add tag_foreach to repo (#594) (#595)

* add tag_foreach to repo (#594)

* switch to raw bytes for tag name

src/lib.rs

@@ -679,6 +679,7 @@ mod stash;
 mod status;
 mod submodule;
 mod tag;
+mod tagforeach;
 mod time;
 mod tree;
 mod treebuilder;

src/repo.rs

@@ -14,6 +14,7 @@ use crate::diff::{
 use crate::oid_array::OidArray;
 use crate::stash::{stash_cb, StashApplyOptions, StashCbData};
 use crate::string_array::StringArray;
+use crate::tagforeach::{tag_foreach_cb, TagForeachCB, TagForeachData};
 use crate::util::{self, path_to_repo_path, Binding};
 use crate::CherrypickOptions;
 use crate::RevertOptions;
@@ -1731,6 +1732,26 @@ impl Repository {
         }
     }
 
+    /// iterate over all tags calling `cb` on each.
+    /// the callback is provided the tag id and name
+    pub fn tag_foreach<T>(&self, cb: T) -> Result<(), Error>
+    where
+        T: FnMut(Oid, &[u8]) -> bool,
+    {
+        let mut data = TagForeachData {
+            cb: Box::new(cb) as TagForeachCB<'_>,
+        };
+
+        unsafe {
+            raw::git_tag_foreach(
+                self.raw,
+                Some(tag_foreach_cb),
+                (&mut data) as *mut _ as *mut _,
+            );
+        }
+        Ok(())
+    }
+
     /// Updates files in the index and the working tree to match the content of
     /// the commit pointed at by HEAD.
     pub fn checkout_head(&self, opts: Option<&mut CheckoutBuilder<'_>>) -> Result<(), Error> {

src/tagforeach.rs

@@ -0,0 +1,69 @@
+//! git_tag_foreach support
+//! see original: https://libgit2.org/libgit2/#HEAD/group/tag/git_tag_foreach
+
+use crate::{panic, raw, util::Binding, Oid};
+use libc::{c_char, c_int};
+use raw::git_oid;
+use std::ffi::{c_void, CStr};
+
+/// boxed callback type
+pub(crate) type TagForeachCB<'a> = Box<dyn FnMut(Oid, &[u8]) -> bool + 'a>;
+
+/// helper type to be able to pass callback to payload
+pub(crate) struct TagForeachData<'a> {
+    /// callback
+    pub(crate) cb: TagForeachCB<'a>,
+}
+
+/// c callback forwarding to rust callback inside `TagForeachData`
+/// see original: https://libgit2.org/libgit2/#HEAD/group/callback/git_tag_foreach_cb
+pub(crate) extern "C" fn tag_foreach_cb(
+    name: *const c_char,
+    oid: *mut git_oid,
+    payload: *mut c_void,
+) -> c_int {
+    panic::wrap(|| unsafe {
+        let id: Oid = Binding::from_raw(oid as *const _);
+
+        let name = CStr::from_ptr(name);
+        let name = name.to_bytes();
+
+        let payload = &mut *(payload as *mut TagForeachData<'_>);
+        let cb = &mut payload.cb;
+
+        let res = cb(id, name);
+
+        if res {
+            0
+        } else {
+            -1
+        }
+    })
+    .unwrap_or(-1)
+}
+
+#[cfg(test)]
+mod tests {
+
+    #[test]
+    fn smoke() {
+        let (_td, repo) = crate::test::repo_init();
+        let head = repo.head().unwrap();
+        let id = head.target().unwrap();
+        assert!(repo.find_tag(id).is_err());
+
+        let obj = repo.find_object(id, None).unwrap();
+        let sig = repo.signature().unwrap();
+        let tag_id = repo.tag("foo", &obj, &sig, "msg", false).unwrap();
+
+        let mut tags = Vec::new();
+        repo.tag_foreach(|id, name| {
+            tags.push((id, String::from_utf8(name.into()).unwrap()));
+            true
+        })
+        .unwrap();
+
+        assert_eq!(tags[0].0, tag_id);
+        assert_eq!(tags[0].1, "refs/tags/foo");
+    }
+}