Expose git_merge_file function from libgit2 to repo.rs of git2-rs

.gitignore

@@ -1,3 +1,7 @@
 target
 Cargo.lock
 src/main.rs
+
+.vscode/
+.history/
+.idea/

libgit2-sys/lib.rs

@@ -8,6 +8,7 @@ use libc::{c_char, c_int, c_uchar, c_uint, c_void, size_t};
 #[cfg(feature = "ssh")]
 use libssh2_sys as libssh2;
 use std::ffi::CStr;
+use std::os::raw::c_ushort;
 
 pub const GIT_OID_RAWSZ: usize = 20;
 pub const GIT_OID_HEXSZ: usize = GIT_OID_RAWSZ * 2;
@@ -1305,6 +1306,65 @@ git_enum! {
     }
 }
 
+#[repr(C)]
+pub struct git_merge_file_options {
+    pub version: c_uint,
+
+    /// Label for the ancestor file side of the conflict which will be prepended
+    /// to labels in diff3-format merge files.
+    pub ancestor_label: *const c_char,
+
+    /// Label for our file side of the conflict which will be prepended
+    /// to labels in merge files.
+    pub our_label: *const c_char,
+
+    /// Label for their file side of the conflict which will be prepended
+    /// to labels in merge files.
+    pub their_label: *const c_char,
+
+    /// The file to favor in region conflicts.
+    pub favor: git_merge_file_favor_t,
+
+    /// see `git_merge_file_flag_t`
+    pub flags: c_uint,
+    pub marker_size: c_ushort,
+}
+
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub struct git_merge_file_input {
+    pub version: c_uint,
+    /// Pointer to the contents of the file.
+    pub ptr: *const c_char,
+    /// Size of the contents pointed to in `ptr`.
+    pub size: size_t,
+    /// File name of the conflicted file, or `NULL` to not merge the path.
+    pub path: *const c_char,
+    /// File mode of the conflicted file, or `0` to not merge the mode.
+    pub mode: c_uint,
+}
+
+#[repr(C)]
+#[derive(Copy, Clone)]
+pub struct git_merge_file_result {
+    /// True if the output was automerged, false if the output contains
+    /// conflict markers.
+    pub automergeable: c_uint,
+
+    /// The path that the resultant merge file should use, or NULL if a
+    /// filename conflict would occur.
+    pub path: *const c_char,
+
+    /// The mode that the resultant merge file should use.
+    pub mode: c_uint,
+
+    /// The contents of the merge.
+    pub ptr: *const c_char,
+
+    /// The length of the merge contents.
+    pub len: size_t,
+}
+
 pub type git_transport_cb = Option<
     extern "C" fn(
         out: *mut *mut git_transport,
@@ -3072,7 +3132,6 @@ extern "C" {
     pub fn git_repository_state_cleanup(repo: *mut git_repository) -> c_int;
 
     // merge analysis
-
     pub fn git_merge_analysis(
         analysis_out: *mut git_merge_analysis_t,
         pref_out: *mut git_merge_preference_t,
@@ -3081,6 +3140,22 @@ extern "C" {
         their_heads_len: usize,
     ) -> c_int;
 
+    // For git_merge_file
+    pub fn git_merge_file_options_init(opts: *mut git_merge_file_options, version: c_uint)
+        -> c_int;
+    pub fn git_merge_file_input_init(opts: *mut git_merge_file_input, version: c_uint) -> c_int;
+
+    pub fn git_merge_file(
+        out: *mut git_merge_file_result,
+        ancestor: *const git_merge_file_input,
+        ours: *const git_merge_file_input,
+        theirs: *const git_merge_file_input,
+        opts: *const git_merge_file_options,
+    ) -> c_int;
+
+    // Not used?
+    pub fn git_merge_file_result_free(result: *mut git_merge_file_result);
+
     // notes
     pub fn git_note_author(note: *const git_note) -> *const git_signature;
     pub fn git_note_committer(note: *const git_note) -> *const git_signature;

src/lib.rs

@@ -98,7 +98,9 @@ pub use crate::index::{
 };
 pub use crate::indexer::{IndexerProgress, Progress};
 pub use crate::mempack::Mempack;
-pub use crate::merge::{AnnotatedCommit, MergeOptions};
+pub use crate::merge::{
+    AnnotatedCommit, MergeFileInput, MergeFileOptions, MergeFileResult, MergeOptions,
+};
 pub use crate::message::{message_prettify, DEFAULT_COMMENT_CHAR};
 pub use crate::note::{Note, Notes};
 pub use crate::object::Object;
@@ -1049,6 +1051,20 @@ pub enum FileMode {
     Commit,
 }
 
+impl FileMode {
+    fn from(mode: u32) -> Self {
+        match mode {
+            raw::GIT_FILEMODE_UNREADABLE => FileMode::Unreadable,
+            raw::GIT_FILEMODE_TREE => FileMode::Tree,
+            raw::GIT_FILEMODE_BLOB => FileMode::Blob,
+            raw::GIT_FILEMODE_BLOB_EXECUTABLE => FileMode::BlobExecutable,
+            raw::GIT_FILEMODE_LINK => FileMode::Link,
+            raw::GIT_FILEMODE_COMMIT => FileMode::Commit,
+            mode => panic!("unknown file mode: {}", mode),
+        }
+    }
+}
+
 bitflags! {
     /// Return codes for submodule status.
     ///