/*
 * Copyright 2002-2013, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 */


#include <errno.h>
#include <unistd.h>

#include <errno_private.h>
#include <syscalls.h>
#include <syscall_utils.h>


ssize_t
readlink(const char *path, char *buffer, size_t bufferSize)
{
        return readlinkat(AT_FDCWD, path, buffer, bufferSize);
}


ssize_t
readlinkat(int fd, const char *path, char *buffer, size_t bufferSize)
{
        size_t linkLen = bufferSize;
        status_t status = _kern_read_link(fd, path, buffer, &linkLen);
        if (status < B_OK) {
                __set_errno(status);
                return -1;
        }

        // If the buffer is big enough, null-terminate the string. That's not
        // required by the standard, but helps non-conforming apps.
        if (linkLen < bufferSize)
                buffer[linkLen] = '\0';

        // _kern_read_link() returns the length of the link, but readlinkat() is
        // supposed to return the number of bytes placed into buffer. If the
        // buffer is larger than the link contents, then linkLen is the number
        // of bytes written to the buffer. Otherwise, bufferSize bytes will have
        // been written.
        return min_c(linkLen, bufferSize);
}


int
symlink(const char *toPath, const char *symlinkPath)
{
        return symlinkat(toPath, AT_FDCWD, symlinkPath);
}


int
symlinkat(const char *toPath, int fd, const char *symlinkPath)
{
        RETURN_AND_SET_ERRNO(_kern_create_symlink(fd, symlinkPath, toPath, 0));
}


int
unlink(const char *path)
{
        return unlinkat(AT_FDCWD, path, 0);
}


int
unlinkat(int fd, const char *path, int flag)
{
        if ((flag & AT_REMOVEDIR) != 0)
                RETURN_AND_SET_ERRNO(_kern_remove_dir(fd, path));
        else
                RETURN_AND_SET_ERRNO(_kern_unlink(fd, path));
}


int
link(const char *toPath, const char *linkPath)
{
        return linkat(AT_FDCWD, toPath, AT_FDCWD, linkPath, 0);
}


int
linkat(int toFD, const char *toPath, int linkFD, const char *linkPath, int flag)
{
        int status = _kern_create_link(linkFD, linkPath, toFD, toPath,
                (flag & AT_SYMLINK_FOLLOW) != 0);

        // Haiku -> POSIX error mapping
        if (status == B_UNSUPPORTED)
                status = EPERM;

        RETURN_AND_SET_ERRNO(status);
}