app-shells/bash: add 5.2_p32-r1 with fix for 5.0-introduced regression in read

This backports a fix for an issue whereby the delimiter employed by the
read builtin is ignored in the case that it is part of an invalid
multibyte sequence. Further details can be found within the patch.

[sam: Keep -r0.]

Signed-off-by: Kerin Millar <kfm@plushkava.net>
Signed-off-by: Sam James <sam@gentoo.org>

2 files changed, 700 insertions, 0 deletions

diff --git a/app-shells/bash/bash-5.2_p32-r1.ebuild b/app-shells/bash/bash-5.2_p32-r1.ebuild
new file mode 100644
index 000000000000..e84a17739b2c
--- /dev/null
+++ b/app-shells/bash/bash-5.2_p32-r1.ebuild
@@ -0,0 +1,403 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+VERIFY_SIG_OPENPGP_KEY_PATH=/usr/share/openpgp-keys/chetramey.asc
+inherit flag-o-matic toolchain-funcs prefix verify-sig
+
+# Uncomment if we have a patchset.
+#GENTOO_PATCH_DEV="sam"
+#GENTOO_PATCH_VER="${PV}"
+
+MY_PV=${PV/_p*}
+MY_PV=${MY_PV/_/-}
+MY_P=${PN}-${MY_PV}
+MY_PATCHES=()
+
+# Determine the patchlevel. See ftp://ftp.gnu.org/gnu/bash/bash-5.2-patches/.
+case ${PV} in
+	*_p*)
+		PLEVEL=${PV##*_p}
+		;;
+	9999|*_alpha*|*_beta*|*_rc*)
+		# Set a negative patchlevel to indicate that it's a pre-release.
+		PLEVEL=-1
+		;;
+	*)
+		PLEVEL=0
+esac
+
+# The version of readline this bash normally ships with. Note that we only use
+# the bundled copy of readline for pre-releases.
+READLINE_VER="8.2_p1"
+
+DESCRIPTION="The standard GNU Bourne again shell"
+HOMEPAGE="https://tiswww.case.edu/php/chet/bash/bashtop.html https://git.savannah.gnu.org/cgit/bash.git"
+
+if [[ ${PV} == 9999 ]]; then
+	EGIT_REPO_URI="https://git.savannah.gnu.org/git/bash.git"
+	EGIT_BRANCH=devel
+	inherit git-r3
+else
+	my_urls=( {'mirror://gnu/bash','ftp://ftp.cwru.edu/pub/bash'}/"${MY_P}.tar.gz" )
+
+	# bash-5.1 -> bash51
+	my_p=${PN}$(ver_cut 1-2) my_p=${my_p/.}
+
+	for (( my_patch_idx = 1; my_patch_idx <= PLEVEL; my_patch_idx++ )); do
+		printf -v my_patch_ver %s-%03d "${my_p}" "${my_patch_idx}"
+		my_urls+=( {'mirror://gnu/bash','ftp://ftp.cwru.edu/pub/bash'}/"${MY_P}-patches/${my_patch_ver}" )
+		MY_PATCHES+=( "${DISTDIR}/${my_patch_ver}" )
+	done
+
+	SRC_URI="${my_urls[*]} verify-sig? ( ${my_urls[*]/%/.sig} )"
+
+	unset -v my_urls my_p my_patch_idx my_patch_ver
+fi
+
+if [[ ${GENTOO_PATCH_VER} ]]; then
+	SRC_URI+=" https://dev.gentoo.org/~${GENTOO_PATCH_DEV:?}/distfiles/${CATEGORY}/${PN}/${PN}-${GENTOO_PATCH_VER:?}-patches.tar.xz"
+fi
+
+S=${WORKDIR}/${MY_P}
+
+LICENSE="GPL-3+"
+SLOT="0"
+if (( PLEVEL >= 0 )); then
+	KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~loong ~m68k ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86 ~amd64-linux ~x86-linux ~arm64-macos ~ppc-macos ~x64-macos ~x64-solaris"
+fi
+IUSE="afs bashlogger examples mem-scramble +net nls plugins pgo +readline"
+
+DEPEND="
+	>=sys-libs/ncurses-5.2-r2:=
+	nls? ( virtual/libintl )
+"
+if (( PLEVEL >= 0 )); then
+	DEPEND+=" readline? ( >=sys-libs/readline-${READLINE_VER}:= )"
+fi
+RDEPEND="
+	${DEPEND}
+"
+# We only need bison (yacc) when the .y files get patched (bash42-005, bash51-011).
+BDEPEND="
+	pgo? ( dev-util/gperf )
+	verify-sig? ( sec-keys/openpgp-keys-chetramey )
+"
+
+# EAPI 8 tries to append it but it doesn't exist here.
+QA_CONFIGURE_OPTIONS="--disable-static"
+
+PATCHES=(
+	#"${WORKDIR}"/${PN}-${GENTOO_PATCH_VER}/
+
+	# Patches to or from Chet, posted to the bug-bash mailing list.
+	"${FILESDIR}/${PN}-5.0-syslog-history-extern.patch"
+	"${FILESDIR}/${PN}-5.2_p15-random-ub.patch"
+	"${FILESDIR}/${PN}-5.2_p15-configure-clang16.patch"
+	"${FILESDIR}/${PN}-5.2_p21-wpointer-to-int.patch"
+	"${FILESDIR}/${PN}-5.2_p21-configure-strtold.patch"
+	"${FILESDIR}/${PN}-5.2_p32-memory-leaks.patch"
+	"${FILESDIR}/${PN}-5.2_p32-read-delimiter-in-invalid-mbchar.patch"
+)
+
+pkg_setup() {
+	# bug #7332
+	if is-flag -malign-double; then
+		eerror "Detected bad CFLAGS '-malign-double'.  Do not use this"
+		eerror "as it breaks LFS (struct stat64) on x86."
+		die "remove -malign-double from your CFLAGS mr ricer"
+	fi
+
+	if use bashlogger; then
+		ewarn "The logging patch should ONLY be used in restricted (i.e. honeypot) envs."
+		ewarn "This will log ALL output you enter into the shell, you have been warned."
+	fi
+}
+
+src_unpack() {
+	local patch
+
+	if [[ ${PV} == 9999 ]]; then
+		git-r3_src_unpack
+	else
+		if use verify-sig; then
+			verify-sig_verify_detached "${DISTDIR}/${MY_P}.tar.gz"{,.sig}
+
+			for patch in "${MY_PATCHES[@]}"; do
+				verify-sig_verify_detached "${patch}"{,.sig}
+			done
+		fi
+
+		unpack "${MY_P}.tar.gz"
+
+		if [[ ${GENTOO_PATCH_VER} ]]; then
+			unpack "${PN}-${GENTOO_PATCH_VER}-patches.tar.xz"
+		fi
+	fi
+}
+
+src_prepare() {
+	# Include official patches.
+	(( PLEVEL > 0 )) && eapply -p0 "${MY_PATCHES[@]}"
+
+	# Clean out local libs so we know we use system ones w/releases. The
+	# touch utility is invoked for the benefit of config.status.
+	if (( PLEVEL >= 0 )); then
+		rm -rf lib/{readline,termcap}/* \
+		&& touch lib/{readline,termcap}/Makefile.in \
+		&& sed -i -E 's:\$[{(](RL|HIST)_LIBSRC[)}]/[[:alpha:]_-]*\.h::g' Makefile.in \
+		|| die
+	fi
+
+	# Prefixify hardcoded path names. No-op for non-prefix.
+	hprefixify pathnames.h.in
+
+	# Avoid regenerating docs after patches, bug #407985.
+	sed -i -E '/^(HS|RL)USER/s:=.*:=:' doc/Makefile.in \
+	&& touch -r . doc/* \
+	|| die
+
+	# Sometimes hangs (more noticeable w/ pgo), bug #907403.
+	rm tests/run-jobs || die
+
+	eapply -p0 "${PATCHES[@]}"
+	eapply_user
+}
+
+src_configure() {
+	local -a myconf
+
+	# Upstream only test with Bison and require GNUisms like YYEOF and
+	# YYERRCODE. The former at least may be in POSIX soon:
+	# https://www.austingroupbugs.net/view.php?id=1269.
+	# configure warns on use of non-Bison but doesn't abort. The result
+	# may misbehave at runtime.
+	unset -v YACC
+
+	myconf=(
+		--disable-profiling
+
+		# Force linking with system curses ... the bundled termcap lib
+		# sucks bad compared to ncurses.  For the most part, ncurses
+		# is here because readline needs it.  But bash itself calls
+		# ncurses in one or two small places :(.
+		--with-curses
+
+		$(use_enable mem-scramble)
+		$(use_enable net net-redirections)
+		$(use_enable readline)
+		$(use_enable readline bang-history)
+		$(use_enable readline history)
+		$(use_with afs)
+		$(use_with mem-scramble bash-malloc)
+	)
+
+	# For descriptions of these, see config-top.h.
+	# bashrc/#26952 bash_logout/#90488 ssh/#24762 mktemp/#574426
+	append-cppflags \
+		-DDEFAULT_PATH_VALUE=\'\""${EPREFIX}"/usr/local/sbin:"${EPREFIX}"/usr/local/bin:"${EPREFIX}"/usr/sbin:"${EPREFIX}"/usr/bin:"${EPREFIX}"/sbin:"${EPREFIX}"/bin\"\' \
+		-DSTANDARD_UTILS_PATH=\'\""${EPREFIX}"/bin:"${EPREFIX}"/usr/bin:"${EPREFIX}"/sbin:"${EPREFIX}"/usr/sbin\"\' \
+		-DSYS_BASHRC=\'\""${EPREFIX}"/etc/bash/bashrc\"\' \
+		-DSYS_BASH_LOGOUT=\'\""${EPREFIX}"/etc/bash/bash_logout\"\' \
+		-DNON_INTERACTIVE_LOGIN_SHELLS \
+		-DSSH_SOURCE_BASHRC \
+		$(use bashlogger && echo -DSYSLOG_HISTORY)
+
+	use nls || myconf+=( --disable-nls )
+
+	if (( PLEVEL >= 0 )); then
+		# Historically, we always used the builtin readline, but since
+		# our handling of SONAME upgrades has gotten much more stable
+		# in the PM (and the readline ebuild itself preserves the old
+		# libs during upgrades), linking against the system copy should
+		# be safe.
+		# Exact cached version here doesn't really matter as long as it
+		# is at least what's in the DEPEND up above.
+		export ac_cv_rl_version=${READLINE_VER%%_*}
+
+		# Use system readline only with released versions.
+		myconf+=( --with-installed-readline=. )
+	fi
+
+	if use plugins; then
+		append-ldflags "-Wl,-rpath,${EPREFIX}/usr/$(get_libdir)/bash"
+	else
+		# Disable the plugins logic by hand since bash doesn't provide
+		# a way of doing it.
+		export ac_cv_func_dl{close,open,sym}=no \
+			ac_cv_lib_dl_dlopen=no ac_cv_header_dlfcn_h=no
+
+		sed -i -e '/LOCAL_LDFLAGS=/s:-rdynamic::' configure || die
+	fi
+
+	# bug #444070
+	tc-export AR
+
+	econf "${myconf[@]}"
+}
+
+src_compile() {
+	local -a pgo_generate_flags pgo_use_flags
+	local flag
+
+	# -fprofile-partial-training because upstream notes the test suite isn't
+	# super comprehensive.
+	# https://documentation.suse.com/sbp/all/html/SBP-GCC-10/index.html#sec-gcc10-pgo
+	if use pgo; then
+		pgo_generate_flags=(
+			-fprofile-update=atomic
+			-fprofile-dir="${T}"/pgo
+			-fprofile-generate="${T}"/pgo
+		)
+		pgo_use_flags=(
+			-fprofile-use="${T}"/pgo
+			-fprofile-dir="${T}"/pgo
+		)
+		if flag=$(test-flags-CC -fprofile-partial-training); then
+			pgo_generate_flags+=( "${flag}" )
+			pgo_use_flags+=( "${flag}" )
+		fi
+	fi
+
+	emake CFLAGS="${CFLAGS} ${pgo_generate_flags[*]}"
+	use plugins && emake -C examples/loadables CFLAGS="${CFLAGS} ${pgo_generate_flags[*]}" all others
+
+	# Build Bash and run its tests to generate profiles.
+	if (( ${#pgo_generate_flags[@]} )); then
+		# Used in test suite.
+		unset -v A
+
+		emake CFLAGS="${CFLAGS} ${pgo_generate_flags[*]}" -k check
+
+		if tc-is-clang; then
+			llvm-profdata merge "${T}"/pgo --output="${T}"/pgo/default.profdata || die
+		fi
+
+		# Rebuild Bash using the profiling data we just generated.
+		emake clean
+		emake CFLAGS="${CFLAGS} ${pgo_use_flags[*]}"
+		use plugins && emake -C examples/loadables CFLAGS="${CFLAGS} ${pgo_use_flags[*]}" all others
+	fi
+}
+
+src_test() {
+	# Used in test suite.
+	unset -v A
+
+	default
+}
+
+src_install() {
+	local d f
+
+	default
+
+	my_prefixify() {
+		while read -r; do
+			if [[ $REPLY == *$1* ]]; then
+				REPLY=${REPLY/"/etc/"/"${EPREFIX}/etc/"}
+			fi
+			printf '%s\n' "${REPLY}" || ! break
+		done < "$2" || die
+	}
+
+	dodir /bin
+	mv -- "${ED}"/usr/bin/bash "${ED}"/bin/ || die
+	dosym bash /bin/rbash
+
+	insinto /etc/bash
+	doins "${FILESDIR}"/bash_logout
+	my_prefixify bashrc.d "${FILESDIR}"/bashrc-r1 | newins - bashrc
+
+	insinto /etc/bash/bashrc.d
+	my_prefixify DIR_COLORS "${FILESDIR}"/bashrc.d/10-gentoo-color.bash | newins - 10-gentoo-color.bash
+	newins "${FILESDIR}"/bashrc.d/10-gentoo-title-r1.bash 10-gentoo-title.bash
+	if [[ ! ${EPREFIX} ]]; then
+		doins "${FILESDIR}"/bashrc.d/15-gentoo-bashrc-check.bash
+	fi
+
+	insinto /etc/skel
+	for f in bash{_logout,_profile,rc}; do
+		newins "${FILESDIR}/dot-${f}" ".${f}"
+	done
+
+	if use plugins; then
+		exeinto "/usr/$(get_libdir)/bash"
+		set -- examples/loadables/*.o
+		doexe "${@%.o}"
+
+		insinto /usr/include/bash-plugins
+		doins *.h builtins/*.h include/*.h lib/{glob/glob.h,tilde/tilde.h}
+	fi
+
+	if use examples; then
+		for d in examples/{functions,misc,scripts,startup-files}; do
+			exeinto "/usr/share/doc/${PF}/${d}"
+			docinto "${d}"
+			for f in "${d}"/*; do
+				if [[ ${f##*/} != @(PERMISSION|*README) ]]; then
+					doexe "${f}"
+				else
+					dodoc "${f}"
+				fi
+			done
+		done
+	fi
+
+	# Install bash_builtins.1 and rbash.1.
+	emake -C doc DESTDIR="${D}" install_builtins
+	sed 's:bash\.1:man1/&:' doc/rbash.1 > "${T}"/rbash.1 || die
+	doman "${T}"/rbash.1
+
+	newdoc CWRU/changelog ChangeLog
+	dosym bash.info /usr/share/info/bashref.info
+}
+
+pkg_preinst() {
+	if [[ -e ${EROOT}/etc/bashrc ]] && [[ ! -d ${EROOT}/etc/bash ]]; then
+		mkdir -p -- "${EROOT}"/etc/bash \
+		&& mv -f -- "${EROOT}"/etc/bashrc "${EROOT}"/etc/bash/ \
+		|| die
+	fi
+}
+
+pkg_postinst() {
+	local old_ver
+
+	# If /bin/sh does not exist, provide it.
+	if [[ ! -e ${EROOT}/bin/sh ]]; then
+		ln -sf -- bash "${EROOT}"/bin/sh || die
+	fi
+
+	read -r old_ver <<<"${REPLACING_VERSIONS}"
+	if [[ ! $old_ver ]]; then
+		:
+	elif ver_test "$old_ver" -ge "5.2" && ver_test "$old_ver" -ge "5.2_p26-r8"; then
+		return
+	fi
+
+	while read -r; do ewarn "${REPLY}"; done <<'EOF'
+Files under /etc/bash/bashrc.d must now have a suffix of .sh or .bash.
+
+Gentoo now defaults to defining PROMPT_COMMAND as an array. Depending on the
+characteristics of the operating environment, it may contain a command to set
+the terminal's window title. Those who were already choosing to customise the
+PROMPT_COMMAND variable are now advised to append their commands like so:
+
+PROMPT_COMMAND+=('custom command goes here')
+
+Gentoo no longer defaults to having bash set the window title in the case
+that the terminal is controlled by sshd(8), unless screen is launched on the
+remote side or the terminal reliably supports saving and restoring the title
+(as alacritty, foot and tmux do). Those wanting for the title to be set
+regardless may adjust ~/.bashrc - or create a custom /etc/bash/bashrc.d
+drop-in - to set PROMPT_COMMMAND like so:
+
+PROMPT_COMMAND=(genfun_set_win_title)
+
+Those who would prefer for bash never to interfere with the window title may
+now opt out of the default title setting behaviour, either with the "unset -v
+PROMPT_COMMAND" command or by re-defining PROMPT_COMMAND as desired.
+EOF
+}
diff --git a/app-shells/bash/files/bash-5.2_p32-read-delimiter-in-invalid-mbchar.patch b/app-shells/bash/files/bash-5.2_p32-read-delimiter-in-invalid-mbchar.patch
new file mode 100644
index 000000000000..832520c6e7ec
--- /dev/null
+++ b/app-shells/bash/files/bash-5.2_p32-read-delimiter-in-invalid-mbchar.patch
@@ -0,0 +1,297 @@
+From 0432ec33408ac124b620c44416c9c58f0c10b63b Mon Sep 17 00:00:00 2001
+From: Kerin Millar <kfm@plushkava.net>
+Date: Fri, 23 Aug 2024 04:14:36 +0100
+Subject: [PATCH] Backport fix for issue with read delimiter in invalid
+ mutibyte char
+
+This addresses a regression introduced by 5.0. Consider the following
+test case.
+
+for i in {194..245}; do printf -v o %o "$i"; printf "\\$o\\n"; done |
+while read -r; do declare -p REPLY; done
+
+BEFORE
+
+declare -- REPLY=$'\302\n\303\n\304\n\305\n\306\n\307\n\310\n\311\n\312\
+n\313\n\314\n\315\n\316\n\317\n\320\n\321\n\322\n\323\n\324\n\325\n\326\
+n\327\n\330\n\331\n\332\n\333\n\334\n\335\n\336\n\337\n\340\n\341\n\342\
+n\343\n\344\n\345\n\346\n\347\n\350\n\351\n\352\n\353\n\354\n\355\n\356\
+n\357\n\360\n\361\n\362\n\363\n\364\n\365'
+
+AFTER
+
+declare -- REPLY=$'\302'
+declare -- REPLY=$'\303'
+declare -- REPLY=$'\304'
+declare -- REPLY=$'\305'
+declare -- REPLY=$'\306'
+declare -- REPLY=$'\307'
+declare -- REPLY=$'\310'
+declare -- REPLY=$'\311'
+declare -- REPLY=$'\312'
+declare -- REPLY=$'\313'
+declare -- REPLY=$'\314'
+declare -- REPLY=$'\315'
+declare -- REPLY=$'\316'
+declare -- REPLY=$'\317'
+declare -- REPLY=$'\320'
+declare -- REPLY=$'\321'
+declare -- REPLY=$'\322'
+declare -- REPLY=$'\323'
+declare -- REPLY=$'\324'
+declare -- REPLY=$'\325'
+declare -- REPLY=$'\326'
+declare -- REPLY=$'\327'
+declare -- REPLY=$'\330'
+declare -- REPLY=$'\331'
+declare -- REPLY=$'\332'
+declare -- REPLY=$'\333'
+declare -- REPLY=$'\334'
+declare -- REPLY=$'\335'
+declare -- REPLY=$'\336'
+declare -- REPLY=$'\337'
+declare -- REPLY=$'\340'
+declare -- REPLY=$'\341'
+declare -- REPLY=$'\342'
+declare -- REPLY=$'\343'
+declare -- REPLY=$'\344'
+declare -- REPLY=$'\345'
+declare -- REPLY=$'\346'
+declare -- REPLY=$'\347'
+declare -- REPLY=$'\350'
+declare -- REPLY=$'\351'
+declare -- REPLY=$'\352'
+declare -- REPLY=$'\353'
+declare -- REPLY=$'\354'
+declare -- REPLY=$'\355'
+declare -- REPLY=$'\356'
+declare -- REPLY=$'\357'
+declare -- REPLY=$'\360'
+declare -- REPLY=$'\361'
+declare -- REPLY=$'\362'
+declare -- REPLY=$'\363'
+declare -- REPLY=$'\364'
+declare -- REPLY=$'\365'
+
+Signed-off-by: Kerin Millar <kfm@plushkava.net>
+---
+ builtins/read.def | 25 ++++++++++++----
+ externs.h         |  1 +
+ lib/sh/zread.c    | 74 +++++++++++++++++++++++++++++++++++++++++++++++
+ 3 files changed, 94 insertions(+), 6 deletions(-)
+
+diff --git builtins/read.def builtins/read.def
+index ddd91d32..53b4bd81 100644
+--- builtins/read.def
++++ builtins/read.def
+@@ -130,7 +130,7 @@ static void set_readline_timeout PARAMS((sh_timer *t, time_t, long));
+ #endif
+ static SHELL_VAR *bind_read_variable PARAMS((char *, char *, int));
+ #if defined (HANDLE_MULTIBYTE)
+-static int read_mbchar PARAMS((int, char *, int, int, int));
++static int read_mbchar PARAMS((int, char *, int, int, int, int));
+ #endif
+ static void ttyrestore PARAMS((struct ttsave *));
+ 
+@@ -806,7 +806,7 @@ add_char:
+ 	  else
+ #  endif
+ 	  if (locale_utf8locale == 0 || ((c & 0x80) != 0))
+-	    i += read_mbchar (fd, input_string, i, c, unbuffered_read);
++	    i += read_mbchar (fd, input_string, i, c, delim, unbuffered_read);
+ 	}
+ #endif
+ 
+@@ -1064,10 +1064,10 @@ bind_read_variable (name, value, flags)
+ 
+ #if defined (HANDLE_MULTIBYTE)
+ static int
+-read_mbchar (fd, string, ind, ch, unbuffered)
++read_mbchar (fd, string, ind, ch, delim, unbuffered)
+      int fd;
+      char *string;
+-     int ind, ch, unbuffered;
++     int ind, ch, delim, unbuffered;
+ {
+   char mbchar[MB_LEN_MAX + 1];
+   int i, n, r;
+@@ -1101,8 +1101,21 @@ read_mbchar (fd, string, ind, ch, unbuffered)
+ 	  mbchar[i++] = c;	
+ 	  continue;
+ 	}
+-      else if (ret == (size_t)-1 || ret == (size_t)0 || ret > (size_t)0)
+-	break;
++      else if (ret == (size_t)-1)
++	{
++	  /* If we read a delimiter character that makes this an invalid
++	     multibyte character, we can't just add it to the input string
++	     and treat it as a byte. We need to push it back so a subsequent
++	     zread will pick it up. */
++	  if (c == delim)
++	    {
++	      zungetc (c);
++	      mbchar[--i] = '\0';		/* unget the delimiter */
++	    }
++	  break;		/* invalid multibyte character */
++	}
++      else if (ret == (size_t)0 || ret > (size_t)0)
++	break;		/* valid multibyte character */
+     }
+ 
+ mbchar_return:
+diff --git externs.h externs.h
+index 931dba9c..1b70a13b 100644
+--- externs.h
++++ externs.h
+@@ -536,6 +536,7 @@ extern ssize_t zreadintr PARAMS((int, char *, size_t));
+ extern ssize_t zreadc PARAMS((int, char *));
+ extern ssize_t zreadcintr PARAMS((int, char *));
+ extern ssize_t zreadn PARAMS((int, char *, size_t));
++extern int zungetc PARAMS((int));
+ extern void zreset PARAMS((void));
+ extern void zsyncfd PARAMS((int));
+ 
+diff --git lib/sh/zread.c lib/sh/zread.c
+index dafb7f60..7cfbb288 100644
+--- lib/sh/zread.c
++++ lib/sh/zread.c
+@@ -41,6 +41,10 @@ extern int errno;
+ #  define ZBUFSIZ 4096
+ #endif
+ 
++#ifndef EOF
++#  define EOF -1
++#endif
++
+ extern int executing_builtin;
+ 
+ extern void check_signals_and_traps (void);
+@@ -48,6 +52,11 @@ extern void check_signals (void);
+ extern int signal_is_trapped (int);
+ extern int read_builtin_timeout (int);
+ 
++int zungetc (int);
++
++/* Provide one character of pushback whether we are using read or zread. */
++static int zpushedchar = -1;
++
+ /* Read LEN bytes from FD into BUF.  Retry the read on EINTR.  Any other
+    error causes the loop to break. */
+ ssize_t
+@@ -59,6 +68,15 @@ zread (fd, buf, len)
+   ssize_t r;
+ 
+   check_signals ();	/* check for signals before a blocking read */
++
++  /* If we pushed a char back, return it immediately */
++  if (zpushedchar != -1)
++    {
++      *buf = (unsigned char)zpushedchar;
++      zpushedchar = -1;
++      return 1;
++    }
++
+   /* should generalize into a mechanism where different parts of the shell can
+      `register' timeouts and have them checked here. */
+   while (((r = read_builtin_timeout (fd)) < 0 || (r = read (fd, buf, len)) < 0) &&
+@@ -95,6 +113,14 @@ zreadretry (fd, buf, len)
+   ssize_t r;
+   int nintr;
+ 
++  /* If we pushed a char back, return it immediately */
++  if (zpushedchar != -1)
++    {
++      *buf = (unsigned char)zpushedchar;
++      zpushedchar = -1;
++      return 1;
++    }
++
+   for (nintr = 0; ; )
+     {
+       r = read (fd, buf, len);
+@@ -118,6 +144,15 @@ zreadintr (fd, buf, len)
+      size_t len;
+ {
+   check_signals ();
++
++  /* If we pushed a char back, return it immediately */
++  if (zpushedchar != -1)
++    {
++      *buf = (unsigned char)zpushedchar;
++      zpushedchar = -1;
++      return 1;
++    }
++
+   return (read (fd, buf, len));
+ }
+ 
+@@ -135,6 +170,14 @@ zreadc (fd, cp)
+ {
+   ssize_t nr;
+ 
++  /* If we pushed a char back, return it immediately */
++  if (zpushedchar != -1 && cp)
++    {
++      *cp = (unsigned char)zpushedchar;
++      zpushedchar = -1;
++      return 1;
++    }
++
+   if (lind == lused || lused == 0)
+     {
+       nr = zread (fd, lbuf, sizeof (lbuf));
+@@ -160,6 +203,14 @@ zreadcintr (fd, cp)
+ {
+   ssize_t nr;
+ 
++  /* If we pushed a char back, return it immediately */
++  if (zpushedchar != -1 && cp)
++    {
++      *cp = (unsigned char)zpushedchar;
++      zpushedchar = -1;
++      return 1;
++    }
++
+   if (lind == lused || lused == 0)
+     {
+       nr = zreadintr (fd, lbuf, sizeof (lbuf));
+@@ -186,6 +237,13 @@ zreadn (fd, cp, len)
+ {
+   ssize_t nr;
+ 
++  if (zpushedchar != -1 && cp)
++    {
++      *cp = zpushedchar;
++      zpushedchar = -1;
++      return 1;
++    }
++
+   if (lind == lused || lused == 0)
+     {
+       if (len > sizeof (lbuf))
+@@ -204,6 +262,22 @@ zreadn (fd, cp, len)
+   return 1;
+ }
+ 
++int
++zungetc (c)
++     int c;
++{
++  if (zpushedchar == -1)
++    {
++      zpushedchar = c;
++      return c;
++    }
++
++  if (c == EOF || lind == 0)
++    return (EOF);
++  lbuf[--lind] = c;		/* XXX */
++  return c;
++}
++
+ void
+ zreset ()
+ {
+-- 
+2.45.2
+