Properly detect failure to open logs. Avoid trying to write on failure.

Author: jduck

instruments/base/base.c

@@ -36,8 +36,10 @@ static char logfile[] = "/data/local/tmp/adbi.log";
 static void logmsgtofile(char *msg)
 {
 	int fp = open(logfile, O_WRONLY|O_APPEND);
-	write(fp, msg, strlen(msg));
-	close(fp);
+    if (fp != -1) {
+	    write(fp, msg, strlen(msg));
+	    close(fp);
+    }
 }
 
 static void logmsgtostdout(char *msg)

instruments/example/epoll.c

@@ -32,9 +32,9 @@
 #undef log
 
 #define log(...) \
-        {FILE *fp = fopen("/data/local/tmp/adbi_example.log", "a+");\
+        {FILE *fp = fopen("/data/local/tmp/adbi_example.log", "a+"); if (fp) {\
         fprintf(fp, __VA_ARGS__);\
-        fclose(fp);}
+        fclose(fp);}}
 
 
 // this file is going to be compiled into a thumb mode binary