ash: eval: Restore input files in evalcommand

Upstream commit:

    Date: Tue, 27 Mar 2018 00:39:35 +0800
    eval: Restore input files in evalcommand

    When evalcommand invokes a command that modifies parsefile and
    then bails out without popping the file, we need to ensure the
    input file is restored so that the shell can continue to execute.

    Reported-by: Martijn Dekker <martijn@inlv.org>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

function                                             old     new   delta
unwindfiles                                            -      20     +20
evalcommand                                         1635    1653     +18
getoptscmd                                           584     595     +11
popallfiles                                           20      10     -10
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 2/1 up/down: 49/-10)             Total: 39 bytes

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

1 files changed, 12 insertions, 2 deletions

diff --git a/shell/ash.c b/shell/ash.c
index b596833e7..79ade5df4 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -9942,6 +9942,7 @@ find_builtin(const char *name)
 /*
  * Execute a simple command.
  */
+static void unwindfiles(struct parsefile *stop);
 static int
 isassignment(const char *p)
 {
@@ -9964,6 +9965,7 @@ evalcommand(union node *cmd, int flags)
                 "\0\0", bltincmd /* why three NULs? */
         };
         struct localvar_list *localvar_stop;
+        struct parsefile *file_stop;
         struct redirtab *redir_stop;
         struct stackmark smark;
         union node *argp;
@@ -9989,6 +9991,7 @@ evalcommand(union node *cmd, int flags)
         TRACE(("evalcommand(0x%lx, %d) called\n", (long)cmd, flags));
         setstackmark(&smark);
         localvar_stop = pushlocalvars();
+        file_stop = g_parsefile;
         back_exitstatus = 0;
 
         cmdentry.cmdtype = CMDBUILTIN;
@@ -10260,6 +10263,7 @@ evalcommand(union node *cmd, int flags)
         if (cmd->ncmd.redirect)
                 popredir(/*drop:*/ cmd_is_exec);
         unwindredir(redir_stop);
+        unwindfiles(file_stop);
         unwindlocalvars(localvar_stop);
         if (lastarg) {
                 /* dsl: I think this is intended to be used to support
@@ -10782,14 +10786,20 @@ popfile(void)
         INT_ON;
 }
 
+static void
+unwindfiles(struct parsefile *stop)
+{
+        while (g_parsefile != stop)
+                popfile();
+}
+
 /*
  * Return to top level.
  */
 static void
 popallfiles(void)
 {
-        while (g_parsefile != &basepf)
-                popfile();
+        unwindfiles(&basepf);
 }
 
 /*