Add debug logging for failed credential helpers

Author: alexcrichton

Cargo.toml

@@ -24,6 +24,7 @@ appveyor = { repository = "alexcrichton/git2-rs" }
 url = "1.0"
 bitflags = "1.0"
 libc = "0.2"
+log = "0.4"
 libgit2-sys = { path = "libgit2-sys", version = "0.7.0" }
 
 [target."cfg(all(unix, not(target_os = \"macos\")))".dependencies]

src/cred.rs

@@ -287,7 +287,13 @@ impl CredentialHelper {
     fn execute_cmd(&self, cmd: &str, username: &Option<String>)
                    -> (Option<String>, Option<String>) {
         macro_rules! my_try( ($e:expr) => (
-            match $e { Ok(e) => e, Err(..) => return (None, None) }
+            match $e {
+                Ok(e) => e,
+                Err(e) => {
+                    debug!("{} failed with {}", stringify!($e), e);
+                    return (None, None)
+                }
+            }
         ) );
 
         let mut p = my_try!(Command::new("sh").arg("-c")
@@ -311,7 +317,13 @@ impl CredentialHelper {
             }
         }
         let output = my_try!(p.wait_with_output());
-        if !output.status.success() { return (None, None) }
+        if !output.status.success() {
+            debug!("credential helper failed: {}\nstdout ---\n{}\nstdout ---\n{}",
+                   output.status,
+                   String::from_utf8_lossy(&output.stdout),
+                   String::from_utf8_lossy(&output.stderr));
+            return (None, None)
+        }
         self.parse_output(output.stdout)
     }
 

src/lib.rs

@@ -72,6 +72,7 @@ extern crate libc;
 extern crate url;
 extern crate libgit2_sys as raw;
 #[macro_use] extern crate bitflags;
+#[macro_use] extern crate log;
 #[cfg(test)] extern crate tempdir;
 
 use std::ffi::{CStr, CString};