From c08932c6e5e1609835219e9f42efe46bb6624a7d Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris+github@qwirx.com>
Date: Sat, 24 Feb 2018 08:47:40 +0000
Subject: Fix raidfile tests on 32-bit Linux

A recent fix for Solaris (commit 81e9aa6545f7f19124c9f5e88982b867d8732965)
broke support for 32-bit Linux (which wasn't spotted because we didn't have any
32-bit builders). Try a different approach: detect whether the lseek syscall
takes a 64-bit integer offset, and use that if possible.

CMake: reimplement autoconf tests for 64-bit lseek

(cherry picked from commit 138ea5d174f146f14d91a16bf5d1ce8e479d2024)
---
 infrastructure/m4/ax_check_syscall_lseek.m4 | 111 +++++++++++++++++++---------
 1 file changed, 78 insertions(+), 33 deletions(-)

(limited to 'infrastructure/m4/ax_check_syscall_lseek.m4')

diff --git a/infrastructure/m4/ax_check_syscall_lseek.m4 b/infrastructure/m4/ax_check_syscall_lseek.m4
index 9fd04c81..4fec851a 100644
--- a/infrastructure/m4/ax_check_syscall_lseek.m4
+++ b/infrastructure/m4/ax_check_syscall_lseek.m4
@@ -11,12 +11,14 @@ dnl @category C
 dnl @author Martin Ebourne
 dnl @version 2005/07/03
 dnl @license AllPermissive
+dnl
 
-AC_DEFUN([AX_CHECK_SYSCALL_LSEEK], [
-  AC_REQUIRE([AX_FUNC_SYSCALL])dnl
-  if test "x$ac_cv_header_sys_syscall_h" = "xyes"; then
-    AC_CACHE_CHECK([[whether syscall lseek requires dummy parameter]], [box_cv_have_lseek_dummy_param],
-      [AC_TRY_RUN(
+AC_DEFUN(
+  [AX_TRY_RUN_FD],
+  [
+    AC_REQUIRE([AX_FUNC_SYSCALL])dnl
+    if test "x$ac_cv_header_sys_syscall_h" = "xyes"; then
+      AC_TRY_RUN(
         [
           $ac_includes_default
           #include <fcntl.h>
@@ -30,40 +32,83 @@ AC_DEFUN([AX_CHECK_SYSCALL_LSEEK], [
           #endif
           int main()
           {
-          int fh = creat("lseektest", 0600);
-          int res = 0;
-          if(fh>=0)
+          int fd = creat("lseektest", 0600);
+          int res = 1;
+          if(fd>=0)
           {
+            $1
+            close(fd);
+          }
+          unlink("lseektest");
+          return abs(res);
+          }
+        ],
+        [$2],
+	[$3],
+	[$3 # assume not for cross-compiling]
+      )
+    fi
+  ])dnl
+
+AC_DEFUN([AX_CHECK_SYSCALL_LSEEK_DUMMY_PARAM], [
+  AC_CACHE_CHECK(
+    [[whether syscall lseek requires dummy parameter]],
+    [box_cv_have_lseek_dummy_param],
+    [AX_TRY_RUN_FD(
+      [
             // This test tries first to seek to position 0, with NO
             // "dummy argument". If lseek does actually require a dummy
             // argument, then it will eat SEEK_SET for the offset and
             // try to use 99 as whence, which is invalid, so res will be
-            // -1, the program will return zero and 
-            // have_lseek_dummy_param=yes 
+            // 1, the program will return 1 and we will define
+            // HAVE_LSEEK_DUMMY_PARAM
             // (whew! that took 1 hour to figure out)
             // The "dummy argument" probably means that it takes a 64-bit
-            // offset, so this was probably a bug anyway, and now that
-            // we cast the offset to off_t, it should never be needed
-            // (if my reasoning is correct).
-            res = syscall(SYS_lseek, fh, (off_t)0, SEEK_SET, 99);
-            close(fh);
-          }
-          unlink("lseektest");
-          return res!=-1;
-          }
-        ],
-        [box_cv_have_lseek_dummy_param=yes],
-	[box_cv_have_lseek_dummy_param=no],
-	[box_cv_have_lseek_dummy_param=no # assume not for cross-compiling]
-      )])
-    if test "x$box_cv_have_lseek_dummy_param" = "xyes"; then
-      AC_DEFINE([HAVE_LSEEK_DUMMY_PARAM], 1,
-                [Define to 1 if syscall lseek requires a dummy middle parameter])
-    fi
+            // offset.
+            res = (syscall(SYS_lseek, fd, (int32_t)10, SEEK_SET, 99) == 10) ? 0 : 1;
+      ],
+      dnl if the test program succeeds (res == 0):
+      [box_cv_have_lseek_dummy_param=no],
+      dnl if the test program fails (res != 0):
+      [box_cv_have_lseek_dummy_param=yes],
+    )]
+  )
+  if test "x$box_cv_have_lseek_dummy_param" != "xno"; then
+    AC_DEFINE([HAVE_LSEEK_DUMMY_PARAM], 1,
+              [Define to 1 if syscall lseek requires a dummy middle parameter])
   fi
-  if test "x$box_cv_have_lseek_dummy_param" = "xno"
-  then
-    m4_ifvaln([$1],[$1],[:])dnl
-    m4_ifvaln([$2],[else $2])dnl
+])
+
+# Please note: this does not appear to work! Do not rely on it without further testing:
+AC_DEFUN([AX_CHECK_SYSCALL_LSEEK_64_BIT], [
+  AC_CACHE_CHECK(
+    [[whether syscall lseek takes a 64-bit offset parameter]],
+    [box_cv_have_lseek_64_bit],
+    [AX_TRY_RUN_FD(
+      [
+            // Try to seek to a position that requires a 64-bit representation, and check the return
+            // value, which is the current position.
+            if(syscall(SYS_lseek, fd, (int64_t)5, SEEK_SET) != 5)
+            {
+              res = 2;
+            }
+            else if(syscall(SYS_lseek, fd, (int64_t)10, SEEK_CUR) != 15)
+            {
+              res = 3;
+            }
+            else
+            {
+              res = 0;
+            }
+      ],
+      dnl if the test program succeeds (res == 0):
+      [box_cv_have_lseek_64_bit=yes],
+      dnl if the test program fails (res != 0):
+      [box_cv_have_lseek_64_bit=no]
+    )]
+  )
+  if test "x$box_cv_have_lseek_64_bit" != "xno"; then
+    AC_DEFINE([HAVE_LSEEK_64_BIT], 1,
+              [Define to 1 if syscall lseek takes a 64-bit offset])
   fi
-  ])dnl
+])
-- 
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