1 /**
2 * Copyright © 2020 IBM Corporation
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "presence_service.hpp"
18
19 #include "types.hpp"
20 #include "utility.hpp"
21
22 namespace phosphor::power::regulators
23 {
24
isPresent(const std::string & inventoryPath)25 bool DBusPresenceService::isPresent(const std::string& inventoryPath)
26 {
27 // Initially assume hardware is not present
28 bool present{false};
29
30 // Try to find cached presence value
31 auto it = cache.find(inventoryPath);
32 if (it != cache.end())
33 {
34 present = it->second;
35 }
36 else
37 {
38 // Get presence from D-Bus interface/property
39 try
40 {
41 util::getProperty(INVENTORY_IFACE, PRESENT_PROP, inventoryPath,
42 INVENTORY_MGR_IFACE, bus, present);
43 }
44 catch (const sdbusplus::exception_t& e)
45 {
46 // If exception type is expected and indicates hardware not present
47 if (isExpectedException(e))
48 {
49 present = false;
50 }
51 else
52 {
53 // Re-throw unexpected exception
54 throw;
55 }
56 }
57
58 // Cache presence value
59 cache[inventoryPath] = present;
60 }
61
62 return present;
63 }
64
isExpectedException(const sdbusplus::exception_t & e)65 bool DBusPresenceService::isExpectedException(const sdbusplus::exception_t& e)
66 {
67 // Initially assume exception is not one of the expected types
68 bool isExpected{false};
69
70 // If the D-Bus error name is set within the exception
71 if (e.name() != nullptr)
72 {
73 // Check if the error name is one of the expected values when hardware
74 // is not present.
75 //
76 // Sometimes the object path does not exist. Sometimes the object path
77 // exists, but it does not implement the D-Bus interface that contains
78 // the present property. Both of these cases result in exceptions.
79 //
80 // In the case where the interface is not implemented, the systemd
81 // documentation seems to indicate that the error name should be
82 // SD_BUS_ERROR_UNKNOWN_INTERFACE. However, in OpenBMC the
83 // SD_BUS_ERROR_UNKNOWN_PROPERTY error name can occur.
84 std::string name = e.name();
85 if ((name == SD_BUS_ERROR_UNKNOWN_OBJECT) ||
86 (name == SD_BUS_ERROR_UNKNOWN_INTERFACE) ||
87 (name == SD_BUS_ERROR_UNKNOWN_PROPERTY))
88 {
89 isExpected = true;
90 }
91 }
92
93 return isExpected;
94 }
95
96 } // namespace phosphor::power::regulators
97