From b427defc39e22451bc099ce880e089a243ee98d9 Mon Sep 17 00:00:00 2001
From: Sebastien Marie <semarie@kapouay.eu.org>
Date: Wed, 23 Jul 2025 08:50:50 +0000
Subject: [PATCH] openbsd: implement FILE_CNT() on opaque FILE

On OpenBSD, FILE is opaque (starting from upcoming OpenBSD 7.8).
FILE_CNT() macro is implementable using `size_t __freadahead(FILE *stream)` function (provided for gnulib compat).
---
 src/aclocal.m4                         | 21 ++++++++++-----
 src/configure                          | 37 +++++++++++++++++++++-----
 src/h/config-internal.h.in             |  8 ++++--
 src/util/x86-linux-gnu.cross_config    |  2 +-
 src/util/x86_64-linux-gnu.cross_config |  2 +-
 5 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/src/aclocal.m4 b/src/aclocal.m4
index 30299c816..28c7ffd7c 100644
--- a/src/aclocal.m4
+++ b/src/aclocal.m4
@@ -153,9 +153,10 @@ ECL_NEWLINE=LF
 ### 1.5) Can we guess how many characters are available for reading from
 ###      the FILE structure?
 ###          0 = no
-###          1 = (f)->_IO_read_end - (f)->_IO_read_ptr
-###          2 = (f)->_r
-###          3 = (f)->_cnt
+###          1 = __freadahead((f))
+###          2 = (f)->_IO_read_end - (f)->_IO_read_ptr
+###          3 = (f)->_r
+###          4 = (f)->_cnt
 ECL_FILE_CNT=0
 
 ###
@@ -626,21 +627,29 @@ AC_DEFUN(ECL_FILE_STRUCTURE,[
 AC_SUBST(ECL_FILE_CNT)
 if test -z "${ECL_FILE_CNT}"; then
 ECL_FILE_CNT=0
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+  #include <stdio.h>
+  #include <stdio_ext.h>
+]], [[
+  FILE *f = fopen("conftestval","w");
+  if (__freadahead((f)))
+    return 1;
+]])],[ECL_FILE_CNT=1],[])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]], [[
   FILE *f = fopen("conftestval","w");
   if ((f)->_IO_read_end - (f)->_IO_read_ptr)
     return 1;
-]])],[ECL_FILE_CNT=1],[])
+]])],[ECL_FILE_CNT=2],[])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]], [[
   FILE *f = fopen("conftestval","w");
   if ((f)->_r)
     return 1;
-]])],[ECL_FILE_CNT=2],[])
+]])],[ECL_FILE_CNT=3],[])
 AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>]], [[
   FILE *f = fopen("conftestval","w");
   if ((f)->_cnt)
     return 1;
-]])],[ECL_FILE_CNT=3],[])
+]])],[ECL_FILE_CNT=4],[])
 fi
 ])
 
diff --git a/src/configure b/src/configure
index 6f82dbf9c..57834b92b 100755
--- a/src/configure
+++ b/src/configure
@@ -5886,9 +5886,10 @@ ECL_NEWLINE=LF
 ### 1.5) Can we guess how many characters are available for reading from
 ###      the FILE structure?
 ###          0 = no
-###          1 = (f)->_IO_read_end - (f)->_IO_read_ptr
-###          2 = (f)->_r
-###          3 = (f)->_cnt
+###          1 = __freadahead((f))
+###          2 = (f)->_IO_read_end - (f)->_IO_read_ptr
+###          3 = (f)->_r
+###          4 = (f)->_cnt
 ECL_FILE_CNT=0
 
 ###
@@ -9250,6 +9251,29 @@ fi
 if test -z "${ECL_FILE_CNT}"; then
 ECL_FILE_CNT=0
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+  #include <stdio.h>
+  #include <stdio_ext.h>
+
+int
+main (void)
+{
+
+  FILE *f = fopen("conftestval","w");
+  if (__freadahead((f)))
+    return 1;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"
+then :
+  ECL_FILE_CNT=1
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 #include <stdio.h>
 int
@@ -9266,7 +9290,7 @@ main (void)
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
-  ECL_FILE_CNT=1
+  ECL_FILE_CNT=2
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -9286,7 +9310,7 @@ main (void)
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
-  ECL_FILE_CNT=2
+  ECL_FILE_CNT=3
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
@@ -9306,7 +9330,7 @@ main (void)
 _ACEOF
 if ac_fn_c_try_compile "$LINENO"
 then :
-  ECL_FILE_CNT=3
+  ECL_FILE_CNT=4
 fi
 rm -f core conftest.err conftest.$ac_objext conftest.beam conftest.$ac_ext
 fi
@@ -12810,4 +12834,3 @@ fi
 
 
 for i in $srcdir/c/*/; do mkdir -p c/`basename $i`; done
-
diff --git a/src/h/config-internal.h.in b/src/h/config-internal.h.in
index ebb2792fd..952b41ee1 100644
--- a/src/h/config-internal.h.in
+++ b/src/h/config-internal.h.in
@@ -176,12 +176,16 @@
 
 #undef FILE_CNT
 #if @ECL_FILE_CNT@ == 1
-#  define FILE_CNT(fp)  ((fp)->_IO_read_end - (fp)->_IO_read_ptr)
+#  include <stdio_ext.h>
+#  define FILE_CNT(fp)  (__freadahead((fp)))
 #endif
 #if @ECL_FILE_CNT@ == 2
-#  define FILE_CNT(fp)  ((fp)->_r)
+#  define FILE_CNT(fp)  ((fp)->_IO_read_end - (fp)->_IO_read_ptr)
 #endif
 #if @ECL_FILE_CNT@ == 3
+#  define FILE_CNT(fp)  ((fp)->_r)
+#endif
+#if @ECL_FILE_CNT@ == 4
 #  define FILE_CNT(fp)  ((fp)->_cnt)
 #endif
 
diff --git a/src/util/x86-linux-gnu.cross_config b/src/util/x86-linux-gnu.cross_config
index 03be03df5..d309b5c60 100644
--- a/src/util/x86-linux-gnu.cross_config
+++ b/src/util/x86-linux-gnu.cross_config
@@ -8,7 +8,7 @@ CL_LONG_BITS=32
 ECL_STACK_DIR=down
 ECL_BIGENDIAN=no
 ECL_NEWLINE=LF
-ECL_FILE_CNT=1
+ECL_FILE_CNT=2
 ECL_STDINT_HEADER="#include <stdint.h>"
 ECL_UINT8_T=uint8_t
 ECL_UINT16_T=uint16_t
diff --git a/src/util/x86_64-linux-gnu.cross_config b/src/util/x86_64-linux-gnu.cross_config
index e6d83dd73..0fbf2a9d8 100644
--- a/src/util/x86_64-linux-gnu.cross_config
+++ b/src/util/x86_64-linux-gnu.cross_config
@@ -8,7 +8,7 @@ CL_LONG_BITS=64
 ECL_STACK_DIR=down
 ECL_BIGENDIAN=no
 ECL_NEWLINE=LF
-ECL_FILE_CNT=1
+ECL_FILE_CNT=2
 ECL_STDINT_HEADER="#include <stdint.h>"
 ECL_UINT8_T=uint8_t
 ECL_UINT16_T=uint16_t
-- 
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