From 1f9855b2439d1ce39342bfe100fb07084ccd7ffd Mon Sep 17 00:00:00 2001
From: nick black <dankamongmen@gmail.com>
Date: Mon, 15 Jun 2020 23:52:34 -0400
Subject: [PATCH] ncplane_content: add diagnostics #520

---
 src/lib/internal.h  | 4 +++-
 src/lib/notcurses.c | 6 ++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/lib/internal.h b/src/lib/internal.h
index c015f3eb3..738ded425 100644
--- a/src/lib/internal.h
+++ b/src/lib/internal.h
@@ -760,7 +760,9 @@ calc_gradient_channels(uint64_t* channels, uint64_t ul, uint64_t ur,
 void nclog(const char* fmt, ...);
 
 // logging
-#define logerror(nc, fmt, ...) do{ if(nc->loglevel >= NCLOGLEVEL_ERROR){ nclog(__FILE__ ":%d:" fmt, __LINE__, ##__VA_ARGS__); } }while(0);
+#define logerror(nc, fmt, ...) do{ \
+  if((nc)->loglevel >= NCLOGLEVEL_ERROR){ \
+    nclog("%s:%d:" fmt, __func__, __LINE__, ##__VA_ARGS__); } }while(0);
 
 #ifdef __cplusplus
 }
diff --git a/src/lib/notcurses.c b/src/lib/notcurses.c
index 4604c7996..4927070ab 100644
--- a/src/lib/notcurses.c
+++ b/src/lib/notcurses.c
@@ -2095,9 +2095,12 @@ uint32_t* ncplane_rgba(const ncplane* nc, ncblitter_e blit,
 
 char* ncplane_contents(const ncplane* nc, int begy, int begx, int leny, int lenx){
   if(begy < 0 || begx < 0){
+    logerror(nc->nc, "Beginning coordinates (%d/%d) below 0\n", begy, begx);
     return NULL;
   }
   if(begx >= nc->lenx || begy >= nc->leny){
+    logerror(nc->nc, "Beginning coordinates (%d/%d) exceeded lengths (%d/%d)\n",
+             begy, begx, nc->leny, nc->lenx);
     return NULL;
   }
   if(lenx == -1){ // -1 means "to the end"; use all space available
@@ -2107,9 +2110,12 @@ char* ncplane_contents(const ncplane* nc, int begy, int begx, int leny, int lenx
     leny = nc->leny - begy;
   }
   if(lenx < 0 || leny < 0){ // no need to draw zero-size object, exit
+    logerror(nc->nc, "Lengths (%d/%d) below 0\n", leny, lenx);
     return NULL;
   }
   if(begx + lenx > nc->lenx || begy + leny > nc->leny){
+    logerror(nc->nc, "Ending coordinates (%d/%d) exceeded lengths (%d/%d)\n",
+             begy + leny, begx + lenx, nc->leny, nc->lenx);
     return NULL;
   }
   size_t retlen = 1;