[newlib-cygwin/main] Cygwin: mbsnrtowci: like mbsnrtowcs, just for wint_t

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=149cabea8220c7baf1185ccfaea03922bbfd390a

commit 149cabea8220c7baf1185ccfaea03922bbfd390a
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Wed Mar 1 10:44:52 2023 +0100
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Wed Mar 1 10:54:52 2023 +0100

    Cygwin: mbsnrtowci: like mbsnrtowcs, just for wint_t
    
    Deviation from standard: If the input is broken, the output will be
    broken.  I. e., we just copy the current byte over into the wint_t
    destination and try to pick up on the next byte.  This is in line
    with the way fnmatch works.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/local_includes/wchar.h |  8 ++++++
 winsup/cygwin/strfuncs.cc            | 53 ++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)

diff --git a/winsup/cygwin/local_includes/wchar.h b/winsup/cygwin/local_includes/wchar.h
index d1b63859177e..ecf489cd588d 100644
--- a/winsup/cygwin/local_includes/wchar.h
+++ b/winsup/cygwin/local_includes/wchar.h
@@ -52,6 +52,14 @@ size_t wirtomb (char *, wint_t, mbstate_t *);
    a UTF-32 value. Defined in strfuncs.cc */
 extern size_t mbrtowi (wint_t *, const char *, size_t, mbstate_t *);
 
+/* replacement function for mbsnrtowcs, returning a wint_t representing
+   a UTF-32 value. Defined in strfuncs.cc.
+   Deviation from standard: If the input is broken, the output will be
+   broken.  I. e., we just copy the current byte over into the wint_t
+   destination and try to pick up on the next byte.  This is in line
+   with the way fnmatch works. */
+extern size_t mbsnrtowci(wint_t *, const char **, size_t, size_t, mbstate_t *);
+
 /* convert wint_t string to char string, but *only* if the string consists
    entirely of ASCII chars */
 static inline void
diff --git a/winsup/cygwin/strfuncs.cc b/winsup/cygwin/strfuncs.cc
index 80e3eb0ad6a8..9324e155319f 100644
--- a/winsup/cygwin/strfuncs.cc
+++ b/winsup/cygwin/strfuncs.cc
@@ -180,6 +180,59 @@ mbrtowi (wint_t *pwi, const char *s, size_t n, mbstate_t *ps)
   return len;
 }
 
+extern "C" size_t
+mbsnrtowci(wint_t *dst, const char **src, size_t nms, size_t len, mbstate_t *ps)
+{
+  wint_t *ptr = dst;
+  const char *tmp_src;
+  size_t max;
+  size_t count = 0;
+  size_t bytes;
+
+  if (dst == NULL)
+    {
+      /* Ignore original len value and do not alter src pointer if the
+         dst pointer is NULL.  */
+      len = (size_t)-1;
+      tmp_src = *src;
+      src = &tmp_src;
+    }
+  max = len;
+  while (len > 0)
+    {
+      bytes = mbrtowi (ptr, *src, MB_CUR_MAX, ps);
+      if (bytes > 0)
+        {
+          *src += bytes;
+          nms -= bytes;
+          ++count;
+          ptr = (dst == NULL) ? NULL : ptr + 1;
+          --len;
+        }
+      else if (bytes == 0)
+        {
+          *src = NULL;
+          return count;
+        }
+      else
+        {
+	  /* Deviation from standard: If the input is broken, the output
+	     will be broken.  I. e., we just copy the current byte over
+	     into the wint_t destination and try to pick up on the next
+	     byte.  This is in line with the way fnmatch works. */
+          ps->__count = 0;
+          if (dst)
+	    {
+	      *ptr++ = (const wint_t) *(*src)++;
+	      ++count;
+	      --nms;
+	      --len;
+	    }
+        }
+    }
+  return (size_t) max;
+}
+
 /* The SJIS, JIS and eucJP conversion in newlib does not use UTF as
    wchar_t character representation.  That's unfortunate for us since
    we require UTF for the OS.  What we do here is to have our own