lib/: Add ispfchar(), and use it instead of its pattern

[alejandro-colomar]

• Queued after Add C-locale variants of isascii(3) APIs, and use them #1471.

---

Revisions:

v2

• Move ispfchar() under lib/string/.
• Document it in lib/string/README.

$ git rd 
1:  247466ab6 ! 1:  85d3d8cb4 lib/ctype/: ispfchar(): Add function
    @@ Metadata
     Author: Alejandro Colomar <alx@kernel.org>
     
      ## Commit message ##
    -    lib/ctype/: ispfchar(): Add function
    +    lib/string/ctype/isascii/: ispfchar(): Add function
     
         This function returns true if the input character is a character from
         the POSIX portable filename character set.
    @@ Commit message
     
      ## lib/Makefile.am ##
     @@ lib/Makefile.am: libshadow_la_SOURCES = \
    -   console.c \
    -   copydir.c \
    -   csrand.c \
    -+  ctype/ispfchar.c \
    -+  ctype/ispfchar.h \
    -   defines.h \
    -   encrypt.c \
    -   env.c \
    +   spawn.c \
    +   sssd.c \
    +   sssd.h \
    ++  string/ctype/isascii/ispfchar.c \
    ++  string/ctype/isascii/ispfchar.h \
    +   string/ctype/strchrisascii/strchriscntrl.c \
    +   string/ctype/strchrisascii/strchriscntrl.h \
    +   string/ctype/strisascii/strisdigit.c \
     
    - ## lib/ctype/ispfchar.c (new) ##
    + ## lib/string/README ##
    +@@ lib/string/README: Specific guidelines:
    + 
    + ctype/ - Character classification and conversion functions
    + 
    ++    isascii/
    ++  The functions defined under this directory
    ++  return true
    ++  is the character
    ++  belongs to the category specified in the function name.
    ++
    +     strchrisascii/
    +   The functions defined under this directory
    +   return true
    +
    + ## lib/string/ctype/isascii/ispfchar.c (new) ##
     @@
    -+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
    ++// SPDX-FileCopyrightText: 2024-2025, Alejandro Colomar <alx@kernel.org>
     +// SPDX-License-Identifier: BSD-3-Clause
     +
     +
     +#include <config.h>
     +
    -+#include "ctype/ispfchar.h"
    ++#include "string/ctype/isascii/ispfchar.h"
     +
     +#include <stdbool.h>
     +
     +
     +extern inline bool ispfchar(unsigned char c);
     
    - ## lib/ctype/ispfchar.h (new) ##
    + ## lib/string/ctype/isascii/ispfchar.h (new) ##
     @@
    -+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
    ++// SPDX-FileCopyrightText: 2024-2025, Alejandro Colomar <alx@kernel.org>
     +// SPDX-License-Identifier: BSD-3-Clause
     +
     +
    -+#ifndef SHADOW_INCLUDE_LIB_CTYPE_ISPFCHAR_H_
    -+#define SHADOW_INCLUDE_LIB_CTYPE_ISPFCHAR_H_
    ++#ifndef SHADOW_INCLUDE_LIB_STRING_CTYPE_ISASCII_ISPFCHAR_H_
    ++#define SHADOW_INCLUDE_LIB_STRING_CTYPE_ISASCII_ISPFCHAR_H_
     +
     +
     +#include <config.h>
2:  219955397 = 2:  1b917a73d lib/chkname.c: is_valid_name(): Use isalnum(3) instead of its pattern
3:  92332a203 = 3:  e2d77042a lib/chkname.c: is_valid_name(): Split Samba check
4:  1ead5c62f ! 4:  8fd9e48f6 lib/chkname.c: is_valid_name(): Use ispfchar() to simplify
    @@ lib/chkname.c
      
      #include "defines.h"
      #include "chkname.h"
    -+#include "ctype/ispfchar.h"
    ++#include "string/ctype/isascii/ispfchar.h"
      #include "string/ctype/strchrisascii/strchriscntrl.h"
      #include "string/ctype/strisascii/strisdigit.h"
      #include "string/strcmp/streq.h"

v2b

• tfix

$ git rd 
1:  85d3d8cb4 ! 1:  d339ea77e lib/string/ctype/isascii/: ispfchar(): Add function
    @@ lib/string/README: Specific guidelines:
     +    isascii/
     +  The functions defined under this directory
     +  return true
    -+  is the character
    ++  if the character
     +  belongs to the category specified in the function name.
     +
          strchrisascii/
2:  1b917a73d = 2:  7f83c18fe lib/chkname.c: is_valid_name(): Use isalnum(3) instead of its pattern
3:  e2d77042a = 3:  4c7cee7bc lib/chkname.c: is_valid_name(): Split Samba check
4:  8fd9e48f6 = 4:  d39008cae lib/chkname.c: is_valid_name(): Use ispfchar() to simplify

v3

• Rebase after Add C-locale variants of isascii(3) APIs, and use them #1471.

$ git range-diff master..gh/chkname gh/isascii_c..chkname 
1:  d339ea77e < -:  --------- lib/string/ctype/isascii/: ispfchar(): Add function
-:  --------- > 1:  02df1aa64 lib/string/ctype/isascii.h: ispfchar_c(): Add function
2:  7f83c18fe = 2:  4259b5bba lib/chkname.c: is_valid_name(): Use isalnum(3) instead of its pattern
3:  4c7cee7bc = 3:  69076fb30 lib/chkname.c: is_valid_name(): Split Samba check
4:  d39008cae ! 4:  1cabaf3f8 lib/chkname.c: is_valid_name(): Use ispfchar() to simplify
    @@ Metadata
     Author: Alejandro Colomar <alx@kernel.org>
     
      ## Commit message ##
    -    lib/chkname.c: is_valid_name(): Use ispfchar() to simplify
    +    lib/chkname.c: is_valid_name(): Use ispfchar_c() to simplify
     
         In the first case, we can do the transformation because a few lines
         above, we explicitly reject a name starting with a '-'.
     
    -    In the second case, we're obviously using ispfchar() instead of its
    +    In the second case, we're obviously using ispfchar_c() instead of its
         pattern.
     
         Signed-off-by: Alejandro Colomar <alx@kernel.org>
    @@ lib/chkname.c
      
      #include "defines.h"
      #include "chkname.h"
    -+#include "string/ctype/isascii/ispfchar.h"
    - #include "string/ctype/strchrisascii/strchriscntrl.h"
    - #include "string/ctype/strisascii/strisdigit.h"
    ++#include "string/ctype/isascii.h"
    + #include "string/ctype/strchrisascii.h"
    + #include "string/ctype/strisascii.h"
      #include "string/strcmp/streq.h"
     @@ lib/chkname.c: is_valid_name(const char *name)
         * sake of Samba 3.x "add machine script"
    @@ lib/chkname.c: is_valid_name(const char *name)
     -        *name == '_' ||
     -        *name == '.'))
     -  {
    -+  if (!ispfchar(*name)) {
    ++  if (!ispfchar_c(*name)) {
                errno = EILSEQ;
                return false;
        }
    @@ lib/chkname.c: is_valid_name(const char *name)
     -                *name == '-'
     -               ))
     -          {
    -+          if (!ispfchar(*name)) {
    ++          if (!ispfchar_c(*name)) {
                        errno = EILSEQ;
                        return false;
                }

v3b

• Rebase

$ git range-diff 02df1aa649b7^..gh/chkname isascii_c..chkname 
1:  02df1aa64 = 1:  04d41a43c lib/string/ctype/isascii.h: ispfchar_c(): Add function
2:  4259b5bba = 2:  f15392da0 lib/chkname.c: is_valid_name(): Use isalnum(3) instead of its pattern
3:  69076fb30 = 3:  ecccb9861 lib/chkname.c: is_valid_name(): Split Samba check
4:  1cabaf3f8 = 4:  e371b465b lib/chkname.c: is_valid_name(): Use ispfchar_c() to simplify

v3c

• Fix typo.

$ git range-diff gh/isascii_c gh/chkname chkname 
1:  04d41a43c ! 1:  d9c21d8e5 lib/string/ctype/isascii.h: ispfchar_c(): Add function
    @@ lib/string/ctype/isascii.h
      #define CTYPE_PRINT_C   CTYPE_GRAPH_C " "
      #define CTYPE_XDIGIT_C  CTYPE_DIGIT_C "abcdefABCDEF"
      #define CTYPE_ASCII_C   CTYPE_PRINT_C CTYPE_CNTRL_C /*NUL*/
    -+#define CTYPE_PFCHAR_C  CTYPE_ALNUM "._-"  // portable filename character set
    ++#define CTYPE_PFCHAR_C  CTYPE_ALNUM_C "._-"  // portable filename character set
      
      
      // isascii_c - is [:ascii:] C-locale
2:  f15392da0 = 2:  44af79d71 lib/chkname.c: is_valid_name(): Use isalnum(3) instead of its pattern
3:  ecccb9861 = 3:  ea9364860 lib/chkname.c: is_valid_name(): Split Samba check
4:  e371b465b = 4:  000c8c170 lib/chkname.c: is_valid_name(): Use ispfchar_c() to simplify

Resolved.