[PATCH v2] unicode: Expose available encodings in sysfs

[PATCH v2] unicode: Expose available encodings in sysfs

[Gabriel Krisman Bertazi]

A filesystem configuration utility has no way to detect which filename
encodings are supported by the running kernel.  This means, for
instance, mkfs has no way to tell if the generated filesystem will be
mountable in the current kernel or not.  Also, users have no easy way to
know if they can update the encoding in their filesystems and still have
something functional in the end.

This exposes details of the encodings available in the unicode
subsystem, to fill that gap.

Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>

---
Changes since v1:
  - Make init functions static. (lkp)

 Documentation/ABI/testing/sysfs-fs-unicode | 13 +++++
 fs/unicode/utf8-core.c                     | 64 ++++++++++++++++++++++
 fs/unicode/utf8-norm.c                     | 18 ++++++
 fs/unicode/utf8n.h                         |  5 ++
 4 files changed, 100 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-fs-unicode

diff --git a/Documentation/ABI/testing/sysfs-fs-unicode b/Documentation/ABI/testing/sysfs-fs-unicode
new file mode 100644
index 000000000000..15c63367bb8e
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-fs-unicode
@@ -0,0 +1,13 @@
+What:		/sys/fs/unicode/latest
+Date:		April 2020
+Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
+Description:
+		The latest version of the Unicode Standard supported by
+		this kernel
+
+What:		/sys/fs/unicode/encodings
+Date:		April 2020
+Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
+Description:
+		List of encodings and corresponding versions supported
+		by this kernel
diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
index 2a878b739115..b48e13e823a5 100644
--- a/fs/unicode/utf8-core.c
+++ b/fs/unicode/utf8-core.c
@@ -6,6 +6,7 @@
 #include <linux/parser.h>
 #include <linux/errno.h>
 #include <linux/unicode.h>
+#include <linux/fs.h>
 
 #include "utf8n.h"
 
@@ -212,4 +213,67 @@ void utf8_unload(struct unicode_map *um)
 }
 EXPORT_SYMBOL(utf8_unload);
 
+static ssize_t latest_show(struct kobject *kobj,
+			   struct kobj_attribute *attr, char *buf)
+{
+	int l = utf8version_latest();
+
+	return snprintf(buf, PAGE_SIZE, "UTF-8 %d.%d.%d\n", UNICODE_AGE_MAJ(l),
+			UNICODE_AGE_MIN(l), UNICODE_AGE_REV(l));
+
+}
+static ssize_t encodings_show(struct kobject *kobj,
+			      struct kobj_attribute *attr, char *buf)
+{
+	int n;
+
+	n = snprintf(buf, PAGE_SIZE, "UTF-8:");
+	n += utf8version_list(buf + n, PAGE_SIZE - n);
+	n += snprintf(buf+n, PAGE_SIZE-n, "\n");
+
+	return n;
+}
+
+#define UCD_ATTR(x) \
+	static struct kobj_attribute x ## _attr = __ATTR_RO(x)
+
+UCD_ATTR(latest);
+UCD_ATTR(encodings);
+
+static struct attribute *ucd_attrs[] = {
+	&latest_attr.attr,
+	&encodings_attr.attr,
+	NULL,
+};
+static const struct attribute_group ucd_attr_group = {
+	.attrs = ucd_attrs,
+};
+static struct kobject *ucd_root;
+
+static int __init ucd_init(void)
+{
+	int ret;
+
+	ucd_root = kobject_create_and_add("unicode", fs_kobj);
+	if (!ucd_root)
+		return -ENOMEM;
+
+	ret = sysfs_create_group(ucd_root, &ucd_attr_group);
+	if (ret) {
+		kobject_put(ucd_root);
+		ucd_root = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+static void __exit ucd_exit(void)
+{
+	kobject_put(ucd_root);
+}
+
+module_init(ucd_init);
+module_exit(ucd_exit)
+
 MODULE_LICENSE("GPL v2");
diff --git a/fs/unicode/utf8-norm.c b/fs/unicode/utf8-norm.c
index 1d2d2e5b906a..f9ebba89a138 100644
--- a/fs/unicode/utf8-norm.c
+++ b/fs/unicode/utf8-norm.c
@@ -35,6 +35,24 @@ int utf8version_latest(void)
 }
 EXPORT_SYMBOL(utf8version_latest);
 
+int utf8version_list(char *buf, int len)
+{
+	int i = ARRAY_SIZE(utf8agetab) - 1;
+	int ret = 0;
+
+	/*
+	 * Print most relevant (latest) first.  No filesystem uses
+	 * unicode <= 12.0.0, so don't expose them to userspace.
+	 */
+	for (; utf8agetab[i] >= UNICODE_AGE(12, 0, 0); i--) {
+		ret += snprintf(buf+ret, len-ret, " %d.%d.%d",
+				UNICODE_AGE_MAJ(utf8agetab[i]),
+				UNICODE_AGE_MIN(utf8agetab[i]),
+				UNICODE_AGE_REV(utf8agetab[i]));
+	}
+	return ret;
+}
+
 /*
  * UTF-8 valid ranges.
  *
diff --git a/fs/unicode/utf8n.h b/fs/unicode/utf8n.h
index 0acd530c2c79..5dea2c4af1f3 100644
--- a/fs/unicode/utf8n.h
+++ b/fs/unicode/utf8n.h
@@ -21,9 +21,14 @@
 	 ((unsigned int)(MIN) << UNICODE_MIN_SHIFT) |	\
 	 ((unsigned int)(REV)))
 
+#define UNICODE_AGE_MAJ(x) ((x) >> UNICODE_MAJ_SHIFT & 0xff)
+#define UNICODE_AGE_MIN(x) ((x) >> UNICODE_MIN_SHIFT & 0xff)
+#define UNICODE_AGE_REV(x) ((x) & 0xff)
+
 /* Highest unicode version supported by the data tables. */
 extern int utf8version_is_supported(u8 maj, u8 min, u8 rev);
 extern int utf8version_latest(void);
+extern int utf8version_list(char *buf, int len);
 
 /*
  * Look for the correct const struct utf8data for a unicode version.
-- 
2.26.0

Re: [PATCH v2] unicode: Expose available encodings in sysfs

[Ezequiel Garcia]

Hey Gabriel,

On Mon, 2020-04-13 at 12:53 -0400, Gabriel Krisman Bertazi wrote:
> A filesystem configuration utility has no way to detect which filename
> encodings are supported by the running kernel.  This means, for
> instance, mkfs has no way to tell if the generated filesystem will be
> mountable in the current kernel or not.  Also, users have no easy way to
> know if they can update the encoding in their filesystems and still have
> something functional in the end.
> 
> This exposes details of the encodings available in the unicode
> subsystem, to fill that gap.
> 
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Jaegeuk Kim <jaegeuk@kernel.org>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> 
> ---
> Changes since v1:
>   - Make init functions static. (lkp)
> 
>  Documentation/ABI/testing/sysfs-fs-unicode | 13 +++++
>  fs/unicode/utf8-core.c                     | 64 ++++++++++++++++++++++
>  fs/unicode/utf8-norm.c                     | 18 ++++++
>  fs/unicode/utf8n.h                         |  5 ++
>  4 files changed, 100 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-fs-unicode
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-unicode b/Documentation/ABI/testing/sysfs-fs-unicode
> new file mode 100644
> index 000000000000..15c63367bb8e
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-fs-unicode
> @@ -0,0 +1,13 @@
> +What:		/sys/fs/unicode/latest
> +Date:		April 2020
> +Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
> +Description:
> +		The latest version of the Unicode Standard supported by
> +		this kernel
> +

Missing stop at the end of the sentence?

> +What:		/sys/fs/unicode/encodings
> +Date:		April 2020
> +Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
> +Description:
> +		List of encodings and corresponding versions supported
> +		by this kernel

Ditto.

> diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
> index 2a878b739115..b48e13e823a5 100644
> --- a/fs/unicode/utf8-core.c
> +++ b/fs/unicode/utf8-core.c
> @@ -6,6 +6,7 @@
>  #include <linux/parser.h>
>  #include <linux/errno.h>
>  #include <linux/unicode.h>
> +#include <linux/fs.h>
>  
>  #include "utf8n.h"
>  
> @@ -212,4 +213,67 @@ void utf8_unload(struct unicode_map *um)
>  }
>  EXPORT_SYMBOL(utf8_unload);
>  
> +static ssize_t latest_show(struct kobject *kobj,
> +			   struct kobj_attribute *attr, char *buf)
> +{
> +	int l = utf8version_latest();
> +
> +	return snprintf(buf, PAGE_SIZE, "UTF-8 %d.%d.%d\n", UNICODE_AGE_MAJ(l),
> +			UNICODE_AGE_MIN(l), UNICODE_AGE_REV(l));
> +
> +}
> +static ssize_t encodings_show(struct kobject *kobj,
> +			      struct kobj_attribute *attr, char *buf)
> +{
> +	int n;
> +
> +	n = snprintf(buf, PAGE_SIZE, "UTF-8:");
> +	n += utf8version_list(buf + n, PAGE_SIZE - n);
> +	n += snprintf(buf+n, PAGE_SIZE-n, "\n");
> +

I was wondering how sysfs-compliant this was,
in terms of one value per attribute.

Although, we do seem to break this on a few cases.

> +	return n;
> +}
> +
> +#define UCD_ATTR(x) \
> +	static struct kobj_attribute x ## _attr = __ATTR_RO(x)
> +
> +UCD_ATTR(latest);
> +UCD_ATTR(encodings);
> +
> +static struct attribute *ucd_attrs[] = {
> +	&latest_attr.attr,
> +	&encodings_attr.attr,
> +	NULL,
> +};
> +static const struct attribute_group ucd_attr_group = {
> +	.attrs = ucd_attrs,
> +};
> +static struct kobject *ucd_root;
> +
> +static int __init ucd_init(void)
> +{
> +	int ret;
> +
> +	ucd_root = kobject_create_and_add("unicode", fs_kobj);
> +	if (!ucd_root)
> +		return -ENOMEM;
> +
> +	ret = sysfs_create_group(ucd_root, &ucd_attr_group);
> +	if (ret) {
> +		kobject_put(ucd_root);
> +		ucd_root = NULL;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void __exit ucd_exit(void)
> +{
> +	kobject_put(ucd_root);
> +}
> +
> +module_init(ucd_init);

This code is not a module, so how about fs_initcall?

> +module_exit(ucd_exit)
> +

I can be wrong, but I see no way to remove it :-)

Thanks,
Ezequiel

Re: [PATCH v2] unicode: Expose available encodings in sysfs

[Gabriel Krisman Bertazi]

Ezequiel Garcia <ezequiel@collabora.com> writes:

> Hey Gabriel,
>
> On Mon, 2020-04-13 at 12:53 -0400, Gabriel Krisman Bertazi wrote:
>> A filesystem configuration utility has no way to detect which filename
>> encodings are supported by the running kernel.  This means, for
>> instance, mkfs has no way to tell if the generated filesystem will be
>> mountable in the current kernel or not.  Also, users have no easy way to
>> know if they can update the encoding in their filesystems and still have
>> something functional in the end.
>> 
>> This exposes details of the encodings available in the unicode
>> subsystem, to fill that gap.
>> 
>> Cc: Theodore Ts'o <tytso@mit.edu>
>> Cc: Jaegeuk Kim <jaegeuk@kernel.org>
>> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
>> 
>> ---
>> Changes since v1:
>>   - Make init functions static. (lkp)
>> 
>>  Documentation/ABI/testing/sysfs-fs-unicode | 13 +++++
>>  fs/unicode/utf8-core.c                     | 64 ++++++++++++++++++++++
>>  fs/unicode/utf8-norm.c                     | 18 ++++++
>>  fs/unicode/utf8n.h                         |  5 ++
>>  4 files changed, 100 insertions(+)
>>  create mode 100644 Documentation/ABI/testing/sysfs-fs-unicode
>> 
>> diff --git a/Documentation/ABI/testing/sysfs-fs-unicode b/Documentation/ABI/testing/sysfs-fs-unicode
>> new file mode 100644
>> index 000000000000..15c63367bb8e
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/sysfs-fs-unicode
>> @@ -0,0 +1,13 @@
>> +What:		/sys/fs/unicode/latest
>> +Date:		April 2020
>> +Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
>> +Description:
>> +		The latest version of the Unicode Standard supported by
>> +		this kernel
>> +
>
> Missing stop at the end of the sentence?
>
>> +What:		/sys/fs/unicode/encodings
>> +Date:		April 2020
>> +Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
>> +Description:
>> +		List of encodings and corresponding versions supported
>> +		by this kernel
>
> Ditto.
>
>> diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
>> index 2a878b739115..b48e13e823a5 100644
>> --- a/fs/unicode/utf8-core.c
>> +++ b/fs/unicode/utf8-core.c
>> @@ -6,6 +6,7 @@
>>  #include <linux/parser.h>
>>  #include <linux/errno.h>
>>  #include <linux/unicode.h>
>> +#include <linux/fs.h>
>>  
>>  #include "utf8n.h"
>>  
>> @@ -212,4 +213,67 @@ void utf8_unload(struct unicode_map *um)
>>  }
>>  EXPORT_SYMBOL(utf8_unload);
>>  
>> +static ssize_t latest_show(struct kobject *kobj,
>> +			   struct kobj_attribute *attr, char *buf)
>> +{
>> +	int l = utf8version_latest();
>> +
>> +	return snprintf(buf, PAGE_SIZE, "UTF-8 %d.%d.%d\n", UNICODE_AGE_MAJ(l),
>> +			UNICODE_AGE_MIN(l), UNICODE_AGE_REV(l));
>> +
>> +}
>> +static ssize_t encodings_show(struct kobject *kobj,
>> +			      struct kobj_attribute *attr, char *buf)
>> +{
>> +	int n;
>> +
>> +	n = snprintf(buf, PAGE_SIZE, "UTF-8:");
>> +	n += utf8version_list(buf + n, PAGE_SIZE - n);
>> +	n += snprintf(buf+n, PAGE_SIZE-n, "\n");
>> +
>
> I was wondering how sysfs-compliant this was,
> in terms of one value per attribute.
>
> Although, we do seem to break this on a few cases.

I thought about making it more one-value-per-attribute, by considering
each tuple (encoding,version) a different object.  So the structure
would look like:

/sys/fs/unicode/utf-8/<version>/

But it felt completely over-engineered, considering we don't support
anything other than utf-8, and I don't see versions having specific
attributes.  But maybe this way is more future-proof.


>
>> +	return n;
>> +}
>> +
>> +#define UCD_ATTR(x) \
>> +	static struct kobj_attribute x ## _attr = __ATTR_RO(x)
>> +
>> +UCD_ATTR(latest);
>> +UCD_ATTR(encodings);
>> +
>> +static struct attribute *ucd_attrs[] = {
>> +	&latest_attr.attr,
>> +	&encodings_attr.attr,
>> +	NULL,
>> +};
>> +static const struct attribute_group ucd_attr_group = {
>> +	.attrs = ucd_attrs,
>> +};
>> +static struct kobject *ucd_root;
>> +
>> +static int __init ucd_init(void)
>> +{
>> +	int ret;
>> +
>> +	ucd_root = kobject_create_and_add("unicode", fs_kobj);
>> +	if (!ucd_root)
>> +		return -ENOMEM;
>> +
>> +	ret = sysfs_create_group(ucd_root, &ucd_attr_group);
>> +	if (ret) {
>> +		kobject_put(ucd_root);
>> +		ucd_root = NULL;
>> +		return ret;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void __exit ucd_exit(void)
>> +{
>> +	kobject_put(ucd_root);
>> +}
>> +
>> +module_init(ucd_init);
>
> This code is not a module, so how about fs_initcall?

Right.  for the record, I'm planing to make part of it build as a module
in a future patch to reduce the large footprint of the decoding table on
systems that don't care about it.  Will fix on v3.


>
>> +module_exit(ucd_exit)
>> +
>
> I can be wrong, but I see no way to remove it :-)
>
> Thanks,
> Ezequiel

-- 
Gabriel Krisman Bertazi

Re: [PATCH v2] unicode: Expose available encodings in sysfs

[Anirudh Rayabharam]

On Mon, Apr 13, 2020 at 12:53:52PM -0400, Gabriel Krisman Bertazi wrote:
> A filesystem configuration utility has no way to detect which filename
> encodings are supported by the running kernel.  This means, for
> instance, mkfs has no way to tell if the generated filesystem will be
> mountable in the current kernel or not.  Also, users have no easy way to
> know if they can update the encoding in their filesystems and still have
> something functional in the end.
> 
> This exposes details of the encodings available in the unicode
> subsystem, to fill that gap.
> 
> Cc: Theodore Ts'o <tytso@mit.edu>
> Cc: Jaegeuk Kim <jaegeuk@kernel.org>
> Signed-off-by: Gabriel Krisman Bertazi <krisman@collabora.com>
> 
> ---
> Changes since v1:
>   - Make init functions static. (lkp)
> 
>  Documentation/ABI/testing/sysfs-fs-unicode | 13 +++++
>  fs/unicode/utf8-core.c                     | 64 ++++++++++++++++++++++
>  fs/unicode/utf8-norm.c                     | 18 ++++++
>  fs/unicode/utf8n.h                         |  5 ++
>  4 files changed, 100 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-fs-unicode
> 
> diff --git a/Documentation/ABI/testing/sysfs-fs-unicode b/Documentation/ABI/testing/sysfs-fs-unicode
> new file mode 100644
> index 000000000000..15c63367bb8e
> --- /dev/null
> +++ b/Documentation/ABI/testing/sysfs-fs-unicode
> @@ -0,0 +1,13 @@
> +What:		/sys/fs/unicode/latest
> +Date:		April 2020
> +Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
> +Description:
> +		The latest version of the Unicode Standard supported by
> +		this kernel
> +
> +What:		/sys/fs/unicode/encodings
> +Date:		April 2020
> +Contact:	Gabriel Krisman Bertazi <krisman@collabora.com>
> +Description:
> +		List of encodings and corresponding versions supported
> +		by this kernel
> diff --git a/fs/unicode/utf8-core.c b/fs/unicode/utf8-core.c
> index 2a878b739115..b48e13e823a5 100644
> --- a/fs/unicode/utf8-core.c
> +++ b/fs/unicode/utf8-core.c
> @@ -6,6 +6,7 @@
>  #include <linux/parser.h>
>  #include <linux/errno.h>
>  #include <linux/unicode.h>
> +#include <linux/fs.h>
>  
>  #include "utf8n.h"
>  
> @@ -212,4 +213,67 @@ void utf8_unload(struct unicode_map *um)
>  }
>  EXPORT_SYMBOL(utf8_unload);
>  
> +static ssize_t latest_show(struct kobject *kobj,
> +			   struct kobj_attribute *attr, char *buf)
> +{
> +	int l = utf8version_latest();
> +
> +	return snprintf(buf, PAGE_SIZE, "UTF-8 %d.%d.%d\n", UNICODE_AGE_MAJ(l),
> +			UNICODE_AGE_MIN(l), UNICODE_AGE_REV(l));
> +
> +}
> +static ssize_t encodings_show(struct kobject *kobj,
> +			      struct kobj_attribute *attr, char *buf)
> +{
> +	int n;
> +
> +	n = snprintf(buf, PAGE_SIZE, "UTF-8:");
> +	n += utf8version_list(buf + n, PAGE_SIZE - n);
> +	n += snprintf(buf+n, PAGE_SIZE-n, "\n");

Spaces before and after the '+' and '-' operators?

	n += snprintf(buf + n, PAGE_SIZE - n, "\n");

Thanks,
Anirudh

> +
> +	return n;
> +}
> +
> +#define UCD_ATTR(x) \
> +	static struct kobj_attribute x ## _attr = __ATTR_RO(x)
> +
> +UCD_ATTR(latest);
> +UCD_ATTR(encodings);
> +
> +static struct attribute *ucd_attrs[] = {
> +	&latest_attr.attr,
> +	&encodings_attr.attr,
> +	NULL,
> +};
> +static const struct attribute_group ucd_attr_group = {
> +	.attrs = ucd_attrs,
> +};
> +static struct kobject *ucd_root;
> +
> +static int __init ucd_init(void)
> +{
> +	int ret;
> +
> +	ucd_root = kobject_create_and_add("unicode", fs_kobj);
> +	if (!ucd_root)
> +		return -ENOMEM;
> +
> +	ret = sysfs_create_group(ucd_root, &ucd_attr_group);
> +	if (ret) {
> +		kobject_put(ucd_root);
> +		ucd_root = NULL;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void __exit ucd_exit(void)
> +{
> +	kobject_put(ucd_root);
> +}
> +
> +module_init(ucd_init);
> +module_exit(ucd_exit)
> +
>  MODULE_LICENSE("GPL v2");
> diff --git a/fs/unicode/utf8-norm.c b/fs/unicode/utf8-norm.c
> index 1d2d2e5b906a..f9ebba89a138 100644
> --- a/fs/unicode/utf8-norm.c
> +++ b/fs/unicode/utf8-norm.c
> @@ -35,6 +35,24 @@ int utf8version_latest(void)
>  }
>  EXPORT_SYMBOL(utf8version_latest);
>  
> +int utf8version_list(char *buf, int len)
> +{
> +	int i = ARRAY_SIZE(utf8agetab) - 1;
> +	int ret = 0;
> +
> +	/*
> +	 * Print most relevant (latest) first.  No filesystem uses
> +	 * unicode <= 12.0.0, so don't expose them to userspace.
> +	 */
> +	for (; utf8agetab[i] >= UNICODE_AGE(12, 0, 0); i--) {
> +		ret += snprintf(buf+ret, len-ret, " %d.%d.%d",
> +				UNICODE_AGE_MAJ(utf8agetab[i]),
> +				UNICODE_AGE_MIN(utf8agetab[i]),
> +				UNICODE_AGE_REV(utf8agetab[i]));
> +	}
> +	return ret;
> +}
> +
>  /*
>   * UTF-8 valid ranges.
>   *
> diff --git a/fs/unicode/utf8n.h b/fs/unicode/utf8n.h
> index 0acd530c2c79..5dea2c4af1f3 100644
> --- a/fs/unicode/utf8n.h
> +++ b/fs/unicode/utf8n.h
> @@ -21,9 +21,14 @@
>  	 ((unsigned int)(MIN) << UNICODE_MIN_SHIFT) |	\
>  	 ((unsigned int)(REV)))
>  
> +#define UNICODE_AGE_MAJ(x) ((x) >> UNICODE_MAJ_SHIFT & 0xff)
> +#define UNICODE_AGE_MIN(x) ((x) >> UNICODE_MIN_SHIFT & 0xff)
> +#define UNICODE_AGE_REV(x) ((x) & 0xff)
> +
>  /* Highest unicode version supported by the data tables. */
>  extern int utf8version_is_supported(u8 maj, u8 min, u8 rev);
>  extern int utf8version_latest(void);
> +extern int utf8version_list(char *buf, int len);
>  
>  /*
>   * Look for the correct const struct utf8data for a unicode version.
> -- 
> 2.26.0
>