libc/versionsort: support versionsort and strverscmp

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>

include/dirent.h

@@ -154,6 +154,8 @@ int        scandir(FAR const char *path, FAR struct dirent ***namelist,
                                       FAR const struct dirent **));
 int        alphasort(FAR const struct dirent **a,
                      FAR const struct dirent **b);
+int        versionsort(FAR const struct dirent **a,
+                       FAR const struct dirent **b);
 
 int        dirfd(FAR DIR *dirp);
 

include/string.h

@@ -91,6 +91,7 @@ FAR char  *strsignal(int signum);
 FAR char  *strtok(FAR char *, FAR const char *);
 FAR char  *strtok_r(FAR char *, FAR const char *, FAR char **);
 size_t     strxfrm(FAR char *, FAR const char *, size_t n);
+int        strverscmp(FAR const char *s1, FAR const char *s2);
 
 FAR void  *memchr(FAR const void *s, int c, size_t n);
 FAR void  *memrchr(FAR const void *s, int c, size_t n);

libs/libc/dirent/Make.defs

@@ -23,7 +23,7 @@
 CSRCS += lib_readdirr.c lib_telldir.c lib_alphasort.c lib_scandir.c
 CSRCS += lib_ftw.c lib_nftw.c
 CSRCS += lib_opendir.c lib_fdopendir.c lib_closedir.c lib_readdir.c
-CSRCS += lib_rewinddir.c lib_seekdir.c lib_dirfd.c
+CSRCS += lib_rewinddir.c lib_seekdir.c lib_dirfd.c lib_versionsort.c
 
 # Add the dirent directory to the build
 

libs/libc/dirent/lib_versionsort.c

@@ -0,0 +1,54 @@
+/****************************************************************************
+ * libs/libc/dirent/lib_versionsort.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <string.h>
+#include <dirent.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: versionsort
+ *
+ * Description:
+ *   The versionsort() function can be used as the comparison function
+ *   compar() for scandir().  It sorts directory entries using strverscmp
+ *   on the strings (*a)->d_name and (*b)->d_name.
+ *
+ * Input Parameters:
+ *   a - The first direntry to compare
+ *   b - The second direntry to compare
+ *
+ * Returned Value:
+ *   An integer less than, equal to, or greater than zero if the first
+ *   argument is considered to be respectively less than, equal to, or
+ *   greater than the second.
+ *
+ ****************************************************************************/
+
+int versionsort(FAR const struct dirent **a, FAR const struct dirent **b)
+{
+  return strverscmp((*a)->d_name, (*b)->d_name);
+}

libs/libc/string/Make.defs

@@ -29,7 +29,7 @@ CSRCS += lib_strerror.c lib_strncasecmp.c lib_strncat.c lib_strncmp.c
 CSRCS += lib_strndup.c lib_strcasestr.c lib_strpbrk.c lib_strrchr.c
 CSRCS += lib_strspn.c lib_strstr.c lib_strtok.c lib_strtokr.c
 CSRCS += lib_strsep.c lib_strerrorr.c lib_explicit_bzero.c lib_strsignal.c
-CSRCS += lib_index.c lib_rindex.c lib_timingsafe_bcmp.c
+CSRCS += lib_index.c lib_rindex.c lib_timingsafe_bcmp.c lib_strverscmp.c
 
 ifneq ($(CONFIG_LIBC_ARCH_MEMCHR),y)
 CSRCS += lib_memchr.c

libs/libc/string/lib_strverscmp.c

@@ -0,0 +1,129 @@
+/****************************************************************************
+ * libs/libc/string/lib_strverscmp.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <ctype.h>
+#include <string.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: strverscmp
+ *
+ * Description:
+ *   Often one has files jan1, jan2, ..., jan9, jan10, ... and it feels
+ *   wrong when ls orders them jan1, jan10, ..., jan2, ..., jan9. In
+ *   order to rectify this, GNU introduced the -v option to ls, which is
+ *   implemented using versionsort, which again uses strverscmp().
+ *
+ *   Thus, the task of strverscmp() is to compare two strings and find the
+ *   "right" order, while strcmp finds only the lexicographic order. This
+ *   function does not use the locale category LC_COLLATE, so is meant
+ *   mostly for situations where the strings are expected to be in ASCII.
+ *
+ *   What this function does is the following. If both strings are
+ *   equal, return 0. Otherwise, find the position between two bytes with
+ *   the property that before it both strings are equal, while directly
+ *   after it there is a difference. Find the largest consecutive digit
+ *   strings containing (or starting at, or ending at) this position.
+ *   If one or both of these is empty, then return what strcmp would have
+ *   returned (numerical ordering of byte values). Otherwise, compare both
+ *   digit strings numerically, where digit strings with one or more
+ *   leading zeros are interpreted as if they have a decimal point
+ *   in front (so that in particular digit strings with more leading zeros
+ *   come before digit strings with fewer leading zeros). Thus, the
+ *   ordering is 000, 00, 01, 010, 09, 0, 1, 9, 10.
+ *
+ * Returned Value:
+ *   The strverscmp() function returns an integer less than, equal to, or
+ *   greater than zero if s1 is found, respectively, to be earlier than,
+ *   equal to, or later than s2.
+ *
+ ****************************************************************************/
+
+int strverscmp(FAR const char *s1, FAR const char *s2)
+{
+  FAR const unsigned char *str1 = (FAR const void *)s1;
+  FAR const unsigned char *str2 = (FAR const void *)s2;
+  size_t i;
+  size_t j;
+  size_t dp;
+  int z = 1;
+
+  /* Find maximal matching prefix and track its maximal digit
+   * suffix and whether those digits are all zeros.
+   */
+
+  for (dp = i = 0; str1[i] == str2[i]; i++)
+    {
+      int c = str1[i];
+
+      if (c == 0)
+        {
+          return 0;
+        }
+
+      if (!isdigit(c))
+        {
+          dp = i + 1;
+          z = 1;
+        }
+      else if (c != '0')
+        {
+          z = 0;
+        }
+    }
+
+  if (str1[dp] != '0' && str2[dp] != '0')
+    {
+      /* If we're not looking at a digit sequence that began
+       * with a zero, longest digit string is greater.
+       */
+
+      for (j = i; isdigit(str1[j]); j++)
+        {
+          if (!isdigit(str2[j]))
+            {
+              return 1;
+            }
+        }
+
+      if (isdigit(str2[j]))
+        {
+          return -1;
+        }
+    }
+  else if (z && dp < i && (isdigit(str1[i]) || isdigit(str2[i])))
+    {
+      /* Otherwise, if common prefix of digit sequence is
+       * all zeros, digits order less than non-digits.
+       */
+
+      return (unsigned char)(str1[i] - '0') -
+             (unsigned char)(str2[i] - '0');
+    }
+
+  return str1[i] - str2[i];
+}