win32: work around problem with ConEmu

When running the busybox-w32 shell in ConEmu, if:

- ANSI emulation is disabled (which it will be, by default)
- a non-builtin command is run

there is a window of a few seconds after the command completes during
which ConEmu is in XTerm mode.  During this time any attempt to use
the arrows keys will result in [A[B[C[D appearing.  This appears to
be a common problem:

   https://github.com/Maximus5/ConEmu/issues/2316

Try to detect if we're running under ConEmu and alter the default
behaviour to prefer ANSI emulation.  The user can override this
preference by setting BB_SKIP_ANSI_EMULATION if desired.

By a quirk of fate, old MSYS2 programs (from 2021) which required
a workaround in busybox-w32 (commit 54d2ea4b4) are immune to the
problem with ConEmu.

(GitHib issue #287)

1 files changed, 3 insertions, 1 deletions

diff --git a/win32/winansi.c b/win32/winansi.c
index 27559e3f5..1400ea3bb 100644
--- a/win32/winansi.c
+++ b/win32/winansi.c
@@ -77,7 +77,9 @@ int skip_ansi_emulation(int reset)
 
         if (skip < 0 || reset) {
                 const char *var = getenv(BB_SKIP_ANSI_EMULATION);
-                int dflt = is_wine() ? 0 : CONFIG_SKIP_ANSI_EMULATION_DEFAULT;
+                int dflt = CONFIG_SKIP_ANSI_EMULATION_DEFAULT;
+                if (is_wine() || getenv("CONEMUPID") != NULL)
+                        dflt = 0;
                 skip = var == NULL ? dflt : atoi(var);
                 if (skip < 0 || skip > 2)
                         skip = 0;