composefs: Inline small files

Since we're changing composefs format anyway (due to the usr/etc relabel)
might as well import the change from mkcomposefs that inlines files up
to 64 bytes.

src/libostree/ostree-repo-composefs.c

@@ -38,6 +38,8 @@
 #include <linux/fsverity.h>
 #endif
 
+#define OSTREE_COMPOSEFS_INLINE_MAX_SIZE 64
+
 gboolean
 _ostree_repo_parse_composefs_config (OstreeRepo *self, GError **error)
 {
@@ -327,32 +329,46 @@ checkout_one_composefs_file_at (OstreeRepo *repo, const char *checksum, struct l
       if (lcfs_node_set_payload (node, loose_path_buf) != 0)
         return glnx_null_throw_errno (error);
 
-      guchar *known_digest = NULL;
+      if (source_size <= OSTREE_COMPOSEFS_INLINE_MAX_SIZE)
+        {
+          guchar buf[OSTREE_COMPOSEFS_INLINE_MAX_SIZE];
+          gsize bytes_read;
 
-#ifdef HAVE_LINUX_FSVERITY_H
-      /* First try to get the digest directly from the bare repo file.
-       * This is the typical case when we're pulled into the target
-       * system repo with verity on and are recreating the composefs
-       * image during deploy. */
-      char buf[sizeof (struct fsverity_digest) + OSTREE_SHA256_DIGEST_LEN];
+          if (!g_input_stream_read_all (input, buf, source_size, &bytes_read, cancellable, error))
+            return NULL;
 
-      if (G_IS_UNIX_INPUT_STREAM (input))
-        {
-          int content_fd = g_unix_input_stream_get_fd (G_UNIX_INPUT_STREAM (input));
-          struct fsverity_digest *d = (struct fsverity_digest *)&buf;
-          d->digest_size = OSTREE_SHA256_DIGEST_LEN;
-
-          if (ioctl (content_fd, FS_IOC_MEASURE_VERITY, d) == 0
-              && d->digest_size == OSTREE_SHA256_DIGEST_LEN
-              && d->digest_algorithm == FS_VERITY_HASH_ALG_SHA256)
-            known_digest = d->digest;
+          if (lcfs_node_set_content (node, buf, bytes_read) != 0)
+            return glnx_null_throw_errno (error);
         }
+      else
+        {
+          guchar *known_digest = NULL;
+
+#ifdef HAVE_LINUX_FSVERITY_H
+          /* First try to get the digest directly from the bare repo file.
+           * This is the typical case when we're pulled into the target
+           * system repo with verity on and are recreating the composefs
+           * image during deploy. */
+          char buf[sizeof (struct fsverity_digest) + OSTREE_SHA256_DIGEST_LEN];
+
+          if (G_IS_UNIX_INPUT_STREAM (input))
+            {
+              int content_fd = g_unix_input_stream_get_fd (G_UNIX_INPUT_STREAM (input));
+              struct fsverity_digest *d = (struct fsverity_digest *)&buf;
+              d->digest_size = OSTREE_SHA256_DIGEST_LEN;
+
+              if (ioctl (content_fd, FS_IOC_MEASURE_VERITY, d) == 0
+                  && d->digest_size == OSTREE_SHA256_DIGEST_LEN
+                  && d->digest_algorithm == FS_VERITY_HASH_ALG_SHA256)
+                known_digest = d->digest;
+            }
 #endif
 
-      if (known_digest)
-        lcfs_node_set_fsverity_digest (node, known_digest);
-      else if (lcfs_node_set_fsverity_from_content (node, input, _composefs_read_cb) != 0)
-        return glnx_null_throw_errno (error);
+          if (known_digest)
+            lcfs_node_set_fsverity_digest (node, known_digest);
+          else if (lcfs_node_set_fsverity_from_content (node, input, _composefs_read_cb) != 0)
+            return glnx_null_throw_errno (error);
+        }
     }
 
   if (xattrs)