From ac91a79b121297454e9b1d4496cf1fc44de1a1ba Mon Sep 17 00:00:00 2001
From: Maxime Coste <mawww@kakoune.org>
Date: Sun, 18 Mar 2018 23:23:00 +1100
Subject: [PATCH] Fix implementation of real_path to handle non-existing
 directories in /

Fixes #1937
---
 src/file.cc                                            | 10 +++++-----
 .../1937-opening-missing-file-by-full-path-fails/cmd   |  1 +
 .../1937-opening-missing-file-by-full-path-fails/in    |  1 +
 .../1937-opening-missing-file-by-full-path-fails/out   |  1 +
 .../1937-opening-missing-file-by-full-path-fails/rc    |  4 ++++
 5 files changed, 12 insertions(+), 5 deletions(-)
 create mode 100644 test/regression/1937-opening-missing-file-by-full-path-fails/cmd
 create mode 100644 test/regression/1937-opening-missing-file-by-full-path-fails/in
 create mode 100644 test/regression/1937-opening-missing-file-by-full-path-fails/out
 create mode 100644 test/regression/1937-opening-missing-file-by-full-path-fails/rc

diff --git a/src/file.cc b/src/file.cc
index 3dee5db57..f4e92e19f 100644
--- a/src/file.cc
+++ b/src/file.cc
@@ -67,6 +67,7 @@ std::pair<StringView, StringView> split_path(StringView path)
 
 String real_path(StringView filename)
 {
+    kak_assert(not filename.empty());
     char buffer[PATH_MAX+1];
 
     StringView existing = filename;
@@ -74,22 +75,21 @@ String real_path(StringView filename)
 
     while (true)
     {
-        char* res = realpath(existing.zstr(), buffer);
-        if (res)
+        if (char* res = realpath(existing.zstr(), buffer))
         {
             if (non_existing.empty())
                 return res;
-            return format("{}/{}", res, non_existing);
+            return format("{}{}", res, non_existing);
         }
 
-        auto it = find(existing.rbegin(), existing.rend(), '/');
+        auto it = find(existing.rbegin() + 1, existing.rend(), '/');
         if (it == existing.rend())
         {
             char cwd[1024];
             return format("{}/{}", getcwd(cwd, 1024), filename);
         }
 
-        existing = StringView{existing.begin(), it.base()-1};
+        existing = StringView{existing.begin(), it.base()};
         non_existing = StringView{it.base(), filename.end()};
     }
 }
diff --git a/test/regression/1937-opening-missing-file-by-full-path-fails/cmd b/test/regression/1937-opening-missing-file-by-full-path-fails/cmd
new file mode 100644
index 000000000..c22f6feea
--- /dev/null
+++ b/test/regression/1937-opening-missing-file-by-full-path-fails/cmd
@@ -0,0 +1 @@
+"aP
diff --git a/test/regression/1937-opening-missing-file-by-full-path-fails/in b/test/regression/1937-opening-missing-file-by-full-path-fails/in
new file mode 100644
index 000000000..8b1378917
--- /dev/null
+++ b/test/regression/1937-opening-missing-file-by-full-path-fails/in
@@ -0,0 +1 @@
+
diff --git a/test/regression/1937-opening-missing-file-by-full-path-fails/out b/test/regression/1937-opening-missing-file-by-full-path-fails/out
new file mode 100644
index 000000000..321fce9c6
--- /dev/null
+++ b/test/regression/1937-opening-missing-file-by-full-path-fails/out
@@ -0,0 +1 @@
+/kakoune-inexisting-directory/missing-file
diff --git a/test/regression/1937-opening-missing-file-by-full-path-fails/rc b/test/regression/1937-opening-missing-file-by-full-path-fails/rc
new file mode 100644
index 000000000..05a21ce5f
--- /dev/null
+++ b/test/regression/1937-opening-missing-file-by-full-path-fails/rc
@@ -0,0 +1,4 @@
+eval -draft %{
+    edit /kakoune-inexisting-directory/missing-file
+    reg a %val{buffile}
+}