term: respect LINES, COLUMNS; do not crash without vi/ve

2 files changed, 16 insertions, 6 deletions

diff --git a/doc/cha.1 b/doc/cha.1
index 435482b2..141d45ee 100644
--- a/doc/cha.1
+++ b/doc/cha.1
@@ -129,6 +129,10 @@ defaults to \fIdosansi\fR.
 \fBEDITOR\fR
 Used to determine the editor to use when the \fIexternal.editor\fR
 configuration option is not set.
+.TP
+\fBLINES, COLUMNS\fR
+When set, these are used as fallback values if window size detection
+fails.
 
 .SH CONFIGURATION
 Configuration options are described in \fBcha-config\fR(5).
diff --git a/src/local/term.nim b/src/local/term.nim
index 948d0f24..bc9919b8 100644
--- a/src/local/term.nim
+++ b/src/local/term.nim
@@ -597,14 +597,14 @@ proc generateSwapOutput(term: Terminal): string =
 
 proc hideCursor*(term: Terminal) =
   when TermcapFound:
-    if term.tc != nil:
+    if term.tc != nil and term.hascap vi:
       term.write(term.ccap vi)
       return
   term.write(CIVIS)
 
 proc showCursor*(term: Terminal) =
   when TermcapFound:
-    if term.tc != nil:
+    if term.tc != nil and term.hascap ve:
       term.write(term.ccap ve)
       return
   term.write(CNORM)
@@ -1277,10 +1277,16 @@ proc detectTermAttributes(term: Terminal; windowOnly: bool): TermStartResult =
       term.tname = "dosansi"
   var win: IOctl_WinSize
   if ioctl(term.istream.fd, TIOCGWINSZ, addr win) != -1:
-    term.attrs.width = int(win.ws_col)
-    term.attrs.height = int(win.ws_row)
-    term.attrs.ppc = int(win.ws_xpixel) div term.attrs.width
-    term.attrs.ppl = int(win.ws_ypixel) div term.attrs.height
+    if win.ws_col > 0:
+      term.attrs.width = int(win.ws_col)
+      term.attrs.ppc = int(win.ws_xpixel) div term.attrs.width
+    if win.ws_row > 0:
+      term.attrs.height = int(win.ws_row)
+      term.attrs.ppl = int(win.ws_ypixel) div term.attrs.height
+  if term.attrs.width == 0:
+    term.attrs.width = int(parseInt32(getEnv("COLUMNS")).get(0))
+  if term.attrs.height == 0:
+    term.attrs.height = int(parseInt32(getEnv("LINES")).get(0))
   if term.config.display.query_da1:
     let r = term.queryAttrs(windowOnly)
     if r.success: # DA1 success