From cf9308cb74fee4f4401cf06a8701318f885a6bd3 Mon Sep 17 00:00:00 2001
From: Maxime Devos <maximedevos@telenet.be>
Date: Thu, 11 Mar 2021 22:47:16 +0100
Subject: [PATCH 08/17] =?UTF-8?q?Define=20a=20Scheme=20binding=20to=20?=
 =?UTF-8?q?=E2=80=98renameat=E2=80=99=20when=20it=20exists.?=
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* configure.ac: Detect if ‘renameat’ is defined.
* libguile/filesys.c (scm_renameat): Define a Scheme binding
  to the ‘renameat’ system call.
* doc/ref/posix.texi (File System): Document it.
* libguile/filesys.h (scm_renameat): Make it part of the C API.
---
 configure.ac       |  2 +-
 doc/ref/posix.texi |  8 ++++++++
 libguile/filesys.c | 27 +++++++++++++++++++++++++++
 libguile/filesys.h |  1 +
 4 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 15b0ff4a9..a2ad3364f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -482,7 +482,7 @@ AC_CHECK_HEADERS([assert.h crt_externs.h])
 #
 AC_CHECK_FUNCS([DINFINITY DQNAN cexp chsize clog clog10 ctermid         \
   fesetround ftime ftruncate fchown fchmod fchdir readlinkat		\
-  symlinkat mkdirat getcwd geteuid getsid				\
+  symlinkat mkdirat renameat getcwd geteuid getsid				\
   gettimeofday getuid getgid gmtime_r ioctl lstat mkdir mkdtemp mknod   \
   nice readlink rename rmdir setegid seteuid                            \
   setlocale setuid setgid setpgid setsid sigaction siginterrupt stat64  \
diff --git a/doc/ref/posix.texi b/doc/ref/posix.texi
index 72e0c3032..a5dabf5e1 100644
--- a/doc/ref/posix.texi
+++ b/doc/ref/posix.texi
@@ -905,6 +905,14 @@ Renames the file specified by @var{oldname} to @var{newname}.
 The return value is unspecified.
 @end deffn
 
+@findex renameat
+@deffn {Scheme Procedure} rename-file-at olddir oldname newdir newname
+@deffnx {C Function} scm_renameat (olddir, oldname, newdir, newname)
+Like @code{rename-file}, but resolve @var{oldname} and @var{newname}
+relative to the directories referred to by the file ports @var{olddir}
+and @var{newdir} respectively.
+@end deffn
+
 @deffn {Scheme Procedure} link oldpath newpath
 @deffnx {C Function} scm_link (oldpath, newpath)
 Creates a new name @var{newpath} in the file system for the
diff --git a/libguile/filesys.c b/libguile/filesys.c
index 2d0c619af..61a16f981 100644
--- a/libguile/filesys.c
+++ b/libguile/filesys.c
@@ -1454,6 +1454,33 @@ SCM_DEFINE (scm_rename, "rename-file", 2, 0, 0,
 }
 #undef FUNC_NAME
 
+#ifdef HAVE_RENAMEAT
+SCM_DEFINE (scm_renameat, "rename-file-at", 4, 0, 0,
+            (SCM olddir, SCM oldname, SCM newdir, SCM newname),
+            "Like @code{rename-file}, but resolve @var{oldname} and @var{newname}\n"
+            "relative to the directories referred to by the file ports @var{olddir}\n"
+            "and @var{newdir} respectively.")
+#define FUNC_NAME s_scm_renameat
+{
+  int rv;
+  int old_fdes, new_fdes;
+
+  SCM_VALIDATE_OPFPORT (SCM_ARG1, olddir);
+  SCM_VALIDATE_OPFPORT (SCM_ARG3, newdir);
+
+  old_fdes = SCM_FPORT_FDES (olddir);
+  new_fdes = SCM_FPORT_FDES (newdir);
+
+  STRING2_SYSCALL (oldname, c_oldname,
+		   newname, c_newname,
+		   rv = renameat (old_fdes, c_oldname, new_fdes, c_newname));
+  scm_remember_upto_here_2 (olddir, newdir);
+  if (rv != 0)
+    SCM_SYSERROR;
+  return SCM_UNSPECIFIED;
+}
+#undef FUNC_NAME
+#endif
 
 SCM_DEFINE (scm_delete_file, "delete-file", 1, 0, 0, 
            (SCM str),
diff --git a/libguile/filesys.h b/libguile/filesys.h
index f0dd35ede..7e17cc585 100644
--- a/libguile/filesys.h
+++ b/libguile/filesys.h
@@ -48,6 +48,7 @@ SCM_API SCM scm_close_fdes (SCM fd);
 SCM_API SCM scm_stat (SCM object, SCM exception_on_error);
 SCM_API SCM scm_link (SCM oldpath, SCM newpath);
 SCM_API SCM scm_rename (SCM oldname, SCM newname);
+SCM_API SCM scm_renameat (SCM olddir, SCM oldname, SCM newdir, SCM newname);
 SCM_API SCM scm_delete_file (SCM str);
 SCM_API SCM scm_mkdir (SCM path, SCM mode);
 SCM_API SCM scm_mkdirat (SCM dir, SCM path, SCM mode);
-- 
2.30.2