From: Denis Ovsienko <denis@ovsienko.info>
Date: Sat, 22 Jul 2023 12:50:16 +0000 (+0100)
Subject: Autoconf: Get --with-user and --with-chroot right.  [skip appveyor]
X-Git-Tag: tcpdump-4.99.5~181
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/e6e2db1ca398a11fabd27bac2a81f110c7b2de06

Autoconf: Get --with-user and --with-chroot right.  [skip appveyor]

As Francois-Xavier points it out, my commit 3aa6574 fixed one bug, but
introduced another: running "./configure --with-gcc" also erroneously
takes the --with-user code path because withval is set to "yes" after
the --with-gcc block:

./configure --with-gcc
[...]
checking whether to drop root privileges by default... configure:
  error: --with-user requires a username

The matter is, in Autoconf AC_ARG_WITH() without ation-if-not-given
assigns withval only if with_xxxx is set to any value (including an
empty string), so make sure withval is always set in AC_ARG_WITH() and
spell all possible withval values in AS_CASE(), this way regardless of
any other options the behaviour is correct.

Rejected:
--with-user
--with-user=
--with-user=yes
--with-chroot
--with-chroot=
--with-chroot=yes

Accepted:
--without-user
--with-user=no
--with-user=someuser
--without-chroot
--with-chroot=no
--with-chroot=/somedir

(cherry picked from commit df376cdfb5aca21ffb516e9b4ae9cccf0da4d166)

Moreover:
Run autoreconf2.69 -f.
---

diff --git a/configure b/configure
index b12f9366..4b06488b 100755
--- a/configure
+++ b/configure
@@ -4367,47 +4367,64 @@ $as_echo "no" >&6; }
 	;;
 esac
 
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to drop root privileges by default" >&5
+$as_echo_n "checking whether to drop root privileges by default... " >&6; }
 
 # Check whether --with-user was given.
 if test "${with_user+set}" = set; then :
   withval=$with_user;
+else
+  withval=no
 fi
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to drop root privileges by default" >&5
-$as_echo_n "checking whether to drop root privileges by default... " >&6; }
-if test ! -z "$with_user" ; then
+case "$withval" in #(
+  no) :
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; } ;; #(
+  ''|yes) :
+    as_fn_error $? "--with-user requires a username" "$LINENO" 5 ;; #(
+  *) :
+
 
 cat >>confdefs.h <<_ACEOF
 #define WITH_USER "$withval"
 _ACEOF
 
-       { $as_echo "$as_me:${as_lineno-$LINENO}: result: to \"$withval\"" >&5
-$as_echo "to \"$withval\"" >&6; }
-else
-       { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes, to user \"$withval\"" >&5
+$as_echo "yes, to user \"$withval\"" >&6; }
 
+ ;;
+esac
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to chroot" >&5
+$as_echo_n "checking whether to chroot... " >&6; }
 
 # Check whether --with-chroot was given.
 if test "${with_chroot+set}" = set; then :
   withval=$with_chroot;
+else
+  withval=no
+
 fi
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to chroot" >&5
-$as_echo_n "checking whether to chroot... " >&6; }
-if test ! -z "$with_chroot" && test "$with_chroot" != "no" ; then
+case "$withval" in #(
+  no) :
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; } ;; #(
+  ''|yes) :
+    as_fn_error $? "--with-chroot requires a directory" "$LINENO" 5 ;; #(
+  *) :
+
 
 cat >>confdefs.h <<_ACEOF
 #define WITH_CHROOT "$withval"
 _ACEOF
 
-       { $as_echo "$as_me:${as_lineno-$LINENO}: result: to \"$withval\"" >&5
-$as_echo "to \"$withval\"" >&6; }
-else
-       { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
-$as_echo "no" >&6; }
-fi
+		{ $as_echo "$as_me:${as_lineno-$LINENO}: result: yes, to directory \"$withval\"" >&5
+$as_echo "yes, to directory \"$withval\"" >&6; }
+
+ ;;
+esac
 
 
 # Check whether --with-sandbox-capsicum was given.
diff --git a/configure.ac b/configure.ac
index 21a0f701..1eed05a1 100644
--- a/configure.ac
+++ b/configure.ac
@@ -153,31 +153,42 @@ yes)	AC_MSG_RESULT(yes)
 	;;
 esac
 
-AC_ARG_WITH(user, [  --with-user=USERNAME    drop privileges by default to USERNAME])
 AC_MSG_CHECKING([whether to drop root privileges by default])
-if test ! -z "$withval" && test "$withval" != "no" ; then
-       if test "$withval" = "yes" ; then
-           AC_MSG_ERROR([--with-user requires a username])
-       fi
-       AC_DEFINE_UNQUOTED(WITH_USER, "$withval",
-           [define if should drop privileges by default])
-       AC_MSG_RESULT([yes, to user "$withval"])
-else
-       AC_MSG_RESULT(no)
-fi
+AC_ARG_WITH(
+	[user],
+	[AS_HELP_STRING([--with-user=USERNAME],
+		[drop privileges by default to USERNAME]
+	)],
+	[],
+	[withval=no])
+AS_CASE(["$withval"],
+	[no], [AC_MSG_RESULT(no)],
+	[''|yes], [AC_MSG_ERROR([--with-user requires a username])],
+	[
+		AC_DEFINE_UNQUOTED(WITH_USER, "$withval",
+		    [define if should drop privileges by default])
+		AC_MSG_RESULT([yes, to user "$withval"])
+	]
+)
 
-AC_ARG_WITH(chroot, [  --with-chroot=DIRECTORY when dropping privileges, chroot to DIRECTORY])
 AC_MSG_CHECKING([whether to chroot])
-if test ! -z "$withval" && test "$withval" != "no" ; then
-       if test "$withval" = "yes" ; then
-           AC_MSG_ERROR([--with-chroot requires a directory])
-       fi
-       AC_DEFINE_UNQUOTED(WITH_CHROOT, "$withval",
-           [define if should chroot when dropping privileges])
-       AC_MSG_RESULT([yes, to directory "$withval"])
-else
-       AC_MSG_RESULT(no)
-fi
+AC_ARG_WITH(
+	[chroot],
+	[AS_HELP_STRING([--with-chroot=DIRECTORY],
+		[when dropping privileges, chroot to DIRECTORY]
+	)],
+	[],
+	[withval=no]
+)
+AS_CASE(["$withval"],
+	[no], [AC_MSG_RESULT(no)],
+	[''|yes], [AC_MSG_ERROR([--with-chroot requires a directory])],
+	[
+		AC_DEFINE_UNQUOTED(WITH_CHROOT, "$withval",
+		    [define if should chroot when dropping privileges])
+		AC_MSG_RESULT([yes, to directory "$withval"])
+	]
+)
 
 AC_ARG_WITH(sandbox-capsicum,
 	AS_HELP_STRING([--with-sandbox-capsicum],