ash: fix nofork bug where environment is not properly passed to a command

function                                             old     new   delta
listvars                                             144     252    +108
evalcommand                                         1500    1546     +46
showvars                                             142     147      +5
shellexec                                            242     245      +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 162/0)             Total: 162 bytes

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

5 files changed, 88 insertions, 5 deletions

diff --git a/shell/ash.c b/shell/ash.c
index 7a0b88c68..e69ddb4ff 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -2380,8 +2380,11 @@ listsetvar(struct strlist *list_set_var, int flags)
 /*
  * Generate a list of variables satisfying the given conditions.
  */
+#if !ENABLE_FEATURE_SH_NOFORK
+# define listvars(on, off, lp, end) listvars(on, off, end)
+#endif
 static char **
-listvars(int on, int off, char ***end)
+listvars(int on, int off, struct strlist *lp, char ***end)
 {
         struct var **vpp;
         struct var *vp;
@@ -2394,12 +2397,40 @@ listvars(int on, int off, char ***end)
         do {
                 for (vp = *vpp; vp; vp = vp->next) {
                         if ((vp->flags & mask) == on) {
+#if ENABLE_FEATURE_SH_NOFORK
+                                /* If variable with the same name is both
+                                 * exported and temporarily set for a command:
+                                 *  export ZVAR=5
+                                 *  ZVAR=6 printenv
+                                 * then "ZVAR=6" will be both in vartab and
+                                 * lp lists. Do not pass it twice to printenv.
+                                 */
+                                struct strlist *lp1 = lp;
+                                while (lp1) {
+                                        if (strcmp(lp1->text, vp->var_text) == 0)
+                                                goto skip;
+                                        lp1 = lp1->next;
+                                }
+#endif
                                 if (ep == stackstrend())
                                         ep = growstackstr();
                                 *ep++ = (char*)vp->var_text;
+#if ENABLE_FEATURE_SH_NOFORK
+ skip: ;
+#endif
                         }
                 }
         } while (++vpp < vartab + VTABSIZE);
+
+#if ENABLE_FEATURE_SH_NOFORK
+        while (lp) {
+                if (ep == stackstrend())
+                        ep = growstackstr();
+                *ep++ = lp->text;
+                lp = lp->next;
+        }
+#endif
+
         if (ep == stackstrend())
                 ep = growstackstr();
         if (end)
@@ -7860,7 +7891,7 @@ static void shellexec(char *prog, char **argv, const char *path, int idx)
         int exerrno;
         int applet_no = -1; /* used only by FEATURE_SH_STANDALONE */
 
-        envp = listvars(VEXPORT, VUNSET, /*end:*/ NULL);
+        envp = listvars(VEXPORT, VUNSET, /*strlist:*/ NULL, /*end:*/ NULL);
         if (strchr(prog, '/') != NULL
 #if ENABLE_FEATURE_SH_STANDALONE
          || (applet_no = find_applet_by_name(prog)) >= 0
@@ -9930,7 +9961,11 @@ evalcommand(union node *cmd, int flags)
                 /* find_command() encodes applet_no as (-2 - applet_no) */
                 int applet_no = (- cmdentry.u.index - 2);
                 if (applet_no >= 0 && APPLET_IS_NOFORK(applet_no)) {
-                        listsetvar(varlist.list, VEXPORT|VSTACK);
+                        char **sv_environ;
+
+                        INT_OFF;
+                        sv_environ = environ;
+                        environ = listvars(VEXPORT, VUNSET, varlist.list, /*end:*/ NULL);
                         /*
                          * Run <applet>_main().
                          * Signals (^C) can't interrupt here.
@@ -9939,8 +9974,8 @@ evalcommand(union node *cmd, int flags)
                          * and/or wait for user input ineligible for NOFORK:
                          * for example, "yes" or "rm" (rm -i waits for input).
                          */
-                        INT_OFF;
                         status = run_nofork_applet(applet_no, argv);
+                        environ = sv_environ;
                         /*
                          * Try enabling NOFORK for "yes" applet.
                          * ^C _will_ stop it (write returns EINTR),
@@ -10854,7 +10889,7 @@ showvars(const char *sep_prefix, int on, int off)
         const char *sep;
         char **ep, **epend;
 
-        ep = listvars(on, off, &epend);
+        ep = listvars(on, off, /*strlist:*/ NULL, &epend);
         qsort(ep, epend - ep, sizeof(char *), vpcmp);
 
         sep = *sep_prefix ? " " : sep_prefix;
diff --git a/shell/ash_test/ash-standalone/nofork_env.right b/shell/ash_test/ash-standalone/nofork_env.right
new file mode 100644
index 000000000..3f16ff458
--- /dev/null
+++ b/shell/ash_test/ash-standalone/nofork_env.right
@@ -0,0 +1,9 @@
+ZVAR=1
+ZVAR=2
+ZVAR=3
+ZVAR=4
+ZVAR=5
+ZVAR=6
+ZVAR=7
+ZVAR=8
+Ok:0
diff --git a/shell/ash_test/ash-standalone/nofork_env.tests b/shell/ash_test/ash-standalone/nofork_env.tests
new file mode 100755
index 000000000..111e564d2
--- /dev/null
+++ b/shell/ash_test/ash-standalone/nofork_env.tests
@@ -0,0 +1,15 @@
+# ash had a bug where NOFORKed applet (env/printenv) was not seeing new exported variables
+
+(export ZVAR=1; printenv) | grep ^ZVAR=
+(ZVAR=2 printenv) | grep ^ZVAR=
+
+(export ZVAR=3; env) | grep ^ZVAR=
+(ZVAR=4 env) | grep ^ZVAR=
+
+export ZVAR=5; printenv | grep ^ZVAR=
+ZVAR=6 printenv | grep ^ZVAR=
+
+export ZVAR=7; env | grep ^ZVAR=
+ZVAR=8 env | grep ^ZVAR=
+
+echo Ok:$?
diff --git a/shell/hush_test/hush-standalone/nofork_env.right b/shell/hush_test/hush-standalone/nofork_env.right
new file mode 100644
index 000000000..3f16ff458
--- /dev/null
+++ b/shell/hush_test/hush-standalone/nofork_env.right
@@ -0,0 +1,9 @@
+ZVAR=1
+ZVAR=2
+ZVAR=3
+ZVAR=4
+ZVAR=5
+ZVAR=6
+ZVAR=7
+ZVAR=8
+Ok:0
diff --git a/shell/hush_test/hush-standalone/nofork_env.tests b/shell/hush_test/hush-standalone/nofork_env.tests
new file mode 100755
index 000000000..111e564d2
--- /dev/null
+++ b/shell/hush_test/hush-standalone/nofork_env.tests
@@ -0,0 +1,15 @@
+# ash had a bug where NOFORKed applet (env/printenv) was not seeing new exported variables
+
+(export ZVAR=1; printenv) | grep ^ZVAR=
+(ZVAR=2 printenv) | grep ^ZVAR=
+
+(export ZVAR=3; env) | grep ^ZVAR=
+(ZVAR=4 env) | grep ^ZVAR=
+
+export ZVAR=5; printenv | grep ^ZVAR=
+ZVAR=6 printenv | grep ^ZVAR=
+
+export ZVAR=7; env | grep ^ZVAR=
+ZVAR=8 env | grep ^ZVAR=
+
+echo Ok:$?