fix #8255 numerous issues with splitFile

2 files changed, 28 insertions, 4 deletions

diff --git a/lib/pure/os.nim b/lib/pure/os.nim
index 68c1e28a2..46e4e7b69 100644
--- a/lib/pure/os.nim
+++ b/lib/pure/os.nim
@@ -349,19 +349,28 @@ proc splitFile*(path: string): tuple[dir, name, ext: string] {.
   ## If `path` has no extension, `ext` is the empty string.
   ## If `path` has no directory component, `dir` is the empty string.
   ## If `path` has no filename component, `name` and `ext` are empty strings.
-  if path.len == 0 or path[path.len-1] in {DirSep, AltSep}:
-    result = (path, "", "")
+  if path.len == 0 or path[^1] in {DirSep, AltSep}:
+    if path.len == 1:
+      # issue #8255
+      result = (path[0 .. ^1], "", "")
+    else:
+      result = (path[0 ..< ^1], "", "")
   else:
     var sepPos = -1
     var dotPos = path.len
     for i in countdown(len(path)-1, 0):
       if path[i] == ExtSep:
         if dotPos == path.len and i > 0 and
-            path[i-1] notin {DirSep, AltSep}: dotPos = i
+            path[i-1] notin {DirSep, AltSep, ExtSep}: dotPos = i
       elif path[i] in {DirSep, AltSep}:
         sepPos = i
         break
-    result.dir = substr(path, 0, sepPos-1)
+    if sepPos-1 >= 0:
+      result.dir = substr(path, 0, sepPos-1)
+    elif path[0] in {DirSep, AltSep}:
+      # issue #8255
+      result.dir = $path[0]
+
     result.name = substr(path, sepPos+1, dotPos-1)
     result.ext = substr(path, dotPos)
 
diff --git a/tests/stdlib/tos.nim b/tests/stdlib/tos.nim
index ed3737844..e49ab2506 100644
--- a/tests/stdlib/tos.nim
+++ b/tests/stdlib/tos.nim
@@ -239,3 +239,18 @@ block absolutePath:
     doAssert absolutePath("a", "/b/c") == "/b/c" / "a"
     doAssert absolutePath("/a", "b/") == "/a"
 
+block splitFile:
+  doAssert splitFile("abc/") == ("abc", "", "")
+  doAssert splitFile("/") == ("/", "", "")
+  doAssert splitFile("./abc") == (".", "abc", "")
+  doAssert splitFile(".txt") == ("", ".txt", "")
+  doAssert splitFile("abc/.txt") == ("abc", ".txt", "")
+  doAssert splitFile("abc") == ("", "abc", "")
+  doAssert splitFile("abc.txt") == ("", "abc", ".txt")
+  doAssert splitFile("/abc.txt") == ("/", "abc", ".txt")
+  doAssert splitFile("/foo/abc.txt") == ("/foo", "abc", ".txt")
+  doAssert splitFile("/foo/abc.txt.gz") == ("/foo", "abc.txt", ".gz")
+  doAssert splitFile(".") == ("", ".", "")
+  doAssert splitFile("abc/.") == ("abc", ".", "")
+  doAssert splitFile("..") == ("", "..", "")
+  doAssert splitFile("a/..") == ("a", "..", "")