util: Add one helper virReadFCHost to read the value of fc_host entry

"open_wwn_file" in node_device_linux_sysfs.c is redundant, on one
hand it duplicates work of virFileReadAll, on the other hand, it's
waste to use a function for it, as there is no other users of it.
So I don't see why the file opening work cannot be done in
"read_wwn_linux".

"read_wwn_linux" can be abstracted as an util function. As what all
it does is to read the sysfs entry.

So this patch removes "open_wwn_file", and abstract "read_wwn_linux"
as an util function "virReadFCHost" (a more general name, because
after changes, it can read each of the fc_host entry now).

* src/util/virutil.h: (Declare virReadFCHost)
* src/util/virutil.c: (Implement virReadFCHost)
* src/node_device/node_device_linux_sysfs.c: (Remove open_wwn_file,
  and read_wwn_linux)
src/node_device/node_device_driver.h: (Remove the declaration of
  read_wwn_linux, and the related macros)
src/libvirt_private.syms: (Export virReadFCHost)

src/libvirt_private.syms

@@ -1868,6 +1868,7 @@ virIsDevMapperDevice;
 virParseNumber;
 virParseVersionString;
 virPipeReadUntilEOF;
+virReadFCHost;
 virScaleInteger;
 virSetBlocking;
 virSetCloseExec;

src/node_device/node_device_driver.h

@@ -59,14 +59,10 @@ int check_fc_host_linux(union _virNodeDevCapData *d);
 #  define check_vport_capable(d) check_vport_capable_linux(d)
 int check_vport_capable_linux(union _virNodeDevCapData *d);
 
-#  define read_wwn(host, file, wwn) read_wwn_linux(host, file, wwn)
-int read_wwn_linux(int host, const char *file, char **wwn);
-
 # else  /* __linux__ */
 
 #  define check_fc_host(d)                      (-1)
 #  define check_vport_capable(d)                (-1)
-#  define read_wwn(host, file, wwn)
 
 # endif /* __linux__ */
 

src/node_device/node_device_linux_sysfs.c

@@ -37,77 +37,6 @@
 
 #ifdef __linux__
 
-static int open_wwn_file(const char *prefix,
-                         int host,
-                         const char *file,
-                         int *fd)
-{
-    int retval = 0;
-    char *wwn_path = NULL;
-
-    if (virAsprintf(&wwn_path, "%s/host%d/%s", prefix, host, file) < 0) {
-        virReportOOMError();
-        retval = -1;
-        goto out;
-    }
-
-    /* fd will be closed by caller */
-    if ((*fd = open(wwn_path, O_RDONLY)) != -1) {
-        VIR_DEBUG("Opened WWN path '%s' for reading",
-                  wwn_path);
-    } else {
-        VIR_ERROR(_("Failed to open WWN path '%s' for reading"),
-                  wwn_path);
-    }
-
-out:
-    VIR_FREE(wwn_path);
-    return retval;
-}
-
-
-int read_wwn_linux(int host, const char *file, char **wwn)
-{
-    char *p = NULL;
-    int fd = -1, retval = 0;
-    char buf[65] = "";
-
-    if (open_wwn_file(LINUX_SYSFS_FC_HOST_PREFIX, host, file, &fd) < 0) {
-        goto out;
-    }
-
-    if (saferead(fd, buf, sizeof(buf) - 1) < 0) {
-        retval = -1;
-        VIR_DEBUG("Failed to read WWN for host%d '%s'",
-                  host, file);
-        goto out;
-    }
-
-    p = strstr(buf, "0x");
-    if (p != NULL) {
-        p += strlen("0x");
-    } else {
-        p = buf;
-    }
-
-    *wwn = strndup(p, sizeof(buf));
-    if (*wwn == NULL) {
-        virReportOOMError();
-        retval = -1;
-        goto out;
-    }
-
-    p = strchr(*wwn, '\n');
-    if (p != NULL) {
-        *p = '\0';
-    }
-
-out:
-    VIR_FORCE_CLOSE(fd);
-    return retval;
-}
-
-
 int check_fc_host_linux(union _virNodeDevCapData *d)
 {
     char *sysfs_path = NULL;
@@ -131,26 +60,29 @@ int check_fc_host_linux(union _virNodeDevCapData *d)
 
     d->scsi_host.flags |= VIR_NODE_DEV_CAP_FLAG_HBA_FC_HOST;
 
-    if (read_wwn(d->scsi_host.host,
-                 "port_name",
-                 &d->scsi_host.wwpn) == -1) {
+    if (virReadFCHost(NULL,
+                      d->scsi_host.host,
+                      "port_name",
+                      &d->scsi_host.wwpn) == -1) {
         VIR_ERROR(_("Failed to read WWPN for host%d"),
                   d->scsi_host.host);
         retval = -1;
         goto out;
     }
 
-    if (read_wwn(d->scsi_host.host,
-                 "node_name",
-                 &d->scsi_host.wwnn) == -1) {
+    if (virReadFCHost(NULL,
+                      d->scsi_host.host,
+                      "node_name",
+                      &d->scsi_host.wwnn) == -1) {
         VIR_ERROR(_("Failed to read WWNN for host%d"),
                   d->scsi_host.host);
         retval = -1;
     }
 
-    if (read_wwn(d->scsi_host.host,
-                 "fabric_name",
-                 &d->scsi_host.fabric_wwn) == -1) {
+    if (virReadFCHost(NULL,
+                      d->scsi_host.host,
+                      "fabric_name",
+                      &d->scsi_host.fabric_wwn) == -1) {
         VIR_ERROR(_("Failed to read fabric WWN for host%d"),
                   d->scsi_host.host);
         retval = -1;

src/util/virutil.c

@@ -3383,3 +3383,70 @@ cleanup:
     VIR_FREE(buf);
     return ret;
 }
+
+#ifdef __linux__
+# define SYSFS_FC_HOST_PATH "/sys/class/fc_host/"
+
+/* virReadFCHost:
+ * @sysfs_prefix: "fc_host" sysfs path, defaults to SYSFS_FC_HOST_PATH
+ * @host: Host number, E.g. 5 of "fc_host/host5"
+ * @entry: Name of the sysfs entry to read
+ * @result: Return the entry value as string
+ *
+ * Read the value of sysfs "fc_host" entry.
+ *
+ * Returns 0 on success, and @result is filled with the entry value.
+ * as string, Otherwise returns -1. Caller must free @result after
+ * use.
+ */
+int
+virReadFCHost(const char *sysfs_prefix,
+              int host,
+              const char *entry,
+              char **result)
+{
+    char *sysfs_path = NULL;
+    char *p = NULL;
+    int ret = -1;
+    char *buf = NULL;
+
+    if (virAsprintf(&sysfs_path, "%s/host%d/%s",
+                    sysfs_prefix ? sysfs_prefix : SYSFS_FC_HOST_PATH,
+                    host, entry) < 0) {
+        virReportOOMError();
+        goto cleanup;
+    }
+
+    if (virFileReadAll(sysfs_path, 1024, &buf) < 0)
+        goto cleanup;
+
+    if ((p = strchr(buf, '\n')))
+        *p = '\0';
+
+    if ((p = strstr(buf, "0x")))
+        p += strlen("0x");
+    else
+        p = buf;
+
+    if (!(*result = strndup(p, sizeof(buf)))) {
+        virReportOOMError();
+        goto cleanup;
+    }
+
+    ret = 0;
+cleanup:
+    VIR_FREE(sysfs_path);
+    VIR_FREE(buf);
+    return ret;
+}
+#else
+int
+virReadFCHost(const char *sysfs_prefix ATTRIBUTE_UNUSED,
+              int host ATTRIBUTE_UNUSED,
+              const char *entry ATTRIBUTE_UNUSED,
+              char **result ATTRIBUTE_UNUSED)
+{
+    virReportSystemError(ENOSYS, "%s", _("Not supported on this platform"));
+    return -1;
+}
+#endif /* __linux__ */

src/util/virutil.h

@@ -297,5 +297,10 @@ int virGetDeviceUnprivSGIO(const char *path,
                            int *unpriv_sgio);
 char * virGetUnprivSGIOSysfsPath(const char *path,
                                  const char *sysfs_dir);
+int virReadFCHost(const char *sysfs_prefix,
+                  int host,
+                  const char *entry,
+                  char **result)
+    ATTRIBUTE_NONNULL(3) ATTRIBUTE_NONNULL(4);
 
 #endif /* __VIR_UTIL_H__ */