namedos fix for ~1 sequenced

src/namedos.c

@@ -150,6 +150,16 @@ static void dos83_build_alias_candidate(const uint8 *src, int seq,
     snprintf((char *)out, out_size, "%s%s", stem, seqbuf);
 }
 
+static int dos83_candidate_sequence(const uint8 *candidate)
+{
+  const char *tilde = strchr((const char *)candidate, '~');
+
+  if (!tilde)
+    return 0;
+
+  return atoi(tilde + 1);
+}
+
 static int dos83_alias_used_in_dir(const char *dir_unix,
                                    const uint8 *src,
                                    const uint8 *candidate,
@@ -157,6 +167,7 @@ static int dos83_alias_used_in_dir(const char *dir_unix,
 {
   DIR *d;
   struct dirent *dirbuff;
+  int candidate_seq = dos83_candidate_sequence(candidate);
 
   d = opendir(dir_unix);
   if (!d) {
@@ -167,6 +178,13 @@ static int dos83_alias_used_in_dir(const char *dir_unix,
   if (!d)
     return 0;
 
+  XDPRINTF((2,0,
+    "DOS83 COLLISION CHECK dir='%s' src='%s' candidate='%s' seq=%d",
+    dir_unix ? dir_unix : "(null)",
+    src ? (char *)src : "(null)",
+    candidate ? (char *)candidate : "(null)",
+    candidate_seq));
+
   while ((dirbuff = readdir(d)) != NULL) {
     uint8 other[DOS83_NAME_MAX + 1];
 
@@ -181,20 +199,23 @@ static int dos83_alias_used_in_dir(const char *dir_unix,
       strncpy((char *)other, dirbuff->d_name, sizeof(other) - 1);
       other[sizeof(other) - 1] = '\0';
       up_fn(other);
-
-      if (!strcmp((char *)other, (const char *)candidate)) {
-        closedir(d);
-        return 1;
-      }
+    } else if (candidate_seq > 0) {
+      /*
+       * When the current candidate is a numbered alias, compare other long
+       * filenames against the same numbered candidate. This avoids treating
+       * every later long filename as if only ~1 mattered.
+       */
+      dos83_build_alias_candidate((uint8 *)dirbuff->d_name,
+                                  candidate_seq,
+                                  other,
+                                  sizeof(other));
     } else {
       char base[260], ext[260];
       char nbase[9], next[4];
 
       /*
-       * First test the same unnumbered short alias that dos83_build_name_in_dir()
-       * tries before falling back to ~n aliases. This prevents two different long
-       * filenames like "long_file_name.txt" and "long_file_name_too.txt" from
-       * both receiving "LONG_FIL.TXT".
+       * For the first unnumbered probe, compare other long filenames against
+       * the same unnumbered short alias.
        */
       dos83_split_name((uint8 *)dirbuff->d_name, base, sizeof(base), ext, sizeof(ext));
       dos83_normalize_part(base, nbase, sizeof(nbase), 8);
@@ -205,23 +226,25 @@ static int dos83_alias_used_in_dir(const char *dir_unix,
           snprintf((char *)other, sizeof(other), "%s.%s", nbase, next);
         else
           snprintf((char *)other, sizeof(other), "%s", nbase);
-
-        if (!strcmp((char *)other, (const char *)candidate)) {
-          closedir(d);
-          return 1;
-        }
+      } else {
+        other[0] = '\0';
       }
+    }
 
-      /*
-       * Also test the first numbered alias candidate. This keeps the old behavior
-       * for collision checks once numbering starts.
-       */
-      dos83_build_alias_candidate((uint8 *)dirbuff->d_name, 1, other, sizeof(other));
+    XDPRINTF((2,0,
+      "DOS83 COLLISION OTHER raw='%s' alias='%s' candidate='%s'",
+      dirbuff->d_name,
+      other,
+      candidate));
 
-      if (!strcmp((char *)other, (const char *)candidate)) {
-        closedir(d);
-        return 1;
-      }
+    if (!strcmp((char *)other, (const char *)candidate)) {
+      XDPRINTF((2,0,
+        "DOS83 COLLISION HIT raw='%s' alias='%s' candidate='%s'",
+        dirbuff->d_name,
+        other,
+        candidate));
+      closedir(d);
+      return 1;
     }
   }