * and to permit persons to whom the Software is furnished to do so, subject to
> + * the following conditions:
> + * 
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + * 
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
> + * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +
> +/* Simplified asprintf. */
> +char *kasprintf(gfp_t gfp, const char *fmt, ...)
> +{
> +	va_list ap;
> +	unsigned int len;
> +	char *p;
> +
> +	va_start(ap, fmt);
> +	len = vsnprintf(NULL, 0, fmt, ap);
> +	va_end(ap);
> +
> +	p = kmalloc(len+1, gfp);
> +	if (!p)
> +		return NULL;
> +	va_start(ap, fmt);
> +	vsnprintf(p, len+1, fmt, ap);
> +	va_end(ap);
> +	return p;
> +}
> +EXPORT_SYMBOL(kasprintf);

---
~Randy

Re: [PATCH] Implement kasprintf

[Jeremy Fitzhardinge]

Randy.Dunlap wrote:
> Why do we want a separate source file for this one function?
>   
Because if it shared a file with something else, someone would complain 
about it bloating code which doesn't use it...  At the moment there are 
no in-tree users (though I'm sure there's something out there with an 
open-coded version of this), but we'll be needing it for Xen.

I'm happy to fold it into vsprintf.c though.

    J

Re: [PATCH] Implement kasprintf

[Randy.Dunlap]

On Tue, 20 Jun 2006 17:14:55 -0700 Jeremy Fitzhardinge wrote:

> Randy.Dunlap wrote:
> > Why do we want a separate source file for this one function?
> >   
> Because if it shared a file with something else, someone would complain 
> about it bloating code which doesn't use it...  At the moment there are 
> no in-tree users (though I'm sure there's something out there with an 
> open-coded version of this), but we'll be needing it for Xen.

Doesn't this already add the bloat/code? ::

diff -r c175fd50e604 lib/Makefile
--- a/lib/Makefile	Tue Jun 20 16:47:53 2006 -0700
+++ b/lib/Makefile	Tue Jun 20 16:53:19 2006 -0700
@@ -5,7 +5,7 @@ lib-y := errno.o ctype.o string.o vsprin
 lib-y := errno.o ctype.o string.o vsprintf.o cmdline.o \
 	 bust_spinlocks.o rbtree.o radix-tree.o dump_stack.o \
 	 idr.o div64.o int_sqrt.o bitmap.o extable.o prio_tree.o \
-	 sha1.o
+	 sha1.o kasprintf.o

> I'm happy to fold it into vsprintf.c though.

That makes sense to me.

Thanks,
---
~Randy

Re: [PATCH] Implement kasprintf

[Jeremy Fitzhardinge]

Randy.Dunlap wrote:
> Doesn't this already add the bloat/code? ::
>   
Yup.  My back-of-the-mind unexamined assumption was that this was going 
into a .a, which it isn't.

Updated patch below.

    J


--

From: Jeremy Fitzhardinge <jeremy@xensource.com>

Implement kasprintf, a kernel version of asprintf.  This allocates the
memory required for the formatted string, including the trailing '\0'.
Returns NULL on allocation failure.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

---
 include/linux/kernel.h |    2 ++
 lib/vsprintf.c         |   23 +++++++++++++++++++++++
 2 files changed, 25 insertions(+)


diff -r cd45ea4bb813 include/linux/kernel.h
--- a/include/linux/kernel.h	Tue Jun 20 17:28:16 2006 -0700
+++ b/include/linux/kernel.h	Tue Jun 20 17:29:18 2006 -0700
@@ -114,6 +114,8 @@ extern int scnprintf(char * buf, size_t 
 	__attribute__ ((format (printf, 3, 4)));
 extern int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
 	__attribute__ ((format (printf, 3, 0)));
+extern char *kasprintf(gfp_t gfp, const char *fmt, ...)
+	__attribute__ ((format (printf, 2, 3)));
 
 extern int sscanf(const char *, const char *, ...)
 	__attribute__ ((format (scanf, 2, 3)));
diff -r cd45ea4bb813 lib/vsprintf.c
--- a/lib/vsprintf.c	Tue Jun 20 17:28:16 2006 -0700
+++ b/lib/vsprintf.c	Tue Jun 20 17:29:18 2006 -0700
@@ -849,3 +849,26 @@ int sscanf(const char * buf, const char 
 }
 
 EXPORT_SYMBOL(sscanf);
+
+
+/* Simplified asprintf. */
+char *kasprintf(gfp_t gfp, const char *fmt, ...)
+{
+	va_list ap;
+	unsigned int len;
+	char *p;
+
+	va_start(ap, fmt);
+	len = vsnprintf(NULL, 0, fmt, ap);
+	va_end(ap);
+
+	p = kmalloc(len+1, gfp);
+	if (!p)
+		return NULL;
+	va_start(ap, fmt);
+	vsnprintf(p, len+1, fmt, ap);
+	va_end(ap);
+	return p;
+}
+
+EXPORT_SYMBOL(kasprintf);

Re: [PATCH] Implement kasprintf

[Kyle McMartin]

On Tue, Jun 20, 2006 at 04:57:16PM -0700, Jeremy Fitzhardinge wrote:
> +char *kasprintf(gfp_t gfp, const char *fmt, ...)
> +{

Why not just asprintf? We don't have ksprintf... 

% grep EXPORT_SYMBOL lib/vsprintf.c
EXPORT_SYMBOL(simple_strtoul);
EXPORT_SYMBOL(simple_strtol);
EXPORT_SYMBOL(simple_strtoull);
EXPORT_SYMBOL(vsnprintf);
EXPORT_SYMBOL(vscnprintf);
EXPORT_SYMBOL(snprintf);
EXPORT_SYMBOL(scnprintf);
EXPORT_SYMBOL(vsprintf);
EXPORT_SYMBOL(sprintf);
EXPORT_SYMBOL(vsscanf);
EXPORT_SYMBOL(sscanf);

?

Cheers,
	Kyle M.

Re: [PATCH] Implement kasprintf

[Andrew Morton]

On Tue, 20 Jun 2006 23:04:44 -0400
Kyle McMartin <kyle@parisc-linux.org> wrote:

> On Tue, Jun 20, 2006 at 04:57:16PM -0700, Jeremy Fitzhardinge wrote:
> > +char *kasprintf(gfp_t gfp, const char *fmt, ...)
> > +{
> 
> Why not just asprintf? We don't have ksprintf... 

asprintf() doesn't take a gfp_t arg.

Re: [PATCH] Implement kasprintf

[H. Peter Anvin]

Andrew Morton wrote:
> On Tue, 20 Jun 2006 23:04:44 -0400
> Kyle McMartin <kyle@parisc-linux.org> wrote:
> 
>> On Tue, Jun 20, 2006 at 04:57:16PM -0700, Jeremy Fitzhardinge wrote:
>>> +char *kasprintf(gfp_t gfp, const char *fmt, ...)
>>> +{
>> Why not just asprintf? We don't have ksprintf... 
> asprintf() doesn't take a gfp_t arg.
> 

Or, more generally: if we change the API, change the name.  kmalloc() is 
different from malloc() as it is invoked differently, as is kasprintf().

printk() was arguably a mistake, although it's semi-justified a posteori 
since it takes the priority pseudo-argument now.

	-hpa

Re: [PATCH] Implement kasprintf

[Kyle McMartin]

On Tue, Jun 20, 2006 at 08:26:17PM -0700, Andrew Morton wrote:
> 
> asprintf() doesn't take a gfp_t arg.
> 

Good point. :)

Cheers,
	Kyle