[Libguestfs] [PATCH 7/7] copy-in/copy-out: Capture errors from tar subprocess (RHBZ#1267032).

[Richard W.M. Jones]

Modify the copy-in/copy-out APIs to use the new guestfs_int_cmd_pipe
internal API.

This new API allows us to capture the stderr from the tar subprocess
if it fails, fixing RHBZ#1267032.  The user will now see errors like
this:

$ guestfish -N fs -m /dev/sda1 copy-in '/tmp/d/*' / : ll /
libguestfs: error: tar subprocess failed: tar: *: Cannot stat: No such file or directory
tar: Exiting with failure status due to previous errors
---
 src/copy-in-out.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/copy-in-out.c b/src/copy-in-out.c
index 975c217..d5e7fb0 100644
--- a/src/copy-in-out.c
+++ b/src/copy-in-out.c
@@ -68,8 +68,10 @@ guestfs_impl_copy_in (guestfs_h *g,
   guestfs_int_cmd_add_arg (cmd, "-");
   guestfs_int_cmd_add_arg (cmd, basename);
 
-  r = guestfs_int_cmd_run_async (cmd, NULL, NULL, &fd, NULL);
-  if (r == -1)
+  guestfs_int_cmd_clear_capture_errors (cmd);
+
+  fd = guestfs_int_cmd_pipe_run (cmd, "r");
+  if (fd == -1)
     return -1;
 
   snprintf (fdbuf, sizeof fdbuf, "/dev/fd/%d", fd);
@@ -81,11 +83,16 @@ guestfs_impl_copy_in (guestfs_h *g,
     return -1;
   }
 
-  r = guestfs_int_cmd_wait (cmd);
+  r = guestfs_int_cmd_pipe_wait (cmd);
   if (r == -1)
     return -1;
-  if (!(WIFEXITED (r) && WEXITSTATUS (r) == 0))
+  if (!WIFEXITED (r) || WEXITSTATUS (r) != 0) {
+    CLEANUP_FREE char *errors = guestfs_int_cmd_get_pipe_errors (cmd);
+    if (errors == NULL)
+      return -1;
+    error (g, "tar subprocess failed: %s", errors);
     return -1;
+  }
 
   return 0;
 }
@@ -190,8 +197,10 @@ guestfs_impl_copy_out (guestfs_h *g,
     guestfs_int_cmd_add_arg (cmd, "-xf");
     guestfs_int_cmd_add_arg (cmd, "-");
 
-    r = guestfs_int_cmd_run_async (cmd, NULL, &fd, NULL, NULL);
-    if (r == -1)
+    guestfs_int_cmd_clear_capture_errors (cmd);
+
+    fd = guestfs_int_cmd_pipe_run (cmd, "w");
+    if (fd == -1)
       return -1;
 
     snprintf (fdbuf, sizeof fdbuf, "/dev/fd/%d", fd);
@@ -203,11 +212,16 @@ guestfs_impl_copy_out (guestfs_h *g,
       return -1;
     }
 
-    r = guestfs_int_cmd_wait (cmd);
+    r = guestfs_int_cmd_pipe_wait (cmd);
     if (r == -1)
       return -1;
-    if (!(WIFEXITED (r) && WEXITSTATUS (r) == 0))
+    if (!WIFEXITED (r) || WEXITSTATUS (r) != 0) {
+      CLEANUP_FREE char *errors = guestfs_int_cmd_get_pipe_errors (cmd);
+      if (errors == NULL)
+        return -1;
+      error (g, "tar subprocess failed: %s", errors);
       return -1;
+    }
   }
 
   return 0;
-- 
2.5.0