[PATCH 10/11] stdio-common: Support large offsets with %lln

[Florian Weimer <fweimer@redhat.com>]

Use of Xprintf_buffer_done is unnecessary because it performs
overflow detection against int and sets errno.
---
 stdio-common/Makefile               |  1 +
 stdio-common/tst-printf-large-n.c   | 81 +++++++++++++++++++++++++++++
 stdio-common/vfprintf-process-arg.c |  2 +-
 3 files changed, 83 insertions(+), 1 deletion(-)
 create mode 100644 stdio-common/tst-printf-large-n.c

diff --git a/stdio-common/Makefile b/stdio-common/Makefile
index d610ed67e6..482d841f96 100644
--- a/stdio-common/Makefile
+++ b/stdio-common/Makefile
@@ -234,6 +234,7 @@ tests := \
   tst-printf-fp-free \
   tst-printf-fp-leak \
   tst-printf-intn \
+  tst-printf-large-n \
   tst-printf-oct \
   tst-printf-round \
   tst-printfsz \
diff --git a/stdio-common/tst-printf-large-n.c b/stdio-common/tst-printf-large-n.c
new file mode 100644
index 0000000000..4504a693d2
--- /dev/null
+++ b/stdio-common/tst-printf-large-n.c
@@ -0,0 +1,81 @@
+/* Test that %n can report values larger than INT_MAX.
+   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 <limits.h>
+#include <stdio.h>
+#include <wchar.h>
+
+#include <support/blob_repeat.h>
+#include <support/check.h>
+#include <support/xstdio.h>
+
+static int
+do_test (void)
+{
+  enum { string_length = 1 << 28 };
+
+  FILE *fp = xfopen ("/dev/null", "w");
+
+  /* Byte-oriented streams.  */
+  {
+    struct support_blob_repeat repeat
+      = support_blob_repeat_allocate ("a", 1, string_length + 1);
+    char *string = repeat.start;
+    if (string == NULL)
+      FAIL_UNSUPPORTED ("cannot allocate large string");
+    string[string_length] = '\0';
+
+      long long int n;
+    TEST_COMPARE (fprintf (fp, "%s %s %s %s %s %s %s %s %lln",
+                           string, string, string, string, string, string,
+                           string, string, &n), -1);
+    TEST_COMPARE (errno, EOVERFLOW);
+    TEST_COMPARE (n, 8 * (string_length + 1LL));
+    TEST_VERIFY (n > INT_MAX);
+
+      support_blob_repeat_free (&repeat);
+  }
+
+  /* Wide-oriented streams.  */
+  {
+    struct support_blob_repeat repeat
+      = support_blob_repeat_allocate (L"a", sizeof (wchar_t),
+                                      string_length + 1);
+    wchar_t *string = repeat.start;
+    if (string == NULL)
+      FAIL_UNSUPPORTED ("cannot allocate large wide string");
+    string[string_length] = '\0';
+
+    long long int n;
+    TEST_COMPARE (fwprintf (fp, L"%Ls %Ls %Ls %Ls %Ls %Ls %Ls %Ls %lln",
+                            string, string, string, string, string, string,
+                            string, string, &n), -1);
+    TEST_COMPARE (errno, EOVERFLOW);
+    TEST_COMPARE (n, 8 * (string_length + 1LL));
+    TEST_VERIFY (n > INT_MAX);
+
+      support_blob_repeat_free (&repeat);
+  }
+
+  xfclose (fp);
+
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/stdio-common/vfprintf-process-arg.c b/stdio-common/vfprintf-process-arg.c
index af6b570ea9..dbc78d4942 100644
--- a/stdio-common/vfprintf-process-arg.c
+++ b/stdio-common/vfprintf-process-arg.c
@@ -337,7 +337,7 @@ LABEL (form_number):
     }
   /* Answer the count of characters written.  */
   void *ptrptr = process_arg_pointer ();
-  unsigned int written = Xprintf_buffer_done (buf);
+  uint64_t written = buf->written + (buf->write_ptr - buf->write_base);
   if (is_longlong)
     *(long long int *) ptrptr = written;
   else if (is_long_num)
-- 
2.43.0