Description: Fix undefind sprintf usage

Author: Christoph Biedl <[email protected]> Last-Update: 2016-07-18 Documentation states appending to a buffer using sprintf (buf, "%s.foo", buf); results in undefined behaviour. Work around it.
RIPE-NCC · Aug 18, 2016 · 504e791 · 504e791
1 parent c57fb8c
commit 504e791
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Showing 3 changed files with 7 additions and 6 deletions.
diff --git a/bgpdump.c b/bgpdump.c
@@ -273,19 +273,20 @@ void process(BGPDUMP_ENTRY *entry) {
     char prefix[BGPDUMP_ADDRSTRLEN];
     char *bgp4mp_format;
     char *bgp4mp_subtype_format;
+    int len;
 
 	date=gmtime(&entry->time);
 	time2str(date,time_str_fixed);
 
     if (mode == 1) {
         // Timestamp mode
-        sprintf(time_str, "%lld", (long long)entry->time);
+        len = sprintf(time_str, "%lld", (long long)entry->time);
     } else {
-        time2str(date,time_str);
+        len = time2str(date,time_str);
     }
     // Appending microseconds to time_str if needed
     if (entry->type == BGPDUMP_TYPE_ZEBRA_BGP_ET) {
-        sprintf(time_str, "%s.%06ld", time_str, entry->ms);
+        sprintf(time_str + len, ".%06ld", entry->ms);
     }
 
 	if (mode==0)

diff --git a/util.c b/util.c
@@ -66,9 +66,9 @@ void err(const char *fmt, ...) { log(ERR, error); }
 void warn(const char *fmt, ...) { log(WARNING, warn); }
 void debug(const char *fmt, ...) { log(INFO, info); }
 
-void time2str(struct tm* date,char *time_str)
+int time2str(struct tm* date,char *time_str)
 {
-    sprintf(time_str, "%02d/%02d/%02d %02d:%02d:%02d", date->tm_mon+1, date->tm_mday, date->tm_year%100,
+    return sprintf(time_str, "%02d/%02d/%02d %02d:%02d:%02d", date->tm_mon+1, date->tm_mday, date->tm_year%100,
             date->tm_hour, date->tm_min, date->tm_sec);
 }
 

diff --git a/util.h b/util.h
@@ -38,7 +38,7 @@ char *fmt_ipv4(BGPDUMP_IP_ADDRESS addr, char *buffer);
 char *fmt_ipv6(BGPDUMP_IP_ADDRESS addr, char *buffer);
 void test_fmt_ip(void);
 
-void time2str(struct tm* date,char *time_str);
+int time2str(struct tm* date,char *time_str);
 int int2str(uint32_t value, char* str);
 void test_utils(void);