vim-patch:8.2.3153: URLs with a dash in the scheme are not recognized

Problem:    URLs with a dash in the scheme are not recognized.
Solution:   Allow for a scheme with a dash, but not at the start or end.
            (Tsuyoshi CHO, closes vim/vim#8299)
https://github.com/vim/vim/commit/7b7a118e74d25ff35cd277c2bb5191ae44bb20b2

2 files changed, 52 insertions, 3 deletions

diff --git a/src/nvim/path.c b/src/nvim/path.c
index 674d67e21a..b12dd57938 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -1743,14 +1743,32 @@ int path_is_url(const char *p)
   return 0;
 }
 
-/// Check if "fname" starts with "name://".  Return URL_SLASH if it does.
+/// Check if "fname" starts with "name://" or "name:\\".
 ///
 /// @param  fname         is the filename to test
-/// @return URL_BACKSLASH for "name:\\", zero otherwise.
+/// @return URL_SLASH for "name://", URL_BACKSLASH for "name:\\", zero otherwise.
 int path_with_url(const char *fname)
 {
   const char *p;
-  for (p = fname; isalpha(*p); p++) {}
+
+  // We accept alphabetic characters and a dash in scheme part.
+  // RFC 3986 allows for more, but it increases the risk of matching
+  // non-URL text.
+
+  // first character must be alpha
+  if (!isalpha(*fname)) {
+    return 0;
+  }
+
+  // check body: alpha or dash
+  for (p = fname; (isalpha(*p) || (*p == '-')); p++) {}
+
+  // check last char is not a dash
+  if (p[-1] == '-') {
+    return 0;
+  }
+
+  // "://" or ":\\" must follow
   return path_is_url(p);
 }
 
diff --git a/src/nvim/testdir/test_buffer.vim b/src/nvim/testdir/test_buffer.vim
index 40111fdf06..a31cdbb49a 100644
--- a/src/nvim/testdir/test_buffer.vim
+++ b/src/nvim/testdir/test_buffer.vim
@@ -1,5 +1,7 @@
 " Tests for Vim buffer
 
+source check.vim
+
 func Test_buffer_error()
   new foo1
   new foo2
@@ -30,4 +32,33 @@ func Test_balt()
   call assert_equal('OtherBuffer', bufname())
 endfunc
 
+" Test for buffer match URL(scheme) check
+" scheme is alpha and inner hyphen only.
+func Test_buffer_scheme()
+  CheckMSWindows
+
+  set noshellslash
+  %bwipe!
+  let bufnames = [
+    \ #{id: 'b0', name: 'test://xyz/foo/b0'    , match: 1},
+    \ #{id: 'b1', name: 'test+abc://xyz/foo/b1', match: 0},
+    \ #{id: 'b2', name: 'test_abc://xyz/foo/b2', match: 0},
+    \ #{id: 'b3', name: 'test-abc://xyz/foo/b3', match: 1},
+    \ #{id: 'b4', name: '-test://xyz/foo/b4'   , match: 0},
+    \ #{id: 'b5', name: 'test-://xyz/foo/b5'   , match: 0},
+    \]
+  for buf in bufnames
+    new `=buf.name`
+    if buf.match
+      call assert_equal(buf.name,    getbufinfo(buf.id)[0].name)
+    else
+      " slashes will have become backslashes
+      call assert_notequal(buf.name, getbufinfo(buf.id)[0].name)
+    endif
+    bwipe
+  endfor
+
+  set shellslash&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab