bash: preserve an existing ENV value

Our bash shell integration code uses ENV (in POSIX mode) to bootstrap
our shell integration script. This had the side effect of overwriting an
existing ENV value.

This change preserves ENV by storing it temporarily in GHOSTTY_BASH_ENV.

Note that this doesn't enable --posix mode support for automatic shell
integration. (--posix does work; we just skip shell integration when
that flag is specified.) We can reconsider implementing full --posix
support separately.

2 files changed, 27 insertions, 0 deletions

diff --git a/src/shell-integration/bash/ghostty.bash b/src/shell-integration/bash/ghostty.bash
index aacf37c3a..ca5a012c6 100644
--- a/src/shell-integration/bash/ghostty.bash
+++ b/src/shell-integration/bash/ghostty.bash
@@ -26,6 +26,12 @@ if [ -n "$GHOSTTY_BASH_INJECT" ]; then
   builtin declare __ghostty_bash_flags="$GHOSTTY_BASH_INJECT"
   builtin unset ENV GHOSTTY_BASH_INJECT
 
+  # Restore an existing ENV that was replaced by the shell integration code.
+  if [[ -n "$GHOSTTY_BASH_ENV" ]]; then
+    builtin export ENV=$GHOSTTY_BASH_ENV
+    builtin unset GHOSTTY_BASH_ENV
+  fi
+
   # Restore bash's default 'posix' behavior. Also reset 'inherit_errexit',
   # which doesn't happen as part of the 'posix' reset.
   builtin set +o posix
diff --git a/src/termio/shell_integration.zig b/src/termio/shell_integration.zig
index 469ff2859..438c2a0ea 100644
--- a/src/termio/shell_integration.zig
+++ b/src/termio/shell_integration.zig
@@ -340,6 +340,11 @@ fn setupBash(
         }
     }
 
+    // Preserve an existing ENV value. We're about to overwrite it.
+    if (env.get("ENV")) |v| {
+        try env.put("GHOSTTY_BASH_ENV", v);
+    }
+
     // Set our new ENV to point to our integration script.
     var path_buf: [std.fs.max_path_bytes]u8 = undefined;
     const integ_dir = try std.fmt.bufPrint(
@@ -502,6 +507,22 @@ test "bash: HISTFILE" {
     }
 }
 
+test "bash: ENV" {
+    const testing = std.testing;
+    var arena = ArenaAllocator.init(testing.allocator);
+    defer arena.deinit();
+    const alloc = arena.allocator();
+
+    var env = EnvMap.init(alloc);
+    defer env.deinit();
+
+    try env.put("ENV", "env.sh");
+
+    _ = try setupBash(alloc, .{ .shell = "bash" }, ".", &env);
+    try testing.expectEqualStrings("./shell-integration/bash/ghostty.bash", env.get("ENV").?);
+    try testing.expectEqualStrings("env.sh", env.get("GHOSTTY_BASH_ENV").?);
+}
+
 test "bash: additional arguments" {
     const testing = std.testing;
     var arena = ArenaAllocator.init(testing.allocator);