[libvirt] [PATCH v3 1/3] virFile: Add APIs for extended attributes handling

[Michal Privoznik]

Currently, only three wrappers are being implemented:
virFileSetAttr for setting attributes
virFileGetAttr for querying attributes (note we need to call it twice,
first time to get length of attribute value, second to get actual value)
virFileRemoveAttr for removing attributes
---

diff to v2:
-drop multiple check for libattr

 src/libvirt_private.syms |   3 ++
 src/util/virfile.c       | 106 +++++++++++++++++++++++++++++++++++++++++++++++
 src/util/virfile.h       |  12 ++++++
 3 files changed, 121 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 599b71e..f787a12 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1273,8 +1273,11 @@ virFileClose;
 virFileDirectFdFlag;
 virFileFclose;
 virFileFdopen;
+virFileGetAttr;
 virFileLoopDeviceAssociate;
+virFileRemoveAttr;
 virFileRewrite;
+virFileSetAttr;
 virFileTouch;
 virFileUpdatePerm;
 virFileWrapperFdClose;
diff --git a/src/util/virfile.c b/src/util/virfile.c
index 4a9fa81..aae7101 100644
--- a/src/util/virfile.c
+++ b/src/util/virfile.c
@@ -37,6 +37,11 @@
 # include <sys/ioctl.h>
 #endif
 
+#ifdef HAVE_LIBATTR
+# include <attr/xattr.h>
+# include <sys/types.h>
+#endif
+
 #include "vircommand.h"
 #include "configmake.h"
 #include "viralloc.h"
@@ -644,3 +649,104 @@ int virFileLoopDeviceAssociate(const char *file,
 }
 
 #endif /* __linux__ */
+
+#ifdef HAVE_LIBATTR
+int
+virFileSetAttr(const char *file,
+               const char *name,
+               const char *value)
+{
+    size_t valueSize = strlen(value);
+    if (setxattr(file, name, value, valueSize, 0) < 0) {
+        virReportSystemError(errno,
+                             _("Unable to set extended attribute '%s' on '%s'"),
+                             name, file);
+        return -1;
+    }
+    return 0;
+}
+
+int
+virFileGetAttr(const char *file,
+               const char *name,
+               char **value)
+{
+    int ret = -1;
+    char *buf = NULL;
+    ssize_t valueSize;
+
+    /* get attribute length */
+    if ((valueSize = getxattr(file, name, NULL, 0)) < 0) {
+        /* The Linux kernel does not define ENOATTR, but maps it to ENODATA. */
+        if (errno == ENOATTR || errno == ENODATA) {
+            *value = NULL;
+            return 0;
+        } else {
+            virReportSystemError(errno,
+                                 _("Unable to get extended attribute '%s' on '%s'"),
+                                 name, file);
+            return ret;
+        }
+    }
+
+    if (VIR_ALLOC_N(buf, valueSize) < 0) {
+        virReportOOMError();
+        return ret;
+    }
+
+    if ((ret = getxattr(file, name, buf, valueSize)) < 0) {
+        VIR_FREE(buf);
+        virReportSystemError(errno,
+                             _("Unable to get extended attribute '%s' on '%s'"),
+                             name, file);
+    } else {
+        *value = buf;
+    }
+
+    return ret;
+}
+
+int
+virFileRemoveAttr(const char *file,
+                  const char *name)
+{
+    if (removexattr(file, name) < 0) {
+        virReportSystemError(errno,
+                             _("Unable to remove extended attribute '%s' on '%s'"),
+                             name, file);
+        return -1;
+    }
+    return 0;
+}
+
+#else /* HAVE_LIBATTR */
+
+int
+virFileSetAttr(const char *file ATTRIBUTE_UNUSED,
+               const char *name ATTRIBUTE_UNUSED,
+               const char *value ATTRIBUTE_UNUSED)
+{
+    virReportSystemError(ENOSYS, "%s",
+                         _("Unable to set extended attributes"));
+    return -1;
+}
+
+int
+virFileGetAttr(const char *file ATTRIBUTE_UNUSED,
+               const char *name ATTRIBUTE_UNUSED,
+               char **value ATTRIBUTE_UNUSED)
+{
+    virReportSystemError(ENOSYS, "%s",
+                         _("Unable to get extended attributes"));
+    return -1;
+}
+
+int
+virFileRemoveAttr(const char *file ATTRIBUTE_UNUSED,
+                  const char *name ATTRIBUTE_UNUSED)
+{
+    virReportSystemError(ENOSYS, "%s",
+                         _("Unable to remove extended attributes"));
+    return -1;
+}
+#endif /* HAVE_LIBATTR */
diff --git a/src/util/virfile.h b/src/util/virfile.h
index c885b73..3b4d672 100644
--- a/src/util/virfile.h
+++ b/src/util/virfile.h
@@ -108,4 +108,16 @@ int virFileUpdatePerm(const char *path,
 int virFileLoopDeviceAssociate(const char *file,
                                char **dev);
 
+int virFileSetAttr(const char *file,
+                   const char *name,
+                   const char *value)
+    ATTRIBUTE_NONNULL(3);
+
+int virFileGetAttr(const char *file,
+                   const char *name,
+                   char **value);
+
+int virFileRemoveAttr(const char *file,
+                      const char *name);
+
 #endif /* __VIR_FILES_H */
-- 
1.8.1.5