[libvirt] [PATCH v2 2/4] virnetdev: Introduce virNetDevGetLinkInfo

[Michal Privoznik]

The purpose of this function is to fetch link state
and link speed for given NIC name from the SYSFS.

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---
 src/libvirt_private.syms |   1 +
 src/util/virnetdev.c     | 104 +++++++++++++++++++++++++++++++++++++++++++++++
 src/util/virnetdev.h     |   6 +++
 3 files changed, 111 insertions(+)

diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 394c086..6d08ee9 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -1540,6 +1540,7 @@ virNetDevClearIPv4Address;
 virNetDevExists;
 virNetDevGetIndex;
 virNetDevGetIPv4Address;
+virNetDevGetLinkInfo;
 virNetDevGetMAC;
 virNetDevGetMTU;
 virNetDevGetPhysicalFunction;
diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
index 3a60cf7..9d2c0d2 100644
--- a/src/util/virnetdev.c
+++ b/src/util/virnetdev.c
@@ -1832,3 +1832,107 @@ virNetDevRestoreNetConfig(const char *linkdev ATTRIBUTE_UNUSED,
 }
 
 #endif /* defined(__linux__) && defined(HAVE_LIBNL) */
+
+#ifdef __linux__
+# define SYSFS_PREFIX "/sys/class/net/"
+int
+virNetDevGetLinkInfo(const char *ifname,
+                     virInterfaceState *state,
+                     unsigned int *speed)
+{
+    int ret = -1;
+    char *path = NULL;
+    char *buf = NULL;
+    char *tmp;
+    int tmp_state;
+    unsigned int tmp_speed;
+
+    if (state) {
+        if (virAsprintf(&path, SYSFS_PREFIX "%s/operstate", ifname) < 0)
+            goto cleanup;
+
+        if (virFileReadAll(path, 1024, &buf) < 0) {
+            virReportSystemError(errno,
+                                 _("unable to read: %s"),
+                                 path);
+            goto cleanup;
+        }
+
+        if (!(tmp = strchr(buf, '\n'))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Unable to parse: %s"),
+                           buf);
+            goto cleanup;
+        }
+
+        *tmp = '\0';
+
+        /* We shouldn't allow 0 here, because
+         * virInterfaceState enum starts from 1. */
+        if ((tmp_state = virInterfaceStateTypeFromString(buf)) <= 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Unable to parse: %s"),
+                           buf);
+            goto cleanup;
+        }
+
+        *state = tmp_state;
+
+        VIR_FREE(path);
+        VIR_FREE(buf);
+    }
+
+    if (speed) {
+        if (virAsprintf(&path, SYSFS_PREFIX "%s/speed", ifname) < 0)
+            goto cleanup;
+
+        if (virFileReadAll(path, 1024, &buf) < 0) {
+            /* Some devices doesn't report speed, in which case we get EINVAL */
+            if (errno == EINVAL) {
+                ret = 0;
+                goto cleanup;
+            }
+            virReportSystemError(errno,
+                                 _("unable to read: %s"),
+                                 path);
+            goto cleanup;
+        }
+
+        if (virStrToLong_ui(buf, &tmp, 10, &tmp_speed) < 0 ||
+            *tmp != '\n') {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("Unable to parse: %s"),
+                           buf);
+            goto cleanup;
+        }
+
+        /* Workaround broken kernel API. If the link is unplugged then
+         * depending on the NIC driver, link speed can be reported as -1.
+         * However, the value is printed out as unsigned integer instead of
+         * signed one. Terrifying but true. */
+        *speed = (int) tmp_speed == -1 ? 0 : tmp_speed;
+    }
+
+    ret = 0;
+ cleanup:
+    VIR_FREE(buf);
+    VIR_FREE(path);
+    return ret;
+}
+
+#else
+
+int
+virNetDevGetLinkInfo(const char *ifname,
+                     virInterfaceState *state,
+                     unsigned int *speed)
+{
+    /* Port me */
+    VIR_DEBUG("Getting link info on %s is not implemented on this platform");
+    if (state)
+        *state = 0;
+    if (speed)
+        *speed = 0;
+    return 0;
+}
+#endif /* defined(__linux__) */
diff --git a/src/util/virnetdev.h b/src/util/virnetdev.h
index 00c82e0..de33323 100644
--- a/src/util/virnetdev.h
+++ b/src/util/virnetdev.h
@@ -29,6 +29,7 @@
 # include "virnetlink.h"
 # include "virmacaddr.h"
 # include "virpci.h"
+# include "device_conf.h"
 
 # ifdef HAVE_STRUCT_IFREQ
 typedef struct ifreq virIfreq;
@@ -145,4 +146,9 @@ int virNetDevGetVirtualFunctionInfo(const char *vfname, char **pfname,
                                     int *vf)
     ATTRIBUTE_NONNULL(1);
 
+int virNetDevGetLinkInfo(const char *ifname,
+                         virInterfaceState *state,
+                         unsigned int *speed)
+    ATTRIBUTE_NONNULL(1);
+
 #endif /* __VIR_NETDEV_H__ */
-- 
2.0.0