[orchagent]: Enhance initSaiPhyApi (sonic-net#2367)

* Add support for generic hwinfo string in gearbox_config.json
The SAI_SWITCH_ATTR_SWITCH_HARDWARE_INFO formatting is vendor specific.
 * Remove the formating check that assumes its of the mdio sysfs format
 * Note the the count remains without including the NULL termintor,
   which is not compliant with the SAI header definintion that indicates
   a NULL terminated string.

Signed-off-by: aaronp@arista.com

* Add support to allow Firmware Major Version to return unsupported"

Some external phys do not support Firmware upgrades and therefore
do not have a firmware version.
The SAI_SWITCH_ATTR_FIRMWARE_MAJOR_VERSION may return
SAI_STATUS_ATTR_NOT_SUPPORTED which needs to be gracefully
supported and allow the phy to be created.
* Allow SAI_STATUS_NOT_SUPPORTED return value and set
  version to empty string.

Signed-off-by: Aaron Payment <aaronp@arista.com>

* Address review comments
* Address review comments, fix hwinfo

Co-authored-by: Aaron Payment <aaronp@arista.com>

orchagent/saihelper.cpp

@@ -359,9 +359,6 @@ sai_status_t initSaiPhyApi(swss::gearbox_phy_t *phy)
     sai_status_t status;
     char fwPath[PATH_MAX];
     char hwinfo[HWINFO_MAX_SIZE + 1];
-    char hwinfoIntf[IFNAMSIZ + 1];
-    unsigned int hwinfoPhyid;
-    int ret;
 
     SWSS_LOG_ENTER();
 
@@ -377,22 +374,15 @@ sai_status_t initSaiPhyApi(swss::gearbox_phy_t *phy)
     attr.value.u32 = 0;
     attrs.push_back(attr);
 
-    ret = sscanf(phy->hwinfo.c_str(), "%" STR(IFNAMSIZ) "[^/]/%u", hwinfoIntf, &hwinfoPhyid);
-    if (ret != 2) {
-        SWSS_LOG_ERROR("BOX: hardware info doesn't match the 'interface_name/phyid' "
-                       "format");
-        return SAI_STATUS_FAILURE;
+    if( phy->hwinfo.length() > HWINFO_MAX_SIZE ) {
+       SWSS_LOG_ERROR( "hwinfo string attribute is too long." );
+       return SAI_STATUS_FAILURE;
     }
-
-    if (hwinfoPhyid > std::numeric_limits<uint16_t>::max()) {
-        SWSS_LOG_ERROR("BOX: phyid is bigger than maximum limit");
-        return SAI_STATUS_FAILURE;
-    }
-
-    strcpy(hwinfo, phy->hwinfo.c_str());
+    memset(hwinfo, 0, HWINFO_MAX_SIZE + 1);
+    strncpy(hwinfo, phy->hwinfo.c_str(), phy->hwinfo.length());
 
     attr.id = SAI_SWITCH_ATTR_SWITCH_HARDWARE_INFO;
-    attr.value.s8list.count = (uint32_t) phy->hwinfo.length();
+    attr.value.s8list.count = (uint32_t) phy->hwinfo.length() + 1;
     attr.value.s8list.list = (int8_t *) hwinfo;
     attrs.push_back(attr);
 
@@ -452,17 +442,21 @@ sai_status_t initSaiPhyApi(swss::gearbox_phy_t *phy)
 
     phy->phy_oid = sai_serialize_object_id(phyOid);
 
-    attr.id = SAI_SWITCH_ATTR_FIRMWARE_MAJOR_VERSION;
-    status = sai_switch_api->get_switch_attribute(phyOid, 1, &attr);
-    if (status != SAI_STATUS_SUCCESS)
-    {
-        SWSS_LOG_ERROR("BOX: Failed to get firmware major version:%d rtn:%d", phy->phy_id, status);
-        return status;
-    }
-    else
+    if (phy->firmware.length() != 0)
     {
-        phy->firmware_major_version = string(attr.value.chardata);
+        attr.id = SAI_SWITCH_ATTR_FIRMWARE_MAJOR_VERSION;
+        status = sai_switch_api->get_switch_attribute(phyOid, 1, &attr);
+        if (status != SAI_STATUS_SUCCESS)
+        {
+            SWSS_LOG_ERROR("BOX: Failed to get firmware major version for hwinfo:%s, phy:%d, rtn:%d",
+                           phy->hwinfo.c_str(), phy->phy_id, status);
+            return status;
+        }
+        else
+        {
+            phy->firmware_major_version = string(attr.value.chardata);
+        }
     }
-
     return status;
 }
+