Handle sensors that can not be found in SystemManager

When a sensor id is not managed in yaml the code tries to get it from
legacy SystemManager;
And when the sensor id can not be found in SystemManager, it returns
empty path, and cause segment fault.

This commit makes it return -EINVAL when path is empty, and thus the
code will handle this case properly without crash.

Resolves openbmc/openbmc#3062

Tested: Boot host without ipmid crash on Romulus.

Change-Id: I4240b9be54824543b5e795e898330aeb02c5eb90
Signed-off-by: Lei YU <mine260309@gmail.com>

1 files changed, 8 insertions, 1 deletions

diff --git a/sensorhandler.cpp b/sensorhandler.cpp
index 4fabac5..3a47e20 100644
--- a/sensorhandler.cpp
+++ b/sensorhandler.cpp
@@ -105,6 +105,13 @@ int legacy_dbus_openbmc_path(const char *type, const uint8_t num, dbus_interface
         goto final;
     }
 
+    if (strlen(str2) == 0)
+    {
+        // Path being empty occurs when the sensor id is not in SystemManager
+        r = -EINVAL;
+        goto final;
+    }
+
     r = get_bus_for_path(str2, &str1);
     if (r < 0) {
         fprintf(stderr, "Failed to get %s busname: %s\n",
@@ -311,7 +318,7 @@ uint8_t find_type_for_sensor_number(uint8_t num) {
     r = find_openbmc_path(num, &dbus_if);
     if (r < 0) {
         fprintf(stderr, "Could not find sensor %d\n", num);
-        return r;
+        return 0;
     }
     return get_type_from_interface(dbus_if);
 }