From 210a25afdeceb386b8dac84c0fedcaa12ca36370 Mon Sep 17 00:00:00 2001
From: Marek Blaha <mblaha@redhat.com>
Date: Tue, 5 Dec 2023 11:30:49 +0100
Subject: [PATCH 1/2] vars: Use uname() for architecture autodetection

The %_host_cpu macro is not runtime detected, it's only usable to detect
which architecture rpm was built for.
To detect that dnf5 is running on 32bit personality on x86_64 we need to
use uname().
The code is taken from libdnf (see libdnf/hy-util.cpp).

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2252671
---
 libdnf5/conf/vars.cpp | 46 +++++++++++++++++++++++++++++++++++++------
 1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/libdnf5/conf/vars.cpp b/libdnf5/conf/vars.cpp
index 5905069ab..08785ea71 100644
--- a/libdnf5/conf/vars.cpp
+++ b/libdnf5/conf/vars.cpp
@@ -33,7 +33,9 @@ along with libdnf.  If not, see <https://www.gnu.org/licenses/>.
 #include <rpm/rpmmacro.h>
 #include <rpm/rpmts.h>
 #include <stdlib.h>
+#include <sys/auxv.h>
 #include <sys/types.h>
+#include <sys/utsname.h>
 
 #include <algorithm>
 #include <cstring>
@@ -73,14 +75,46 @@ static constexpr const char * DISTROVERPKGS[] = {
     "redhat-release",
     "suse-release"};
 
+/* ARM specific HWCAP defines may be missing on non-ARM devices */
+#ifndef HWCAP_ARM_VFP
+#define HWCAP_ARM_VFP (1 << 6)
+#endif
+#ifndef HWCAP_ARM_NEON
+#define HWCAP_ARM_NEON (1 << 12)
+#endif
+
 static std::string detect_arch() {
-    std::string value{};
-    char * tmp = rpmExpand("%{_host_cpu}", NULL);
-    if (tmp != nullptr) {
-        value = tmp;
-        free(tmp);
+    struct utsname un;
+
+    if (uname(&un) < 0) {
+        throw RuntimeError(M_("Failed to execute uname()"));
+    }
+
+    if (!strncmp(un.machine, "armv", 4)) {
+        /* un.machine is armvXE, where X is version number and E is
+         * endianness (b or l); we need to add modifiers such as
+         * h (hardfloat), n (neon). Neon is a requirement of armv8 so
+         * as far as rpm is concerned armv8l is the equivilent of armv7hnl
+         * (or 7hnb) so we don't explicitly add 'n' for 8+ as it's expected. */
+        char endian = un.machine[strlen(un.machine) - 1];
+        char * modifier = un.machine + 5;
+        while (isdigit(*modifier)) /* keep armv7, armv8, armv9, armv10, armv100, ... */
+            modifier++;
+        if (getauxval(AT_HWCAP) & HWCAP_ARM_VFP)
+            *modifier++ = 'h';
+        if ((atoi(un.machine + 4) == 7) && (getauxval(AT_HWCAP) & HWCAP_ARM_NEON))
+            *modifier++ = 'n';
+        *modifier++ = endian;
+        *modifier = 0;
     }
-    return value;
+#ifdef __MIPSEL__
+    // support for little endian MIPS
+    if (!strcmp(un.machine, "mips"))
+        strcpy(un.machine, "mipsel");
+    else if (!strcmp(un.machine, "mips64"))
+        strcpy(un.machine, "mips64el");
+#endif
+    return un.machine;
 }
 
 

From 8086e212c5e85c4954f237e1fa7aed55f0144ea6 Mon Sep 17 00:00:00 2001
From: Marek Blaha <mblaha@redhat.com>
Date: Wed, 6 Dec 2023 10:59:59 +0100
Subject: [PATCH 2/2] vars: Always init librpm with correct architecture

Now that detect_arch() no longer relies on initialized librpm, we can
defer the librpm initialization until after the arch is detected and use
the detected architecture as its argument.
---
 libdnf5/conf/vars.cpp | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/libdnf5/conf/vars.cpp b/libdnf5/conf/vars.cpp
index 08785ea71..a017e2000 100644
--- a/libdnf5/conf/vars.cpp
+++ b/libdnf5/conf/vars.cpp
@@ -411,15 +411,11 @@ void Vars::load(const std::string & installroot, const std::vector<std::string>
 }
 
 void Vars::detect_vars(const std::string & installroot) {
-    const char * arch = nullptr;
-    if (contains("arch")) {
-        arch = get_value("arch").c_str();
-    }
-    init_lib_rpm(arch);
-
     set_lazy(
         "arch", []() -> auto { return std::make_unique<std::string>(detect_arch()); }, Priority::AUTO);
 
+    init_lib_rpm(get_value("arch").c_str());
+
     set_lazy(
         "basearch",
         [this]() -> auto {