fix: find and source ~/.jq file on windows (fixes #3104)

Author: kirkoman

docs/content/manual/manual.yml

@@ -3662,7 +3662,8 @@ sections:
       For example, with `-L$HOME/.jq` a module `foo` can be found in
       `$HOME/.jq/foo.jq` and `$HOME/.jq/foo/foo.jq`.
 
-      If `$HOME/.jq` is a file, it is sourced into the main program.
+      If `.jq` exists in the user's home directory, and is a file (not a
+      directory), it is automatically sourced into the main program.
 
     entries:
       - title: "`import RelativePathString as NAME [<metadata>];`"

jq.1.prebuilt

@@ -420,14 +420,16 @@ int load_program(jq_state *jq, struct locfile* src, block *out_block) {
     return 1;
   }
 
-  char* home = getenv("HOME");
-  if (home) {    // silently ignore no $HOME
-    /* Import ~/.jq as a library named "" found in $HOME */
+  jv home = get_home();
+  if (jv_is_valid(home)) {
+    /* Import ~/.jq as a library named "" found in $HOME or %USERPROFILE% */
     block import = gen_import_meta(gen_import("", NULL, 0),
         gen_const(JV_OBJECT(
             jv_string("optional"), jv_true(),
-            jv_string("search"), jv_string(home))));
+            jv_string("search"), home)));
     program = BLOCK(import, program);
+  } else {    // silently ignore if home dir not determined
+    jv_free(home);
   }
 
   nerrors = process_dependencies(jq, jq_get_jq_origin(jq), jq_get_prog_origin(jq), &program, &lib_state);

src/linker.c

@@ -359,6 +359,17 @@ if [ "$(HOME="$mods/home1" $VALGRIND $Q $JQ -nr fg)" != foobar ]; then
     exit 1
 fi
 
+if $msys || $mingw; then
+    HOME_BAK=$HOME
+    unset HOME
+    if [ "$(USERPROFILE="$mods/home1" $VALGRIND $Q $JQ -nr foo)" != baz ]; then
+        echo "Bug #3104 regressed (sourcing %USERPROFILE%/.jq on Windows)" 1>&2
+        exit 1
+    fi
+    export HOME=$HOME_BAK
+    unset HOME_BAK
+fi
+
 if [ $(HOME="$mods/home1" $VALGRIND $Q $JQ --debug-dump-disasm -n fg | grep '^[a-z]' | wc -l) -ne 3 ]; then
     echo "Binding too many defs into program" 1>&2
     exit 1