Give reason while file open failed.

src/ports/SkOSFile_stdio.cpp

Index: src/ports/SkOSFile_stdio.cpp
diff --git a/src/ports/SkOSFile_stdio.cpp b/src/ports/SkOSFile_stdio.cpp
index 5b497d417a93683d3fadc8a48f49d871edffd862..b7268a3f5b35975d1aba3c7857b1ee83a37622e2 100644
--- a/src/ports/SkOSFile_stdio.cpp
+++ b/src/ports/SkOSFile_stdio.cpp
@@ -32,7 +32,12 @@ SkFILE* sk_fopen(const char path[], SkFILE_Flags flags) {
 
     //TODO: on Windows fopen is just ASCII or the current code page,
     //convert to utf16 and use _wfopen
-    return (SkFILE*)::fopen(path, perm);
+    SkFILE* file = (SkFILE*)::fopen(path, perm);
+    if (nullptr == file) {
+        SkDEBUGF(("sk_fopen: fopen(%s, %s) returned NULL errno:%d :%s\n",
+                                 path, perm,                errno, strerror(errno)));

[djsollen, 2015/09/02 18:44:06]

fix spacing but otherwise lgtm

[bungeman-skia, 2015/09/02 19:35:54]

Done.

+    }
+    return file;
 }
 
 char* sk_fgets(char* str, int size, SkFILE* f) {