[PATCH v2 03/15] libxl: add libxl__xs_path_cleanup

[Roger Pau Monne <roger.pau@citrix.com>]

Add a function which behaves like "xenstore-rm -t", and which will be
used to clean xenstore after unplug since we will be no longer
executing xen-hotplug-cleanup script, that used to do that for us.

Changes since v5:

 * Abort if no transaction or user_path supplied.

 * Log all errors.

Changes since v4:

 * Caller must supply a transaction.

Changes since v3:

 * Better error checking and function description.

Changes since v2:

 * Moved the function to libxl_xshelp.c and added the prototype to
   libxl_internal.h.

Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
---
 tools/libxl/libxl_internal.h |    8 ++++++++
 tools/libxl/libxl_xshelp.c   |   38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 46 insertions(+), 0 deletions(-)

diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index aaaf644..ae5527b 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -494,6 +494,14 @@ _hidden bool libxl__xs_mkdir(libxl__gc *gc, xs_transaction_t t,
 
 _hidden char *libxl__xs_libxl_path(libxl__gc *gc, uint32_t domid);
 
+/*
+ * This is a recursive delete, from top to bottom. What this function does
+ * is remove empty folders that contained the deleted entry.
+ *
+ * It mimics xenstore-rm -t behaviour.
+ */
+_hidden int libxl__xs_path_cleanup(libxl__gc *gc, xs_transaction_t t,
+                                   char *user_path);
 
 /*
  * Event generation functions provided by the libxl event core to the
diff --git a/tools/libxl/libxl_xshelp.c b/tools/libxl/libxl_xshelp.c
index 6ca1afe..c5b5364 100644
--- a/tools/libxl/libxl_xshelp.c
+++ b/tools/libxl/libxl_xshelp.c
@@ -135,6 +135,44 @@ char *libxl__xs_libxl_path(libxl__gc *gc, uint32_t domid)
     return s;
 }
 
+int libxl__xs_path_cleanup(libxl__gc *gc, xs_transaction_t t, char *user_path)
+{
+    unsigned int nb = 0;
+    char *path, *last, *val;
+    int rc;
+
+    /* A path and transaction must be provided by the caller */
+    assert(user_path && t);
+
+    path = libxl__strdup(gc, user_path);
+    if (!xs_rm(CTX->xsh, t, path)) {
+        LOGE(DEBUG, "unable to remove path %s", path);
+        rc = ERROR_FAIL;
+        goto out;
+    }
+
+    for (last = strrchr(path, '/'); last != NULL; last = strrchr(path, '/')) {
+        *last = '\0';
+
+        if (!strlen(path)) break;
+
+        val = libxl__xs_read(gc, t, path);
+        if (!val || strlen(val) != 0) break;
+
+        if (!libxl__xs_directory(gc, t, path, &nb) || nb != 0) break;
+
+        if (!xs_rm(CTX->xsh, t, path)) {
+            LOGE(DEBUG, "unable to remove path %s", path);
+            rc = ERROR_FAIL;
+            goto out;
+        }
+    }
+    rc = 0;
+
+out:
+    return rc;
+}
+
 /*
  * Local variables:
  * mode: C
-- 
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