1 files changed, 30 insertions, 22 deletions

diff --git a/gl/m4/getdelim.m4 b/gl/m4/getdelim.m4
index 61139039..8b6eff47 100644
--- a/gl/m4/getdelim.m4
+++ b/gl/m4/getdelim.m4
@@ -1,11 +1,12 @@
 # getdelim.m4
-# serial 19
+# serial 21
 
-dnl Copyright (C) 2005-2007, 2009-2024 Free Software Foundation, Inc.
+dnl Copyright (C) 2005-2007, 2009-2026 Free Software Foundation, Inc.
 dnl
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
+dnl This file is offered as-is, without any warranty.
 
 AC_PREREQ([2.59])
 
@@ -36,6 +37,7 @@ AC_DEFUN([gl_FUNC_GETDELIM],
            gl_cv_func_working_getdelim=no ;;
          *)
            echo fooNbarN | tr -d '\012' | tr N '\012' > conftest.data
+           touch conftest.empty
            AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #    include <stdio.h>
 #    include <stdlib.h>
@@ -43,6 +45,7 @@ AC_DEFUN([gl_FUNC_GETDELIM],
     int main ()
     {
       FILE *in = fopen ("./conftest.data", "r");
+      int result = 0;
       if (!in)
         return 1;
       {
@@ -52,7 +55,7 @@ AC_DEFUN([gl_FUNC_GETDELIM],
         size_t siz = 0;
         int len = getdelim (&line, &siz, '\n', in);
         if (!(len == 4 && line && strcmp (line, "foo\n") == 0))
-          { free (line); fclose (in); return 2; }
+          result |= 2;
         free (line);
       }
       {
@@ -61,35 +64,40 @@ AC_DEFUN([gl_FUNC_GETDELIM],
         char *line = NULL;
         size_t siz = (size_t)(~0) / 4;
         if (getdelim (&line, &siz, '\n', in) == -1)
-          { fclose (in); return 3; }
+          result |= 4;
         free (line);
       }
       fclose (in);
-      return 0;
+      {
+        /* Test that reading EOF as the first character sets the first byte
+           in the buffer to NUL.  This fails on glibc 2.42 and earlier.  */
+        in = fopen ("./conftest.empty", "r");
+        if (!in)
+          return 1;
+        char *line = malloc (1);
+        line[0] = 'A';
+        size_t siz = 1;
+        if (getdelim (&line, &siz, '\n', in) != -1 || line[0] != '\0')
+          result |= 8;
+        free (line);
+      }
+      fclose (in);
+      return result;
     }
     ]])],
              [gl_cv_func_working_getdelim=yes],
              [gl_cv_func_working_getdelim=no],
-             [dnl We're cross compiling.
-              dnl Guess it works on glibc2 systems and musl systems.
-              AC_EGREP_CPP([Lucky GNU user],
-                [
-#include <features.h>
-#ifdef __GNU_LIBRARY__
- #if (__GLIBC__ >= 2) && !defined __UCLIBC__
-  Lucky GNU user
- #endif
-#endif
-                ],
-                [gl_cv_func_working_getdelim="guessing yes"],
-                [case "$host_os" in
-                   *-musl* | midipix*) gl_cv_func_working_getdelim="guessing yes" ;;
-                   *)                  gl_cv_func_working_getdelim="$gl_cross_guess_normal" ;;
-                 esac
-                ])
+             [case "$host_os" in
+                                    # Guess yes on musl.
+                *-musl* | midipix*) gl_cv_func_working_getdelim="guessing yes" ;;
+                                    # Guess no on glibc.
+                *-gnu* | gnu*)      gl_cv_func_working_getdelim="guessing no" ;;
+                *)                  gl_cv_func_working_getdelim="$gl_cross_guess_normal" ;;
+              esac
              ])
            ;;
        esac
+       rm -f conftest.data conftest.empty
       ])
     case "$gl_cv_func_working_getdelim" in
       *yes) ;;