From 700394c8ed3c3db06fe2c3b4667a33896d3b1e74 Mon Sep 17 00:00:00 2001
From: Florian Weimer <fweimer@redhat.com>
Date: Sun, 27 Jun 2021 15:06:13 +0200
Subject: [PATCH] Add automatic requires if building against glibc development
 snapshots

---
 glibc.attr   |  3 +++
 glibc.req.in | 40 ++++++++++++++++++++++++++++++++++++++++
 glibc.spec   | 37 +++++++++++++++++++++++++++++++++++--
 3 files changed, 78 insertions(+), 2 deletions(-)
 create mode 100644 glibc.attr
 create mode 100644 glibc.req.in

diff --git a/glibc.attr b/glibc.attr
new file mode 100644
index 0000000..fddfd91
--- /dev/null
+++ b/glibc.attr
@@ -0,0 +1,3 @@
+%__glibc_requires %{_rpmconfigdir}/glibc.req
+%__glibc_magic ELF
+%__glibc_flags exeonly
diff --git a/glibc.req.in b/glibc.req.in
new file mode 100644
index 0000000..3f922d1
--- /dev/null
+++ b/glibc.req.in
@@ -0,0 +1,40 @@
+#!/bin/bash
+# Auto-generating dependencies for glibc development snapshots.
+#
+# A glibc development snapshot (say version 2.33.9000) may define
+# symbols in its under-development symbol version (GLIBC_2.34).  RPM
+# automatically derives RPM dependencies such as
+# libc.so.6(GLIBC_2.34)(64bit) from that.  While the GLIBC_2.34
+# version is under development, these dependencies may be inaccurate
+# and could be satisfied by glibc RPM package versions that lack the
+# symbols because they were created from an earlier development
+# snapshot that had some other GLIBC_2.34 symbols.  Therefore, if the
+# latest, under-development ELF symbol version is detected, this
+# dependency generator adds an explicit RPM dependencies on the glibc
+# packaging version against which an RPM package is built.
+#
+# This script runs for the glibc build itself.  In this case, it may
+# produce a >= dependency on the build-time glibc, but there will also
+# be an (potentially indirect) = dependency, which takes precedence.
+
+set -e
+set -o pipefail
+
+searching=true
+# Pre-filter using eu-elfclassify, to skip kernel modules.
+eu-elfclassify --loadable --file --stdin --print | while read path; do
+    # Assume that all dynamically linked objects depend on glibc in
+    # some way.
+    if $searching; then
+	# Undefined symbols within latest, under-development
+	# (changing) symbol versions trigger the versioned RPM
+	# dependency.
+	if eu-readelf -s "$path" | egrep -q '\sUNDEF\s.*@''@SYMVER@(\s|$)'
+	then
+	    echo 'glibc >= @VERSION@-@RELEASE@'
+	    # Stop searching after the first match, but keep reading from
+	    # the pipe.
+	    searching=false
+	fi
+    fi
+done
diff --git a/glibc.spec b/glibc.spec
index 07018c4..5568230 100644
--- a/glibc.spec
+++ b/glibc.spec
@@ -8,8 +8,22 @@
 # gzip -9 $(git describe --match 'glibc-*').tar
 #
 # glibc_release_url is only defined when we have a release tarball.
+# Conversly, glibc_autorequires is set for development snapshots, where
+# dependencies based on symbol versions are inaccurate.
 %{lua: if string.match(rpm.expand("%glibcsrcdir"), "^glibc%-[0-9.]+$") then
-  rpm.define("glibc_release_url https://ftp.gnu.org/gnu/glibc/") end}
+    rpm.define("glibc_release_url https://ftp.gnu.org/gnu/glibc/")
+  end
+  local major, minor = string.match(rpm.expand("%glibcversion"),
+                                    "^([0-9]+)%.([0-9]+)%.9000$")
+  if major and minor then
+    rpm.define("glibc_autorequires 1")
+    -- The minor version in a .9000 development version lags the actual
+    -- symbol version by one.
+    local symver = "GLIBC_" .. major .. "." .. (minor + 1)
+    rpm.define("glibc_autorequires_symver " .. symver)
+  else
+    rpm.define("glibc_autorequires 0")
+  end}
 ##############################################################################
 # We support the following options:
 # --with/--without,
@@ -97,7 +111,7 @@
 Summary: The GNU libc libraries
 Name: glibc
 Version: %{glibcversion}
-Release: 25%{?dist}
+Release: 26%{?dist}
 
 # In general, GPLv2+ is used by programs, LGPLv2+ is used for
 # libraries.
@@ -131,6 +145,8 @@ Source0: %{?glibc_release_url}%{glibcsrcdir}.tar.xz
 Source1: nscd.conf
 Source2: bench.mk
 Source3: glibc-bench-compare
+Source4: glibc.req.in
+Source5: glibc.attr
 Source10: wrap-find-debuginfo.sh
 Source11: parse-SUPPORTED.py
 # Include in the source RPM for reference.
@@ -1660,6 +1676,16 @@ sed -i -e '\,libmemusage.so,d' \
 	-e '\,/libnss_[a-z]*\.so$,d' \
 	devel.filelist
 
+%if %{glibc_autorequires}
+mkdir -p %{glibc_sysroot}/%{_rpmconfigdir} %{glibc_sysroot}/%{_fileattrsdir}
+sed < %{SOURCE4} \
+    -e s/@VERSION@/%{version}/ \
+    -e s/@RELEASE@/%{release}/ \
+    -e s/@SYMVER@/%{glibc_autorequires_symver}/ \
+    > %{glibc_sysroot}/%{_rpmconfigdir}/glibc.req
+cp %{SOURCE5} %{glibc_sysroot}/%{_fileattrsdir}/glibc.attr
+%endif
+
 ###############################################################################
 # glibc-doc
 ###############################################################################
@@ -2133,6 +2159,10 @@ fi
 %{_prefix}/share/i18n/charmaps/*
 
 %files -f devel.filelist devel
+%if %{glibc_autorequires}
+%attr(0755,root,root) %{_rpmconfigdir}/glibc.req
+%{_fileattrsdir}/glibc.attr
+%endif
 
 %if %{with docs}
 %files -f doc.filelist doc
@@ -2183,6 +2213,9 @@ fi
 %files -f compat-libpthread-nonshared.filelist -n compat-libpthread-nonshared
 
 %changelog
+* Sun Jun 27 2021 Florian Weimer <fweimer@redhat.com> - 2.33.9000-26
+- Add automatic requires if building against glibc development snapshots
+
 * Thu Jun 24 2021 Carlos O'Donell <carlos@redhat.com> - 2.33.9000-25
 - Fix thread local storage corruption (#1974970)