libposix: add readlink and readlinkat (both failing with EINVAL)

sys/src/lib/posix/build.json

@@ -14,6 +14,7 @@
 			"errors.c",
 			"files.c",
 			"initlib.c",
+			"links.c",
 			"memory.c",
 			"others.c",
 			"processes.c",

sys/src/lib/posix/files.c

@@ -357,31 +357,6 @@ POSIX_close(int *errno, int file)
 	return -1;
 }
 
-int
-POSIX_link(int *errnop, const char *old, const char *new)
-{
-	int err;
-	/* let choose the most appropriate error */
-	if(old == nil || new == nil || old[0] == 0 || new[0] == 0)
-		err = __libposix_get_errno(PosixENOENT);
-	else if(access(new, AEXIST) == 0)
-		err = __libposix_get_errno(PosixEEXIST);
-	else if(access(old, AEXIST) == 0)
-		err = __libposix_get_errno(PosixENOENT);
-	else {
-		/* Jehanne does not support links.
-		 * A custom overlay filesystem might support them in
-		 * the future but so far it does not exists yet.
-		 *
-		 * We return EXDEV so that a posix compliant caller
-		 * can fallback to a simple copy.
-		 */
-		err = __libposix_get_errno(PosixEXDEV);
-	}
-	*errnop = err;
-	return -1;
-}
-
 int
 POSIX_unlink(int *errnop, const char *name)
 {
@@ -459,12 +434,6 @@ POSIX_stat(int *errnop, const char *file, void *pstat)
 	return -1;
 }
 
-int
-POSIX_lstat(int *errnop, const char *file, void *pstat)
-{
-	return POSIX_stat(errnop, file, pstat);
-}
-
 int
 POSIX_chmod(int *errnop, const char *path, int mode)
 {
@@ -581,13 +550,6 @@ POSIX_fchownat(int *errnop, int fd, const char *path, int owner, int group, int
 	return 0;
 }
 
-int
-POSIX_lchown(int *errnop, const char *path, int owner, int group)
-{
-	/* TODO: implement when actually needed */
-	return 0;
-}
-
 int
 POSIX_chdir(int *errnop, const char *path)
 {

sys/src/lib/posix/links.c

@@ -0,0 +1,74 @@
+/*
+ * This file is part of Jehanne.
+ *
+ * Copyright (C) 2017 Giacomo Tesio <giacomo@tesio.it>
+ *
+ * This is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, version 3 of the License.
+ *
+ * Jehanne 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 Affero General Public License
+ * along with Jehanne.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <u.h>
+#include <lib9.h>
+#include <9P2000.h>
+#include <posix.h>
+#include "internal.h"
+
+int
+POSIX_lchown(int *errnop, const char *path, int owner, int group)
+{
+	/* TODO: implement when actually needed */
+	return 0;
+}
+
+int
+POSIX_link(int *errnop, const char *old, const char *new)
+{
+	int err;
+	/* let choose the most appropriate error */
+	if(old == nil || new == nil || old[0] == 0 || new[0] == 0)
+		err = __libposix_get_errno(PosixENOENT);
+	else if(access(new, AEXIST) == 0)
+		err = __libposix_get_errno(PosixEEXIST);
+	else if(access(old, AEXIST) == 0)
+		err = __libposix_get_errno(PosixENOENT);
+	else {
+		/* Jehanne does not support links.
+		 * A custom overlay filesystem might support them in
+		 * the future but so far it does not exists yet.
+		 *
+		 * We return EXDEV so that a posix compliant caller
+		 * can fallback to a simple copy.
+		 */
+		err = __libposix_get_errno(PosixEXDEV);
+	}
+	*errnop = err;
+	return -1;
+}
+
+int
+POSIX_lstat(int *errnop, const char *file, void *pstat)
+{
+	return POSIX_stat(errnop, file, pstat);
+}
+
+int
+POSIX_readlink(int *errnop, const char *path, char *buf, int bufsize)
+{
+	*errnop = __libposix_get_errno(PosixEINVAL);
+	return -1;
+}
+
+int
+POSIX_readlinkat(int *errnop, int fd, const char *path, char *buf, int bufsize)
+{
+	*errnop = __libposix_get_errno(PosixEINVAL);
+	return -1;
+}