[PATCH 4/4] io: Reorganize the getcwd implementation

[Adhemerval Zanella <adhemerval.zanella@linaro.org>]

The generic implementation uses two internal symbols: __getcwd_system
(which might be overriden by the system) and __getcwd_generic (the
generic implementation shared with gnulib).  The Linux implementation
is moved to __getcwd_system and generic POSIX implementation is moved
to __getcwd_generic.

This change aims to make the code sync with gnulib easier and simplify
the Linux override implementation.

The dl-fxstatat64 is not required anymore and adding it explicit issue
a duplicate symbol in libc.so linking.

Hurd still overrides the getcwd altogether and one possibility would
to be move its implementation to __getcwd_system and reimplement the
__getcwd_generic to be a empty one.

Checked on x86_64-linux-gnu and i686-linux-gnu.
---
 include/unistd.h                              |  2 +
 io/Makefile                                   |  2 +-
 sysdeps/posix/getcwd.c => io/getcwd-generic.c |  7 +--
 io/getcwd-system.c                            | 28 +++++++++
 io/getcwd.c                                   |  9 ++-
 sysdeps/unix/sysv/linux/Makefile              |  3 +-
 sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c |  1 -
 sysdeps/unix/sysv/linux/dl-fxstatat64.c       |  1 -
 sysdeps/unix/sysv/linux/dl-getcwd.c           |  1 -
 .../sysv/linux/{getcwd.c => getcwd-system.c}  | 58 +------------------
 .../sysv/linux/sparc/sparc64/dl-fxstatat64.c  |  1 -
 .../sysv/linux/wordsize-64/dl-fxstatat64.c    |  1 -
 12 files changed, 40 insertions(+), 74 deletions(-)
 rename sysdeps/posix/getcwd.c => io/getcwd-generic.c (99%)
 create mode 100644 io/getcwd-system.c
 delete mode 100644 sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c
 delete mode 100644 sysdeps/unix/sysv/linux/dl-fxstatat64.c
 delete mode 100644 sysdeps/unix/sysv/linux/dl-getcwd.c
 rename sysdeps/unix/sysv/linux/{getcwd.c => getcwd-system.c} (53%)
 delete mode 100644 sysdeps/unix/sysv/linux/sparc/sparc64/dl-fxstatat64.c
 delete mode 100644 sysdeps/unix/sysv/linux/wordsize-64/dl-fxstatat64.c

diff --git a/include/unistd.h b/include/unistd.h
index f48da2c7a3..792cfdff0b 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -76,6 +76,8 @@ extern int __lchown (const char *__file, __uid_t __owner,
 		     __gid_t __group);
 extern int __chdir (const char *__path) attribute_hidden;
 extern int __fchdir (int __fd) attribute_hidden;
+extern char *__getcwd_generic (char *__buf, size_t __size) attribute_hidden;
+extern char *__getcwd_system (char *__buf, size_t __size) attribute_hidden;
 extern char *__getcwd (char *__buf, size_t __size);
 libc_hidden_proto (__getcwd)
 extern int __rmdir (const char *__path) attribute_hidden;
diff --git a/io/Makefile b/io/Makefile
index cf380f3516..26dfe047c0 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -46,7 +46,7 @@ routines :=								\
 	close dup dup2 dup3 pipe pipe2					\
 	creat creat64							\
 	chdir fchdir							\
-	getcwd getwd getdirname						\
+	getcwd getwd getcwd-system getcwd-generic getdirname		\
 	chown fchown lchown fchownat					\
 	ttyname ttyname_r isatty					\
 	link linkat symlink symlinkat readlink readlinkat		\
diff --git a/sysdeps/posix/getcwd.c b/io/getcwd-generic.c
similarity index 99%
rename from sysdeps/posix/getcwd.c
rename to io/getcwd-generic.c
index 1e6fc9b845..e259ce14da 100644
--- a/sysdeps/posix/getcwd.c
+++ b/io/getcwd-generic.c
@@ -154,7 +154,7 @@ getcwd_nothrow (char *buf, size_t size)
    bytes long, unless SIZE == 0, in which case it is as big as necessary.  */
 
 char *
-__getcwd (char *buf, size_t size)
+__getcwd_generic (char *buf, size_t size)
 {
   /* Lengths of big file name components and entire file names, and a
      deep level of file name nesting.  These numbers are not upper
@@ -486,8 +486,3 @@ __getcwd (char *buf, size_t size)
   }
   return NULL;
 }
-
-#if defined _LIBC && !defined __getcwd
-libc_hidden_def (__getcwd)
-weak_alias (__getcwd, getcwd)
-#endif
diff --git a/io/getcwd-system.c b/io/getcwd-system.c
new file mode 100644
index 0000000000..4390479aa2
--- /dev/null
+++ b/io/getcwd-system.c
@@ -0,0 +1,28 @@
+/* Architectur specific getcwd implementation.  Generic implementation.
+   Copyright (C) 2020 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 <unistd.h>
+
+/* This function is called by the generic 'getcwd' implementation to allow
+   a system to implement if the it provides a faster or simpler way to obtain
+   the current direction (e.g. through a syscall).  */
+char *
+__getcwd_system (char *buf, size_t size)
+{
+  return NULL;
+}
diff --git a/io/getcwd.c b/io/getcwd.c
index 0fabd98131..cf7a8e1a30 100644
--- a/io/getcwd.c
+++ b/io/getcwd.c
@@ -29,11 +29,10 @@
 char *
 __getcwd (char *buf, size_t size)
 {
-  __set_errno (ENOSYS);
-  return NULL;
+  char *r = __getcwd_system (buf, size);
+  if (r == NULL)
+    r = __getcwd_generic (buf, size);
+  return r;
 }
 libc_hidden_def (__getcwd)
 weak_alias (__getcwd, getcwd)
-
-stub_warning (__getcwd)
-stub_warning (getcwd)
diff --git a/sysdeps/unix/sysv/linux/Makefile b/sysdeps/unix/sysv/linux/Makefile
index 9b2a253032..465ffe7104 100644
--- a/sysdeps/unix/sysv/linux/Makefile
+++ b/sysdeps/unix/sysv/linux/Makefile
@@ -280,8 +280,7 @@ tests += tst-fallocate tst-fallocate64 tst-o_path-locks
 endif
 
 ifeq ($(subdir),elf)
-sysdep-rtld-routines += dl-brk dl-sbrk dl-getcwd dl-openat64 dl-opendir \
-			dl-fxstatat64
+sysdep-rtld-routines += dl-brk dl-sbrk dl-openat64 dl-opendir
 
 libof-lddlibc4 = lddlibc4
 
diff --git a/sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c b/sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c
deleted file mode 100644
index 330b33f7c7..0000000000
--- a/sysdeps/unix/sysv/linux/alpha/dl-fxstatat64.c
+++ /dev/null
@@ -1 +0,0 @@
-#include "fxstatat.c"
diff --git a/sysdeps/unix/sysv/linux/dl-fxstatat64.c b/sysdeps/unix/sysv/linux/dl-fxstatat64.c
deleted file mode 100644
index d229d0ea0f..0000000000
--- a/sysdeps/unix/sysv/linux/dl-fxstatat64.c
+++ /dev/null
@@ -1 +0,0 @@
-#include <fxstatat64.c>
diff --git a/sysdeps/unix/sysv/linux/dl-getcwd.c b/sysdeps/unix/sysv/linux/dl-getcwd.c
deleted file mode 100644
index 4bd5657f1e..0000000000
--- a/sysdeps/unix/sysv/linux/dl-getcwd.c
+++ /dev/null
@@ -1 +0,0 @@
-#include "getcwd.c"
diff --git a/sysdeps/unix/sysv/linux/getcwd.c b/sysdeps/unix/sysv/linux/getcwd-system.c
similarity index 53%
rename from sysdeps/unix/sysv/linux/getcwd.c
rename to sysdeps/unix/sysv/linux/getcwd-system.c
index fabc4bb8cc..a7e8535b72 100644
--- a/sysdeps/unix/sysv/linux/getcwd.c
+++ b/sysdeps/unix/sysv/linux/getcwd-system.c
@@ -17,16 +17,8 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#include <assert.h>
-#include <errno.h>
-#include <limits.h>
-#include <stdlib.h>
 #include <unistd.h>
-#include <sys/param.h>
-
 #include <sysdep.h>
-#include <sys/syscall.h>
-
 
 /* If we compile the file for use in ld.so we don't need the feature
    that getcwd() allocates the buffers itself.  */
@@ -34,19 +26,10 @@
 # define NO_ALLOCATION	1
 #endif
 
-
-/* The "proc" filesystem provides an easy method to retrieve the value.
-   For each process, the corresponding directory contains a symbolic link
-   named `cwd'.  Reading the content of this link immediate gives us the
-   information.  But we have to take care for systems which do not have
-   the proc filesystem mounted.  Use the POSIX implementation in this case.  */
-static char *generic_getcwd (char *buf, size_t size);
-
 char *
-__getcwd (char *buf, size_t size)
+__getcwd_system (char *buf, size_t size)
 {
   char *path;
-  char *result;
 
 #ifndef NO_ALLOCATION
   size_t alloc_size = size;
@@ -58,7 +41,7 @@ __getcwd (char *buf, size_t size)
 	  return NULL;
 	}
 
-      alloc_size = MAX (PATH_MAX, __getpagesize ());
+      alloc_size = PATH_MAX;
     }
 
   if (buf == NULL)
@@ -75,7 +58,7 @@ __getcwd (char *buf, size_t size)
 
   int retval;
 
-  retval = INLINE_SYSCALL (getcwd, 2, path, alloc_size);
+  retval = INLINE_SYSCALL_CALL (getcwd, path, alloc_size);
   if (retval > 0 && path[0] == '/')
     {
 #ifndef NO_ALLOCATION
@@ -92,34 +75,6 @@ __getcwd (char *buf, size_t size)
       return buf;
     }
 
-  /* The system call either cannot handle paths longer than a page
-     or can succeed without returning an absolute path.  Just use the
-     generic implementation right away.  */
-  if (retval >= 0 || errno == ENAMETOOLONG)
-    {
-#ifndef NO_ALLOCATION
-      if (buf == NULL && size == 0)
-	{
-	  free (path);
-	  path = NULL;
-	}
-#endif
-
-      result = generic_getcwd (path, size);
-
-#ifndef NO_ALLOCATION
-      if (result == NULL && buf == NULL && size != 0)
-	free (path);
-#endif
-
-      return result;
-    }
-
-  /* It should never happen that the `getcwd' syscall failed because
-     the buffer is too small if we allocated the buffer ourselves
-     large enough.  */
-  assert (errno != ERANGE || buf != NULL || size != 0);
-
 #ifndef NO_ALLOCATION
   if (buf == NULL)
     free (path);
@@ -127,10 +82,3 @@ __getcwd (char *buf, size_t size)
 
   return NULL;
 }
-libc_hidden_def (__getcwd)
-weak_alias (__getcwd, getcwd)
-
-/* Get the code for the generic version.  */
-#define GETCWD_RETURN_TYPE	static char *
-#define __getcwd		generic_getcwd
-#include <sysdeps/posix/getcwd.c>
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/dl-fxstatat64.c b/sysdeps/unix/sysv/linux/sparc/sparc64/dl-fxstatat64.c
deleted file mode 100644
index 330b33f7c7..0000000000
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/dl-fxstatat64.c
+++ /dev/null
@@ -1 +0,0 @@
-#include "fxstatat.c"
diff --git a/sysdeps/unix/sysv/linux/wordsize-64/dl-fxstatat64.c b/sysdeps/unix/sysv/linux/wordsize-64/dl-fxstatat64.c
deleted file mode 100644
index 330b33f7c7..0000000000
--- a/sysdeps/unix/sysv/linux/wordsize-64/dl-fxstatat64.c
+++ /dev/null
@@ -1 +0,0 @@
-#include "fxstatat.c"
-- 
2.25.1