Added strverscmp()

.gitignore

@@ -9,8 +9,14 @@
 /find
 /locate
 /ls
+/scandir
+/cat
 /t-compile
 /t-dirent
+/t-scandir
+/t-cplusplus
+/t-unicode
+/t-strverscmp
 /updatedb
 /*.filters
 /*.vcxproj

CMakeLists.txt

@@ -56,4 +56,5 @@ if(DIRENT_BUILD_TESTS)
     add_test_executable (t-scandir tests/t-scandir.c)
     add_test_executable (t-unicode tests/t-unicode.c)
     add_test_executable (t-cplusplus tests/t-cplusplus.cpp)
+    add_test_executable (t-strverscmp tests/t-strverscmp.c)
 endif(DIRENT_BUILD_TESTS)

include/dirent.h

@@ -313,6 +313,7 @@ static int alphasort (const struct dirent **a, const struct dirent **b);
 
 static int versionsort (const struct dirent **a, const struct dirent **b);
 
+static int strverscmp (const char *a, const char *b);
 
 /* For compatibility with Symbian */
 #define wdirent _wdirent
@@ -1033,8 +1034,71 @@ static int
 versionsort(
     const struct dirent **a, const struct dirent **b)
 {
-    /* FIXME: implement strverscmp and use that */
-    return alphasort (a, b);
+    return strverscmp ((*a)->d_name, (*b)->d_name);
+}
+
+/* Compare strings */
+static int
+strverscmp(
+    const char *a, const char *b)
+{
+    unsigned int i = 0;
+    unsigned int j;
+
+    /* Find first difference */
+    while (a[i] != '\0' && a[i] == b[i]) {
+        ++i;
+    }
+    if (a[i] == b[i]) {
+        /* No difference found */
+        return 0;
+    }
+
+    /* Count backwards and find the leftmost digit of the differing number */
+    j = i;
+    while (j > 0 && '0' <= a[j-1] && a[j-1] <= '9') {
+        --j;
+    }
+
+    /* Determine mode of comparison */
+    if (a[j] == '0' || b[j] == '0') {
+        /* Zero mode */
+        unsigned int k = j;
+
+        /* Find the next non-zero digit */
+        while (a[k] == '0' && a[k] == b[k]) {
+            k++;
+        }
+
+        /* String with greater number of digits is smaller, e.g 002 < 01 */
+        if (isdigit(a[k])) {
+            if (!isdigit(b[k])) {
+                return -1;
+            }
+        } else if (isdigit(b[k])) {
+            return 1;
+        }
+    } else if (isdigit(a[j]) && isdigit(b[j])) {
+        /* Numeric comparison */
+        unsigned int k = j;
+
+        /* Find the next non-digit */
+        while (isdigit(a[k]) && isdigit(b[k])) {
+            k++;
+        }
+
+        /* Number with greater number of digits is bigger */
+        if (isdigit(a[k])) {
+            if (!isdigit(b[k])) {
+                return 1;
+            }
+        } else if (isdigit(b[k])) {
+            return -1;
+        }
+    }
+
+    /* Alphabetical comparison */
+    return (int) ((unsigned char) a[i]) - ((unsigned char) b[i]);
 }
 
 /* Convert multi-byte string to wide character string */

tests/t-scandir.c

@@ -7,9 +7,12 @@
  * https://github.com/tronkko/dirent
  */
 
-/* Silence warning about fopen being insecure */
+/* Silence warning about fopen being insecure (MS Visual Studio) */
 #define _CRT_SECURE_NO_WARNINGS
 
+/* Include prototype for versionsort (Linux) */
+#define _GNU_SOURCE
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -76,7 +79,7 @@ main(
         assert (strcmp (files[7]->d_name, "dirent.dat") == 0);
         assert (strcmp (files[8]->d_name, "empty.dat") == 0);
         assert (strcmp (files[9]->d_name, "sane-1.12.0.dat") == 0);
-        assert (strcmp (files[10]->d_name, "sane-1.2.3.dat") == 0);
+        assert (strcmp (files[10]->d_name, "sane-1.2.30.dat") == 0);
         assert (strcmp (files[11]->d_name, "sane-1.2.4.dat") == 0);
         assert (strcmp (files[12]->d_name, "zebra.dat") == 0);
 
@@ -96,7 +99,7 @@ main(
         /* Make sure that we got all the FILE names in the REVERSE order */
         assert (strcmp (files[0]->d_name, "zebra.dat") == 0);
         assert (strcmp (files[1]->d_name, "sane-1.2.4.dat") == 0);
-        assert (strcmp (files[2]->d_name, "sane-1.2.3.dat") == 0);
+        assert (strcmp (files[2]->d_name, "sane-1.2.30.dat") == 0);
         assert (strcmp (files[3]->d_name, "sane-1.12.0.dat") == 0);
         assert (strcmp (files[4]->d_name, "empty.dat") == 0);
         assert (strcmp (files[5]->d_name, "dirent.dat") == 0);
@@ -131,6 +134,35 @@ main(
         assert (errno == ENOTDIR);
     }
 
+    /* Sort files using versionsort() */
+    {
+        files = NULL;
+        n = scandir ("tests/3", &files, no_directories, versionsort);
+        assert (n == 11);
+
+        /*
+         * Make sure that we got all the file names in the proper order:
+         * 1.2.4 < 1.2.30 < 1.12.0
+         */
+        assert (strcmp (files[0]->d_name, "3zero.dat") == 0);
+        assert (strcmp (files[1]->d_name, "666.dat") == 0);
+        assert (strcmp (files[2]->d_name, "Qwerty-my-aunt.dat") == 0);
+        assert (strcmp (files[3]->d_name, "README.txt") == 0);
+        assert (strcmp (files[4]->d_name, "aaa.dat") == 0);
+        assert (strcmp (files[5]->d_name, "dirent.dat") == 0);
+        assert (strcmp (files[6]->d_name, "empty.dat") == 0);
+        assert (strcmp (files[7]->d_name, "sane-1.2.4.dat") == 0);
+        assert (strcmp (files[8]->d_name, "sane-1.2.30.dat") == 0);
+        assert (strcmp (files[9]->d_name, "sane-1.12.0.dat") == 0);
+        assert (strcmp (files[10]->d_name, "zebra.dat") == 0);
+
+        /* Release file names */
+        for (i = 0; i < n; i++) {
+            free (files[i]);
+        }
+        free (files);
+    }
+
     /* Scan large directory */
     {
         char dirname[PATH_MAX+1];

tests/t-strverscmp.c

@@ -0,0 +1,186 @@
+/*
+ * Test program to make sure that strverscmp works correctly
+ *
+ * Copyright (C) 1998-2019 Toni Ronkko
+ * This file is part of dirent.  Dirent may be freely distributed
+ * under the MIT license.  For all details and documentation, see
+ * https://github.com/tronkko/dirent
+ */
+
+/* Include prototype for strverscmp */
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <dirent.h>
+#include <ctype.h>
+
+int
+main(
+    int argc, char *argv[])
+{
+    (void) argc;
+    (void) argv;
+
+    /* Strings without digits are compared as in strcmp() */
+    assert (strverscmp ("", "") == 0);
+    assert (strverscmp ("abc", "abc") == 0);
+    assert (strverscmp ("a", "b") < 0);
+    assert (strverscmp ("b", "a") > 0);
+
+    /* Shorter string is smaller, other things being equal */
+    assert (strverscmp ("a", "aa") < 0);
+    assert (strverscmp ("aa", "a") > 0);
+    assert (strverscmp ("abcdef", "abcdefg") < 0);
+    assert (strverscmp ("abcdefg", "abcdef") > 0);
+
+    /* Integers with equal length are compared as in strcmp() */
+    assert (strverscmp ("0", "0") == 0);
+    assert (strverscmp ("000", "000") == 0);
+    assert (strverscmp ("1", "2") < 0);
+    assert (strverscmp ("2", "1") > 0);
+    assert (strverscmp ("001", "100") < 0);
+    assert (strverscmp ("100", "001") > 0);
+    assert (strverscmp ("2020-07-01", "2020-07-02") < 0);
+    assert (strverscmp ("2020-07-02", "2020-07-01") > 0);
+    assert (strverscmp ("jan999", "jan999") == 0);
+
+    /* Integers of different length are compared as numbers */
+    assert (strverscmp ("jan9", "jan10") < 0);
+    assert (strverscmp ("jan10", "jan9") > 0);
+    assert (strverscmp ("999", "1000") < 0);
+    assert (strverscmp ("1000", "999") > 0);
+    assert (strverscmp ("t12-1000", "t12-9999") < 0);
+    assert (strverscmp ("t12-9999", "t12-1000") > 0);
+
+    /* If numbers starts with zero, then longer number is smaller */
+    assert (strverscmp ("00", "0") < 0);
+    assert (strverscmp ("0", "00") > 0);
+    assert (strverscmp ("a000", "a00") < 0);
+    assert (strverscmp ("a00", "a000") > 0);
+    assert (strverscmp ("0000", "000") < 0);
+    assert (strverscmp ("000", "0000") > 0);
+    assert (strverscmp ("1.01", "1.0") < 0);
+    assert (strverscmp ("1.0", "1.01") > 0);
+
+    /* Number having more leading zeros is considered smaller */
+    assert (strverscmp ("item-0001", "item-001") < 0);
+    assert (strverscmp ("item-001", "item-0001") > 0);
+    assert (strverscmp ("item-001", "item-01") < 0);
+    assert (strverscmp ("item-01", "item-001") > 0);
+    assert (strverscmp (".0001000", ".001") < 0);
+    assert (strverscmp (".001", ".0001000") > 0);
+    assert (strverscmp (".0001000", ".01") < 0);
+    assert (strverscmp (".01", ".0001000") > 0);
+    assert (strverscmp (".0001000", ".1") < 0);
+    assert (strverscmp (".1", ".0001000") > 0);
+    assert (strverscmp ("1.0002", "1.0010000") < 0);
+    assert (strverscmp ("1.0010000", "1.0002") > 0);
+
+    /* Number starting with zero is smaller than any number */
+    assert (strverscmp ("item-009", "item-1") < 0);
+    assert (strverscmp ("item-1", "item-009") > 0);
+    assert (strverscmp ("item-099", "item-2") < 0);
+    assert (strverscmp ("item-2", "item-099") > 0);
+
+    /* Number vs alphabetical comparison */
+    assert (strverscmp ("1.001", "1.00!") < 0);
+    assert (strverscmp ("1.00!", "1.001") > 0);
+    assert (strverscmp ("1.001", "1.00x") < 0);
+    assert (strverscmp ("1.00x", "1.001") > 0);
+    assert (strverscmp ("1", "x") < 0);
+    assert (strverscmp ("x", "1") > 0);
+    assert (strverscmp ("1", "!") > 0);
+    assert (strverscmp ("!", "1") < 0);
+
+    /* Handling the end of string */
+    assert (strverscmp ("01", "011") < 0);
+    assert (strverscmp ("011", "01") > 0);
+    assert (strverscmp ("0100", "01000") < 0);
+    assert (strverscmp ("01000", "0100") > 0);
+    assert (strverscmp ("1", "1!") < 0);
+    assert (strverscmp ("1!", "1") > 0);
+    assert (strverscmp ("1", "1z") < 0);
+    assert (strverscmp ("1z", "1") > 0);
+
+    /* Ordering 000 < 00 < 01 < 010 < 09 < 0 < 1 < 9 < 10 */
+    assert (strverscmp ("000", "00") < 0);
+    assert (strverscmp ("000", "01") < 0);
+    assert (strverscmp ("000", "010") < 0);
+    assert (strverscmp ("000", "09") < 0);
+    assert (strverscmp ("000", "0") < 0);
+    assert (strverscmp ("000", "1") < 0);
+    assert (strverscmp ("000", "9") < 0);
+    assert (strverscmp ("000", "10") < 0);
+
+    assert (strverscmp ("00", "01") < 0);
+    assert (strverscmp ("00", "010") < 0);
+    assert (strverscmp ("00", "09") < 0);
+    assert (strverscmp ("00", "0") < 0);
+    assert (strverscmp ("00", "1") < 0);
+    assert (strverscmp ("00", "9") < 0);
+    assert (strverscmp ("00", "10") < 0);
+
+    assert (strverscmp ("01", "010") < 0);
+    assert (strverscmp ("01", "09") < 0);
+    assert (strverscmp ("01", "0") < 0);
+    assert (strverscmp ("01", "1") < 0);
+    assert (strverscmp ("01", "9") < 0);
+    assert (strverscmp ("01", "10") < 0);
+
+    assert (strverscmp ("010", "09") < 0);
+    assert (strverscmp ("010", "0") < 0);
+    assert (strverscmp ("010", "1") < 0);
+    assert (strverscmp ("010", "9") < 0);
+    assert (strverscmp ("010", "10") < 0);
+
+    assert (strverscmp ("09", "0") < 0);
+    assert (strverscmp ("09", "1") < 0);
+    assert (strverscmp ("09", "9") < 0);
+    assert (strverscmp ("09", "10") < 0);
+
+    assert (strverscmp ("0", "1") < 0);
+    assert (strverscmp ("0", "9") < 0);
+    assert (strverscmp ("0", "10") < 0);
+
+    assert (strverscmp ("1", "9") < 0);
+    assert (strverscmp ("1", "10") < 0);
+
+    assert (strverscmp ("9", "10") < 0);
+
+    /* Compare speed */
+    {
+#define LENGTH 100
+#define REPEAT 1000000
+        char a[LENGTH+1];
+        char b[LENGTH+1];
+        unsigned int i;
+        unsigned int j;
+        char letters[] = "01234567890123456789abdefghjkpqrtwxyz-/.";
+        unsigned int n = strlen(letters);
+
+        /* Repeat test */
+        for (i = 0; i < REPEAT; i++) {
+            /*
+             * Generate random string of LENGTH characters.  Be ware that
+             * the string has to be created inside the loop or otherwise the
+             * compiler can reduce the loop into single call!
+             */
+            for (j = 0; j < LENGTH; j++) {
+                char c = letters[rand() % n];
+                a[j] = c;
+                b[j] = c;
+            }
+            a[j] = '\0';
+            b[j] = '\0';
+
+            /* Both strings must be equal */
+            assert (strverscmp (a, b) == 0);
+        }
+    }
+
+    printf ("OK\n");
+    return EXIT_SUCCESS;
+}