hush: support $PPID

function                                             old     new   delta
get_local_var_value                                   33      72     +39
hush_main                                            951     983     +32
block_signals                                        152     155      +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 3/0 up/down: 74/0)               Total: 74 bytes

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

1 files changed, 15 insertions, 4 deletions

diff --git a/shell/hush.c b/shell/hush.c
index ec38023ff..3028d795c 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -484,6 +484,7 @@ struct globals {
         line_input_t *line_input_state;
 #endif
         pid_t root_pid;
+        pid_t root_ppid;
         pid_t last_bg_pid;
 #if ENABLE_HUSH_JOB
         int run_list_level;
@@ -1307,6 +1308,9 @@ static const char *get_local_var_value(const char *name)
         struct variable **pp = get_ptr_to_local_var(name);
         if (pp)
                 return strchr((*pp)->varstr, '=') + 1;
+        if (strcmp(name, "PPID") == 0)
+                return utoa(G.root_ppid);
+        // bash compat: UID? EUID?
         return NULL;
 }
 
@@ -2687,8 +2691,9 @@ static void re_execute_shell(char ***to_free, const char *s,
         if (pp) while (*pp++)
                 cnt++;
 
-        sprintf(param_buf, "-$%x:%x:%x:%x" IF_HUSH_LOOPS(":%x")
+        sprintf(param_buf, "-$%x:%x:%x:%x:%x" IF_HUSH_LOOPS(":%x")
                         , (unsigned) G.root_pid
+                        , (unsigned) G.root_ppid
                         , (unsigned) G.last_bg_pid
                         , (unsigned) G.last_exitcode
                         , cnt
@@ -6510,7 +6515,7 @@ int hush_main(int argc, char **argv)
          * MACHTYPE=i386-pc-linux-gnu
          * OSTYPE=linux-gnu
          * HOSTNAME=<xxxxxxxxxx>
-         * PPID=<NNNNN>
+         * PPID=<NNNNN> - we also do it elsewhere
          * EUID=<NNNNN>
          * UID=<NNNNN>
          * GROUPS=()
@@ -6587,8 +6592,10 @@ int hush_main(int argc, char **argv)
                          * Note: this form never happens:
                          * sh ... -c 'builtin' [BARGV...] ""
                          */
-                        if (!G.root_pid)
+                        if (!G.root_pid) {
                                 G.root_pid = getpid();
+                                G.root_ppid = getppid();
+                        }
                         G.global_argv = argv + optind;
                         G.global_argc = argc - optind;
                         if (builtin_argc) {
@@ -6630,6 +6637,8 @@ int hush_main(int argc, char **argv)
                 case '$':
                         G.root_pid = bb_strtou(optarg, &optarg, 16);
                         optarg++;
+                        G.root_ppid = bb_strtou(optarg, &optarg, 16);
+                        optarg++;
                         G.last_bg_pid = bb_strtou(optarg, &optarg, 16);
                         optarg++;
                         G.last_exitcode = bb_strtou(optarg, &optarg, 16);
@@ -6670,8 +6679,10 @@ int hush_main(int argc, char **argv)
                 }
         } /* option parsing loop */
 
-        if (!G.root_pid)
+        if (!G.root_pid) {
                 G.root_pid = getpid();
+                G.root_ppid = getppid();
+        }
 
         /* If we are login shell... */
         if (argv[0] && argv[0][0] == '-') {