paranoia mode for strcmp

3 files changed, 24 insertions, 6 deletions

diff --git a/common.c b/common.c
index e6c2113..439540d 100644
--- a/common.c
+++ b/common.c
@@ -3,6 +3,7 @@
 #include <glcdskin/type.h>
 
 #include <vdr/plugin.h>
+#include <string.h>
 
 #if APIVERSNUM < 10503
 #include <locale.h>
@@ -141,3 +142,18 @@ GLCD::cType DurationType(int Index, const std::string &Format)
     }
     return false;
 }
+
+int ParanoiaStrcmp(const char *s1, const char *s2)
+{
+    if (! s1 || ! s2)
+        return -1;
+    
+    // s1 must be under 'our' control (and thus valid), s2 may be a string w/ unexpected content
+    size_t n = strlen(s1);
+    
+    int rv = strncmp(s1, s2, n);
+    if (rv == 0)
+        return (s2[n] == '\0') ? 0 : -1;
+    else
+        return rv;
+}
diff --git a/common.h b/common.h
index 579da60..6412d17 100644
--- a/common.h
+++ b/common.h
@@ -1,2 +1,3 @@
 GLCD::cType TimeType(time_t Time, const std::string &Format);
 GLCD::cType DurationType(int Index, const std::string &Format);
+int ParanoiaStrcmp(const char *s1, const char *s2);
diff --git a/service.c b/service.c
index 9399e75..15d761c 100644
--- a/service.c
+++ b/service.c
@@ -12,6 +12,7 @@
 #include <limits>
 
 #include "service.h"
+#include "common.h"
 
 #include <vdr/plugin.h>
 
@@ -269,9 +270,9 @@ bool cGraphLCDService::NeedsUpdate(uint64_t CurrentTime)
                 if (
                         (currRTSData.rds_info != checkRTSData.rds_info) ||
                         (currRTSData.rds_pty != checkRTSData.rds_pty) ||
-                        (checkRTSData.rds_text   && (strcmp(currRTSData.rds_text, checkRTSData.rds_text) != 0)) ||
-                        (checkRTSData.rds_title  && (strcmp(currRTSData.rds_title, checkRTSData.rds_title) != 0)) ||
-                        (checkRTSData.rds_artist && (strcmp(currRTSData.rds_artist, checkRTSData.rds_artist) != 0))
+                        (ParanoiaStrcmp(currRTSData.rds_text, checkRTSData.rds_text) != 0) ||
+                        (ParanoiaStrcmp(currRTSData.rds_title, checkRTSData.rds_title) != 0) ||
+                        (ParanoiaStrcmp(currRTSData.rds_artist, checkRTSData.rds_artist) != 0)
                   )
                 {
                     currRTSData.rds_info   = checkRTSData.rds_info;
@@ -300,9 +301,9 @@ bool cGraphLCDService::NeedsUpdate(uint64_t CurrentTime)
             if (cPluginManager::CallFirstService("LcrService-v1.0", &checkLcrData)) {
                 lcrActive = true;
                 if (
-                        (((const char*)checkLcrData.destination) && (strcmp(currLcrData.destination, checkLcrData.destination) != 0)) ||
-                        (((const char*)checkLcrData.price)       && (strcmp(currLcrData.price, checkLcrData.price) != 0)) ||
-                        (((const char*)checkLcrData.pulse)       && (strcmp(currLcrData.pulse, checkLcrData.pulse) != 0))
+                        (ParanoiaStrcmp(currLcrData.destination, checkLcrData.destination) != 0) ||
+                        (ParanoiaStrcmp(currLcrData.price, checkLcrData.price) != 0) ||
+                        (ParanoiaStrcmp(currLcrData.pulse, checkLcrData.pulse) != 0)
                   )
                 {
                     currLcrData.destination = checkLcrData.destination;