hush: add bash-compatible EPOCH variables

Bash 5.0 added the dynamic variable EPOCHSECONDS and EPOCHREALTIME
which return the number of seconds since the Unix Epoch as an
integer or float.  These are useful for logging or tracing.

function                                             old     new   delta
get_local_var_value                                  207     302     +95
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/0 up/down: 95/0)               Total: 95 bytes
   text	   data	    bss	    dec	    hex	filename
 938702	   4203	   1888	 944793	  e6a99	busybox_old
 938797	   4203	   1888	 944888	  e6af8	busybox_unstripped

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/shell/hush.c b/shell/hush.c
index fa9afa38e..d745148f4 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -379,6 +379,7 @@
 #define BASH_SUBSTR        ENABLE_HUSH_BASH_COMPAT
 #define BASH_SOURCE        ENABLE_HUSH_BASH_COMPAT
 #define BASH_HOSTNAME_VAR  ENABLE_HUSH_BASH_COMPAT
+#define BASH_EPOCH_VARS    ENABLE_HUSH_BASH_COMPAT
 #define BASH_TEST2         (ENABLE_HUSH_BASH_COMPAT && ENABLE_HUSH_TEST)
 #define BASH_READ_D        ENABLE_HUSH_BASH_COMPAT
 
@@ -1011,6 +1012,9 @@ struct globals {
         int debug_indent;
 #endif
         struct sigaction sa;
+#if BASH_EPOCH_VARS
+        char epoch_buf[sizeof("%lu.nnnnnn") + sizeof(long)*3];
+#endif
 #if ENABLE_FEATURE_EDITING
         char user_input_buf[CONFIG_FEATURE_EDITING_MAX_LEN];
 #endif
@@ -2228,6 +2232,22 @@ static const char* FAST_FUNC get_local_var_value(const char *name)
         if (strcmp(name, "RANDOM") == 0)
                 return utoa(next_random(&G.random_gen));
 #endif
+#if BASH_EPOCH_VARS
+        {
+                const char *fmt = NULL;
+                if (strcmp(name, "EPOCHSECONDS") == 0)
+                        fmt = "%lu";
+                else if (strcmp(name, "EPOCHREALTIME") == 0)
+                        fmt = "%lu.%06u";
+                if (fmt) {
+                        struct timeval tv;
+                        gettimeofday(&tv, NULL);
+                        sprintf(G.epoch_buf, fmt, (unsigned long)tv.tv_sec,
+                                        (unsigned)tv.tv_usec);
+                        return G.epoch_buf;
+                }
+        }
+#endif
         return NULL;
 }