fix(elan-utils/utils): go back to HTML parsing since lean-nightly doe…

…s not have a latest (stable) release...

CHANGELOG.md

@@ -1,3 +1,9 @@
+# Unreleased
+
+## Changed
+
+- Fix release lookup once more with feeling
+
 # 0.7.4 - 2019-03-20
 
 ## Changed

src/elan-utils/src/utils.rs

@@ -528,32 +528,33 @@ pub fn toolchain_sort<T: AsRef<str>>(v: &mut Vec<T>) {
     });
 }
 
-// fetch from HTTP redirect header instead of Github API to avoid rate limiting
+// fetch from HTML page instead of Github API to avoid rate limit
 pub fn fetch_latest_release_tag(repo_slug: &str) -> Result<String> {
     use regex::Regex;
 
     let latest_url = format!("https://github.com/{}/releases/latest", repo_slug);
-    let mut tag: Option<String> = None;
-    let re = Regex::new(r#"Location:.*/tag/(.+)"#).unwrap();
 
+    let mut data = Vec::new();
     ::download::curl::EASY.with(|handle| {
         let mut handle = handle.borrow_mut();
         handle.url(&latest_url).unwrap();
-        handle.follow_location(false).unwrap();
+        handle.follow_location(true).unwrap();
         {
             let mut transfer = handle.transfer();
-            transfer.header_function(|header| {
-                if tag.is_some() { return true }
-                if let Ok(header) = ::std::str::from_utf8(&header) {
-                    let capture = re.captures(&header);
-                    tag = capture.map(|cap| cap.get(1).unwrap().as_str().trim().to_string());
-                }
-                true
+            transfer.write_function(|new_data| {
+                data.extend_from_slice(new_data);
+                Ok(new_data.len())
             }).unwrap();
             transfer.perform().unwrap();
         }
     });
-    tag.ok_or("failed to parse latest release tag".into())
+    let redirect = ::std::str::from_utf8(&data).chain_err(|| "failed to decode release tag response")?;
+    let re = Regex::new(r#"/tag/([-a-z0-9.]+)"#).unwrap();
+    let capture = re.captures(&redirect);
+    match capture {
+        Some(cap) => Ok(cap.get(1).unwrap().as_str().to_string()),
+        None => Err("failed to parse latest release tag".into()),
+    }
 }
 
 #[cfg(test)]