If you have config with an implicit bool like:

  [trace2]
  envvars

we'll segfault, as we unconditionally try to xstrdup() the value. We
should instead detect and complain, as a boolean value has no meaning
here. The same is true for every variable in tr2_sysenv_settings (and
this patch covers them all, as we check them in a loop).

Signed-off-by: Jeff King <redacted>
---
 trace2/tr2_sysenv.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/trace2/tr2_sysenv.c b/trace2/tr2_sysenv.c
index d3ecac2772..048cdd5438 100644
--- a/trace2/tr2_sysenv.c
+++ b/trace2/tr2_sysenv.c

@@ -68,6 +68,8 @@ static int tr2_sysenv_cb(const char *key, const char *value,
 
 	for (k = 0; k < ARRAY_SIZE(tr2_sysenv_settings); k++) {
 		if (!strcmp(key, tr2_sysenv_settings[k].git_config_name)) {
+			if (!value)
+				return config_error_nonbool(key);
 			free(tr2_sysenv_settings[k].value);
 			tr2_sysenv_settings[k].value = xstrdup(value);
 			return 0;

-- 
2.43.0.664.ga12c899002