lib: Add "open dfd iter handling noent" helper, port tree-wide

Follow up to a previous patch that addressed a double-close; I
realized we already had a helper for doing "open dfd iter, do nothing
if we get ENOENT".  Raise it to libotuil, and port all consumers.

Closes: #863
Approved by: jlebon

src/libostree/ostree-repo-prune.c

@@ -114,19 +114,14 @@ _ostree_repo_prune_tmp (OstreeRepo *self,
   if (self->cache_dir_fd == -1)
     return TRUE;
 
-  glnx_fd_close int fd = glnx_opendirat_with_errno (self->cache_dir_fd, _OSTREE_SUMMARY_CACHE_DIR, FALSE);
-  if (fd < 0)
-    {
-      /* Note early return */
-      if (errno == ENOENT)
-        return TRUE;
-      else
-        return glnx_throw_errno_prefix (error, "opendirat(%s)", _OSTREE_SUMMARY_CACHE_DIR);
-    }
-
   g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
-  if (!glnx_dirfd_iterator_init_take_fd (dup (fd), &dfd_iter, error))
+  gboolean exists;
+  if (!ot_dfd_iter_init_allow_noent (self->cache_dir_fd, _OSTREE_SUMMARY_CACHE_DIR,
+                                     &dfd_iter, &exists, error))
     return FALSE;
+  /* Note early return */
+  if (!exists)
+    return TRUE;
 
   while (TRUE)
     {
@@ -152,7 +147,7 @@ _ostree_repo_prune_tmp (OstreeRepo *self,
           if (has_sig_suffix)
             dent->d_name[len - 4] = '.';
 
-          if (unlinkat (fd, dent->d_name, 0) < 0)
+          if (unlinkat (dfd_iter.fd, dent->d_name, 0) < 0)
             return glnx_throw_errno_prefix (error, "unlinkat");
         }
     }

src/libostree/ostree-repo-static-delta-core.c

@@ -73,27 +73,19 @@ ostree_repo_list_static_delta_names (OstreeRepo                  *self,
                                      GCancellable                *cancellable,
                                      GError                     **error)
 {
-  g_autoptr(GPtrArray) ret_deltas = NULL;
+  g_autoptr(GPtrArray) ret_deltas = g_ptr_array_new_with_free_func (g_free);
-  glnx_fd_close int dfd = -1;
 
-  ret_deltas = g_ptr_array_new_with_free_func (g_free);
-
-  dfd = glnx_opendirat_with_errno (self->repo_dir_fd, "deltas", TRUE);
-  if (dfd < 0)
-    {
-      if (errno != ENOENT)
-        {
-          glnx_set_error_from_errno (error);
-          return FALSE;
-        }
-    }
-  else
-    {
   g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
-
+  gboolean exists;
-      if (!glnx_dirfd_iterator_init_take_fd (dfd, &dfd_iter, error))
+  if (!ot_dfd_iter_init_allow_noent (self->repo_dir_fd, "deltas", &dfd_iter,
+                                     &exists, error))
     return FALSE;
-      dfd = -1;
+  if (!exists)
+    {
+      /* Note early return */
+      ot_transfer_out_value (out_deltas, &ret_deltas);
+      return TRUE;
+    }
 
   while (TRUE)
     {
@@ -162,10 +154,8 @@ ostree_repo_list_static_delta_names (OstreeRepo                  *self,
             }
         }
     }
-    }
 
-  if (out_deltas)
+  ot_transfer_out_value (out_deltas, &ret_deltas);
-    *out_deltas = g_steal_pointer (&ret_deltas);
   return TRUE;
 }
 

src/libostree/ostree-repo.c

@@ -2272,18 +2272,13 @@ list_loose_objects_at (OstreeRepo             *self,
 {
   GVariant *key, *value;
 
-  glnx_fd_close int target_dfd = glnx_opendirat_with_errno (dfd, prefix, FALSE);
-  if (target_dfd < 0)
-    {
-      /* Nothing to do if this dir doesn't exist */
-      if (errno == ENOENT)
-        return TRUE;
-      return glnx_throw_errno (error);
-    }
   g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
-  if (!glnx_dirfd_iterator_init_take_fd (target_dfd, &dfd_iter, error))
+  gboolean exists;
+  if (!ot_dfd_iter_init_allow_noent (dfd, prefix, &dfd_iter, &exists, error))
     return FALSE;
-  target_dfd = -1; /* Transferred */
+  /* Note early return */
+  if (!exists)
+    return TRUE;
 
   while (TRUE)
     {

src/libostree/ostree-sysroot-cleanup.c

@@ -25,31 +25,6 @@
 
 #include "ostree-sysroot-private.h"
 
-/* Like glnx_dirfd_iterator_init_at(), but if %ENOENT, then set
- * @out_exists to %FALSE, and return successfully.
- */
-static gboolean
-dfd_iter_init_allow_noent (int dfd,
-                           const char *path,
-                           GLnxDirFdIterator *dfd_iter,
-                           gboolean *out_exists,
-                           GError **error)
-{
-  glnx_fd_close int fd = glnx_opendirat_with_errno (dfd, path, TRUE);
-  if (fd < 0)
-    {
-      if (errno != ENOENT)
-        return glnx_throw_errno (error);
-      *out_exists = FALSE;
-      return TRUE;
-    }
-  if (!glnx_dirfd_iterator_init_take_fd (fd, dfd_iter, error))
-    return FALSE;
-  fd = -1;
-  *out_exists = TRUE;
-  return TRUE;
-}
-
 /* @deploydir_dfd: Directory FD for ostree/deploy
  * @osname: Target osname
  * @inout_deployments: All deployments in this subdir will be appended to this array
@@ -64,7 +39,7 @@ _ostree_sysroot_list_deployment_dirs_for_os (int                  deploydir_dfd,
   g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
   gboolean exists;
   const char *osdeploy_path = glnx_strjoina (osname, "/deploy");
-  if (!dfd_iter_init_allow_noent (deploydir_dfd, osdeploy_path, &dfd_iter, &exists, error))
+  if (!ot_dfd_iter_init_allow_noent (deploydir_dfd, osdeploy_path, &dfd_iter, &exists, error))
     return FALSE;
   if (!exists)
     return TRUE;
@@ -106,7 +81,7 @@ list_all_deployment_directories (OstreeSysroot       *self,
 
   g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
   gboolean exists;
-  if (!dfd_iter_init_allow_noent (self->sysroot_fd, "ostree/deploy", &dfd_iter, &exists, error))
+  if (!ot_dfd_iter_init_allow_noent (self->sysroot_fd, "ostree/deploy", &dfd_iter, &exists, error))
     return FALSE;
   if (!exists)
     return TRUE;

src/libostree/ostree-sysroot.c

@@ -421,23 +421,17 @@ _ostree_sysroot_read_boot_loader_configs (OstreeSysroot *self,
     g_ptr_array_new_with_free_func ((GDestroyNotify)g_object_unref);
 
   g_autofree char *entries_path = g_strdup_printf ("boot/loader.%d/entries", bootversion);
-  /* Temporary owned by iterator */
+  gboolean entries_exists;
-  int fd = glnx_opendirat_with_errno (self->sysroot_fd, entries_path, TRUE);
+  g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
-  if (fd == -1)
+  if (!ot_dfd_iter_init_allow_noent (self->sysroot_fd, entries_path,
-    {
+                                     &dfd_iter, &entries_exists, error))
-      if (errno != ENOENT)
+    return FALSE;
-        return glnx_throw_errno (error);
+  if (!entries_exists)
-      else
     {
       /* Note early return */
       *out_loader_configs = g_steal_pointer (&ret_loader_configs);
       return TRUE;
     }
-    }
-
-  g_auto(GLnxDirFdIterator) dfd_iter = { 0, };
-  if (!glnx_dirfd_iterator_init_take_fd (fd, &dfd_iter, error))
-    return FALSE;
 
   while (TRUE)
     {

src/libotutil/ot-fs-utils.c

@@ -172,6 +172,31 @@ ot_openat_ignore_enoent (int dfd,
   return ret;
 }
 
+/* Like glnx_dirfd_iterator_init_at(), but if %ENOENT, then set
+ * @out_exists to %FALSE, and return successfully.
+ */
+gboolean
+ot_dfd_iter_init_allow_noent (int dfd,
+                              const char *path,
+                              GLnxDirFdIterator *dfd_iter,
+                              gboolean *out_exists,
+                              GError **error)
+{
+  glnx_fd_close int fd = glnx_opendirat_with_errno (dfd, path, TRUE);
+  if (fd < 0)
+    {
+      if (errno != ENOENT)
+        return glnx_throw_errno_prefix (error, "opendirat");
+      *out_exists = FALSE;
+      return TRUE;
+    }
+  if (!glnx_dirfd_iterator_init_take_fd (fd, dfd_iter, error))
+    return FALSE;
+  fd = -1;
+  *out_exists = TRUE;
+  return TRUE;
+}
+
 GBytes *
 ot_file_mapat_bytes (int dfd,
                      const char *path,

src/libotutil/ot-fs-utils.h

@@ -21,6 +21,7 @@
 #pragma once
 
 #include "ot-unix-utils.h"
+#include "libglnx.h"
 
 G_BEGIN_DECLS
 
@@ -53,6 +54,12 @@ gboolean ot_openat_ignore_enoent (int dfd,
                                   int *out_fd,
                                   GError **error);
 
+gboolean ot_dfd_iter_init_allow_noent (int dfd,
+                                       const char *path,
+                                       GLnxDirFdIterator *dfd_iter,
+                                       gboolean *out_exists,
+                                       GError **error);
+
 GBytes *ot_file_mapat_bytes (int dfd,
                              const char *path,
                              GError **error);