From eeceeea7632dfdaded119f0716b17e3c4e235ba1 Mon Sep 17 00:00:00 2001
From: Ben Webb <ben@salilab.org>
Date: Fri, 7 Feb 2025 21:35:43 -0800
Subject: [PATCH 1/2] Don't ignore errors reported by skip_bytes()

If our read or skip callback reports an error
here we should return immediately, rather than
ignoring the error.
---
 cmp.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/cmp.c b/cmp.c
index f8712da..0aebd74 100644
--- a/cmp.c
+++ b/cmp.c
@@ -2739,7 +2739,9 @@ bool cmp_skip_object(cmp_ctx_t *ctx, cmp_object_t *obj) {
             break;
         }
 
-        skip_bytes(ctx, size);
+        if (!skip_bytes(ctx, size)) {
+          return false;
+        }
       }
   }
 
@@ -2806,7 +2808,9 @@ bool cmp_skip_object_flat(cmp_ctx_t *ctx, cmp_object_t *obj) {
               break;
           }
 
-          skip_bytes(ctx, size);
+          if (!skip_bytes(ctx, size)) {
+            return false;
+          }
         }
     }
 
@@ -2883,7 +2887,9 @@ bool cmp_skip_object_no_limit(cmp_ctx_t *ctx) {
               break;
           }
 
-          skip_bytes(ctx, size);
+          if (!skip_bytes(ctx, size)) {
+            return false;
+          }
         }
     }
 
@@ -2975,7 +2981,9 @@ bool cmp_skip_object_limit(cmp_ctx_t *ctx, cmp_object_t *obj, uint32_t limit) {
               break;
           }
 
-          skip_bytes(ctx, size);
+          if (!skip_bytes(ctx, size)) {
+            return false;
+          }
         }
     }
 

From b2e01867a4e3412db3002c5fe38d1f2ba5d1ba01 Mon Sep 17 00:00:00 2001
From: Ben Webb <ben@salilab.org>
Date: Sat, 8 Feb 2025 23:08:13 -0800
Subject: [PATCH 2/2] Add test for skip_bytes() fix

---
 test/test.c  |  3 ++-
 test/tests.c | 31 +++++++++++++++++++++++++++++++
 test/tests.h |  1 +
 3 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/test/test.c b/test/test.c
index 89d263e..13fd597 100644
--- a/test/test.c
+++ b/test/test.c
@@ -33,7 +33,7 @@ THE SOFTWARE.
 
 int main(void) {
   /* Use the old CMocka API because Travis' latest Ubuntu is Trusty */
-  const UnitTest tests[17] = {
+  const UnitTest tests[18] = {
     unit_test(test_msgpack),
     unit_test(test_fixedint),
     unit_test(test_numbers),
@@ -51,6 +51,7 @@ int main(void) {
 #endif
 
     unit_test(test_skipping),
+    unit_test(test_skip_bytes),
     unit_test(test_deprecated_limited_skipping),
     unit_test(test_errors),
     unit_test(test_version),
diff --git a/test/tests.c b/test/tests.c
index 9e1046f..d9f96b1 100644
--- a/test/tests.c
+++ b/test/tests.c
@@ -4696,6 +4696,37 @@ void test_skipping(void **state) {
   teardown_cmp_and_buf(&cmp, &buf);
 }
 
+void test_skip_bytes(void **state) {
+  buf_t buf;
+  cmp_ctx_t cmp;
+  cmp_object_t obj;
+
+  (void)state;
+
+  setup_cmp_and_buf(&cmp, &buf);
+
+  M_BufferEnsureCapacity(&buf, 100);
+
+  /* Write the string marker but omit the string contents. This should ensure
+     that skip_bytes() (and thus cmp_skip_object*) will fail when it tries
+     to skip the string. */
+  assert_true(cmp_write_str_marker(&cmp, 20));
+
+  M_BufferSeek(&buf, 0);
+  assert_false(cmp_skip_object(&cmp, &obj));
+
+  M_BufferSeek(&buf, 0);
+  assert_false(cmp_skip_object_flat(&cmp, &obj));
+
+  M_BufferSeek(&buf, 0);
+  assert_false(cmp_skip_object_no_limit(&cmp));
+
+  M_BufferSeek(&buf, 0);
+  assert_false(cmp_skip_object_limit(&cmp, &obj, 1));
+
+  teardown_cmp_and_buf(&cmp, &buf);
+}
+
 void test_deprecated_limited_skipping(void **state) {
   buf_t buf;
   cmp_ctx_t cmp;
diff --git a/test/tests.h b/test/tests.h
index 57f458c..ec9535d 100644
--- a/test/tests.h
+++ b/test/tests.h
@@ -38,6 +38,7 @@ void test_obj(void **state);
 void test_float_flip(void **state);
 #endif
 void test_skipping(void **state);
+void test_skip_bytes(void **state);
 void test_deprecated_limited_skipping(void **state);
 void test_errors(void **state);
 void test_version(void **state);