From 6fb7ee330af7acbbcd93d559761229329b4d0bf2 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Thomas=20Wei=C3=9Fschuh?= <thomas@t-8ch.de>
Date: Fri, 7 Nov 2025 12:47:20 +0100
Subject: [PATCH] build: simplify checks for fallocate() and posix_fallocate()
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The bespoke test logic for those two functions was only necessary for
old glibc versions which have long gone out of support.

Align the checks with all other ones.

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
 configure.ac | 63 ++--------------------------------------------------
 meson.build  | 34 ++--------------------------
 2 files changed, 4 insertions(+), 93 deletions(-)

diff --git a/configure.ac b/configure.ac
index 6836f0564..297b9fb3f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -614,6 +614,7 @@ AC_CHECK_FUNCS([ \
 	explicit_bzero \
 	__fpending \
 	__fpurge \
+	fallocate \
 	fpurge \
 	fnmatch \
 	fsconfig \
@@ -652,6 +653,7 @@ AC_CHECK_FUNCS([ \
 	pidfd_open \
 	pidfd_send_signal \
 	posix_fadvise \
+	posix_fallocate \
 	prctl \
 	qsort_r \
 	reallocarray \
@@ -1590,67 +1592,6 @@ UL_REQUIRES_LINUX([fallocate])
 UL_REQUIRES_SYSCALL_CHECK([fallocate], [UL_CHECK_SYSCALL([fallocate])])
 AM_CONDITIONAL([BUILD_FALLOCATE], [test "x$build_fallocate" = xyes])
 
-AS_IF([test "x$build_fallocate" = xyes], [
-  dnl check for valid fallocate() function
-  dnl with 32 bits glibc 2.10, fallocate() exists but not fallocate64()
-  dnl when _FILE_OFFSET_BITS==64, fallocate() is redirect to fallocate64()
-  dnl and program can't be linked.
-  dnl AC_CHECK_FUNC can't catch such errors since it's redefining
-  dnl function prototype.
-  AC_MSG_CHECKING([for valid fallocate() function])
-  AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
-#endif
-#ifdef HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
-#ifdef HAVE_LINUX_FALLOC_H
-# include <linux/falloc.h>
-#endif
-#ifdef HAVE_FCNTL_H
-# include <fcntl.h>
-#endif
-]],[[
-   long ret;
-   ret = fallocate(0, FALLOC_FL_KEEP_SIZE, 0xfffffffful, 0xfffffffful);
-   if (ret != 0) {
-      return 1;
-   }
-   ]])],[
-  AC_MSG_RESULT([yes])
-  AC_DEFINE([HAVE_FALLOCATE], [1], [Have valid fallocate() function])],[
-  AC_MSG_RESULT([no])])
-])
-
-AS_IF([test "x$build_fallocate" = xyes], [
-  dnl check for valid posix_fallocate() function
-  AC_MSG_CHECKING([for valid posix_fallocate() function])
-  AC_LINK_IFELSE([AC_LANG_PROGRAM([[
-#ifdef HAVE_UNISTD_H
-# include <unistd.h>
-#endif
-#ifdef HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
-#ifdef HAVE_LINUX_FALLOC_H
-# include <linux/falloc.h>
-#endif
-#ifdef HAVE_FCNTL_H
-# include <fcntl.h>
-#endif
-]],[[
-   long ret;
-   ret = posix_fallocate(0, 0xfffffffful, 0xfffffffful);
-   if (ret != 0) {
-      return 1;
-   }
-   ]])],[
-  AC_MSG_RESULT([yes])
-  AC_DEFINE([HAVE_POSIX_FALLOCATE], [1], [Have valid posix_fallocate() function])],[
-  AC_MSG_RESULT([no])])
-])
-
 
 AC_ARG_ENABLE([unshare],
   AS_HELP_STRING([--disable-unshare], [do not build unshare]),
diff --git a/meson.build b/meson.build
index 7a995d612..00c24c751 100644
--- a/meson.build
+++ b/meson.build
@@ -606,6 +606,7 @@ funcs = '''
         err
         errx
         explicit_bzero
+        fallocate
         fnmatch
         fseeko
         fsconfig
@@ -644,6 +645,7 @@ funcs = '''
         pidfd_open
         pidfd_send_signal
         posix_fadvise
+        posix_fallocate
         prctl
         qsort_r
         reallocarray
@@ -890,38 +892,6 @@ summary('plymouth support',
         build_plymouth_support  ? 'enabled' : 'disabled',
         section : 'components')
 
-# check for valid fallocate() function
-# with 32 bits glibc 2.10, fallocate() exists but not fallocate64()
-# when _FILE_OFFSET_BITS==64, fallocate() is redirect to fallocate64()
-# and program can't be linked.
-code = '''
-#define _GNU_SOURCE
-#include <unistd.h>
-#include <fcntl.h>
-
-int main(void) {
-   long ret;
-   ret = fallocate(0, FALLOC_FL_KEEP_SIZE, 0xfffffffful, 0xfffffffful);
-   return ret == 0 ? 0 : 1;
-}
-'''
-have = cc.links(code, name : 'fallocate() function')
-conf.set('HAVE_FALLOCATE', have ? 1 : false)
-
-code = '''
-#define _POSIX_C_SOURCE 200112L
-#include <unistd.h>
-#include <fcntl.h>
-
-int main(void) {
-   long ret;
-   ret = posix_fallocate(0, 0xfffffffful, 0xfffffffful);
-   return ret == 0 ? 0 : 1;
-}
-'''
-have = cc.links(code, name : 'posix_fallocate() function')
-conf.set('HAVE_POSIX_FALLOCATE', have ? 1 : false)
-
 use_hwclock_cmos = host_machine.cpu_family() in ['x86', 'x86_64']
 message('Use CMOS clock: @0@'.format(use_hwclock_cmos))
 conf.set('USE_HWCLOCK_CMOS', use_hwclock_cmos ? 1 : false)
-- 
2.47.3