ls_remote function

NAMESPACE

@@ -10,6 +10,7 @@ export(libgit2_features)
 export(libgit2_sha)
 export(libgit2_version)
 export(punch_card)
+export(remote_ls)
 exportClasses(cred_env)
 exportClasses(cred_ssh_key)
 exportClasses(cred_token)
@@ -96,6 +97,7 @@ exportMethods(push)
 exportMethods(references)
 exportMethods(reflog)
 exportMethods(remote_add)
+exportMethods(remote_ls)
 exportMethods(remote_remove)
 exportMethods(remote_rename)
 exportMethods(remote_set_url)

NEWS

@@ -3,6 +3,9 @@ git2r 0.11.0.9000
 
 NEW FEATURES
 
+* Add 'remote_ls' method to list references in a remote repository akin to the
+  `git ls-remote` command.
+
 * Add 'remote_set_url' method to set the remote's url in the
   configuration.
 

R/remote.r

@@ -350,3 +350,44 @@ setMethod("remote_url",
               .Call(git2r_remote_url, repo, remote)
           }
 )
+
+
+##' List references in a remote repository
+##'
+##' Displays references available in a remote repository along with the
+##' associated commit IDs.  Akin to the 'git ls-remote' command.
+##' @rdname remote_ls-methods
+##' @docType methods
+##' @param name Character vector with the "remote" repository URL to query or
+##' the name of the remote if a \code{repo} argument is given.
+##' @param repo an optional repository object used if remotes are specified by name.
+##' @param credentials The credentials for the remote repository.
+##' @keywords methods
+##' @return Character vector for each reference with the associated commit IDs.
+##' @examples
+##' \dontrun{
+##' remote_ls("https://github.com/ropensci/git2r")
+##' }
+##' @export
+setGeneric("remote_ls",
+           signature = c("name"),
+           function(name,
+                    repo = NULL,
+                    credentials = NULL)
+           standardGeneric("remote_ls"))
+
+##' @rdname remote_ls-methods
+##' @export
+setMethod("remote_ls",
+          signature(name = "character"),
+          function(name, repo, credentials)
+          {
+              if (is.null(repo)) {
+                  path <- tempdir()
+                  repo <- git2r::init(path)
+                  on.exit(unlink(file.path(path, ".git"), recursive = TRUE))
+              }
+
+              .Call(git2r_remote_ls, name, repo, credentials)
+          }
+)

man/remote_ls-methods.Rd

@@ -0,0 +1,34 @@
+% Generated by roxygen2 (4.1.1): do not edit by hand
+% Please edit documentation in R/remote.r
+\docType{methods}
+\name{remote_ls}
+\alias{remote_ls}
+\alias{remote_ls,character-method}
+\title{List references in a remote repository}
+\usage{
+remote_ls(name, repo = NULL, credentials = NULL)
+
+\S4method{remote_ls}{character}(name, repo = NULL, credentials = NULL)
+}
+\arguments{
+\item{name}{Character vector with the "remote" repository URL to query or
+the name of the remote if a \code{repo} argument is given.}
+
+\item{repo}{an optional repository object used if remotes are specified by name.}
+
+\item{credentials}{The credentials for the remote repository.}
+}
+\value{
+Character vector for each reference with the associated commit IDs.
+}
+\description{
+Displays references available in a remote repository along with the
+associated commit IDs.  Akin to the 'git ls-remote' command.
+}
+\examples{
+\dontrun{
+remote_ls("https://github.com/ropensci/git2r")
+}
+}
+\keyword{methods}
+

src/git2r.c

@@ -119,6 +119,7 @@ static const R_CallMethodDef callMethods[] =
     {"git2r_remote_rename", (DL_FUNC)&git2r_remote_rename, 3},
     {"git2r_remote_set_url", (DL_FUNC)&git2r_remote_set_url, 3},
     {"git2r_remote_url", (DL_FUNC)&git2r_remote_url, 2},
+    {"git2r_remote_ls", (DL_FUNC)&git2r_remote_ls, 3},
     {"git2r_repository_can_open", (DL_FUNC)&git2r_repository_can_open, 1},
     {"git2r_repository_discover", (DL_FUNC)&git2r_repository_discover, 1},
     {"git2r_repository_fetch_heads", (DL_FUNC)&git2r_repository_fetch_heads, 1},

src/git2r_remote.c

@@ -391,3 +391,78 @@ SEXP git2r_remote_url(SEXP repo, SEXP remote)
 
     return url;
 }
+
+/**
+ * Get the remote's url
+ *
+ * Based on https://github.com/libgit2/libgit2/blob/babdc376c7/examples/network/ls-remote.c
+ * @param repo S4 class git_repository
+ * @param name Character vector with URL of remote.
+ * @return Character vector for each reference with the associated commit IDs.
+ */
+SEXP git2r_remote_ls(SEXP name, SEXP repo, SEXP credentials)
+{
+    const char *name_ = CHAR(STRING_ELT(name, 0));
+    SEXP result = R_NilValue;
+    SEXP names = R_NilValue;
+    git_remote *remote = NULL;
+    int err;
+    const git_remote_head **refs;
+    size_t refs_len, i;
+    git_remote_callbacks callbacks = GIT_REMOTE_CALLBACKS_INIT;
+    git2r_transfer_data payload = GIT2R_TRANSFER_DATA_INIT;
+    git_repository *repository = NULL;
+
+    if (git2r_arg_check_string(name))
+        git2r_error(__func__, NULL, "'name'", git2r_err_string_arg);
+
+    if (git2r_arg_check_credentials(credentials))
+        git2r_error(__func__, NULL, "'credentials'", git2r_err_credentials_arg);
+
+    repository = git2r_repository_open(repo);
+
+    if (!repository)
+        git2r_error(__func__, NULL, git2r_err_invalid_repository, NULL);
+
+    err = git_remote_lookup(&remote, repository, name_);
+    if (err < 0) {
+        err = git_remote_create_anonymous(&remote, repository, name_);
+        if (err < 0) {
+            goto cleanup;
+        }
+    }
+
+    payload.credentials = credentials;
+    callbacks.payload = &payload;
+    callbacks.credentials = &git2r_cred_acquire_cb;
+
+    err = git_remote_connect(remote, GIT_DIRECTION_FETCH, &callbacks);
+    if (err < 0)
+        goto cleanup;
+
+    err = git_remote_ls(&refs, &refs_len, remote);
+    if (err < 0)
+        goto cleanup;
+
+    PROTECT(result = allocVector(STRSXP, refs_len));
+    setAttrib(result, R_NamesSymbol, names = allocVector(STRSXP, refs_len));
+
+    for (i = 0; i < refs_len; i++) {
+        char oid[GIT_OID_HEXSZ + 1] = {0};
+        git_oid_fmt(oid, &refs[i]->oid);
+        SET_STRING_ELT(result, i, mkChar(oid));
+        SET_STRING_ELT(names, i, mkChar(refs[i]->name));
+    }
+
+cleanup:
+    if (repository)
+        git_repository_free(repository);
+
+    if (result != R_NilValue)
+        UNPROTECT(1);
+
+    if (err)
+        git2r_error(__func__, giterr_last(), NULL, NULL);
+
+    return(result);
+}

src/git2r_remote.h

@@ -33,5 +33,6 @@ SEXP git2r_remote_remove(SEXP repo, SEXP remote);
 SEXP git2r_remote_rename(SEXP repo, SEXP oldname, SEXP newname);
 SEXP git2r_remote_set_url(SEXP repo, SEXP name, SEXP url);
 SEXP git2r_remote_url(SEXP repo, SEXP remote);
+SEXP git2r_remote_ls(SEXP name, SEXP repo, SEXP credentials);
 
 #endif

tests/remotes.R

@@ -56,5 +56,13 @@ remote_remove(repo, "foobar")
 
 stopifnot(identical(remotes(repo), character(0)))
 
+refs <- remote_ls("https://github.com/ropensci/git2r")
+stopifnot(length(refs) > 0)
+stopifnot(names(refs) > 0)
+stopifnot(any(names(refs) == "HEAD"))
+
+# an invalid URL should throw an error
+tools::assertError(remote_ls("bad"))
+
 ## Cleanup
 unlink(path, recursive=TRUE)