Add gnulib modules to replace missing libc functionality

This enables us to build a fully featured elfutils package on systems
with reduced C libraries, such as windows. All the modules are built
into libgnu.a, which is then linked into all binaries if
--enable-gnulib is given on the configure line.

Change-Id: I743fd22172bc85d9f10dcc3dad8eb921f462b554
Reviewed-by: Christian Kandeler <[email protected]>

1 files changed, 126 insertions, 0 deletions

diff --git a/libgnu/getcwd-lgpl.c b/libgnu/getcwd-lgpl.c
new file mode 100644
index 00000000..34603c19
--- /dev/null
+++ b/libgnu/getcwd-lgpl.c
@@ -0,0 +1,126 @@
+/* Copyright (C) 2011-2017 Free Software Foundation, Inc.
+   This file is part of gnulib.
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification */
+#include <unistd.h>
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if GNULIB_GETCWD
+/* Favor GPL getcwd.c if both getcwd and getcwd-lgpl modules are in use.  */
+typedef int dummy;
+#else
+
+/* Get the name of the current working directory, and put it in SIZE
+   bytes of BUF.  Returns NULL if the directory couldn't be determined
+   (perhaps because the absolute name was longer than PATH_MAX, or
+   because of missing read/search permissions on parent directories)
+   or SIZE was too small.  If successful, returns BUF.  If BUF is
+   NULL, an array is allocated with 'malloc'; the array is SIZE bytes
+   long, unless SIZE == 0, in which case it is as big as
+   necessary.  */
+
+# undef getcwd
+char *
+rpl_getcwd (char *buf, size_t size)
+{
+  char *ptr;
+  char *result;
+
+  /* Handle single size operations.  */
+  if (buf)
+    {
+      if (!size)
+        {
+          errno = EINVAL;
+          return NULL;
+        }
+      return getcwd (buf, size);
+    }
+
+  if (size)
+    {
+      buf = malloc (size);
+      if (!buf)
+        {
+          errno = ENOMEM;
+          return NULL;
+        }
+      result = getcwd (buf, size);
+      if (!result)
+        {
+          int saved_errno = errno;
+          free (buf);
+          errno = saved_errno;
+        }
+      return result;
+    }
+
+  /* Flexible sizing requested.  Avoid over-allocation for the common
+     case of a name that fits within a 4k page, minus some space for
+     local variables, to be sure we don't skip over a guard page.  */
+  {
+    char tmp[4032];
+    size = sizeof tmp;
+    ptr = getcwd (tmp, size);
+    if (ptr)
+      {
+        result = strdup (ptr);
+        if (!result)
+          errno = ENOMEM;
+        return result;
+      }
+    if (errno != ERANGE)
+      return NULL;
+  }
+
+  /* My what a large directory name we have.  */
+  do
+    {
+      size <<= 1;
+      ptr = realloc (buf, size);
+      if (ptr == NULL)
+        {
+          free (buf);
+          errno = ENOMEM;
+          return NULL;
+        }
+      buf = ptr;
+      result = getcwd (buf, size);
+    }
+  while (!result && errno == ERANGE);
+
+  if (!result)
+    {
+      int saved_errno = errno;
+      free (buf);
+      errno = saved_errno;
+    }
+  else
+    {
+      /* Trim to fit, if possible.  */
+      result = realloc (buf, strlen (buf) + 1);
+      if (!result)
+        result = buf;
+    }
+  return result;
+}
+
+#endif