lib/fs/readlink/, lib/: areadlink(): Move and rename function

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/fs/readlink/areadlink.c

@@ -0,0 +1,10 @@
+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#include <config.h>
+
+#include "fs/readlink/areadlink.h"
+
+
+extern inline char *areadlink(const char *path);

lib/fs/readlink/areadlink.h

@@ -0,0 +1,51 @@
+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#ifndef SHADOW_INCLUDE_LIB_FS_READLINK_AREADLINK_H_
+#define SHADOW_INCLUDE_LIB_FS_READLINK_AREADLINK_H_
+
+
+#include <config.h>
+
+#include <errno.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+#include "alloc/malloc.h"
+#include "attr.h"
+#include "fs/readlink/readlinknul.h"
+
+
+ATTR_STRING(1)
+inline char *areadlink(const char *path);
+
+
+// Similar to readlink(2), but allocate and terminate the string.
+inline char *
+areadlink(const char *filename)
+{
+	size_t size = 1024;
+
+	while (true) {
+		int  len;
+		char *buffer = MALLOC(size, char);
+		if (NULL == buffer) {
+			return NULL;
+		}
+
+		len = readlinknul(filename, buffer, size);
+		if (len != -1)
+			return buffer;
+
+		free(buffer);
+		if (errno != E2BIG)
+			return NULL;
+
+		size *= 2;
+	}
+}
+
+
+#endif  // include guard