Remove redundant code in FPDFAnnot_GetInkListPath().

No need to validate the path index, as GetArrayAt() will do it anyway.
Also mark more pointers as const, use more ternary operators, and change
some 0 values to nullptrs.

Change-Id: Idfcf01daed50ae01b18237a2c0c6b54300668c9e
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium/+/79290
Reviewed-by: Daniel Hosseinian <dhoss@chromium.org>
Commit-Queue: Lei Zhang <thestig@chromium.org>

fpdfsdk/fpdf_annot.cpp

diff --git a/fpdfsdk/fpdf_annot.cpp b/fpdfsdk/fpdf_annot.cpp
index d6b66f7..6ae9c9f 100644
--- a/fpdfsdk/fpdf_annot.cpp
+++ b/fpdfsdk/fpdf_annot.cpp
@@ -297,16 +297,14 @@
   return pFormControl ? pForm->GetWidget(pFormControl) : nullptr;
 }
 
-CPDF_Array* GetInkList(FPDF_ANNOTATION annot) {
+const CPDF_Array* GetInkList(FPDF_ANNOTATION annot) {
   FPDF_ANNOTATION_SUBTYPE subtype = FPDFAnnot_GetSubtype(annot);
   if (subtype != FPDF_ANNOT_INK)
-    return 0;
+    return nullptr;
 
-  CPDF_Dictionary* annot_dict = GetAnnotDictFromFPDFAnnotation(annot);
-  if (!annot_dict)
-    return 0;
-
-  return annot_dict->GetArrayFor(pdfium::annotation::kInkList);
+  const CPDF_Dictionary* annot_dict = GetAnnotDictFromFPDFAnnotation(annot);
+  return annot_dict ? annot_dict->GetArrayFor(pdfium::annotation::kInkList)
+                    : nullptr;
 }
 
 }  // namespace
@@ -863,11 +861,8 @@
 
 FPDF_EXPORT unsigned long FPDF_CALLCONV
 FPDFAnnot_GetInkListCount(FPDF_ANNOTATION annot) {
-  CPDF_Array* ink_list = GetInkList(annot);
-  if (!ink_list)
-    return 0;
-
-  return ink_list->size();
+  const CPDF_Array* ink_list = GetInkList(annot);
+  return ink_list ? ink_list->size() : 0;
 }
 
 FPDF_EXPORT unsigned long FPDF_CALLCONV
@@ -875,15 +870,11 @@
                          unsigned long path_index,
                          FS_POINTF* buffer,
                          unsigned long length) {
-  unsigned long path_count = FPDFAnnot_GetInkListCount(annot);
-  if (path_index >= path_count)
-    return 0;
-
-  CPDF_Array* ink_list = GetInkList(annot);
+  const CPDF_Array* ink_list = GetInkList(annot);
   if (!ink_list)
     return 0;
 
-  CPDF_Array* path = ink_list->GetArrayAt(path_index);
+  const CPDF_Array* path = ink_list->GetArrayAt(path_index);
   if (!path)
     return 0;
 
@@ -895,7 +886,6 @@
       buffer[i].y = path->GetNumberAt(i * 2 + 1);
     }
   }
-
   return points_len;
 }