libotutil: factor out utility to parse file by line

This will be used in the checkout CLI as well.

Closes: #1442
Approved by: cgwalters

src/libotutil/ot-fs-utils.c

@@ -221,3 +221,29 @@ ot_map_anonymous_tmpfile_from_content (GInputStream *instream,
     return NULL;
   return g_mapped_file_get_bytes (mfile);
 }
+
+gboolean
+ot_parse_file_by_line (const char    *path,
+                       gboolean     (*cb)(const char*, void*, GError**),
+                       void          *cbdata,
+                       GCancellable  *cancellable,
+                       GError       **error)
+{
+  g_autofree char *contents =
+    glnx_file_get_contents_utf8_at (AT_FDCWD, path, NULL, cancellable, error);
+  if (!contents)
+    return FALSE;
+
+  g_auto(GStrv) lines = g_strsplit (contents, "\n", -1);
+  for (char **iter = lines; iter && *iter; iter++)
+    {
+      /* skip empty lines at least */
+      if (**iter == '\0')
+        continue;
+
+      if (!cb (*iter, cbdata, error))
+        return FALSE;
+    }
+
+  return TRUE;
+}

src/libotutil/ot-fs-utils.h

@@ -90,4 +90,11 @@ ot_map_anonymous_tmpfile_from_content (GInputStream *instream,
 GBytes *ot_fd_readall_or_mmap (int fd, goffset offset,
                                GError **error);
 
+gboolean
+ot_parse_file_by_line (const char    *path,
+                       gboolean     (*cb)(const char*, void*, GError**),
+                       void          *cbdata,
+                       GCancellable  *cancellable,
+                       GError       **error);
+
 G_END_DECLS