[Libguestfs] [PATCH] inspect: check for errors in files parsed with augeas (RHBZ#1229119)

[Pino Toscano]

During the inspection phase, check for errors after aug_load: if any of
the errors happened in any of the requested files, then report the error
straight away; ignoring the error means that information would be
silently lost.  For example, a malformed /etc/fstab would have caused
the inspection to not handle any of the additional mount points, giving
cryptic errors later on when trying to access files in any of the mount
points.

Now guests with invalid files such as /etc/fstab, /etc/mdadm.conf, and
/etc/sysconfig/network will cause the inspection to fail, instead of
being reported with a single mount point ('/').
---
 src/inspect-fs-unix.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/src/inspect-fs-unix.c b/src/inspect-fs-unix.c
index 3d19276..e9822ca 100644
--- a/src/inspect-fs-unix.c
+++ b/src/inspect-fs-unix.c
@@ -1983,6 +1983,9 @@ inspect_with_augeas (guestfs_h *g, struct inspect_fs *fs,
   int64_t size;
   int r;
   CLEANUP_FREE char *pathexpr = NULL;
+  CLEANUP_FREE_STRING_LIST char **matches = NULL;
+  char **match;
+  size_t len;
 
   /* Security: Refuse to do this if a config file is too large. */
   for (i = 0; configfiles[i] != NULL; ++i) {
@@ -2019,6 +2022,22 @@ inspect_with_augeas (guestfs_h *g, struct inspect_fs *fs,
   if (guestfs_aug_load (g) == -1)
     goto out;
 
+  /* Check that augeas did not get a parse error for any of the configfiles,
+   * otherwise we are silently missing information. */
+  matches = guestfs_aug_match (g, "/augeas/files//error");
+  for (match = matches; *match != NULL; ++match) {
+    for (i = 0; configfiles[i] != NULL; ++i) {
+      len = strlen (configfiles[i]);
+      if (strlen (*match) == (13 /* len(/augeas/files) */ + len + 6 /* len(/error) */) &&
+        STRPREFIX(*match, "/augeas/files") &&
+        STREQLEN(*match + 13, configfiles[i], len) &&
+        STREQ(*match + 13 + len, "/error")) {
+        error (g, _("augeas could not parse %s"), configfiles[i]);
+        return -1;
+      }
+    }
+  }
+
   r = f (g, fs);
 
  out:
-- 
2.1.0