From 4de95c9bc0ae81eb92d239b712daa629efa612cb Mon Sep 17 00:00:00 2001
From: Giacomo Tesio <giacomo@tesio.it>
Date: Wed, 23 Aug 2017 02:57:41 +0200
Subject: [PATCH] libposix: make AT_FDCWD value configurable

---
 sys/include/posix.h       |  4 ++++
 sys/src/lib/posix/files.c | 13 +++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/sys/include/posix.h b/sys/include/posix.h
index 35bbb45..a055750 100644
--- a/sys/include/posix.h
+++ b/sys/include/posix.h
@@ -180,6 +180,7 @@ typedef enum PosixSignals
  *
  *	libposix_define_errno to set the value of each PosixError
  *	libposix_define_signal to set the value of each PosixSignal
+ *	libposix_define_at_fdcwd to set the value of AT_FDCWD (for fchmodat)
  *	libposix_translate_error to translate error strings to PosixError
  * 	libposix_set_signal_trampoline to dispatch signal received as notes
  *	libposix_set_stat_reader
@@ -206,6 +207,9 @@ typedef PosixError (*PosixErrorTranslator)(char* error, uintptr_t caller);
  */
 extern int libposix_translate_error(PosixErrorTranslator translation, uintptr_t caller);
 
+/* define the value of AT_FDCWD according to the library headers */
+extern int libposix_define_at_fdcwd(int AT_FDCWD);
+
 /* define the value of a specific PosixError according to the library headers */
 extern int libposix_define_errno(PosixError e, int errno);
 
diff --git a/sys/src/lib/posix/files.c b/sys/src/lib/posix/files.c
index bdc6998..3999262 100644
--- a/sys/src/lib/posix/files.c
+++ b/sys/src/lib/posix/files.c
@@ -23,6 +23,7 @@
 
 static PosixStatReader __libposix_stat_reader;
 static PosixOpenTranslator __libposix_open_translation;
+static int __libposix_AT_FDCWD;
 
 typedef enum SeekTypes
 {
@@ -409,14 +410,13 @@ FailWithError:
 int
 POSIX_fchmodat(int *errnop, int fd, const char *path, long mode, int flag)
 {
-#define AT_FDCWD -100 /* from NetBSD; TODO: get from configuration */ 
 	Dir *dir, ndir;
 	long cperm = 0;
 	char fullpath[4096], *p;
 	int l;
 	PosixError e;
 
-	if(fd == AT_FDCWD){
+	if(fd == __libposix_AT_FDCWD){
 		return POSIX_chmod(errnop, path, mode);
 	} else if(path == nil){
 		e = PosixENOENT;
@@ -560,3 +560,12 @@ FailWithEIO:
 	*errnop = __libposix_get_errno(PosixEIO);
 	return -1;
 }
+
+int
+libposix_define_at_fdcwd(int AT_FDCWD)
+{
+	if(__libposix_AT_FDCWD != 0)
+		return -1;
+	__libposix_AT_FDCWD = AT_FDCWD;
+	return 0;
+}