lineedit: add support for history saving on exit

Based on the patch by Dennis Groenen <tj.groenen@gmail.com>

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

5 files changed, 86 insertions, 6 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 63d041957..91343a95e 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -1421,6 +1421,12 @@ typedef struct line_input_t {
         int cur_history;
         int max_history; /* must never be <= 0 */
 #  if ENABLE_FEATURE_EDITING_SAVEHISTORY
+        /* meaning of this field depends on FEATURE_EDITING_SAVE_ON_EXIT:
+         * if !FEATURE_EDITING_SAVE_ON_EXIT: "how many lines are
+         * in on-disk history"
+         * if FEATURE_EDITING_SAVE_ON_EXIT: "how many in-memory lines are
+         * also in on-disk history (and thus need to be skipped on save)"
+         */
         unsigned cnt_history_in_file;
         const char *hist_file;
 #  endif
@@ -1446,6 +1452,9 @@ line_input_t *new_line_input_t(int flags) FAST_FUNC;
  * >0 length of input string, including terminating '\n'
  */
 int read_line_input(line_input_t *st, const char *prompt, char *command, int maxsize, int timeout) FAST_FUNC;
+# if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
+void save_history(line_input_t *st);
+# endif
 #else
 #define MAX_HISTORY 0
 int read_line_input(const char* prompt, char* command, int maxsize) FAST_FUNC;
diff --git a/libbb/Config.src b/libbb/Config.src
index aa442365a..f6f88b9ce 100644
--- a/libbb/Config.src
+++ b/libbb/Config.src
@@ -94,6 +94,13 @@ config FEATURE_EDITING_SAVEHISTORY
         help
           Enable history saving in shells.
 
+config FEATURE_EDITING_SAVE_ON_EXIT
+        bool "Save history on shell exit, not after every command"
+        default n
+        depends on FEATURE_EDITING_SAVEHISTORY
+        help
+          Save history on shell exit, not after every command.
+
 config FEATURE_REVERSE_SEARCH
         bool "Reverse history search"
         default y
diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 5d139043a..0786f9ae6 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -1351,7 +1351,9 @@ static void load_history(line_input_t *st_parm)
 
                 /* fill temp_h[], retaining only last MAX_HISTORY lines */
                 memset(temp_h, 0, sizeof(temp_h));
-                st_parm->cnt_history_in_file = idx = 0;
+                idx = 0;
+                if (!ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
+                        st_parm->cnt_history_in_file = 0;
                 while ((line = xmalloc_fgetline(fp)) != NULL) {
                         if (line[0] == '\0') {
                                 free(line);
@@ -1359,7 +1361,8 @@ static void load_history(line_input_t *st_parm)
                         }
                         free(temp_h[idx]);
                         temp_h[idx] = line;
-                        st_parm->cnt_history_in_file++;
+                        if (!ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
+                                st_parm->cnt_history_in_file++;
                         idx++;
                         if (idx == st_parm->max_history)
                                 idx = 0;
@@ -1389,15 +1392,66 @@ static void load_history(line_input_t *st_parm)
                         st_parm->history[i++] = line;
                 }
                 st_parm->cnt_history = i;
+                if (ENABLE_FEATURE_EDITING_SAVE_ON_EXIT)
+                        st_parm->cnt_history_in_file = i;
         }
 }
 
-/* state->flags is already checked to be nonzero */
+#  if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
+void save_history(line_input_t *st)
+{
+        FILE *fp;
+
+        if (!(st->flags & SAVE_HISTORY))
+                return;
+        if (!st->hist_file)
+                return;
+        if (st->cnt_history <= st->cnt_history_in_file)
+                return;
+
+        fp = fopen(st->hist_file, "a");
+        if (fp) {
+                int i, fd;
+                char *new_name;
+                line_input_t *st_temp;
+
+                for (i = st->cnt_history_in_file; i < st->cnt_history; i++)
+                        fprintf(fp, "%s\n", st->history[i]);
+                fclose(fp);
+
+                /* we may have concurrently written entries from others.
+                 * load them */
+                st_temp = new_line_input_t(st->flags);
+                st_temp->hist_file = st->hist_file;
+                st_temp->max_history = st->max_history;
+                load_history(st_temp);
+
+                /* write out temp file and replace hist_file atomically */
+                new_name = xasprintf("%s.%u.new", st->hist_file, (int) getpid());
+                fd = open(new_name, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+                if (fd >= 0) {
+                        fp = xfdopen_for_write(fd);
+                        for (i = 0; i < st_temp->cnt_history; i++)
+                                fprintf(fp, "%s\n", st_temp->history[i]);
+                        fclose(fp);
+                        if (rename(new_name, st->hist_file) == 0)
+                                st->cnt_history_in_file = st_temp->cnt_history;
+                }
+                free(new_name);
+                free_line_input_t(st_temp);
+        }
+}
+#  else
 static void save_history(char *str)
 {
         int fd;
         int len, len2;
 
+        if (!(state->flags & SAVE_HISTORY))
+                return;
+        if (!state->hist_file)
+                return;
+
         fd = open(state->hist_file, O_WRONLY | O_CREAT | O_APPEND, 0600);
         if (fd < 0)
                 return;
@@ -1441,6 +1495,7 @@ static void save_history(char *str)
                 free_line_input_t(st_temp);
         }
 }
+#  endif
 # else
 #  define load_history(a) ((void)0)
 #  define save_history(a) ((void)0)
@@ -1469,15 +1524,16 @@ static void remember_in_history(char *str)
                 for (i = 0; i < state->max_history-1; i++)
                         state->history[i] = state->history[i+1];
                 /* i == state->max_history-1 */
+                if (ENABLE_FEATURE_EDITING_SAVE_ON_EXIT && state->cnt_history_in_file)
+                        state->cnt_history_in_file--;
         }
         /* i <= state->max_history-1 */
         state->history[i++] = xstrdup(str);
         /* i <= state->max_history */
         state->cur_history = i;
         state->cnt_history = i;
-# if ENABLE_FEATURE_EDITING_SAVEHISTORY
-        if ((state->flags & SAVE_HISTORY) && state->hist_file)
-                save_history(str);
+# if ENABLE_FEATURE_EDITING_SAVEHISTORY && !ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
+        save_history(str);
 # endif
         IF_FEATURE_EDITING_FANCY_PROMPT(num_ok_lines++;)
 }
diff --git a/shell/ash.c b/shell/ash.c
index bf376bd0d..14472cb61 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -12888,6 +12888,10 @@ exitshell(void)
         char *p;
         int status;
 
+#if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
+        save_history(line_input_state);
+#endif
+
         status = exitstatus;
         TRACE(("pid %d, exitshell(%d)\n", getpid(), status));
         if (setjmp(loc.loc)) {
diff --git a/shell/hush.c b/shell/hush.c
index 42143fd9e..a9e2dd311 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -1541,6 +1541,10 @@ static sighandler_t pick_sighandler(unsigned sig)
 static void hush_exit(int exitcode) NORETURN;
 static void hush_exit(int exitcode)
 {
+#if ENABLE_FEATURE_EDITING_SAVE_ON_EXIT
+        save_history(G.line_input_state);
+#endif
+
         fflush_all();
         if (G.exiting <= 0 && G.traps && G.traps[0] && G.traps[0][0]) {
                 char *argv[3];