From: Jason Hood <jadoxa@yahoo.com.au>
Date: Tue, 12 Feb 2019 13:18:47 +0000 (+1000)
Subject: Prevent redirecting to NUL crash
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=87594f81d6f63556f2644fff4ed493aaac97974c;p=jq

Prevent redirecting to NUL crash

Windows regards the `NUL` device as tty, which causes `WriteFile` to
fail (the bytes written pointer cannot be `NULL` in this case).  Tweak
the color test to ensure tty is accurate.
---

diff --git a/src/main.c b/src/main.c
index 233d130..b8c2857 100644
--- a/src/main.c
+++ b/src/main.c
@@ -533,21 +533,19 @@ int main(int argc, char* argv[]) {
 
 #ifdef USE_ISATTY
   if (isatty(STDOUT_FILENO)) {
-    dumpopts |= JV_PRINT_ISATTY;
 #ifndef WIN32
-  /* Disable color by default on Windows builds as Windows
-     terminals tend not to display it correctly */
-    dumpopts |= JV_PRINT_COLOR;
+    dumpopts |= JV_PRINT_ISATTY | JV_PRINT_COLOR;
 #else
-    // Unless ANSICON is installed, or it's Windows 10
-    if (getenv("ANSICON") != NULL)
-      dumpopts |= JV_PRINT_COLOR;
-    else {
-      DWORD mode;
-      HANDLE con = GetStdHandle(STD_OUTPUT_HANDLE);
-      if (GetConsoleMode(con, &mode) &&
-	  SetConsoleMode(con, mode | 4/*ENABLE_VIRTUAL_TERMINAL_PROCESSING*/))
-	dumpopts |= JV_PRINT_COLOR;
+  /* Verify we actually have the console, as the NUL device is also regarded as
+     tty.  Windows can handle color if ANSICON (or ConEmu) is installed, or
+     Windows 10 supports the virtual terminal */
+    DWORD mode;
+    HANDLE con = GetStdHandle(STD_OUTPUT_HANDLE);
+    if (GetConsoleMode(con, &mode)) {
+      dumpopts |= JV_PRINT_ISATTY;
+      if (getenv("ANSICON") != NULL ||
+          SetConsoleMode(con, mode | 4/*ENABLE_VIRTUAL_TERMINAL_PROCESSING*/))
+        dumpopts |= JV_PRINT_COLOR;
     }
 #endif
   }