Make it harder to misinterpret semantics of boolean environment settings

Closes #502.

Co-authored-by: Steffen Dettmer <steffen.dettmer@rail.bombardier.com>

diff --git a/src/conf.c b/src/conf.c
index 92fe34bd630e3e035292308afe209d7aec1bfb1d..a990c9200ff5ed78a3511e8b167322cb260e3be2 100644 (file)
--- a/src/conf.c
+++ b/src/conf.c
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2019 Joel Rosdahl
+// Copyright (C) 2011-2020 Joel Rosdahl
 //
 // This program is free software; you can redistribute it and/or modify it
 // under the terms of the GNU General Public License as published by the Free
@@ -39,15 +39,15 @@ find_env_to_conf(const char *name)
 
 static enum handle_conf_result
 handle_conf_setting(struct conf *conf, const char *key, const char *value,
-                    char **errmsg, bool from_env_variable, bool negate_boolean,
-                    const char *origin)
+                    char **errmsg, const char *env_var_name,
+                    bool negate_boolean, const char *origin)
 {
        const struct conf_item *item = find_conf(key);
        if (!item) {
                return HANDLE_CONF_UNKNOWN;
        }
 
-       if (from_env_variable && item->parser == confitem_parse_bool) {
+       if (env_var_name && item->parser == confitem_parse_bool) {
                // Special rule for boolean settings from the environment: "0", "false",
                // "disable" and "no" (case insensitive) are invalid, and all other values
                // mean true.
@@ -57,7 +57,13 @@ handle_conf_setting(struct conf *conf, const char *key, const char *value,
                // enabled.
                if (str_eq(value, "0") || strcasecmp(value, "false") == 0
                    || strcasecmp(value, "disable") == 0 || strcasecmp(value, "no") == 0) {
-                       fatal("invalid boolean environment variable value \"%s\"", value);
+                       fatal(
+                               "invalid boolean environment variable value \"%s\" for CCACHE_%s%s"
+                               " (did you mean to set \"CCACHE_%s%s=true\"?)",
+                               value,
+                               negate_boolean ? "NO" : "",
+                               env_var_name, negate_boolean ? "" : "NO",
+                               env_var_name);
                }
 
                bool *boolvalue = (bool *)((char *)conf + item->offset);
@@ -218,7 +224,7 @@ conf_read(struct conf *conf, const char *path, char **errmsg)
                bool ok = parse_line(buf, &key, &value, &errmsg2);
                if (ok && key) { // key == NULL if comment or blank line.
                        hcr =
-                               handle_conf_setting(conf, key, value, &errmsg2, false, false, path);
+                               handle_conf_setting(conf, key, value, &errmsg2, NULL, false, path);
                        ok = hcr != HANDLE_CONF_FAIL; // unknown is OK
                }
                free(key);
@@ -274,8 +280,8 @@ conf_update_from_environment(struct conf *conf, char **errmsg)
 
                char *errmsg2 = NULL;
                enum handle_conf_result hcr = handle_conf_setting(
-                       conf, env_to_conf_item->conf_name, q, &errmsg2, true, negate,
-                       "environment");
+                       conf, env_to_conf_item->conf_name, q, &errmsg2,
+                       env_to_conf_item->env_name, negate, "environment");
                if (hcr != HANDLE_CONF_OK) {
                        *errmsg = format("%s: %s", key, errmsg2);
                        free(errmsg2);