[src/netbsd-9]: src/bin/sh Pull up following revision(s) (requested by kre in...

[martin <martin%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/c33ab9bc6f98
branches:  netbsd-9
changeset: 372118:c33ab9bc6f98
user:      martin <martin%NetBSD.org@localhost>
date:      Thu Oct 27 16:14:42 2022 +0000

description:
Pull up following revision(s) (requested by kre in ticket #1549):

        bin/sh/miscbltin.c: revision 1.51
        bin/sh/miscbltin.c: revision 1.52

PR bin/56972  Fix escape ('\') handling in sh read builtin.

In 1.35 (March 2005) (the big read fixup), most escape handling and IFS
processing in the read builtin was corrected.  However 2 cases were missed,
one is a word (something to be assigned to any variable but the last) in
which every character is escaped (the code was relying on a non-escaped char
to set the "in a word" status), and second trailing IFS whitespace at
the end of the line was being deleted, even if the chars had been escaped
(the escape chars are no longer present).

See the PR for more details (including the case that detected the problem).

After fixing this, I looked at the FreeBSD code (normally might do it
before, but these fixes were trivial) to check their implementation.

Their code does similar things to ours now does, but in a completely
different way, their read builtin is more complex than ours needs to
be (they handle more options).   For anyone tempted to simply incorporate
their code, note that it relies upon infrastructure changes elsewhere
in the shell, so would not be a simple cut and drop in exercise.

This needs pullups to -3 -4 -5 -6 -7 -8 and -9 (fortunately this is
happening before -10 is branched, so will never be broken this way there).

 -

Don't output the error for bad usage (no var name given)
after already writing the prompt (set with the -p option).

That results in nonsense like:
        $ read -p foo
        fooread: arg count

While here, improve the error message so it means something.

Now we will get:
$ read -p foo
read: variable name required
Usage: read [-r] [-p prompt] var...

[Detected by code reading while doing the work for the previous fix]

diffstat:

 bin/sh/miscbltin.c |  19 ++++++++++++-------
 1 files changed, 12 insertions(+), 7 deletions(-)

diffs (83 lines):

diff -r 9fa5c1fdb0c3 -r c33ab9bc6f98 bin/sh/miscbltin.c
--- a/bin/sh/miscbltin.c        Thu Oct 27 16:06:24 2022 +0000
+++ b/bin/sh/miscbltin.c        Thu Oct 27 16:14:42 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: miscbltin.c,v 1.44 2017/05/13 15:03:34 gson Exp $      */
+/*     $NetBSD: miscbltin.c,v 1.44.12.1 2022/10/27 16:14:42 martin Exp $       */
 
 /*-
  * Copyright (c) 1991, 1993
@@ -37,7 +37,7 @@
 #if 0
 static char sccsid[] = "@(#)miscbltin.c        8.4 (Berkeley) 5/4/95";
 #else
-__RCSID("$NetBSD: miscbltin.c,v 1.44 2017/05/13 15:03:34 gson Exp $");
+__RCSID("$NetBSD: miscbltin.c,v 1.44.12.1 2022/10/27 16:14:42 martin Exp $");
 #endif
 #endif /* not lint */
 
@@ -99,6 +99,7 @@
        int i;
        int is_ifs;
        int saveall = 0;
+       ptrdiff_t wordlen = 0;
 
        rflag = 0;
        prompt = NULL;
@@ -109,14 +110,15 @@
                        rflag = 1;
        }
 
+       if (*(ap = argptr) == NULL)
+               error("variable name required\n"
+                       "Usage: read [-r] [-p prompt] var...");
+
        if (prompt && isatty(0)) {
                out2str(prompt);
                flushall();
        }
 
-       if (*(ap = argptr) == NULL)
-               error("arg count");
-
        if ((ifs = bltinlookup("IFS", 1)) == NULL)
                ifs = " \t\n";
 
@@ -136,7 +138,7 @@
                                break;
                        }
                        if (c != '\n')
-                               STPUTC(c, p);
+                               goto wdch;
                        continue;
                }
                if (c == '\n')
@@ -163,12 +165,14 @@
                }
 
                if (is_ifs == 0) {
+  wdch:;
                        /* append this character to the current variable */
                        startword = 0;
                        if (saveall)
                                /* Not just a spare terminator */
                                saveall++;
                        STPUTC(c, p);
+                       wordlen = p - stackblock();
                        continue;
                }
 
@@ -186,11 +190,12 @@
                setvar(*ap, stackblock(), 0);
                ap++;
                STARTSTACKSTR(p);
+               wordlen = 0;
        }
        STACKSTRNUL(p);
 
        /* Remove trailing IFS chars */
-       for (; stackblock() <= --p; *p = 0) {
+       for (; stackblock() + wordlen <= --p; *p = 0) {
                if (!strchr(ifs, *p))
                        break;
                if (strchr(" \t\n", *p))