Enhance error diagnostics about invalid syscalls in fault injection syntax

Validate syscall set before the whole fault injection syntax.

* filter_qualify.c (parse_inject_expression): Add const qualifier to
return type.  Return an empty string when no syscall set is specified.
(qualify_inject_common): Add const qualifier to "name".  Move
qualify_syscall_tokens invocation right after parse_inject_expression.
* tests/qual_fault-syntax.test: Update expected output.
* tests/qual_inject-syntax.test: Likewise.

filter_qualify.c

@@ -150,19 +150,20 @@ parse_inject_token(const char *const token, struct inject_opts *const fopts,
 	return true;
 }
 
-static char *
+static const char *
 parse_inject_expression(char *const str,
 			struct inject_opts *const fopts,
 			const bool fault_tokens_only)
 {
-	char *saveptr = NULL;
-	char *name = NULL;
+	if (str[0] == '\0' || str[0] == ':')
+		return "";
 
-	for (char *token = strtok_r(str, ":", &saveptr);
-	     token; token = strtok_r(NULL, ":", &saveptr)) {
-		if (!name)
-			name = token;
-		else if (!parse_inject_token(token, fopts, fault_tokens_only))
+	char *saveptr = NULL;
+	const char *name = strtok_r(str, ":", &saveptr);
+
+	char *token;
+	while ((token = strtok_r(NULL, ":", &saveptr))) {
+		if (!parse_inject_token(token, fopts, fault_tokens_only))
 			return NULL;
 	}
 
@@ -235,10 +236,17 @@ qualify_inject_common(const char *const str,
 		.step = 1
 	};
 	char *copy = xstrdup(str);
-	char *name = parse_inject_expression(copy, &opts, fault_tokens_only);
+	const char *name =
+		parse_inject_expression(copy, &opts, fault_tokens_only);
 	if (!name)
 		error_msg_and_die("invalid %s '%s'", description, str);
 
+	struct number_set *tmp_set =
+		alloc_number_set_array(SUPPORTED_PERSONALITIES);
+	qualify_syscall_tokens(name, tmp_set);
+
+	free(copy);
+
 	/* If neither of retval, error, or signal is specified, then ... */
 	if (!opts.data.flags) {
 		if (fault_tokens_only) {
@@ -251,12 +259,6 @@ qualify_inject_common(const char *const str,
 		}
 	}
 
-	struct number_set *tmp_set =
-		alloc_number_set_array(SUPPORTED_PERSONALITIES);
-	qualify_syscall_tokens(name, tmp_set);
-
-	free(copy);
-
 	/*
 	 * Initialize inject_vec according to tmp_set.
 	 * Merge tmp_set into inject_set.

tests/qual_fault-syntax.test

@@ -40,7 +40,7 @@ fail_with()
 		"strace -e fault=$* failed to handle an argument error properly"
 }
 
-for arg in , ,, ,,, \! \!, \!: \
+for arg in '' : :: ::: , ,, ,,, \! \!, \!: \
 	   invalid_syscall_name \
 	   invalid_syscall_name:when=3 \
 	   -1 \!-1 \
@@ -62,7 +62,7 @@ for arg in , ,, ,,, \! \!, \!: \
 		fail_with "$arg"
 done
 
-for arg in '' : :: ::: chdir:42 \!chdir:42 \
+for arg in chdir:42 \!chdir:42 \
 	   chdir:42:when=7 \
 	   chdir:invalid \
 	   chdir:invalid:when=8 \

tests/qual_inject-syntax.test

@@ -40,7 +40,7 @@ fail_with()
 		"strace -e inject=$* failed to handle an argument error properly"
 }
 
-for arg in '' , ,, ,,, : :: ::: \! \!, \!: \
+for arg in '' : :: ::: , ,, ,,, \! \!, \!: \
 	   invalid_syscall_name \
 	   invalid_syscall_name:when=3 \
 	   -1 \!-1 \
@@ -49,8 +49,20 @@ for arg in '' , ,, ,,, : :: ::: \! \!, \!: \
 	   -2:when=5 \
 	   32767 \!32767 \
 	   32767:when=6 \
-	   42 \
-	   chdir \
+	   file,nonsense \
+	   \!desc,nonsense \
+	   chdir,nonsense \
+	   \!chdir,nonsense \
+	   1,nonsense \
+	   \!1,nonsense \
+	   ; do
+	$STRACE -e inject="$arg" true 2> "$LOG" &&
+		fail_with "$arg"
+	LC_ALL=C grep -F "invalid system call '" < "$LOG" > /dev/null ||
+		fail_with "$arg"
+done
+
+for arg in 42 chdir \
 	   chdir:42 \!chdir:42 \
 	   chdir:42:when=7 \
 	   chdir:invalid \
@@ -94,12 +106,6 @@ for arg in '' , ,, ,,, : :: ::: \! \!, \!: \
 	   chdir:when=65536:error=30 \
 	   chdir:when=1+65536 \
 	   chdir:when=1+65536:error=31 \
-	   file,nonsense \
-	   \!desc,nonsense \
-	   chdir,nonsense \
-	   \!chdir,nonsense \
-	   1,nonsense \
-	   \!1,nonsense \
 	   chdir:retval=-1 \
 	   chdir:signal=0 \
 	   chdir:signal=129 \