Remove 'grp' and merge into 'nss' and 'posix'

The majority of grp routines are entry points for nss functionality.
This commit removes the 'grp' subdirectory and moves all nss-relevant
functionality and all tests to 'nss', and the 'setgroups' stub into
'posix' (alongside the 'getgroups' stub).  References to grp/ are
accordingly changed.  In addition, compat-initgroups.c, a fallback
implementation of initgroups is renamed to initgroups-fallback.c so that
the build system does not confuse it for nss_compat/compat-initgroups.c.

Build time improves very slightly; e.g. down from an average of 45.5s to
44.5s on an 8-thread mobile x86_64 CPU.
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 87 insertions, 0 deletions

diff --git a/nss/fgetgrent.c b/nss/fgetgrent.c
new file mode 100644
index 0000000000..2e7c7fe5fb
--- /dev/null
+++ b/nss/fgetgrent.c
@@ -0,0 +1,87 @@
+/* Copyright (C) 1991-2023 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 <grp.h>
+#include <libc-lock.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <set-freeres.h>
+
+
+/* We need to protect the dynamic buffer handling.  */
+__libc_lock_define_initialized (static, lock);
+
+static char *buffer;
+
+/* Read one entry from the given stream.  */
+struct group *
+fgetgrent (FILE *stream)
+{
+  static size_t buffer_size;
+  static struct group resbuf;
+  fpos_t pos;
+  struct group *result;
+  int save;
+
+  if (__builtin_expect (fgetpos (stream, &pos), 0) != 0)
+    return NULL;
+
+  /* Get lock.  */
+  __libc_lock_lock (lock);
+
+  /* Allocate buffer if not yet available.  */
+  if (buffer == NULL)
+    {
+      buffer_size = NSS_BUFLEN_GROUP;
+      buffer = malloc (buffer_size);
+    }
+
+  while (buffer != NULL
+	 && (__fgetgrent_r (stream, &resbuf, buffer, buffer_size, &result)
+	     == ERANGE))
+    {
+      char *new_buf;
+      buffer_size += NSS_BUFLEN_GROUP;
+      new_buf = realloc (buffer, buffer_size);
+      if (__glibc_unlikely (new_buf == NULL))
+	{
+	  /* We are out of memory.  Free the current buffer so that the
+	     process gets a chance for a normal termination.  */
+	  save = errno;
+	  free (buffer);
+	  __set_errno (save);
+	}
+      buffer = new_buf;
+
+      /* Reset the stream.  */
+      if (fsetpos (stream, &pos) != 0)
+	buffer = NULL;
+    }
+
+  if (buffer == NULL)
+    result = NULL;
+
+  /* Release lock.  Preserve error value.  */
+  save = errno;
+  __libc_lock_unlock (lock);
+  __set_errno (save);
+
+  return result;
+}
+
+weak_alias (buffer, __libc_fgetgrent_freemem_ptr)