libio: Test for fdopen memory leak without SEEK_END support (bug 31840)

The bug report used /dev/mem, but /proc/self/mem works as well
(if available).

libio/Makefile

@@ -94,6 +94,7 @@ tests = \
   tst-eof \
   tst-ext \
   tst-ext2 \
+  tst-fdopen-seek-failure \
   tst-fgetc-after-eof \
   tst-fgetwc \
   tst-fgetws \
@@ -250,6 +251,9 @@ tst_wprintf2-ARGS = "Some Text"
 
 test-fmemopen-ENV = MALLOC_TRACE=$(objpfx)test-fmemopen.mtrace \
 		    LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
+tst-fdopen-seek-failure-ENV = \
+  MALLOC_TRACE=$(objpfx)tst-fdopen-seek-failure.mtrace \
+  LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
 tst-fopenloc-ENV = MALLOC_TRACE=$(objpfx)tst-fopenloc.mtrace \
 		   LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
 tst-bz22415-ENV = MALLOC_TRACE=$(objpfx)tst-bz22415.mtrace \
@@ -258,6 +262,7 @@ tst-bz24228-ENV = MALLOC_TRACE=$(objpfx)tst-bz24228.mtrace \
 		  LD_PRELOAD=$(common-objpfx)/malloc/libc_malloc_debug.so
 
 generated += test-fmemopen.mtrace test-fmemopen.check
+generated += tst-fdopen-seek-failure.mtrace tst-fdopen-seek-failure.check
 generated += tst-fopenloc.mtrace tst-fopenloc.check
 generated += tst-bz22415.mtrace tst-bz22415.check
 
@@ -280,8 +285,12 @@ shared-only-routines = oldiofopen oldiofdopen oldiofclose oldfileops	\
 		       oldiofsetpos64
 
 ifeq ($(run-built-tests),yes)
-tests-special += $(objpfx)test-freopen.out $(objpfx)test-fmemopen-mem.out \
+tests-special += \
-		 $(objpfx)tst-bz22415-mem.out
+  $(objpfx)test-fmemopen-mem.out \
+  $(objpfx)test-freopen.out \
+  $(objpfx)tst-bz22415-mem.out \
+  $(objpfx)tst-fdopen-seek-failure-mem.out \
+  # tests-special
 ifeq (yes,$(build-shared))
 # Run tst-fopenloc-cmp.out and tst-openloc-mem.out only if shared
 # library is enabled since they depend on tst-fopenloc.out.
@@ -369,6 +378,11 @@ $(objpfx)test-fmemopen-mem.out: $(objpfx)test-fmemopen.out
 	$(common-objpfx)malloc/mtrace $(objpfx)test-fmemopen.mtrace > $@; \
 	$(evaluate-test)
 
+$(objpfx)tst-fdopen-seek-failure-mem.out: $(objpfx)tst-fdopen-seek-failure.out
+	$(common-objpfx)malloc/mtrace \
+	  $(objpfx)tst-fdopen-seek-failure.mtrace > $@; \
+	$(evaluate-test)
+
 $(objpfx)tst-fopenloc-mem.out: $(objpfx)tst-fopenloc.out
 	$(common-objpfx)malloc/mtrace $(objpfx)tst-fopenloc.mtrace > $@; \
 	$(evaluate-test)

libio/tst-fdopen-seek-failure.c

@@ -0,0 +1,48 @@
+/* Test for fdopen memory leak without SEEK_END support (bug 31840).
+   Copyright (C) 2024 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+
+#include <errno.h>
+#include <fcntl.h>
+#include <mcheck.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <support/check.h>
+#include <support/xunistd.h>
+#include <unistd.h>
+
+static int
+do_test (void)
+{
+  mtrace ();
+
+  /* This file is special because it is seekable, but only
+     with SEEK_SET, not SEEK_END.  */
+  int fd = open ("/proc/self/mem", O_RDWR);
+  if (fd < 0)
+    FAIL_UNSUPPORTED ("/proc/self/mem not found: %m");
+  FILE *fp = fdopen (fd, "a");
+  /* The fdopen call should have failed because it tried to use
+     SEEK_END.  */
+  TEST_VERIFY (fp == NULL);
+  TEST_COMPARE (errno, EINVAL);
+  xclose (fd);
+  return 0;
+}
+
+#include <support/test-driver.c>