From df65c8bcac2ea2ce084b498cc6437980679f28bc Mon Sep 17 00:00:00 2001
From: Joshua Potter <jrpotter2112@gmail.com>
Date: Sat, 25 Nov 2023 15:58:13 -0700
Subject: [PATCH] Ensure keys are alphanumeric, underscores, and do not begin
 with digits.

---
 README.md             |  4 ++--
 include/error.h       |  3 +++
 src/validator.c       | 18 ++++++++++++++++++
 test/test.c           |  2 ++
 test/test_validator.h | 37 +++++++++++++++++++++++++++++++++++++
 5 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 6dd62e9..d948083 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,6 @@ CLI utility for defining custom project initialization scripts.
 TODO:
 - [ ] Add evaluator tests.
 - [ ] Color output to console.
-- [ ] Ensure keys are alphanumeric, underscore
 
 ## Overview
 
@@ -120,7 +119,8 @@ a string (submitted with a newline).
 
 If the user were to enter, say `fieldvalue`, in response to the prompt,
 the `runner` script would then have access to an environment variable
-`FIELDNAME` set to `fieldvalue` on launch.
+`FIELDNAME` set to `fieldvalue` on launch. Field names should consist of
+alphanumeric characters or underscores, and may not start with a digit.
 
 #### Types
 
diff --git a/include/error.h b/include/error.h
index 3108cda..61b2111 100644
--- a/include/error.h
+++ b/include/error.h
@@ -37,6 +37,9 @@ enum ErrorCode {
   ERROR_VALIDATOR_TOP_LEVEL_NOT_OBJECT,
   /// A field in `spec.json` is not an object.
   ERROR_VALIDATOR_FIELD_NOT_OBJECT,
+  /// A field name in `spec.json` is not alphanumeric and beginning with a
+  /// non-digit.
+  ERROR_VALIDATOR_FIELD_NAME_INVALID,
   /// The `type` of a `spec.json` field is not a string.
   ERROR_VALIDATOR_FIELD_TYPE_INVALID,
   /// The `type` of a `spec.json` field does not correspond to a known prompt
diff --git a/src/validator.c b/src/validator.c
index 477bfb4..5d8f65a 100644
--- a/src/validator.c
+++ b/src/validator.c
@@ -1,5 +1,7 @@
 #include "validator.h"
 
+#include <ctype.h>
+
 #include "string_utils.h"
 
 static struct Error *read_field(const cJSON *const field, struct Field **out) {
@@ -12,6 +14,22 @@ static struct Error *read_field(const cJSON *const field, struct Field **out) {
     );
   }
 
+  if (isdigit(field->string[0])) {
+    return ERROR_NEW(
+      ERROR_VALIDATOR_FIELD_NAME_INVALID,
+      "Field names may not begin with a digit."
+    );
+  } else {
+    for (const char *c = field->string; *c; ++c) {
+      if (*c != '_' && !isalnum(*c)) {
+        return ERROR_NEW(
+          ERROR_VALIDATOR_FIELD_NAME_INVALID,
+          "Field names must consist of alphanumeric characters or underscores."
+        );
+      }
+    }
+  }
+
   struct Error *error = 0;
   *out = malloc(sizeof(struct Field));
   (*out)->key = field->string;
diff --git a/test/test.c b/test/test.c
index 55abe74..95dce04 100644
--- a/test/test.c
+++ b/test/test.c
@@ -36,6 +36,8 @@ int main(int argc, char *argv[]) {
   sput_enter_suite("validator");
   sput_run_test(test_validator_toplevel_not_object);
   sput_run_test(test_validator_field_not_object);
+  sput_run_test(test_validator_field_name_leading_digit);
+  sput_run_test(test_validator_field_name_non_alnum);
   sput_run_test(test_validator_field_type_invalid);
   sput_run_test(test_validator_field_type_unknown);
   sput_run_test(test_validator_valid_type_ci);
diff --git a/test/test_validator.h b/test/test_validator.h
index 9aaf0f2..02e21ac 100644
--- a/test/test_validator.h
+++ b/test/test_validator.h
@@ -52,6 +52,43 @@ static void test_validator_field_not_object() {
   test_validator_teardown(fixture);
 }
 
+static void test_validator_field_name_leading_digit() {
+  struct TestValidatorFixture *fixture = test_validator_setup(
+    "{"
+    "  \"1abc\": {"
+    "    \"type\": \"text\""
+    "  }"
+    "}"
+  );
+
+  struct Error *error = validate_spec_json(fixture->parsed, &fixture->prompts);
+  sput_fail_unless(
+    error->code == ERROR_VALIDATOR_FIELD_NAME_INVALID,
+    "field name leading digit"
+  );
+  error_free(error);
+
+  test_validator_teardown(fixture);
+}
+
+static void test_validator_field_name_non_alnum() {
+  struct TestValidatorFixture *fixture = test_validator_setup(
+    "{"
+    "  \"a~bc\": {"
+    "    \"type\": \"text\""
+    "  }"
+    "}"
+  );
+
+  struct Error *error = validate_spec_json(fixture->parsed, &fixture->prompts);
+  sput_fail_unless(
+    error->code == ERROR_VALIDATOR_FIELD_NAME_INVALID, "field name non alnum"
+  );
+  error_free(error);
+
+  test_validator_teardown(fixture);
+}
+
 static void test_validator_field_type_invalid() {
   struct TestValidatorFixture *fixture = test_validator_setup(
     "{"