From 38ea64e86793342b1384a71ae07f0088d9cd891f Mon Sep 17 00:00:00 2001
From: aszlig <aszlig@redmoonstudios.org>
Date: Fri, 16 Dec 2016 12:42:54 +0100
Subject: [PATCH] qemu_test: Make chown() calls to the store a no-op

The "misc" NixOS test is using Nix to query the store and it tries to
change the ownership of it while doing so.

This fails if Nix is not in a seccomp-sandboxed userid namespace, so
let's make chown() a no-op when applied to store paths.

Fixes the misc test (and possibly future tests) on older Nix versions.

Signed-off-by: aszlig <aszlig@redmoonstudios.org>
---
 .../qemu/force-uid0-on-9p.patch               | 53 ++++++++++++++-----
 1 file changed, 41 insertions(+), 12 deletions(-)

diff --git a/pkgs/applications/virtualization/qemu/force-uid0-on-9p.patch b/pkgs/applications/virtualization/qemu/force-uid0-on-9p.patch
index 90269961fdf3..9578d595129f 100644
--- a/pkgs/applications/virtualization/qemu/force-uid0-on-9p.patch
+++ b/pkgs/applications/virtualization/qemu/force-uid0-on-9p.patch
@@ -1,8 +1,32 @@
 diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
-index 845675e..43fa036 100644
+index 3f271fc..dc273f4 100644
 --- a/hw/9pfs/9p-local.c
 +++ b/hw/9pfs/9p-local.c
-@@ -128,6 +128,8 @@ static int local_lstat(FsContext *fs_ctx, V9fsPath *fs_path, struct stat *stbuf)
+@@ -45,6 +45,23 @@
+ 
+ #define VIRTFS_META_DIR ".virtfs_metadata"
+ 
++static int is_in_store_path(const char *path)
++{
++    static char *store_path = NULL;
++    int store_path_len = -1;
++
++    if (store_path_len == -1) {
++        if ((store_path = getenv("NIX_STORE")) != NULL)
++            store_path_len = strlen(store_path);
++        else
++            store_path_len = 0;
++    }
++
++    if (store_path_len > 0)
++        return strncmp(path, store_path, strlen(store_path)) == 0;
++    return 0;
++}
++
+ static char *local_mapped_attr_path(FsContext *ctx, const char *path)
+ {
+     int dirlen;
+@@ -128,6 +145,8 @@ static int local_lstat(FsContext *fs_ctx, V9fsPath *fs_path, struct stat *stbuf)
      if (err) {
          goto err_out;
      }
@@ -11,24 +35,19 @@ index 845675e..43fa036 100644
      if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
          /* Actual credentials are part of extended attrs */
          uid_t tmp_uid;
-@@ -462,6 +464,16 @@ static ssize_t local_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
+@@ -462,6 +481,11 @@ static ssize_t local_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
      return ret;
  }
  
-+static int maybe_chmod(const char *path, mode_t mode)
++static inline int maybe_chmod(const char *path, mode_t mode)
 +{
-+    static char *store_path = NULL;
-+    if (store_path == NULL)
-+        store_path = getenv("NIX_STORE");
-+    if (strncmp(path, store_path, strlen(store_path)) != 0)
-+        return chmod(path, mode);
-+    return 0;
++    return is_in_store_path(path) ? 0 : chmod(path, mode);
 +}
 +
  static int local_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
  {
      char *buffer;
-@@ -477,7 +489,7 @@ static int local_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
+@@ -477,7 +501,7 @@ static int local_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
      } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
                 (fs_ctx->export_flags & V9FS_SM_NONE)) {
          buffer = rpath(fs_ctx, path);
@@ -37,7 +56,7 @@ index 845675e..43fa036 100644
          g_free(buffer);
      }
      return ret;
-@@ -621,6 +633,8 @@ static int local_fstat(FsContext *fs_ctx, int fid_type,
+@@ -621,6 +645,8 @@ static int local_fstat(FsContext *fs_ctx, int fid_type,
      if (err) {
          return err;
      }
@@ -46,3 +65,13 @@ index 845675e..43fa036 100644
      if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
          /* Actual credentials are part of extended attrs */
          uid_t tmp_uid;
+@@ -916,7 +942,8 @@ static int local_chown(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
+         (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
+         (fs_ctx->export_flags & V9FS_SM_NONE)) {
+         buffer = rpath(fs_ctx, path);
+-        ret = lchown(buffer, credp->fc_uid, credp->fc_gid);
++        ret = is_in_store_path(buffer)
++            ? 0 : lchown(buffer, credp->fc_uid, credp->fc_gid);
+         g_free(buffer);
+     } else if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
+         buffer = rpath(fs_ctx, path);