ash,hush: use HOME for tab completion and promptstilde

ash and hush correctly use the value of HOME for tilde expansion.
However the line editing code in libbb obtains the user's home
directory by calling getpwuid().  Thus tildes in tab completion
and prompts may be interpreted differently than in tilde expansion.

When the line editing code is invoked from a shell make it use the
shell's interpretation of tilde.  This is similar to how GNU readline
and bash collaborate.

function                                             old     new   delta
get_homedir_or_NULL                                   29      72     +43
optschanged                                          119     126      +7
hush_main                                           1204    1211      +7
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 57/0)               Total: 57 bytes

v2: Always check for HOME before trying the password database:  this
    is what GNU readline does.

Signed-off-by: Ron Yorston <rmy@pobox.com>

4 files changed, 19 insertions, 16 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 740c25528..1c9198945 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1984,6 +1984,7 @@ unsigned size_from_HISTFILESIZE(const char *hp) FAST_FUNC;
 #  define MAX_HISTORY 0
 # endif
 typedef const char *get_exe_name_t(int i) FAST_FUNC;
+typedef const char *sh_get_var_t(const char *name) FAST_FUNC;
 typedef struct line_input_t {
         int flags;
         int timeout;
@@ -1997,9 +1998,8 @@ typedef struct line_input_t {
 #  if ENABLE_SHELL_ASH || ENABLE_SHELL_HUSH
         /* function to fetch additional application-specific names to match */
         get_exe_name_t *get_exe_name;
-#   define EDITING_HAS_get_exe_name 1
-#  else
-#   define EDITING_HAS_get_exe_name 0
+        /* function to fetch value of shell variable */
+        sh_get_var_t *sh_get_var;
 #  endif
 # endif
 # if MAX_HISTORY
@@ -2053,11 +2053,6 @@ int read_line_input(const char* prompt, char* command, int maxsize) FAST_FUNC;
         read_line_input(prompt, command, maxsize)
 #endif
 
-#ifndef EDITING_HAS_get_exe_name
-# define EDITING_HAS_get_exe_name 0
-#endif
-
-
 #ifndef COMM_LEN
 # ifdef TASK_COMM_LEN
 enum { COMM_LEN = TASK_COMM_LEN };
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 778511d16..06321825c 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -259,6 +259,16 @@ static const char *get_username_str(void)
 
 static NOINLINE const char *get_homedir_or_NULL(void)
 {
+        const char *home;
+
+#if ENABLE_SHELL_ASH || ENABLE_SHELL_HUSH
+        home = state->sh_get_var ? state->sh_get_var("HOME") : getenv("HOME");
+#else
+        home = getenv("HOME");
+#endif
+        if (home != NULL && home[0] != '\0')
+                return home;
+
         if (!got_user_strings)
                 get_user_strings();
         return home_pwd_buf;
@@ -932,7 +942,7 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
                                 continue;
                 }
 # endif
-# if EDITING_HAS_get_exe_name
+# if ENABLE_SHELL_ASH || ENABLE_SHELL_HUSH
                 if (state->get_exe_name) {
                         i = 0;
                         for (;;) {
diff --git a/shell/ash.c b/shell/ash.c
index e8a1e853c..dd806b629 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -10554,7 +10554,7 @@ evalpipe(union node *n, int flags)
 }
 
 /* setinteractive needs this forward reference */
-#if EDITING_HAS_get_exe_name
+#if ENABLE_FEATURE_EDITING
 static const char *get_builtin_name(int i) FAST_FUNC;
 #endif
 
@@ -10591,9 +10591,8 @@ setinteractive(int on)
 #if ENABLE_FEATURE_EDITING
                 if (!line_input_state) {
                         line_input_state = new_line_input_t(FOR_SHELL | WITH_PATH_LOOKUP);
-# if EDITING_HAS_get_exe_name
                         line_input_state->get_exe_name = get_builtin_name;
-# endif
+                        line_input_state->sh_get_var = lookupvar;
                 }
 #endif
         }
@@ -11096,7 +11095,7 @@ find_builtin(const char *name)
         return bp;
 }
 
-#if EDITING_HAS_get_exe_name
+#if ENABLE_FEATURE_EDITING
 static const char * FAST_FUNC
 get_builtin_name(int i)
 {
diff --git a/shell/hush.c b/shell/hush.c
index ae81f0da5..051b123e7 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -8188,7 +8188,7 @@ static const struct built_in_command *find_builtin(const char *name)
         return find_builtin_helper(name, bltins2, &bltins2[ARRAY_SIZE(bltins2)]);
 }
 
-#if ENABLE_HUSH_JOB && EDITING_HAS_get_exe_name
+#if ENABLE_HUSH_JOB && ENABLE_FEATURE_EDITING
 static const char * FAST_FUNC get_builtin_name(int i)
 {
         if (/*i >= 0 && */ i < ARRAY_SIZE(bltins1)) {
@@ -10668,9 +10668,8 @@ int hush_main(int argc, char **argv)
 
 # if ENABLE_FEATURE_EDITING
                 G.line_input_state = new_line_input_t(FOR_SHELL);
-#  if EDITING_HAS_get_exe_name
                 G.line_input_state->get_exe_name = get_builtin_name;
-#  endif
+                G.line_input_state->sh_get_var = get_local_var_value;
 # endif
 # if ENABLE_HUSH_SAVEHISTORY && MAX_HISTORY > 0
                 {