BUG/MINOR: trace: stop rewriting argv with -dt

When using trace with -dt, the trace_parse_cmd() function is doing a
strtok which write \0 into the argv string.

When using the mworker mode, and reloading, argv was modified and the
trace won't work anymore because the first : is replaced by a '\0'.

This patch fixes the issue by allocating a temporary string so we don't
modify the source string directly. It also replace strtok by its
reentrant version strtok_r.

Must be backported as far as 2.9.

include/haproxy/trace.h

@@ -190,7 +190,7 @@ void trace_no_cb(enum trace_level level, uint64_t mask, const struct trace_sourc
 
 void trace_register_source(struct trace_source *source);
 
-int trace_parse_cmd(char *arg, char **errmsg);
+int trace_parse_cmd(const char *arg_src, char **errmsg);
 
 /* return a single char to describe a trace state */
 static inline char trace_state_char(enum trace_state st)

src/trace.c

@@ -966,11 +966,22 @@ void _trace_parse_cmd(struct trace_source *src, int level, int verbosity)
  *
  * Returns 0 on success else non-zero.
  */
-int trace_parse_cmd(char *arg, char **errmsg)
+int trace_parse_cmd(const char *arg_src, char **errmsg)
 {
 	char *str;
+	char *arg, *oarg;
+	char *saveptr;
 
-	if (!arg) {
+	if (arg_src) {
+		/* keep a copy of the ptr for strtok */
+		oarg = arg = strdup(arg_src);
+		if (!arg) {
+			memprintf(errmsg, "Can't allocate !");
+			return 1;
+		}
+	}
+
+	if (!arg_src) {
 		/* No trace specification, activate all sources on error level. */
 		struct trace_source *src = NULL;
 
@@ -979,7 +990,7 @@ int trace_parse_cmd(char *arg, char **errmsg)
 		return 0;
 	}
 
-	while ((str = strtok(arg, ","))) {
+	while ((str = strtok_r(arg, ",", &saveptr))) {
 		struct trace_source *src = NULL;
 		char *field, *name;
 		char *sep;
@@ -1000,6 +1011,7 @@ int trace_parse_cmd(char *arg, char **errmsg)
 			src = trace_find_source(name);
 			if (!src) {
 				memprintf(errmsg, "unknown trace source '%s'", name);
+				ha_free(&oarg);
 				return 1;
 			}
 		}
@@ -1022,6 +1034,7 @@ int trace_parse_cmd(char *arg, char **errmsg)
 			level = trace_parse_level(field);
 			if (level < 0) {
 				memprintf(errmsg, "no such trace level '%s', available levels are 'error', 'user', 'proto', 'state', 'data', and 'developer'", field);
+				ha_free(&oarg);
 				return 1;
 			}
 		}
@@ -1033,6 +1046,7 @@ int trace_parse_cmd(char *arg, char **errmsg)
 		field = str;
 		if (strchr(field, ':')) {
 			memprintf(errmsg, "too many double-colon separators in trace definition");
+			ha_free(&oarg);
 			return 1;
 		}
 
@@ -1049,6 +1063,7 @@ int trace_parse_cmd(char *arg, char **errmsg)
 					memprintf(errmsg, "%s, %s'%s'", *errmsg, (nd + 1)->name ? "" : "and ", nd->name);
 			}
 
+			ha_free(&oarg);
 			return 1;
 		}
 
@@ -1064,7 +1079,7 @@ int trace_parse_cmd(char *arg, char **errmsg)
 		/* Reset arg to NULL for strtok. */
 		arg = NULL;
 	}
-
+	ha_free(&oarg);
 	return 0;
 }