[PATCH v4 1/4] cutils: Introduce bundle mechanism

[Akihiko Odaki <akihiko.odaki@gmail.com>]

Developers often run QEMU without installing. The bundle mechanism
allows to look up files which should be present in installation even in
such a situation.

It is a general mechanism and can find any files located relative
to the installation tree. The build tree must have a new directory,
qemu-bundle, to represent what files the installation tree would
have for reference by the executables.

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
---
 include/qemu/cutils.h | 19 +++++++++++++++++++
 util/cutils.c         | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/include/qemu/cutils.h b/include/qemu/cutils.h
index 40e10e19a7e..3b66026cd3c 100644
--- a/include/qemu/cutils.h
+++ b/include/qemu/cutils.h
@@ -213,6 +213,25 @@ const char *qemu_get_exec_dir(void);
  */
 char *get_relocated_path(const char *dir);
 
+/**
+ * find_bundle:
+ * @path: Relative path
+ *
+ * Returns a path for the specified directory or file bundled in QEMU. It uses
+ * the directory of the running executable as the prefix first. See
+ * get_relocated_path() for the details. The next candidate is "qemu-bundle"
+ * directory in the directory of the running executable. "qemu-bundle"
+ * directory is typically present in the build tree.
+ *
+ * The returned string should be freed by the caller.
+ *
+ * Returns: a path that can access the bundle, or NULL if no matching bundle
+ * exists.
+ */
+char *find_bundle(const char *path);
+
+void list_bundle_candidates(const char *path);
+
 static inline const char *yes_no(bool b)
 {
      return b ? "yes" : "no";
diff --git a/util/cutils.c b/util/cutils.c
index a58bcfd80e7..fe3bbb1c4eb 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -1086,3 +1086,36 @@ char *get_relocated_path(const char *dir)
     }
     return g_string_free(result, false);
 }
+
+static const char * const bundle_formats[] = {
+    "%s" G_DIR_SEPARATOR_S ".." G_DIR_SEPARATOR_S "%s",
+    "%s" G_DIR_SEPARATOR_S "qemu-bundle" G_DIR_SEPARATOR_S "%s"
+};
+
+char *find_bundle(const char *path)
+{
+    const char *dir = qemu_get_exec_dir();
+    char *candidate;
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(bundle_formats); i++) {
+        candidate = g_strdup_printf(bundle_formats[i], dir, path);
+        if (access(candidate, R_OK) == 0) {
+            return candidate;
+        }
+        g_free(candidate);
+    }
+
+    return NULL;
+}
+
+void list_bundle_candidates(const char *path)
+{
+    const char *dir = qemu_get_exec_dir();
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(bundle_formats); i++) {
+        printf(bundle_formats[i], dir, path);
+        putc('\n', stdout);
+    }
+}
-- 
2.32.1 (Apple Git-133)