Index: uspace/lib/posix/Makefile
===================================================================
--- uspace/lib/posix/Makefile	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/Makefile	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -40,4 +40,5 @@
 SOURCES = \
 	ctype.c \
+	errno.c \
 	fcntl.c \
 	fnmatch.c \
Index: uspace/lib/posix/errno.c
===================================================================
--- uspace/lib/posix/errno.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
+++ uspace/lib/posix/errno.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2011 Jiri Zarevucky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libposix
+ * @{
+ */
+/** @file
+ */
+
+#include "errno.h"
+
+#include "stdlib.h"
+#include "libc/fibril.h"
+
+static fibril_local int _posix_errno;
+
+int *__posix_errno(void)
+{
+	if (*__errno() != 0) {
+		_posix_errno = abs(*__errno());
+		*__errno() = 0;
+	}
+	return &_posix_errno;
+}
+
+/** @}
+ */
+
Index: uspace/lib/posix/errno.h
===================================================================
--- uspace/lib/posix/errno.h	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
+++ uspace/lib/posix/errno.h	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -0,0 +1,327 @@
+/*
+ * Copyright (c) 2011 Jiri Zarevucky
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ * - The name of the author may not be used to endorse or promote products
+ *   derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/** @addtogroup libposix
+ * @{
+ */
+/** @file
+ */
+
+#ifndef POSIX_ERRNO_H_
+#define POSIX_ERRNO_H_
+
+#include "libc/errno.h"
+
+/* IMPORTANT:
+ * Since libc uses negative errorcodes, some sort of conversion is necessary to
+ * keep POSIX programs and libraries from breaking. This file maps POSIX error
+ * codes to absolute values of corresponding libc codes where available, and
+ * assigns new code where there is no prior definition in libc.
+ *
+ * A new errno variable is defined. When accessed, the function first looks at
+ * libc errno and iff it is != 0, sets the POSIX errno to absolute value of
+ * libc errno. Given that no library function sets errno to 0 and that all
+ * POSIX libraries will be used solely by POSIX programs (thus, there only needs
+ * to be one way correspondence between errno and posix_errno), this approach
+ * should work as expected in most cases and does not require any wrappers for
+ * libc routines that would just change errno values.
+ *
+ * There is no conditioning by LIBPOSIX_INTERNAL for redefinitions of macros.
+ * If there is a need to check errno for a value not defined by POSIX, it's
+ * necessary to compare errno against abs(ECODE), because there is no
+ * redefinition for such error codes.
+ *
+ * FIXME: maybe all HOS error codes should be redefined
+ *
+ * NOTE: This redefinition is slightly POSIX incompatible, since the
+ *  specification requires the macro values to be usable in preprocessing
+ *  directives. I don't think that's very important, though.
+ */
+
+#undef errno
+#define errno (*__posix_errno())
+
+extern int *__posix_errno(void) __attribute__((const));
+
+#define __TOP_ERRNO (-NO_DATA)
+
+enum {
+	POSIX_E2BIG = __TOP_ERRNO + 1,
+	POSIX_EACCES = __TOP_ERRNO + 2,
+	POSIX_EADDRINUSE = -EADDRINUSE,
+	POSIX_EADDRNOTAVAIL = -EADDRNOTAVAIL,
+	POSIX_EAFNOSUPPORT = -EAFNOSUPPORT,
+	POSIX_EAGAIN = -EAGAIN,
+	POSIX_EALREADY = __TOP_ERRNO + 3,
+	POSIX_EBADF = -EBADF,
+	POSIX_EBADMSG = __TOP_ERRNO + 4,
+	POSIX_EBUSY = -EBUSY,
+	POSIX_ECANCELED = __TOP_ERRNO + 5,
+	POSIX_ECHILD = __TOP_ERRNO + 6,
+	POSIX_ECONNABORTED = __TOP_ERRNO + 7,
+	POSIX_ECONNREFUSED = __TOP_ERRNO + 8,
+	POSIX_ECONNRESET = __TOP_ERRNO + 9,
+	POSIX_EDEADLK = __TOP_ERRNO + 10,
+	POSIX_EDESTADDRREQ = -EDESTADDRREQ,
+	POSIX_EDOM = __TOP_ERRNO + 11,
+	POSIX_EDQUOT = __TOP_ERRNO + 12,
+	POSIX_EEXIST = -EEXIST,
+	POSIX_EFAULT = __TOP_ERRNO + 13,
+	POSIX_EFBIG = __TOP_ERRNO + 14,
+	POSIX_EHOSTUNREACH = __TOP_ERRNO + 15,
+	POSIX_EIDRM = __TOP_ERRNO + 16,
+	POSIX_EILSEQ = __TOP_ERRNO + 17,
+	POSIX_EINPROGRESS = -EINPROGRESS,
+	POSIX_EINTR = -EINTR,
+	POSIX_EINVAL = -EINVAL,
+	POSIX_EIO = -EIO,
+	POSIX_EISCONN = __TOP_ERRNO + 18,
+	POSIX_EISDIR = -EISDIR,
+	POSIX_ELOOP = __TOP_ERRNO + 19,
+	POSIX_EMFILE = -EMFILE,
+	POSIX_EMLINK = -EMLINK,
+	POSIX_EMSGSIZE = __TOP_ERRNO + 20,
+	POSIX_EMULTIHOP = __TOP_ERRNO + 21,
+	POSIX_ENAMETOOLONG = -ENAMETOOLONG,
+	POSIX_ENETDOWN = __TOP_ERRNO + 22,
+	POSIX_ENETRESET = __TOP_ERRNO + 23,
+	POSIX_ENETUNREACH = __TOP_ERRNO + 24,
+	POSIX_ENFILE = __TOP_ERRNO + 25,
+	POSIX_ENOBUFS = __TOP_ERRNO + 26,
+	POSIX_ENODATA = -NO_DATA,
+	POSIX_ENODEV = __TOP_ERRNO + 27,
+	POSIX_ENOENT = -ENOENT,
+	POSIX_ENOEXEC = __TOP_ERRNO + 28,
+	POSIX_ENOLCK = __TOP_ERRNO + 29,
+	POSIX_ENOLINK = __TOP_ERRNO + 30,
+	POSIX_ENOMEM = -ENOMEM,
+	POSIX_ENOMSG = __TOP_ERRNO + 31,
+	POSIX_ENOPROTOOPT = __TOP_ERRNO + 32,
+	POSIX_ENOSPC = -ENOSPC,
+	POSIX_ENOSR = __TOP_ERRNO + 33,
+	POSIX_ENOSTR = __TOP_ERRNO + 34,
+	POSIX_ENOSYS = __TOP_ERRNO + 35,
+	POSIX_ENOTCONN = -ENOTCONN,
+	POSIX_ENOTDIR = -ENOTDIR,
+	POSIX_ENOTEMPTY = -ENOTEMPTY,
+	POSIX_ENOTRECOVERABLE = __TOP_ERRNO + 36,
+	POSIX_ENOTSOCK = -ENOTSOCK,
+	POSIX_ENOTSUP = -ENOTSUP,
+	POSIX_ENOTTY = __TOP_ERRNO + 37,
+	POSIX_ENXIO = __TOP_ERRNO + 38,
+	POSIX_EOPNOTSUPP = POSIX_ENOTSUP,
+	POSIX_EOVERFLOW = -EOVERFLOW,
+	POSIX_EOWNERDEAD = __TOP_ERRNO + 39,
+	POSIX_EPERM = -EPERM,
+	POSIX_EPIPE = __TOP_ERRNO + 40,
+	POSIX_EPROTO = __TOP_ERRNO + 41,
+	POSIX_EPROTONOSUPPORT = -EPROTONOSUPPORT,
+	POSIX_EPROTOTYPE = __TOP_ERRNO + 42,
+	POSIX_ERANGE = -ERANGE,
+	POSIX_EROFS = __TOP_ERRNO + 43,
+	POSIX_ESPIPE = __TOP_ERRNO + 44,
+	POSIX_ESRCH = __TOP_ERRNO + 45,
+	POSIX_ESTALE = __TOP_ERRNO + 46,
+	POSIX_ETIME = __TOP_ERRNO + 47,
+	POSIX_ETIMEDOUT = __TOP_ERRNO + 48,
+	POSIX_ETXTBSY = __TOP_ERRNO + 49,
+	POSIX_EWOULDBLOCK = POSIX_EAGAIN,
+	POSIX_EXDEV = -EXDEV,
+};
+
+#undef __TOP_ERRNO
+
+#undef E2BIG
+#undef EACCES
+#undef EADDRINUSE
+#undef EADDRNOTAVAIL
+#undef EAFNOSUPPORT
+#undef EAGAIN
+#undef EALREADY
+#undef EBADF
+#undef EBADMSG
+#undef EBUSY
+#undef ECANCELED
+#undef ECHILD
+#undef ECONNABORTED
+#undef ECONNREFUSED
+#undef ECONNRESET
+#undef EDEADLK
+#undef EDESTADDRREQ
+#undef EDOM
+#undef EDQUOT
+#undef EEXIST
+#undef EFAULT
+#undef EFBIG
+#undef EHOSTUNREACH
+#undef EIDRM
+#undef EILSEQ
+#undef EINPROGRESS
+#undef EINTR
+#undef EINVAL
+#undef EIO
+#undef EISCONN
+#undef EISDIR
+#undef ELOOP
+#undef EMFILE
+#undef EMLINK
+#undef EMSGSIZE
+#undef EMULTIHOP
+#undef ENAMETOOLONG
+#undef ENETDOWN
+#undef ENETRESET
+#undef ENETUNREACH
+#undef ENFILE
+#undef ENOBUFS
+#undef ENODATA
+#undef ENODEV
+#undef ENOENT
+#undef ENOEXEC
+#undef ENOLCK
+#undef ENOLINK
+#undef ENOMEM
+#undef ENOMSG
+#undef ENOPROTOOPT
+#undef ENOSPC
+#undef ENOSR
+#undef ENOSTR
+#undef ENOSYS
+#undef ENOTCONN
+#undef ENOTDIR
+#undef ENOTEMPTY
+#undef ENOTRECOVERABLE
+#undef ENOTSOCK
+#undef ENOTSUP
+#undef ENOTTY
+#undef ENXIO
+#undef EOPNOTSUPP
+#undef EOVERFLOW
+#undef EOWNERDEAD
+#undef EPERM
+#undef EPIPE
+#undef EPROTO
+#undef EPROTONOSUPPORT
+#undef EPROTOTYPE
+#undef ERANGE
+#undef EROFS
+#undef ESPIPE
+#undef ESRCH
+#undef ESTALE
+#undef ETIME
+#undef ETIMEDOUT
+#undef ETXTBSY
+#undef EWOULDBLOCK
+#undef EXDEV
+
+#define E2BIG POSIX_E2BIG
+#define EACCES POSIX_EACCES
+#define EADDRINUSE POSIX_EADDRINUSE
+#define EADDRNOTAVAIL POSIX_EADDRNOTAVAIL
+#define EAFNOSUPPORT POSIX_EAFNOSUPPORT
+#define EAGAIN POSIX_EAGAIN
+#define EALREADY POSIX_EALREADY
+#define EBADF POSIX_EBADF
+#define EBADMSG POSIX_EBADMSG
+#define EBUSY POSIX_EBUSY
+#define ECANCELED POSIX_ECANCELED
+#define ECHILD POSIX_ECHILD
+#define ECONNABORTED POSIX_ECONNABORTED
+#define ECONNREFUSED POSIX_ECONNREFUSED
+#define ECONNRESET POSIX_ECONNRESET
+#define EDEADLK POSIX_EDEADLK
+#define EDESTADDRREQ POSIX_EDESTADDRREQ
+#define EDOM POSIX_EDOM
+#define EDQUOT POSIX_EDQUOT
+#define EEXIST POSIX_EEXIST
+#define EFAULT POSIX_EFAULT
+#define EFBIG POSIX_EFBIG
+#define EHOSTUNREACH POSIX_EHOSTUNREACH
+#define EIDRM POSIX_EIDRM
+#define EILSEQ POSIX_EILSEQ
+#define EINPROGRESS POSIX_EINPROGRESS
+#define EINTR POSIX_EINTR
+#define EINVAL POSIX_EINVAL
+#define EIO POSIX_EIO
+#define EISCONN POSIX_EISCONN
+#define EISDIR POSIX_EISDIR
+#define ELOOP POSIX_ELOOP
+#define EMFILE POSIX_EMFILE
+#define EMLINK POSIX_EMLINK
+#define EMSGSIZE POSIX_EMSGSIZE
+#define EMULTIHOP POSIX_EMULTIHOP
+#define ENAMETOOLONG POSIX_ENAMETOOLONG
+#define ENETDOWN POSIX_ENETDOWN
+#define ENETRESET POSIX_ENETRESET
+#define ENETUNREACH POSIX_ENETUNREACH
+#define ENFILE POSIX_ENFILE
+#define ENOBUFS POSIX_ENOBUFS
+#define ENODATA POSIX_ENODATA
+#define ENODEV POSIX_ENODEV
+#define ENOENT POSIX_ENOENT
+#define ENOEXEC POSIX_ENOEXEC
+#define ENOLCK POSIX_ENOLCK
+#define ENOLINK POSIX_ENOLINK
+#define ENOMEM POSIX_ENOMEM
+#define ENOMSG POSIX_ENOMSG
+#define ENOPROTOOPT POSIX_ENOPROTOOPT
+#define ENOSPC POSIX_ENOSPC
+#define ENOSR POSIX_ENOSR
+#define ENOSTR POSIX_ENOSTR
+#define ENOSYS POSIX_ENOSYS
+#define ENOTCONN POSIX_ENOTCONN
+#define ENOTDIR POSIX_ENOTDIR
+#define ENOTEMPTY POSIX_ENOTEMPTY
+#define ENOTRECOVERABLE POSIX_ENOTRECOVERABLE
+#define ENOTSOCK POSIX_ENOTSOCK
+#define ENOTSUP POSIX_ENOTSUP
+#define ENOTTY POSIX_ENOTTY
+#define ENXIO POSIX_ENXIO
+#define EOPNOTSUPP POSIX_EOPNOTSUPP
+#define EOVERFLOW POSIX_EOVERFLOW
+#define EOWNERDEAD POSIX_EOWNERDEAD
+#define EPERM POSIX_EPERM
+#define EPIPE POSIX_EPIPE
+#define EPROTO POSIX_EPROTO
+#define EPROTONOSUPPORT POSIX_EPROTONOSUPPORT
+#define EPROTOTYPE POSIX_EPROTOTYPE
+#define ERANGE POSIX_ERANGE
+#define EROFS POSIX_EROFS
+#define ESPIPE POSIX_ESPIPE
+#define ESRCH POSIX_ESRCH
+#define ESTALE POSIX_ESTALE
+#define ETIME POSIX_ETIME
+#define ETIMEDOUT POSIX_ETIMEDOUT
+#define ETXTBSY POSIX_ETXTBSY
+#define EWOULDBLOCK POSIX_EWOULDBLOCK
+#define EXDEV POSIX_EXDEV
+
+#endif /* POSIX_ERRNO_H_ */
+
+/** @}
+ */
+
Index: uspace/lib/posix/fcntl.c
===================================================================
--- uspace/lib/posix/fcntl.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/fcntl.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -37,7 +37,8 @@
 #include "internal/common.h"
 #include "fcntl.h"
+
 #include "libc/unistd.h"
 #include "libc/vfs/vfs.h"
-#include <errno.h>
+#include "errno.h"
 
 /**
@@ -65,5 +66,5 @@
 		rc = fd_node(fd, &node);
 		if (rc != EOK) {
-			// TODO: propagate a POSIX compatible errno
+			errno = -rc;
 			return -1;
 		}
@@ -72,5 +73,5 @@
 		int newfd = open_node(&node, 0);
 		if (newfd < 0) {
-			// TODO: propagate a POSIX compatible errno
+			errno = -newfd;
 			return -1;
 		}
@@ -81,5 +82,5 @@
 		rc = dup2(fd, newfd);
 		if (rc != EOK) {
-			// TODO: propagate a POSIX compatible errno
+			errno = -rc;
 			return -1;
 		}
Index: uspace/lib/posix/stdio/scanf.c
===================================================================
--- uspace/lib/posix/stdio/scanf.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/stdio/scanf.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -39,5 +39,5 @@
 
 #include "../assert.h"
-#include <errno.h>  // FIXME: use POSIX errno
+#include "../errno.h"
 
 #include "../stdio.h"
Index: uspace/lib/posix/stdlib.c
===================================================================
--- uspace/lib/posix/stdlib.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/stdlib.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -39,8 +39,9 @@
 #include "stdlib.h"
 
+#include "errno.h"
+
 #include "libc/sort.h"
 #include "libc/str.h"
 #include "libc/vfs/vfs.h"
-#include <errno.h>  // FIXME: use POSIX errno
 
 /**
Index: uspace/lib/posix/stdlib/strtol.c
===================================================================
--- uspace/lib/posix/stdlib/strtol.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/stdlib/strtol.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -40,5 +40,5 @@
 #include "../limits.h"
 #include "../ctype.h"
-#include <errno.h> // FIXME: use POSIX errno
+#include "../errno.h"
 
 // TODO: documentation
Index: uspace/lib/posix/stdlib/strtold.c
===================================================================
--- uspace/lib/posix/stdlib/strtold.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/stdlib/strtold.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -35,5 +35,5 @@
 #define LIBPOSIX_INTERNAL
 
-/* Has to be first. */
+/* Must be first. */
 #include "../stdbool.h"
 
@@ -45,5 +45,5 @@
 #include "../stdint.h"
 #include "../strings.h"
-#include <errno.h> // FIXME: use POSIX errno
+#include "../errno.h"
 
 #ifndef HUGE_VALL
Index: uspace/lib/posix/string.c
===================================================================
--- uspace/lib/posix/string.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/string.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -510,8 +510,9 @@
 char *posix_strerror(int errnum)
 {
-	/* uses function from libc, we just have to negate errno
-	 * (POSIX uses positive errorcodes, HelenOS has negative)
+	/* Uses function from libc, we just have to negate errno
+	 * (POSIX uses positive errorcodes, HelenOS has negative).
 	 */
-	return (char *) str_error(-errnum);
+	// FIXME: not all POSIX error codes are in libc
+	return (char *) str_error(-posix_abs(errnum));
 }
 
Index: uspace/lib/posix/sys/stat.c
===================================================================
--- uspace/lib/posix/sys/stat.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/sys/stat.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -39,4 +39,5 @@
 #include "stat.h"
 
+#include "../errno.h"
 #include "../libc/mem.h"
 
@@ -76,6 +77,9 @@
 {
 	struct stat hst;
-	if (fstat(fd, &hst) == -1) {
-		// TODO: propagate a POSIX compatible errno
+	int rc = fstat(fd, &hst);
+	if (rc < 0) {
+		/* fstat() returns negative error code instead of using errno.
+		 */
+		errno = -rc;
 		return -1;
 	}
@@ -107,6 +111,9 @@
 {
 	struct stat hst;
-	if (stat(path, &hst) == -1) {
-		// TODO: propagate a POSIX compatible errno
+	int rc = stat(path, &hst);
+	if (rc < 0) {
+		/* stat() returns negative error code instead of using errno.
+		 */
+		errno = -rc;
 		return -1;
 	}
Index: uspace/lib/posix/unistd.c
===================================================================
--- uspace/lib/posix/unistd.c	(revision 3f466c33de0de672c03cfdba923d8079460d710a)
+++ uspace/lib/posix/unistd.c	(revision ec18957a189501a5dd40dfc278bd8ebcad3d256b)
@@ -38,9 +38,11 @@
 #include "internal/common.h"
 #include "unistd.h"
-#include <task.h>
-#include <errno.h>
+
+#include "errno.h"
 #include "string.h"
 #include "fcntl.h"
-#include <stats.h>
+
+#include "libc/task.h"
+#include "libc/stats.h"
 #include "libc/malloc.h"
 
@@ -145,8 +147,12 @@
 		/* Check file existence by attempt to open it. */
 		int fd = open(path, O_RDONLY);
-		// TODO: propagate a POSIX compatible errno
-		int rc = fd < 0 ? -1 : 0;
-		close(fd);
-		return rc;
+		if (fd < 0) {
+			/* FIXME: open() returns error code as negative retval. */
+			errno = -fd;
+			fd = -1;
+		} else {
+			close(fd);
+		}
+		return fd;
 	} else if (amode & (X_OK | W_OK | R_OK)) {
 		/* HelenOS doesn't support permissions, return success. */