thodg/libgit2

diff --git a/src/cache.c b/src/cache.c
index fd42e2c..b0a0931 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -32,7 +32,7 @@
 #define GIT_CACHE_OPENADR 3
 
 
-void git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_ptr)
+int git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_ptr)
 {
 	size_t i;
 
@@ -52,6 +52,8 @@ void git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_p
 	cache->free_obj = free_ptr;
 
 	cache->nodes = git__malloc((size + 1) * sizeof(cache_node));
+	if (cache->nodes == NULL)
+		return GIT_ENOMEM;
 
 	for (i = 0; i < (size + 1); ++i) {
 		git_mutex_init(&cache->nodes[i].lock);
diff --git a/src/cache.h b/src/cache.h
index 975aaff..2d9bb51 100644
--- a/src/cache.h
+++ b/src/cache.h
@@ -31,7 +31,7 @@ typedef struct {
 } git_cache;
 
 
-void git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_ptr);
+int git_cache_init(git_cache *cache, size_t size, git_cached_obj_freeptr free_ptr);
 void git_cache_free(git_cache *cache);
 
 void *git_cache_try_store(git_cache *cache, void *entry);
diff --git a/src/fileops.c b/src/fileops.c
index 5dd4a38..45dd8f4 100644
--- a/src/fileops.c
+++ b/src/fileops.c
@@ -10,7 +10,7 @@ int gitfo_mkdir_2file(const char *file_path)
 
 	error = git__dirname_r(target_folder_path, sizeof(target_folder_path), file_path);
 	if (error < GIT_SUCCESS)
-		return error;
+		return git__throw(GIT_EINVALIDPATH, "Failed to recursively build `%s` tree structure. Unable to parse parent folder name", file_path);
 
 	/* Does the containing folder exist? */
 	if (gitfo_isdir(target_folder_path)) {
@@ -19,7 +19,7 @@ int gitfo_mkdir_2file(const char *file_path)
 		/* Let's create the tree structure */
 		error = gitfo_mkdir_recurs(target_folder_path, mode);
 		if (error < GIT_SUCCESS)
-			return error;
+			return error;	/* The callee already takes care of setting the correct error message. */
 	}
 
 	return GIT_SUCCESS;
@@ -164,19 +164,19 @@ int gitfo_read_file(gitfo_buf *obj, const char *path)
 
 	if (((size = gitfo_size(fd)) < 0) || !git__is_sizet(size+1)) {
 		gitfo_close(fd);
-		return GIT_ERROR;
+		return git__throw(GIT_ERROR, "Failed to read file `%s`. Either an error occured while calculating its size or the file is too large", path);
 	}
 	len = (size_t) size;
 
 	if ((buff = git__malloc(len + 1)) == NULL) {
 		gitfo_close(fd);
-		return GIT_ERROR;
+		return GIT_ENOMEM;
 	}
 
 	if (gitfo_read(fd, buff, len) < 0) {
 		gitfo_close(fd);
 		free(buff);
-		return GIT_ERROR;
+		return git__throw(GIT_ERROR, "Failed to read file `%s`", path);
 	}
 	buff[len] = '\0';
 
@@ -197,13 +197,15 @@ void gitfo_free_buf(gitfo_buf *obj)
 
 int gitfo_mv(const char *from, const char *to)
 {
+	int error;
+
 #ifdef GIT_WIN32
 	/*
 	 * Win32 POSIX compilance my ass. If the destination
 	 * file exists, the `rename` call fails. This is as
 	 * close as it gets with the Win32 API.
 	 */
-	return MoveFileEx(from, to, MOVEFILE_REPLACE_EXISTING | MOVEFILE_COPY_ALLOWED) ? GIT_SUCCESS : GIT_EOSERR;
+	error = MoveFileEx(from, to, MOVEFILE_REPLACE_EXISTING | MOVEFILE_COPY_ALLOWED) ? GIT_SUCCESS : GIT_EOSERR;
 #else
 	/* Don't even try this on Win32 */
 	if (!link(from, to)) {
@@ -214,16 +216,21 @@ int gitfo_mv(const char *from, const char *to)
 	if (!rename(from, to))
 		return GIT_SUCCESS;
 
-	return GIT_EOSERR;
+	error = GIT_EOSERR;
 #endif
+
+	if (error < GIT_SUCCESS)
+		return git__throw(error, "Failed to move file from `%s`to `%s`", from, to);
+
+	return GIT_SUCCESS;
 }
 
 int gitfo_mv_force(const char *from, const char *to)
 {
 	if (gitfo_mkdir_2file(to) < GIT_SUCCESS)
-		return GIT_EOSERR;
+		return GIT_EOSERR;	/* The callee already takes care of setting the correct error message. */
 
-	return gitfo_mv(from, to);
+	return gitfo_mv(from, to);	/* The callee already takes care of setting the correct error message. */
 }
 
 int gitfo_map_ro(git_map *out, git_file fd, git_off_t begin, size_t len)
@@ -338,7 +345,7 @@ int gitfo_dirent(
 	struct dirent *de;
 
 	if (!wd_len || path_sz < wd_len + 2)
-		return GIT_ERROR;
+		return git__throw(GIT_EINVALIDARGS, "Failed to process `%s` tree structure. Path is either empty or buffer size is too short", path);
 
 	while (path[wd_len - 1] == '/')
 		wd_len--;
@@ -347,7 +354,7 @@ int gitfo_dirent(
 
 	dir = opendir(path);
 	if (!dir)
-		return GIT_EOSERR;
+		return git__throw(GIT_EOSERR, "Failed to process `%s` tree structure. An error occured while opening the directory", path);
 
 	while ((de = readdir(dir)) != NULL) {
 		size_t de_len;
@@ -364,14 +371,14 @@ int gitfo_dirent(
 		de_len = strlen(de->d_name);
 		if (path_sz < wd_len + de_len + 1) {
 			closedir(dir);
-			return GIT_ERROR;
+			return git__throw(GIT_ERROR, "Failed to process `%s` tree structure. Buffer size is too short", path);
 		}
 
 		strcpy(path + wd_len, de->d_name);
 		result = fn(arg, path);
 		if (result < GIT_SUCCESS) {
 			closedir(dir);
-			return result;
+			return result;	/* The callee is reponsible for setting the correct error message */
 		}
 		if (result > 0) {
 			closedir(dir);
@@ -399,7 +406,7 @@ int retrieve_path_root_offset(const char *path)
 	if (*(path + offset) == '/')
 		return offset;
 
-	return GIT_ERROR;
+	return -1;	/* Not a real error. Rather a signal than the path is not rooted */
 }
 
 
@@ -438,7 +445,11 @@ int gitfo_mkdir_recurs(const char *path, int mode)
 		error = gitfo_mkdir(path, mode);
 
 	free(path_copy);
-	return error;
+
+	if (error < GIT_SUCCESS)
+		return git__throw(error, "Failed to recursively create `%s` tree structure", path);
+
+	return GIT_SUCCESS;
 }
 
 static int retrieve_previous_path_component_start(const char *path)
@@ -484,7 +495,7 @@ int gitfo_prettify_dir_path(char *buffer_out, size_t size, const char *path)
 	if (root_path_offset < 0) {
 		error = gitfo_getcwd(buffer_out, size);
 		if (error < GIT_SUCCESS)
-			return error;
+			return error;	/* The callee already takes care of setting the correct error message. */
 
 		len = strlen(buffer_out);
 		buffer_out += len;
@@ -529,7 +540,7 @@ int gitfo_prettify_dir_path(char *buffer_out, size_t size, const char *path)
 
 			/* Are we escaping out of the root dir? */
 			if (len < 0)
-				return GIT_EINVALIDPATH;
+				return git__throw(GIT_EINVALIDPATH, "Failed to normalize path `%s`. The path escapes out of the root directory", path);
 
 			buffer_out = (char *)buffer_out_start + len;
 			continue;
@@ -537,7 +548,7 @@ int gitfo_prettify_dir_path(char *buffer_out, size_t size, const char *path)
 
 		/* Guard against potential multiple dot path traversal (cf http://cwe.mitre.org/data/definitions/33.html) */
 		if (only_dots && segment_len > 0)
-			return GIT_EINVALIDPATH;
+			return git__throw(GIT_EINVALIDPATH, "Failed to normalize path `%s`. The path contains a segment with three `.` or more", path);
 
 		*buffer_out++ = '/';
 		len++;
@@ -557,21 +568,21 @@ int gitfo_prettify_file_path(char *buffer_out, size_t size, const char *path)
 
 	/* Let's make sure the filename isn't empty nor a dot */
 	if (path_len == 0 || (path_len == 1 && *path == '.'))
-		return GIT_EINVALIDPATH;
+		return git__throw(GIT_EINVALIDPATH, "Failed to normalize file path `%s`. The path is either empty or equals `.`", path);
 
 	/* Let's make sure the filename doesn't end with "/", "/." or "/.." */
 	for (i = 1; path_len > i && i < 4; i++) {
 		if (!strncmp(path + path_len - i, pattern, i))
-			return GIT_EINVALIDPATH;
+			return git__throw(GIT_EINVALIDPATH, "Failed to normalize file path `%s`. The path points to a folder", path);
 	}
 
 	error =  gitfo_prettify_dir_path(buffer_out, size, path);
 	if (error < GIT_SUCCESS)
-		return error;
+		return error;	/* The callee already takes care of setting the correct error message. */
 
 	path_len = strlen(buffer_out);
-	if (path_len < 2)
-		return GIT_EINVALIDPATH;
+	if (path_len < 2)	/* TODO: Fixme. We should also take of detecting Windows rooted path (probably through usage of retrieve_path_root_offset) */
+		return git__throw(GIT_EINVALIDPATH, "Failed to normalize file path `%s`. The path points to a folder", path);
 
 	/* Remove the trailing slash */
 	buffer_out[path_len - 1] = '\0';
@@ -616,11 +627,11 @@ int gitfo_getcwd(char *buffer_out, size_t size)
 #ifdef GIT_WIN32
 	cwd_buffer = _getcwd(buffer_out, size);
 #else
-	cwd_buffer = getcwd(buffer_out, size); //TODO: Fixme. Ensure the required headers are correctly included
+	cwd_buffer = getcwd(buffer_out, size);
 #endif
 
 	if (cwd_buffer == NULL)
-		return GIT_EOSERR;
+		return git__throw(GIT_EOSERR, "Failed to retrieve current working directory");
 
 	posixify_path(buffer_out);
 
diff --git a/src/odb.c b/src/odb.c
index 3dca977..8637534 100644
--- a/src/odb.c
+++ b/src/odb.c
@@ -234,13 +234,17 @@ static int backend_sort_cmp(const void *a, const void *b)
 
 int git_odb_new(git_odb **out)
 {
+	int error;
+
 	git_odb *db = git__calloc(1, sizeof(*db));
 	if (!db)
 		return GIT_ENOMEM;
 
 	git_cache_init(&db->cache, GIT_DEFAULT_CACHE_SIZE, &free_odb_object);
+	if (error < GIT_SUCCESS)
+		return error;
 
-	if (git_vector_init(&db->backends, 4, backend_sort_cmp) < 0) {
+	if (git_vector_init(&db->backends, 4, backend_sort_cmp) < GIT_SUCCESS) {
 		free(db);
 		return GIT_ENOMEM;
 	}
diff --git a/src/repository.c b/src/repository.c
index 8cc2644..1072b22 100644
--- a/src/repository.c
+++ b/src/repository.c
@@ -124,16 +124,16 @@ static int check_repository_dirs(git_repository *repo)
 	char path_aux[GIT_PATH_MAX];
 
 	if (gitfo_isdir(repo->path_repository) < GIT_SUCCESS)
-		return GIT_ENOTAREPO;
+		return git__throw(GIT_ENOTAREPO, "`%s` is not a folder", repo->path_repository);
 
 	/* Ensure GIT_OBJECT_DIRECTORY exists */
 	if (gitfo_isdir(repo->path_odb) < GIT_SUCCESS)
-		return GIT_ENOTAREPO;
+		return git__throw(GIT_ENOTAREPO, "`%s` does not exist", repo->path_odb);
 
 	/* Ensure HEAD file exists */
 	git__joinpath(path_aux, repo->path_repository, GIT_HEAD_FILE);
 	if (gitfo_exists(path_aux) < 0)
-		return GIT_ENOTAREPO;
+		return git__throw(GIT_ENOTAREPO, "HEAD file is missing");
 
 	return GIT_SUCCESS;
 }
@@ -145,12 +145,12 @@ static int guess_repository_dirs(git_repository *repo, const char *repository_pa
 
 	/* Git directory name */
 	if (git__basename_r(buffer, sizeof(buffer), repository_path) < 0)
-		return GIT_EINVALIDPATH;
+		return git__throw(GIT_EINVALIDPATH, "Unable to parse folder name from `%s`", repository_path);
 
 	if (strcmp(buffer, DOT_GIT) == 0) {
 		/* Path to working dir */
 		if (git__dirname_r(buffer, sizeof(buffer), repository_path) < 0)
-			return GIT_EINVALIDPATH;
+			return git__throw(GIT_EINVALIDPATH, "Unable to parse parent folder name from `%s`", repository_path);
 		path_work_tree = buffer;
 	}
 
@@ -159,13 +159,19 @@ static int guess_repository_dirs(git_repository *repo, const char *repository_pa
 
 static git_repository *repository_alloc()
 {
+	int error;
+
 	git_repository *repo = git__malloc(sizeof(git_repository));
 	if (!repo)
 		return NULL;
 
 	memset(repo, 0x0, sizeof(git_repository));
 
-	git_cache_init(&repo->objects, GIT_DEFAULT_CACHE_SIZE, &git_object__free);
+	error = git_cache_init(&repo->objects, GIT_DEFAULT_CACHE_SIZE, &git_object__free);
+	if (error < GIT_SUCCESS) {
+		free(repo);
+		return NULL;
+	}
 
 	if (git_repository__refcache_init(&repo->references) < GIT_SUCCESS) {
 		free(repo);
@@ -177,7 +183,7 @@ static git_repository *repository_alloc()
 
 static int init_odb(git_repository *repo)
 {
-	return git_odb_open(&repo->db, repo->path_odb);
+	return git_odb_open(&repo->db, repo->path_odb);	/* TODO: Move odb.c to new error handling */
 }
 
 int git_repository_open3(git_repository **repo_out,
@@ -192,7 +198,7 @@ int git_repository_open3(git_repository **repo_out,
 	assert(repo_out);
 
 	if (object_database == NULL)
-		return GIT_ERROR;
+		return git__throw(GIT_EINVALIDARGS, "Failed to open repository. `object_database` can't be null");
 
 	repo = repository_alloc();
 	if (repo == NULL)
@@ -218,7 +224,7 @@ int git_repository_open3(git_repository **repo_out,
 
 cleanup:
 	git_repository_free(repo);
-	return error;
+	return git__rethrow(error, "Failed to open repository");
 }
 
 
@@ -259,7 +265,7 @@ int git_repository_open2(git_repository **repo_out,
 
 cleanup:
 	git_repository_free(repo);
-	return error;
+	return git__rethrow(error, "Failed to open repository");
 }
 
 int git_repository_open(git_repository **repo_out, const char *path)
@@ -290,7 +296,7 @@ int git_repository_open(git_repository **repo_out, const char *path)
 
 cleanup:
 	git_repository_free(repo);
-	return error;
+	return git__rethrow(error, "Failed to open repository");
 }
 
 void git_repository_free(git_repository *repo)
@@ -322,7 +328,7 @@ int git_repository_index(git_index **index_out, git_repository *repo)
 	assert(index_out && repo);
 
 	if (repo->index == NULL) {
-		error = git_index_open_inrepo(&repo->index, repo);
+		error = git_index_open_inrepo(&repo->index, repo);	/* TODO: move index.c to new error handling */
 		if (error < GIT_SUCCESS)
 			return error;
 
@@ -349,7 +355,7 @@ static int repo_init_reinit(repo_init *results)
 static int repo_init_createhead(git_repository *repo)
 {
 	git_reference *head_reference;
-	return  git_reference_create_symbolic(&head_reference, repo, GIT_HEAD_FILE, GIT_REFS_HEADS_MASTER_FILE);
+	return git_reference_create_symbolic(&head_reference, repo, GIT_HEAD_FILE, GIT_REFS_HEADS_MASTER_FILE);	/* TODO: finalize moving refs.c to new error handling */
 }
 
 static int repo_init_check_head_existence(char * repository_path)
@@ -363,6 +369,7 @@ static int repo_init_check_head_existence(char * repository_path)
 static int repo_init_structure(repo_init *results)
 {
 	const int mode = 0755; /* or 0777 ? */
+	int error;
 
 	char temp_path[GIT_PATH_MAX];
 	char *git_dir = results->path_repository;
@@ -372,23 +379,27 @@ static int repo_init_structure(repo_init *results)
 
 	/* Creates the '/objects/info/' directory */
 	git__joinpath(temp_path, git_dir, GIT_OBJECTS_INFO_DIR);
-	if (gitfo_mkdir_recurs(temp_path, mode) < GIT_SUCCESS)
-		return GIT_ERROR;
+	error = gitfo_mkdir_recurs(temp_path, mode);
+	if (error < GIT_SUCCESS)
+		return error;
 
 	/* Creates the '/objects/pack/' directory */
 	git__joinpath(temp_path, git_dir, GIT_OBJECTS_PACK_DIR);
-	if (gitfo_mkdir(temp_path, mode))
-		return GIT_ERROR;
+	error = gitfo_mkdir(temp_path, mode);
+	if (error < GIT_SUCCESS)
+		return git__throw(error, "Unable to create `%s` folder", temp_path);
 
 	/* Creates the '/refs/heads/' directory */
 	git__joinpath(temp_path, git_dir, GIT_REFS_HEADS_DIR);
-	if (gitfo_mkdir_recurs(temp_path, mode))
-		return GIT_ERROR;
+	error = gitfo_mkdir_recurs(temp_path, mode);
+	if (error < GIT_SUCCESS)
+		return error;
 
 	/* Creates the '/refs/tags/' directory */
 	git__joinpath(temp_path, git_dir, GIT_REFS_TAGS_DIR);
-	if (gitfo_mkdir(temp_path, mode))
-		return GIT_ERROR;
+	error = gitfo_mkdir(temp_path, mode);
+	if (error < GIT_SUCCESS)
+		return git__throw(error, "Unable to create `%s` folder", temp_path);
 
 	/* TODO: what's left? templates? */
 
@@ -467,7 +478,7 @@ int git_repository_init(git_repository **repo_out, const char *path, unsigned is
 cleanup:
 	free(results.path_repository);
 	git_repository_free(repo);
-	return error;
+	return git__rethrow(error, "Failed to (re)init the repository `%s`", path);
 }
 
 int git_repository_is_empty(git_repository *repo)
@@ -477,10 +488,10 @@ int git_repository_is_empty(git_repository *repo)
 
 	error = git_reference_lookup(&head, repo, "HEAD");
 	if (error < GIT_SUCCESS)
-		return error;
+		return git__throw(error, "Failed to determine the emptiness of the repository. An error occured while retrieving the HEAD reference");
 
 	if (git_reference_type(head) != GIT_REF_SYMBOLIC)
-		return GIT_EOBJCORRUPTED;
+		return git__throw(GIT_EOBJCORRUPTED, "Failed to determine the emptiness of the repository. HEAD is probably in detached state");
 
 	return git_reference_resolve(&branch, head) == GIT_SUCCESS ? 0 : 1;
 }