fix: fix ls_args_parse segfault on required positional args

2 files changed, 32 insertions, 5 deletions

diff --git a/ls_args.h b/ls_args.h
index 1c9301a..a02b3d1 100644
--- a/ls_args.h
+++ b/ls_args.h
@@ -576,11 +576,21 @@ int ls_args_parse(ls_args* a, int argc, char** argv) {
 
     for (i = 0; i < (int)a->args_len; ++i) {
         if (a->args[i].mode == LS_ARGS_REQUIRED && !a->args[i].found) {
-            const size_t len = 64 + strlen(a->args[i].match.name.long_opt);
-            a->_allocated_error = LS_REALLOC(a->_allocated_error, len);
-            memset(a->_allocated_error, 0, len);
-            sprintf(a->_allocated_error, "Required argument '--%s' not found",
-                a->args[i].match.name.long_opt);
+            size_t len;
+            if (a->args[i].is_pos) {
+                len = 64;
+                a->_allocated_error = LS_REALLOC(a->_allocated_error, len);
+                memset(a->_allocated_error, 0, len);
+                sprintf(a->_allocated_error, "Required positional argument not found (argument %d)",
+                    a->args[i].match.pos);
+            } else {
+                len = 64 + strlen(a->args[i].match.name.long_opt);
+                a->_allocated_error = LS_REALLOC(a->_allocated_error, len);
+                memset(a->_allocated_error, 0, len);
+                sprintf(a->_allocated_error, "Required argument '--%s' not found",
+                    a->args[i].match.name.long_opt);
+            }
+
             a->last_error = a->_allocated_error;
             return 0;
         }
diff --git a/tests/tests.c b/tests/tests.c
index 78c8f24..0a136b1 100644
--- a/tests/tests.c
+++ b/tests/tests.c
@@ -113,6 +113,23 @@ TEST_CASE(too_many_positional_after_double_dash) {
     return 0;
 }
 
+TEST_CASE(basic_args_positional_required_error) {
+    int help = 0;
+    const char* first;
+    ls_args args;
+    char* argv[] = { "./hello", "world", NULL };
+    int argc = sizeof(argv) / sizeof(*argv) - 1;
+
+    ls_args_init(&args);
+    ls_args_pos_string(&args, 0, &first, "First positional argument", LS_ARGS_REQUIRED);
+
+    ASSERT(!ls_args_parse(&args, argc, argv));
+
+    ASSERT_STR_EQ(args.last_error, "Required positional argument not found (argument 0)");
+    ls_args_free(&args);
+    return 0;
+}
+
 TEST_CASE(basic_args_positional_only_error) {
     int help = 0;
     const char* input;