[PATCH 0/3] C23 string func() handling updates

[PATCH 0/3] C23 string func() handling updates

[Nicholas Vinson]

With C23, the following 12 functions were updated to have 'const-aware'
return types:

bsearch(), bsearch_s(), memchr(), strchr(), strpbrk(), strrchr(),
strstr(), wcschr(), wcspbrk(), wcsrchr(), wcsstr(), and wmemchr().

Of these functions, strchr(), strpbrk(), strrchr(), and strstr(), are
used within GRUB, and for 3 of these functions, strchr(), strrchr(), and
strstr(), some of their calls within GRUB are now resulting in
compile-time errors due to the C23 changes and 'discarding qualifier'
errors. The errors are generated by elevating 'discarding qualifier'
warnings to error-level. A promotion GRUB's build system defaults to
doing.

Most of the changes this patch series makes to fix these errors are
simple and only requiring changing a variable's type from 'char *' to
'const char *'.  However, the changes in ofpath.c are more involved as
they also update the way lengths are calculated and *printf() functions
are called as a result of these C23 changes.

Furthermore, the changes are needed as C runtime libraries, notably
glbc starting with version 2.43, are implementing the changes the C23
standard requires.

Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>

Nicholas Vinson (3):
  grub-core/osdep/linux/ofpath.c: Update strstr() calls
  util/probe.c: save strrchr() ret val to const data ptr.
  util/resolve.c: Save str[r]chr() ret val to const data ptr

 grub-core/osdep/linux/ofpath.c | 25 ++++++++++++-------------
 util/probe.c                   |  6 +++---
 util/resolve.c                 | 10 +++++-----
 3 files changed, 20 insertions(+), 21 deletions(-)

-- 
2.53.0


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[PATCH 1/3] grub-core/osdep/linux/ofpath.c: Update strstr() calls

[Nicholas Vinson]

With C23, strstr() returns a 'const char *' if its first agrument is
'const char *', and these changes are implemented in glibc-2.43.

As a result, the first strstr() call in check_sas() now returns a 'const
char *' instead of 'char *' because sysfs_path is a 'const char *'. This
triggers a "discards qualifiers" warning, that is later promoted to an
error and ultimately causes the build to fail.

To fix the issue, this patch converts 'ed', the pointer that stores
strstr()'s return value, to a 'const char *'. Removes the xstrdup()
call and cleans up the rest of the function by updating the *printf()
calls and using pointer arthimetic to compute lengths instead of
strlen().

Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>
---
 grub-core/osdep/linux/ofpath.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/grub-core/osdep/linux/ofpath.c b/grub-core/osdep/linux/ofpath.c
index 24a4d5c8d..8dd311651 100644
--- a/grub-core/osdep/linux/ofpath.c
+++ b/grub-core/osdep/linux/ofpath.c
@@ -488,8 +488,11 @@ check_hba_identifiers (const char *sysfs_path, int *vendor, int *device_id)
 static void
 check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
 {
-  char *ed = strstr (sysfs_path, "end_device");
-  char *p, *q, *path;
+  const char *ed = strstr (sysfs_path, "end_device");
+  int p_len;
+  int ed_len;
+  const char *q;
+  char *path;
   char phy[21];
   int fd;
   size_t path_size;
@@ -498,20 +501,16 @@ check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
     return;
 
   /* SAS devices are identified using disk@$PHY_ID */
-  p = xstrdup (sysfs_path);
-  ed = strstr(p, "end_device");
-  if (!ed)
-    return;
-
   q = ed;
   while (*q && *q != '/')
     q++;
-  *q = '\0';
+  p_len = (int)(q - sysfs_path);
+  ed_len = (int)(q - ed);
 
-  path_size = (strlen (p) + strlen (ed)
-	       + sizeof ("%s/sas_device/%s/phy_identifier"));
+  path_size = (p_len + ed_len + sizeof ("/sas_device//phy_identifier"));
   path = xmalloc (path_size);
-  snprintf (path, path_size, "%s/sas_device/%s/phy_identifier", p, ed);
+  snprintf (path, path_size, "%.*s/sas_device/%.*s/phy_identifier", p_len,
+	    sysfs_path, ed_len, ed);
   fd = open (path, O_RDONLY);
   if (fd < 0)
     grub_util_error (_("cannot open `%s': %s"), path, strerror (errno));
@@ -524,7 +523,8 @@ check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
 
   sscanf (phy, "%d", tgt);
 
-  snprintf (path, path_size, "%s/sas_device/%s/sas_address", p, ed);
+  snprintf (path, path_size, "%.*s/sas_device/%.*s/sas_address", p_len,
+	    sysfs_path, ed_len, ed);
   fd = open (path, O_RDONLY);
   if (fd < 0)
     grub_util_error (_("cannot open `%s': %s"), path, strerror (errno));
@@ -535,7 +535,6 @@ check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
   sscanf (phy, "%lx", sas_address);
 
   free (path);
-  free (p);
   close (fd);
 }
 
-- 
2.53.0


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[PATCH 2/3] util/probe.c: save strrchr() ret val to const data ptr.

[Nicholas Vinson]

With glibc-2.43 implementing the C23 standard, strrchr() now returns
'const char *' when its first agrument is 'const char *'.

The fix is update all pointers receiving strrchr()'s return value so
that they are now 'const char *' instead of 'char *'.

Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>
---
 util/probe.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/util/probe.c b/util/probe.c
index 81d91cf59..a9158d640 100644
--- a/util/probe.c
+++ b/util/probe.c
@@ -70,7 +70,7 @@ char *
 grub_util_guess_bios_drive (const char *orig_path)
 {
   char *canon;
-  char *ptr;
+  const char *ptr;
   canon = grub_canonicalize_file_name (orig_path);
   if (!canon)
     return NULL;
@@ -99,7 +99,7 @@ char *
 grub_util_guess_efi_drive (const char *orig_path)
 {
   char *canon;
-  char *ptr;
+  const char *ptr;
   canon = grub_canonicalize_file_name (orig_path);
   if (!canon)
     return NULL;
@@ -128,7 +128,7 @@ char *
 grub_util_guess_baremetal_drive (const char *orig_path)
 {
   char *canon;
-  char *ptr;
+  const char *ptr;
   canon = grub_canonicalize_file_name (orig_path);
   if (!canon)
     return NULL;
-- 
2.53.0


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[PATCH 3/3] util/resolve.c: Save str[r]chr() ret val to const data ptr

[Nicholas Vinson]

With glibc-2.43 implementing the C23 standard, strrchr() and strchr()
now return 'const char *' when its first agrument is 'const char *'.

The fix is update all pointers receiving strrchr() and strchr()'s return
values so that they are now 'const char *' instead of 'char *'.

Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>
---
 util/resolve.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/util/resolve.c b/util/resolve.c
index b6e26312f..254379195 100644
--- a/util/resolve.c
+++ b/util/resolve.c
@@ -138,12 +138,12 @@ read_dep_list (FILE *fp)
 static char *
 get_module_name (const char *str)
 {
-  char *base;
-  char *ext;
+  const char *base;
+  const char *ext;
 
   base = strrchr (str, '/');
   if (! base)
-    base = (char *) str;
+    base = str;
   else
     base++;
 
@@ -164,9 +164,9 @@ get_module_name (const char *str)
 static char *
 get_module_path (const char *prefix, const char *str)
 {
-  char *dir;
+  const char *dir;
   char *base;
-  char *ext;
+  const char *ext;
   char *ret;
 
   ext = strrchr (str, '.');
-- 
2.53.0


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Re: [PATCH 1/3] grub-core/osdep/linux/ofpath.c: Update strstr() calls

[Daniel Kiper]

On Fri, Feb 13, 2026 at 07:18:35PM -0500, Nicholas Vinson wrote:
> With C23, strstr() returns a 'const char *' if its first agrument is
> 'const char *', and these changes are implemented in glibc-2.43.
>
> As a result, the first strstr() call in check_sas() now returns a 'const
> char *' instead of 'char *' because sysfs_path is a 'const char *'. This
> triggers a "discards qualifiers" warning, that is later promoted to an
> error and ultimately causes the build to fail.
>
> To fix the issue, this patch converts 'ed', the pointer that stores
> strstr()'s return value, to a 'const char *'. Removes the xstrdup()
> call and cleans up the rest of the function by updating the *printf()
> calls and using pointer arthimetic to compute lengths instead of
> strlen().
>
> Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>
> ---
>  grub-core/osdep/linux/ofpath.c | 25 ++++++++++++-------------
>  1 file changed, 12 insertions(+), 13 deletions(-)
>
> diff --git a/grub-core/osdep/linux/ofpath.c b/grub-core/osdep/linux/ofpath.c
> index 24a4d5c8d..8dd311651 100644
> --- a/grub-core/osdep/linux/ofpath.c
> +++ b/grub-core/osdep/linux/ofpath.c
> @@ -488,8 +488,11 @@ check_hba_identifiers (const char *sysfs_path, int *vendor, int *device_id)
>  static void
>  check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
>  {
> -  char *ed = strstr (sysfs_path, "end_device");
> -  char *p, *q, *path;
> +  const char *ed = strstr (sysfs_path, "end_device");
> +  int p_len;
> +  int ed_len;
> +  const char *q;
> +  char *path;
>    char phy[21];
>    int fd;
>    size_t path_size;
> @@ -498,20 +501,16 @@ check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
>      return;
>
>    /* SAS devices are identified using disk@$PHY_ID */
> -  p = xstrdup (sysfs_path);
> -  ed = strstr(p, "end_device");
> -  if (!ed)
> -    return;
> -
>    q = ed;

You blindly assume the "ed" is not NULL here. It is not true after
"if" removal above.

>    while (*q && *q != '/')
>      q++;
> -  *q = '\0';
> +  p_len = (int)(q - sysfs_path);
> +  ed_len = (int)(q - ed);

Missing spaces after (int)...

> -  path_size = (strlen (p) + strlen (ed)
> -	       + sizeof ("%s/sas_device/%s/phy_identifier"));
> +  path_size = (p_len + ed_len + sizeof ("/sas_device//phy_identifier"));

This sizof() change makes sens for me but it has to be reflected in the
commit message.

Daniel

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Re: [PATCH 2/3] util/probe.c: save strrchr() ret val to const data ptr.

[Daniel Kiper]

On Fri, Feb 13, 2026 at 07:18:44PM -0500, Nicholas Vinson wrote:
> With glibc-2.43 implementing the C23 standard, strrchr() now returns
> 'const char *' when its first agrument is 'const char *'.
>
> The fix is update all pointers receiving strrchr()'s return value so
> that they are now 'const char *' instead of 'char *'.
>
> Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Daniel

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Re: [PATCH 3/3] util/resolve.c: Save str[r]chr() ret val to const data ptr

[Daniel Kiper]

On Fri, Feb 13, 2026 at 07:18:50PM -0500, Nicholas Vinson wrote:
> With glibc-2.43 implementing the C23 standard, strrchr() and strchr()
> now return 'const char *' when its first agrument is 'const char *'.
>
> The fix is update all pointers receiving strrchr() and strchr()'s return
> values so that they are now 'const char *' instead of 'char *'.
>
> Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

Daniel

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Re: [PATCH 1/3] grub-core/osdep/linux/ofpath.c: Update strstr() calls

[Nicholas Vinson]

On 2/16/26 11:54, Daniel Kiper wrote:
> On Fri, Feb 13, 2026 at 07:18:35PM -0500, Nicholas Vinson wrote:
>> With C23, strstr() returns a 'const char *' if its first agrument is
>> 'const char *', and these changes are implemented in glibc-2.43.
>>
>> As a result, the first strstr() call in check_sas() now returns a 'const
>> char *' instead of 'char *' because sysfs_path is a 'const char *'. This
>> triggers a "discards qualifiers" warning, that is later promoted to an
>> error and ultimately causes the build to fail.
>>
>> To fix the issue, this patch converts 'ed', the pointer that stores
>> strstr()'s return value, to a 'const char *'. Removes the xstrdup()
>> call and cleans up the rest of the function by updating the *printf()
>> calls and using pointer arthimetic to compute lengths instead of
>> strlen().
>>
>> Signed-off-by: Nicholas Vinson <nvinson234@gmail.com>
>> ---
>>   grub-core/osdep/linux/ofpath.c | 25 ++++++++++++-------------
>>   1 file changed, 12 insertions(+), 13 deletions(-)
>>
>> diff --git a/grub-core/osdep/linux/ofpath.c b/grub-core/osdep/linux/ofpath.c
>> index 24a4d5c8d..8dd311651 100644
>> --- a/grub-core/osdep/linux/ofpath.c
>> +++ b/grub-core/osdep/linux/ofpath.c
>> @@ -488,8 +488,11 @@ check_hba_identifiers (const char *sysfs_path, int *vendor, int *device_id)
>>   static void
>>   check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
>>   {
>> -  char *ed = strstr (sysfs_path, "end_device");
>> -  char *p, *q, *path;
>> +  const char *ed = strstr (sysfs_path, "end_device");
>> +  int p_len;
>> +  int ed_len;
>> +  const char *q;
>> +  char *path;
>>     char phy[21];
>>     int fd;
>>     size_t path_size;
>> @@ -498,20 +501,16 @@ check_sas (const char *sysfs_path, int *tgt, unsigned long int *sas_address)
>>       return;
>>
>>     /* SAS devices are identified using disk@$PHY_ID */
>> -  p = xstrdup (sysfs_path);
>> -  ed = strstr(p, "end_device");
>> -  if (!ed)
>> -    return;
>> -
>>     q = ed;
> 
> You blindly assume the "ed" is not NULL here. It is not true after
> "if" removal above.

There is a "if (!ed)" check between the "size_t path_size;" and the SAS 
devices comment. The check is more than 3 lines away from either hunk so 
it doesn't appear in the diff.

> 
>>     while (*q && *q != '/')
>>       q++;
>> -  *q = '\0';
>> +  p_len = (int)(q - sysfs_path);
>> +  ed_len = (int)(q - ed);
> 
> Missing spaces after (int)...

fixed.

> 
>> -  path_size = (strlen (p) + strlen (ed)
>> -	       + sizeof ("%s/sas_device/%s/phy_identifier"));
>> +  path_size = (p_len + ed_len + sizeof ("/sas_device//phy_identifier"));
> 
> This sizof() change makes sens for me but it has to be reflected in the
> commit message.

I split this out into its own commit.

I'll send an updated patch series within the next day or two.

Thanks,
Nicholas Vinson

> 
> Daniel


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