shell: empty HISTFILE disables history saving, just as unset one did

The rationale here is that unsetting HISTFILE in /etc/profile
does not "stick": if it's unset, the default one is set later
(after /etc/profile is executed) by the shell.
But setting (and exporting, so it is inherited by all
(grand)child shells) an empty one works.

function                                             old     new   delta
save_history                                         296     316     +20

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

3 files changed, 6 insertions, 4 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index fe0dbc5b8..43d1da35c 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -1563,7 +1563,8 @@ void FAST_FUNC save_history(line_input_t *st)
 {
         FILE *fp;
 
-        if (!st || !st->hist_file)
+        /* bash compat: HISTFILE="" disables history saving */
+        if (!st || !st->hist_file || !state->hist_file[0])
                 return;
         if (st->cnt_history <= st->cnt_history_in_file)
                 return; /* no new entries were added */
@@ -1617,7 +1618,8 @@ static void save_history(char *str)
         int fd;
         int len, len2;
 
-        if (!state->hist_file)
+        /* bash compat: HISTFILE="" disables history saving */
+        if (!state->hist_file || !state->hist_file[0])
                 return;
 
         fd = open(state->hist_file, O_WRONLY | O_CREAT | O_APPEND, 0600);
diff --git a/shell/ash.c b/shell/ash.c
index 18344767a..1a85eec71 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -14540,7 +14540,7 @@ exitshell(void)
                 /* HISTFILE: "If unset, the command history is not saved when a shell exits." */
                 hp = lookupvar("HISTFILE");
                 line_input_state->hist_file = hp;
-                save_history(line_input_state); /* no-op if hist_file is NULL */
+                save_history(line_input_state); /* no-op if hist_file is NULL or "" */
         }
 #endif
 
diff --git a/shell/hush.c b/shell/hush.c
index 68aca53a3..0b2bc01f5 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2120,7 +2120,7 @@ static void hush_exit(int exitcode)
                 /* HISTFILE: "If unset, the command history is not saved when a shell exits." */
                 hp = get_local_var_value("HISTFILE");
                 G.line_input_state->hist_file = hp;
-                save_history(G.line_input_state); /* no-op if hist_file is NULL */
+                save_history(G.line_input_state); /* no-op if hist_file is NULL or "" */
         }
 #endif