[gnome-builder] glib: add helper to get file contents from host

[Christian Hergert <chergert src gnome org>]

commit a6e53da5fc730ae506dc2057e936ba4ad06da625
Author: Christian Hergert <chergert redhat com>
Date:   Thu Mar 8 19:04:49 2018 -0800

    glib: add helper to get file contents from host
    
    We might be restricted in what is in /proc and therefore need to access
    the contents from the host instead. We can use our subprocess launcher
    to cheat and get the contents from `cat'.

 src/libide/util/ide-glib.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++
 src/libide/util/ide-glib.h |  5 ++++
 2 files changed, 74 insertions(+)
---
diff --git a/src/libide/util/ide-glib.c b/src/libide/util/ide-glib.c
index e56d0f4be..fb5efa9e1 100644
--- a/src/libide/util/ide-glib.c
+++ b/src/libide/util/ide-glib.c
@@ -22,7 +22,10 @@
 
 #include "config.h"
 
+#include "util/ide-flatpak.h"
 #include "util/ide-glib.h"
+#include "subprocess/ide-subprocess.h"
+#include "subprocess/ide-subprocess-launcher.h"
 #include "vcs/ide-vcs.h"
 
 typedef struct
@@ -553,3 +556,69 @@ ide_g_file_find_finish (GFile         *file,
 
   return g_task_propagate_pointer (G_TASK (result), error);
 }
+
+/**
+ * ide_g_host_file_get_contents:
+ * @path: the path on the host
+ * @contents: (out): a location for the contents
+ * @len: (out): a location for the size, not including trailing \0
+ * @error: location for a #GError, or %NULL
+ *
+ * This is similar to g_get_file_contents() but ensures that we get
+ * the file from the host, rather than our mount namespace.
+ *
+ * Returns: %TRUE if successful; otherwise %FALSE and @error is set.
+ *
+ * Since: 3.28
+ */
+gboolean
+ide_g_host_file_get_contents (const gchar  *path,
+                              gchar       **contents,
+                              gsize        *len,
+                              GError      **error)
+{
+  g_return_val_if_fail (path != NULL, FALSE);
+
+  if (contents != NULL)
+    *contents = NULL;
+
+  if (len != NULL)
+    *len = 0;
+
+  if (!ide_is_flatpak ())
+    return g_file_get_contents (path, contents, len, error);
+
+  {
+    g_autoptr(IdeSubprocessLauncher) launcher = NULL;
+    g_autoptr(IdeSubprocess) subprocess = NULL;
+    g_autoptr(GBytes) stdout_buf = NULL;
+
+    launcher = ide_subprocess_launcher_new (G_SUBPROCESS_FLAGS_STDOUT_PIPE);
+    ide_subprocess_launcher_set_run_on_host (launcher, TRUE);
+    ide_subprocess_launcher_push_argv (launcher, "cat");
+    ide_subprocess_launcher_push_argv (launcher, path);
+
+    if (!(subprocess = ide_subprocess_launcher_spawn (launcher, NULL, error)))
+      return FALSE;
+
+    if (!ide_subprocess_communicate (subprocess, NULL, NULL, &stdout_buf, NULL, error))
+      return FALSE;
+
+    if (len != NULL)
+      *len = g_bytes_get_size (stdout_buf);
+
+    if (contents != NULL)
+      {
+        const guint8 *data;
+        gsize n;
+
+        /* g_file_get_contents() gurantees a trailing null byte */
+        data = g_bytes_get_data (stdout_buf, &n);
+        *contents = g_malloc (n + 1);
+        memcpy (*contents, data, n);
+        (*contents)[n] = '\0';
+      }
+  }
+
+  return TRUE;
+}
diff --git a/src/libide/util/ide-glib.h b/src/libide/util/ide-glib.h
index 2bf5e0ca2..c44ab10c2 100644
--- a/src/libide/util/ide-glib.h
+++ b/src/libide/util/ide-glib.h
@@ -64,5 +64,10 @@ IDE_AVAILABLE_IN_3_28
 GPtrArray   *ide_g_file_get_children_finish           (GFile                *file,
                                                        GAsyncResult         *result,
                                                        GError              **error);
+IDE_AVAILABLE_IN_3_28
+gboolean     ide_g_host_file_get_contents             (const gchar          *path,
+                                                       gchar               **contents,
+                                                       gsize                *len,
+                                                       GError              **error);
 
 G_END_DECLS