hush: IFS fixes

$ IFS=": "; x=" "; set x $x; for v; do echo "|$v|"; done
|x|
$ IFS=": "; x=":"; set x $x; for v; do echo "|$v|"; done
|x|
||

function                                             old     new   delta
run_pipe                                            1789    1870     +81
expand_on_ifs                                        310     361     +51
pseudo_exec_argv                                     588     591      +3
builtin_local                                         50      53      +3
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 138/0)             Total: 138 bytes

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

5 files changed, 54 insertions, 2 deletions

diff --git a/shell/ash_test/ash-vars/var_wordsplit_ifs4.right b/shell/ash_test/ash-vars/var_wordsplit_ifs4.right
new file mode 100644
index 000000000..c27284c31
--- /dev/null
+++ b/shell/ash_test/ash-vars/var_wordsplit_ifs4.right
@@ -0,0 +1,5 @@
+|x|
+Ok1:0
+|x|
+||
+Ok2:0
diff --git a/shell/ash_test/ash-vars/var_wordsplit_ifs4.tests b/shell/ash_test/ash-vars/var_wordsplit_ifs4.tests
new file mode 100755
index 000000000..638bfbb28
--- /dev/null
+++ b/shell/ash_test/ash-vars/var_wordsplit_ifs4.tests
@@ -0,0 +1,4 @@
+IFS=": "; x=" "; set x $x; for v; do echo "|$v|"; done
+echo Ok1:$?
+IFS=": "; x=":"; set x $x; for v; do echo "|$v|"; done
+echo Ok2:$?
diff --git a/shell/hush.c b/shell/hush.c
index 248364be2..8e95a26a6 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -930,6 +930,7 @@ struct globals {
         unsigned getopt_count;
 #endif
         const char *ifs;
+        char *ifs_whitespace; /* = G.ifs or malloced */
         const char *cwd;
         struct variable *top_var;
         char **expanded_assignments;
@@ -5696,10 +5697,20 @@ static int expand_on_ifs(int *ended_with_ifs, o_string *output, int n, const cha
 
                 /* We know str here points to at least one IFS char */
                 last_is_ifs = 1;
-                str += strspn(str, G.ifs); /* skip IFS chars */
+                str += strspn(str, G.ifs_whitespace); /* skip IFS whitespace chars */
                 if (!*str)  /* EOL - do not finalize word */
                         break;
 
+                if (G.ifs_whitespace != G.ifs /* usually false ($IFS is usually all whitespace), */
+                 && strchr(G.ifs, *str)       /* the second check would fail */
+                ) {
+                        /* This is a non-whitespace $IFS char */
+                        /* Skip it and IFS whitespace chars, start new word */
+                        str++;
+                        str += strspn(str, G.ifs_whitespace);
+                        goto new_word;
+                }
+
                 /* Start new word... but not always! */
                 /* Case "v=' a'; echo ''$v": we do need to finalize empty word: */
                 if (output->has_quoted_part
@@ -5710,6 +5721,7 @@ static int expand_on_ifs(int *ended_with_ifs, o_string *output, int n, const cha
                  */
                  || (n > 0 && output->data[output->length - 1])
                 ) {
+ new_word:
                         o_addchr(output, '\0');
                         debug_print_list("expand_on_ifs", output, n);
                         n = o_save_ptr(output, n);
@@ -8283,9 +8295,31 @@ static NOINLINE int run_pipe(struct pipe *pi)
         /* Testcase: set -- q w e; (IFS='' echo "$*"; IFS=''; echo "$*"); echo "$*"
          * Result should be 3 lines: q w e, qwe, q w e
          */
+        if (G.ifs_whitespace != G.ifs)
+                free(G.ifs_whitespace);
         G.ifs = get_local_var_value("IFS");
-        if (!G.ifs)
+        if (G.ifs) {
+                char *p;
+                G.ifs_whitespace = (char*)G.ifs;
+                p = skip_whitespace(G.ifs);
+                if (*p) {
+                        /* Not all $IFS is whitespace */
+                        char *d;
+                        int len = p - G.ifs;
+                        p = skip_non_whitespace(p);
+                        G.ifs_whitespace = xmalloc(len + strlen(p) + 1); /* can overestimate */
+                        d = mempcpy(G.ifs_whitespace, G.ifs, len);
+                        while (*p) {
+                                if (isspace(*p))
+                                        *d++ = *p;
+                                p++;
+                        }
+                        *d = '\0';
+                }
+        } else {
                 G.ifs = defifs;
+                G.ifs_whitespace = (char*)G.ifs;
+        }
 
         IF_HUSH_JOB(pi->pgrp = -1;)
         pi->stopped_cmds = 0;
diff --git a/shell/hush_test/hush-vars/var_wordsplit_ifs4.right b/shell/hush_test/hush-vars/var_wordsplit_ifs4.right
new file mode 100644
index 000000000..c27284c31
--- /dev/null
+++ b/shell/hush_test/hush-vars/var_wordsplit_ifs4.right
@@ -0,0 +1,5 @@
+|x|
+Ok1:0
+|x|
+||
+Ok2:0
diff --git a/shell/hush_test/hush-vars/var_wordsplit_ifs4.tests b/shell/hush_test/hush-vars/var_wordsplit_ifs4.tests
new file mode 100755
index 000000000..638bfbb28
--- /dev/null
+++ b/shell/hush_test/hush-vars/var_wordsplit_ifs4.tests
@@ -0,0 +1,4 @@
+IFS=": "; x=" "; set x $x; for v; do echo "|$v|"; done
+echo Ok1:$?
+IFS=": "; x=":"; set x $x; for v; do echo "|$v|"; done
+echo Ok2:$?