From 91d29c36ee4641ff2f9fc6452900dad26ee8ffb2 Mon Sep 17 00:00:00 2001
From: Sebastian Thiel <sebastian.thiel@icloud.com>
Date: Thu, 1 Aug 2024 20:32:29 +0200
Subject: [PATCH] fix: prohibit full names with a trailing `.`.

Just like in Git, it's considered invalid.
---
 gix-validate/src/reference.rs       | 12 +++++-------
 gix-validate/src/tag.rs             |  6 ++++++
 gix-validate/tests/reference/mod.rs | 16 ++++++++++++++--
 gix-validate/tests/tag/mod.rs       |  2 +-
 4 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/gix-validate/src/reference.rs b/gix-validate/src/reference.rs
index ac222ed105c..15a596a8346 100644
--- a/gix-validate/src/reference.rs
+++ b/gix-validate/src/reference.rs
@@ -15,8 +15,8 @@ pub mod name {
         StartsWithSlash,
         #[error("Multiple slashes in a row are not allowed as they may change the reference's meaning")]
         RepeatedSlash,
-        #[error("Names must not be a single '.', but may contain it.")]
-        SingleDot,
+        #[error("Path components must not start with '.'")]
+        StartsWithDot,
     }
 
     impl From<Infallible> for Error {
@@ -28,8 +28,8 @@ pub mod name {
 
 use bstr::BStr;
 
-/// Validate a reference name running all the tests in the book. This disallows lower-case references, but allows
-/// ones like `HEAD`.
+/// Validate a reference name running all the tests in the book. This disallows lower-case references like `lower`, but also allows
+/// ones like `HEAD`, and `refs/lower`.
 pub fn name(path: &BStr) -> Result<&BStr, name::Error> {
     validate(path, Mode::Complete)
 }
@@ -51,19 +51,17 @@ fn validate(path: &BStr, mode: Mode) -> Result<&BStr, name::Error> {
         return Err(name::Error::StartsWithSlash);
     }
     let mut previous = 0;
-    let mut one_before_previous = 0;
     let mut saw_slash = false;
     for byte in path.iter() {
         match *byte {
-            b'/' if previous == b'.' && one_before_previous == b'/' => return Err(name::Error::SingleDot),
             b'/' if previous == b'/' => return Err(name::Error::RepeatedSlash),
+            b'.' if previous == b'/' => return Err(name::Error::StartsWithDot),
             _ => {}
         }
 
         if *byte == b'/' {
             saw_slash = true;
         }
-        one_before_previous = previous;
         previous = *byte;
     }
 
diff --git a/gix-validate/src/tag.rs b/gix-validate/src/tag.rs
index eb5b7e12066..78202e39a5f 100644
--- a/gix-validate/src/tag.rs
+++ b/gix-validate/src/tag.rs
@@ -21,6 +21,8 @@ pub mod name {
         Asterisk,
         #[error("A ref must not start with a '.'")]
         StartsWithDot,
+        #[error("A ref must not end with a '.'")]
+        EndsWithDot,
         #[error("A ref must not end with a '/'")]
         EndsWithSlash,
         #[error("A ref must not be empty")]
@@ -29,6 +31,7 @@ pub mod name {
 }
 
 /// Assure the given `input` resemble a valid git tag name, which is returned unchanged on success.
+/// Tag names are provided as names, lik` v1.0` or `alpha-1`, without paths.
 pub fn name(input: &BStr) -> Result<&BStr, name::Error> {
     if input.is_empty() {
         return Err(name::Error::Empty);
@@ -55,6 +58,9 @@ pub fn name(input: &BStr) -> Result<&BStr, name::Error> {
     if input[0] == b'.' {
         return Err(name::Error::StartsWithDot);
     }
+    if input[input.len() - 1] == b'.' {
+        return Err(name::Error::EndsWithDot);
+    }
     if input.ends_with(b".lock") {
         return Err(name::Error::LockFileSuffix);
     }
diff --git a/gix-validate/tests/reference/mod.rs b/gix-validate/tests/reference/mod.rs
index 9afbc1602f0..e6923617219 100644
--- a/gix-validate/tests/reference/mod.rs
+++ b/gix-validate/tests/reference/mod.rs
@@ -55,7 +55,7 @@ mod name_partial {
         mktest!(
             refs_path_component_is_singular_dot,
             b"refs/./still-inside-but-not-cool",
-            RefError::SingleDot
+            RefError::StartsWithDot
         );
         mktest!(any_path_starts_with_slash, b"/etc/foo", RefError::StartsWithSlash);
         mktest!(empty_path, b"", RefError::Tag(TagError::Empty));
@@ -107,6 +107,7 @@ mod name {
         mktest!(all_uppercase, b"MAIN");
         mktest!(all_uppercase_with_underscore, b"NEW_HEAD");
         mktest!(chinese_utf8, "refs/heads/你好吗".as_bytes());
+        mktest!(dot_in_directory_component, b"this./totally./works");
     }
 
     mod invalid {
@@ -136,10 +137,21 @@ mod name {
             b".refs/somewhere",
             RefError::Tag(TagError::StartsWithDot)
         );
+
+        mktest!(
+            refs_path_name_starts_with_dot_in_name,
+            b"refs/.somewhere",
+            RefError::StartsWithDot
+        );
+        mktest!(
+            refs_path_name_ends_with_dot_in_name,
+            b"refs/somewhere.",
+            RefError::Tag(TagError::EndsWithDot)
+        );
         mktest!(
             refs_path_component_is_singular_dot,
             b"refs/./still-inside-but-not-cool",
-            RefError::SingleDot
+            RefError::StartsWithDot
         );
         mktest!(capitalized_name_without_path, b"Main", RefError::SomeLowercase);
         mktest!(lowercase_name_without_path, b"main", RefError::SomeLowercase);
diff --git a/gix-validate/tests/tag/mod.rs b/gix-validate/tests/tag/mod.rs
index 95dc2be5063..96838071c3f 100644
--- a/gix-validate/tests/tag/mod.rs
+++ b/gix-validate/tests/tag/mod.rs
@@ -19,7 +19,6 @@ mod name {
         mktest!(contains_brackets, b"this_{is-fine}_too");
         mktest!(contains_brackets_and_at, b"this_{@is-fine@}_too");
         mktest!(dot_in_the_middle, b"token.other");
-        mktest!(dot_at_the_end, b"hello.");
         mktest!(slash_inbetween, b"hello/world");
     }
 
@@ -76,6 +75,7 @@ mod name {
         mktestb!(contains_newline, b"prefix\nsuffix");
         mktestb!(contains_carriage_return, b"prefix\rsuffix");
         mktest!(starts_with_dot, b".with-dot", StartsWithDot);
+        mktest!(ends_with_dot, b"with-dot.", EndsWithDot);
         mktest!(empty, b"", Empty);
     }
 }