Add binding for git_commit_body

This patch adds a binding for git_commit_body to retrieve the commit
message without the summary paragraph. Additionally, this patch updates
the test suite to test commits with a body paragraph.

While the commit body was previously available via Commit::message,
users would have to reimplement libgit2's behaviour to extract the
commit body from it.

libgit2-sys/lib.rs

@@ -2747,6 +2747,7 @@ extern "C" {
     pub fn git_commit_parentcount(commit: *const git_commit) -> c_uint;
     pub fn git_commit_raw_header(commit: *const git_commit) -> *const c_char;
     pub fn git_commit_summary(commit: *mut git_commit) -> *const c_char;
+    pub fn git_commit_body(commit: *mut git_commit) -> *const c_char;
     pub fn git_commit_time(commit: *const git_commit) -> git_time_t;
     pub fn git_commit_time_offset(commit: *const git_commit) -> c_int;
     pub fn git_commit_tree(tree_out: *mut *mut git_tree, commit: *const git_commit) -> c_int;

src/commit.rs

@@ -145,6 +145,29 @@ impl<'repo> Commit<'repo> {
         unsafe { crate::opt_bytes(self, raw::git_commit_summary(self.raw)) }
     }
 
+    /// Get the long "body" of the git commit message.
+    ///
+    /// The returned message is the body of the commit, comprising everything
+    /// but the first paragraph of the message. Leading and trailing whitespaces
+    /// are trimmed.
+    ///
+    /// `None` may be returned if an error occurs or if the summary is not valid
+    /// utf-8.
+    pub fn body(&self) -> Option<&str> {
+        self.body_bytes().and_then(|s| str::from_utf8(s).ok())
+    }
+
+    /// Get the long "body" of the git commit message.
+    ///
+    /// The returned message is the body of the commit, comprising everything
+    /// but the first paragraph of the message. Leading and trailing whitespaces
+    /// are trimmed.
+    ///
+    /// `None` may be returned if an error occurs.
+    pub fn body_bytes(&self) -> Option<&[u8]> {
+        unsafe { crate::opt_bytes(self, raw::git_commit_body(self.raw)) }
+    }
+
     /// Get the commit time (i.e. committer time) of a commit.
     ///
     /// The first element of the tuple is the time, in seconds, since the epoch.
@@ -399,12 +422,14 @@ mod tests {
         let head = repo.head().unwrap();
         let target = head.target().unwrap();
         let commit = repo.find_commit(target).unwrap();
-        assert_eq!(commit.message(), Some("initial"));
+        assert_eq!(commit.message(), Some("initial\n\nbody"));
+        assert_eq!(commit.body(), Some("body"));
         assert_eq!(commit.id(), target);
         commit.message_raw().unwrap();
         commit.raw_header().unwrap();
         commit.message_encoding();
         commit.summary().unwrap();
+        commit.body().unwrap();
         commit.tree_id();
         commit.tree().unwrap();
         assert_eq!(commit.parents().count(), 0);

src/remote.rs

@@ -956,7 +956,7 @@ mod tests {
         let repo = Repository::clone(&url, td3.path()).unwrap();
         let commit = repo.head().unwrap().target().unwrap();
         let commit = repo.find_commit(commit).unwrap();
-        assert_eq!(commit.message(), Some("initial"));
+        assert_eq!(commit.message(), Some("initial\n\nbody"));
     }
 
     #[test]

src/test.rs

@@ -31,7 +31,7 @@ pub fn repo_init() -> (TempDir, Repository) {
 
         let tree = repo.find_tree(id).unwrap();
         let sig = repo.signature().unwrap();
-        repo.commit(Some("HEAD"), &sig, &sig, "initial", &tree, &[])
+        repo.commit(Some("HEAD"), &sig, &sig, "initial\n\nbody", &tree, &[])
             .unwrap();
     }
     (td, repo)