diff --git a/src/out.c b/src/out.c
new file mode 100644
index 0000000..0d2a46b
--- /dev/null
+++ b/src/out.c
@@ -0,0 +1,780 @@
+/**
+ * @file out.c
+ * @author Radek Krejci <rkrejci@cesnet.cz>
+ * @brief libyang output functions.
+ *
+ * Copyright (c) 2015 - 2020 CESNET, z.s.p.o.
+ *
+ * This source code is licensed under BSD 3-Clause License (the "License").
+ * You may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://opensource.org/licenses/BSD-3-Clause
+ */
+
+#define _GNU_SOURCE
+
+#include "out.h"
+#include "out_internal.h"
+
+#include <assert.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "common.h"
+#include "compat.h"
+#include "log.h"
+#include "plugins_types.h"
+#include "printer_data.h"
+#include "printer_internal.h"
+#include "tree.h"
+#include "tree_schema.h"
+
+/**
+ * @brief informational structure shared by printers
+ */
+struct ext_substmt_info_s ext_substmt_info[] = {
+    {NULL, NULL, 0},                            /**< LYEXT_SUBSTMT_SELF */
+    {"argument", "name", SUBST_FLAG_ID},        /**< LYEXT_SUBSTMT_ARGUMENT */
+    {"base", "name", SUBST_FLAG_ID},            /**< LYEXT_SUBSTMT_BASE */
+    {"belongs-to", "module", SUBST_FLAG_ID},    /**< LYEXT_SUBSTMT_BELONGSTO */
+    {"contact", "text", SUBST_FLAG_YIN},        /**< LYEXT_SUBSTMT_CONTACT */
+    {"default", "value", 0},                    /**< LYEXT_SUBSTMT_DEFAULT */
+    {"description", "text", SUBST_FLAG_YIN},    /**< LYEXT_SUBSTMT_DESCRIPTION */
+    {"error-app-tag", "value", 0},              /**< LYEXT_SUBSTMT_ERRTAG */
+    {"error-message", "value", SUBST_FLAG_YIN}, /**< LYEXT_SUBSTMT_ERRMSG */
+    {"key", "value", 0},                        /**< LYEXT_SUBSTMT_KEY */
+    {"namespace", "uri", 0},                    /**< LYEXT_SUBSTMT_NAMESPACE */
+    {"organization", "text", SUBST_FLAG_YIN},   /**< LYEXT_SUBSTMT_ORGANIZATION */
+    {"path", "value", 0},                       /**< LYEXT_SUBSTMT_PATH */
+    {"prefix", "value", SUBST_FLAG_ID},         /**< LYEXT_SUBSTMT_PREFIX */
+    {"presence", "value", 0},                   /**< LYEXT_SUBSTMT_PRESENCE */
+    {"reference", "text", SUBST_FLAG_YIN},      /**< LYEXT_SUBSTMT_REFERENCE */
+    {"revision-date", "date", SUBST_FLAG_ID},   /**< LYEXT_SUBSTMT_REVISIONDATE */
+    {"units", "name", 0},                       /**< LYEXT_SUBSTMT_UNITS */
+    {"value", "value", SUBST_FLAG_ID},          /**< LYEXT_SUBSTMT_VALUE */
+    {"yang-version", "value", SUBST_FLAG_ID},   /**< LYEXT_SUBSTMT_VERSION */
+    {"modifier", "value", SUBST_FLAG_ID},       /**< LYEXT_SUBSTMT_MODIFIER */
+    {"require-instance", "value", SUBST_FLAG_ID}, /**< LYEXT_SUBSTMT_REQINST */
+    {"yin-element", "value", SUBST_FLAG_ID},    /**< LYEXT_SUBSTMT_YINELEM */
+    {"config", "value", SUBST_FLAG_ID},         /**< LYEXT_SUBSTMT_CONFIG */
+    {"mandatory", "value", SUBST_FLAG_ID},      /**< LYEXT_SUBSTMT_MANDATORY */
+    {"ordered-by", "value", SUBST_FLAG_ID},     /**< LYEXT_SUBSTMT_ORDEREDBY */
+    {"status", "value", SUBST_FLAG_ID},         /**< LYEXT_SUBSTMT_STATUS */
+    {"fraction-digits", "value", SUBST_FLAG_ID}, /**< LYEXT_SUBSTMT_DIGITS */
+    {"max-elements", "value", SUBST_FLAG_ID},   /**< LYEXT_SUBSTMT_MAX */
+    {"min-elements", "value", SUBST_FLAG_ID},   /**< LYEXT_SUBSTMT_MIN */
+    {"position", "value", SUBST_FLAG_ID},       /**< LYEXT_SUBSTMT_POSITION */
+    {"unique", "tag", 0},                       /**< LYEXT_SUBSTMT_UNIQUE */
+};
+
+ly_bool
+ly_should_print(const struct lyd_node *node, uint32_t options)
+{
+    const struct lyd_node *elem;
+
+    if (options & LYD_PRINT_WD_TRIM) {
+        /* do not print default nodes */
+        if (node->flags & LYD_DEFAULT) {
+            /* implicit default node/NP container with only default nodes */
+            return 0;
+        } else if (node->schema->nodetype & LYD_NODE_TERM) {
+            if (lyd_is_default(node)) {
+                /* explicit default node */
+                return 0;
+            }
+        }
+    } else if ((node->flags & LYD_DEFAULT) && !(options & LYD_PRINT_WD_MASK) && !(node->schema->flags & LYS_CONFIG_R)) {
+        /* LYDP_WD_EXPLICIT
+         * - print only if it contains status data in its subtree */
+        LYD_TREE_DFS_BEGIN(node, elem) {
+            if ((elem->schema->nodetype != LYS_CONTAINER) || (elem->schema->flags & LYS_PRESENCE)) {
+                if (elem->schema->flags & LYS_CONFIG_R) {
+                    return 1;
+                }
+            }
+            LYD_TREE_DFS_END(node, elem)
+        }
+        return 0;
+    } else if ((node->flags & LYD_DEFAULT) && (node->schema->nodetype == LYS_CONTAINER) && !(options & LYD_PRINT_KEEPEMPTYCONT)) {
+        /* avoid empty default containers */
+        LYD_TREE_DFS_BEGIN(node, elem) {
+            if (elem->schema->nodetype != LYS_CONTAINER) {
+                return 1;
+            }
+            assert(elem->flags & LYD_DEFAULT);
+            LYD_TREE_DFS_END(node, elem)
+        }
+        return 0;
+    }
+
+    return 1;
+}
+
+API LY_OUT_TYPE
+ly_out_type(const struct ly_out *out)
+{
+    LY_CHECK_ARG_RET(NULL, out, LY_OUT_ERROR);
+    return out->type;
+}
+
+API LY_ERR
+ly_out_new_clb(ly_write_clb writeclb, void *user_data, struct ly_out **out)
+{
+    LY_CHECK_ARG_RET(NULL, out, writeclb, LY_EINVAL);
+
+    *out = calloc(1, sizeof **out);
+    LY_CHECK_ERR_RET(!*out, LOGMEM(NULL), LY_EMEM);
+
+    (*out)->type = LY_OUT_CALLBACK;
+    (*out)->method.clb.func = writeclb;
+    (*out)->method.clb.arg = user_data;
+
+    return LY_SUCCESS;
+}
+
+API ly_write_clb
+ly_out_clb(struct ly_out *out, ly_write_clb writeclb)
+{
+    void *prev_clb;
+
+    LY_CHECK_ARG_RET(NULL, out, out->type == LY_OUT_CALLBACK, NULL);
+
+    prev_clb = out->method.clb.func;
+
+    if (writeclb) {
+        out->method.clb.func = writeclb;
+    }
+
+    return prev_clb;
+}
+
+API void *
+ly_out_clb_arg(struct ly_out *out, void *arg)
+{
+    void *prev_arg;
+
+    LY_CHECK_ARG_RET(NULL, out, out->type == LY_OUT_CALLBACK, NULL);
+
+    prev_arg = out->method.clb.arg;
+
+    if (arg) {
+        out->method.clb.arg = arg;
+    }
+
+    return prev_arg;
+}
+
+API LY_ERR
+ly_out_new_fd(int fd, struct ly_out **out)
+{
+    LY_CHECK_ARG_RET(NULL, out, fd != -1, LY_EINVAL);
+
+    *out = calloc(1, sizeof **out);
+    LY_CHECK_ERR_RET(!*out, LOGMEM(NULL), LY_EMEM);
+    (*out)->type = LY_OUT_FD;
+    (*out)->method.fd = fd;
+
+    return LY_SUCCESS;
+}
+
+API int
+ly_out_fd(struct ly_out *out, int fd)
+{
+    int prev_fd;
+
+    LY_CHECK_ARG_RET(NULL, out, out->type <= LY_OUT_FDSTREAM, -1);
+
+    if (out->type == LY_OUT_FDSTREAM) {
+        prev_fd = out->method.fdstream.fd;
+    } else { /* LY_OUT_FD */
+        prev_fd = out->method.fd;
+    }
+
+    if (fd != -1) {
+        /* replace output stream */
+        if (out->type == LY_OUT_FDSTREAM) {
+            int streamfd;
+            FILE *stream;
+
+            streamfd = dup(fd);
+            if (streamfd < 0) {
+                LOGERR(NULL, LY_ESYS, "Unable to duplicate provided file descriptor (%d) for printing the output (%s).", fd, strerror(errno));
+                return -1;
+            }
+            stream = fdopen(streamfd, "a");
+            if (!stream) {
+                LOGERR(NULL, LY_ESYS, "Unable to open provided file descriptor (%d) for printing the output (%s).", fd, strerror(errno));
+                close(streamfd);
+                return -1;
+            }
+            /* close only the internally created stream, file descriptor is returned and supposed to be closed by the caller */
+            fclose(out->method.fdstream.f);
+            out->method.fdstream.f = stream;
+            out->method.fdstream.fd = streamfd;
+        } else { /* LY_OUT_FD */
+            out->method.fd = fd;
+        }
+    }
+
+    return prev_fd;
+}
+
+API LY_ERR
+ly_out_new_file(FILE *f, struct ly_out **out)
+{
+    LY_CHECK_ARG_RET(NULL, out, f, LY_EINVAL);
+
+    *out = calloc(1, sizeof **out);
+    LY_CHECK_ERR_RET(!*out, LOGMEM(NULL), LY_EMEM);
+
+    (*out)->type = LY_OUT_FILE;
+    (*out)->method.f = f;
+
+    return LY_SUCCESS;
+}
+
+API FILE *
+ly_out_file(struct ly_out *out, FILE *f)
+{
+    FILE *prev_f;
+
+    LY_CHECK_ARG_RET(NULL, out, out->type == LY_OUT_FILE, NULL);
+
+    prev_f = out->method.f;
+
+    if (f) {
+        out->method.f = f;
+    }
+
+    return prev_f;
+}
+
+API LY_ERR
+ly_out_new_memory(char **strp, size_t size, struct ly_out **out)
+{
+    LY_CHECK_ARG_RET(NULL, out, strp, LY_EINVAL);
+
+    *out = calloc(1, sizeof **out);
+    LY_CHECK_ERR_RET(!*out, LOGMEM(NULL), LY_EMEM);
+
+    (*out)->type = LY_OUT_MEMORY;
+    (*out)->method.mem.buf = strp;
+    if (!size) {
+        /* buffer is supposed to be allocated */
+        *strp = NULL;
+    } else if (*strp) {
+        /* there is already buffer to use */
+        (*out)->method.mem.size = size;
+    }
+
+    return LY_SUCCESS;
+}
+
+char *
+ly_out_memory(struct ly_out *out, char **strp, size_t size)
+{
+    char *data;
+
+    LY_CHECK_ARG_RET(NULL, out, out->type == LY_OUT_MEMORY, NULL);
+
+    data = *out->method.mem.buf;
+
+    if (strp) {
+        out->method.mem.buf = strp;
+        out->method.mem.len = out->method.mem.size = 0;
+        out->printed = 0;
+        if (!size) {
+            /* buffer is supposed to be allocated */
+            *strp = NULL;
+        } else if (*strp) {
+            /* there is already buffer to use */
+            out->method.mem.size = size;
+        }
+    }
+
+    return data;
+}
+
+API LY_ERR
+ly_out_reset(struct ly_out *out)
+{
+    LY_CHECK_ARG_RET(NULL, out, LY_EINVAL);
+
+    switch (out->type) {
+    case LY_OUT_ERROR:
+        LOGINT(NULL);
+        return LY_EINT;
+    case LY_OUT_FD:
+        if ((lseek(out->method.fd, 0, SEEK_SET) == -1) && (errno != ESPIPE)) {
+            LOGERR(NULL, LY_ESYS, "Seeking output file descriptor failed (%s).", strerror(errno));
+            return LY_ESYS;
+        }
+        if ((errno != ESPIPE) && (ftruncate(out->method.fd, 0) == -1)) {
+            LOGERR(NULL, LY_ESYS, "Truncating output file failed (%s).", strerror(errno));
+            return LY_ESYS;
+        }
+        break;
+    case LY_OUT_FDSTREAM:
+    case LY_OUT_FILE:
+    case LY_OUT_FILEPATH:
+        if ((fseek(out->method.f, 0, SEEK_SET) == -1) && (errno != ESPIPE)) {
+            LOGERR(NULL, LY_ESYS, "Seeking output file stream failed (%s).", strerror(errno));
+            return LY_ESYS;
+        }
+        if ((errno != ESPIPE) && (ftruncate(fileno(out->method.f), 0) == -1)) {
+            LOGERR(NULL, LY_ESYS, "Truncating output file failed (%s).", strerror(errno));
+            return LY_ESYS;
+        }
+        break;
+    case LY_OUT_MEMORY:
+        if (out->method.mem.buf && *out->method.mem.buf) {
+            memset(*out->method.mem.buf, 0, out->method.mem.len);
+        }
+        out->printed = 0;
+        out->method.mem.len = 0;
+        break;
+    case LY_OUT_CALLBACK:
+        /* nothing to do (not seekable) */
+        break;
+    }
+
+    return LY_SUCCESS;
+}
+
+API LY_ERR
+ly_out_new_filepath(const char *filepath, struct ly_out **out)
+{
+    LY_CHECK_ARG_RET(NULL, out, filepath, LY_EINVAL);
+
+    *out = calloc(1, sizeof **out);
+    LY_CHECK_ERR_RET(!*out, LOGMEM(NULL), LY_EMEM);
+
+    (*out)->type = LY_OUT_FILEPATH;
+    (*out)->method.fpath.f = fopen(filepath, "w");
+    if (!(*out)->method.fpath.f) {
+        LOGERR(NULL, LY_ESYS, "Failed to open file \"%s\" (%s).", filepath, strerror(errno));
+        free(*out);
+        *out = NULL;
+        return LY_ESYS;
+    }
+    (*out)->method.fpath.filepath = strdup(filepath);
+    return LY_SUCCESS;
+}
+
+API const char *
+ly_out_filepath(struct ly_out *out, const char *filepath)
+{
+    FILE *f;
+
+    LY_CHECK_ARG_RET(NULL, out, out->type == LY_OUT_FILEPATH, filepath ? NULL : ((void *)-1));
+
+    if (!filepath) {
+        return out->method.fpath.filepath;
+    }
+
+    /* replace filepath */
+    f = out->method.fpath.f;
+    out->method.fpath.f = fopen(filepath, "w");
+    if (!out->method.fpath.f) {
+        LOGERR(NULL, LY_ESYS, "Failed to open file \"%s\" (%s).", filepath, strerror(errno));
+        out->method.fpath.f = f;
+        return (void *)-1;
+    }
+    fclose(f);
+    free(out->method.fpath.filepath);
+    out->method.fpath.filepath = strdup(filepath);
+
+    return NULL;
+}
+
+API void
+ly_out_free(struct ly_out *out, void (*clb_arg_destructor)(void *arg), ly_bool destroy)
+{
+    if (!out) {
+        return;
+    }
+
+    switch (out->type) {
+    case LY_OUT_CALLBACK:
+        if (clb_arg_destructor) {
+            clb_arg_destructor(out->method.clb.arg);
+        }
+        break;
+    case LY_OUT_FDSTREAM:
+        fclose(out->method.fdstream.f);
+        if (destroy) {
+            close(out->method.fdstream.fd);
+        }
+        break;
+    case LY_OUT_FD:
+        if (destroy) {
+            close(out->method.fd);
+        }
+        break;
+    case LY_OUT_FILE:
+        if (destroy) {
+            fclose(out->method.f);
+        }
+        break;
+    case LY_OUT_MEMORY:
+        if (destroy) {
+            free(*out->method.mem.buf);
+        }
+        break;
+    case LY_OUT_FILEPATH:
+        free(out->method.fpath.filepath);
+        fclose(out->method.fpath.f);
+        break;
+    case LY_OUT_ERROR:
+        LOGINT(NULL);
+    }
+    free(out);
+}
+
+static LY_ERR
+ly_vprint_(struct ly_out *out, const char *format, va_list ap)
+{
+    LY_ERR ret;
+    int written = 0;
+    char *msg = NULL, *aux;
+
+    switch (out->type) {
+    case LY_OUT_FD:
+        written = vdprintf(out->method.fd, format, ap);
+        break;
+    case LY_OUT_FDSTREAM:
+    case LY_OUT_FILEPATH:
+    case LY_OUT_FILE:
+        written = vfprintf(out->method.f, format, ap);
+        break;
+    case LY_OUT_MEMORY:
+        if ((written = vasprintf(&msg, format, ap)) < 0) {
+            break;
+        }
+        if (out->method.mem.len + written + 1 > out->method.mem.size) {
+            aux = ly_realloc(*out->method.mem.buf, out->method.mem.len + written + 1);
+            if (!aux) {
+                out->method.mem.buf = NULL;
+                out->method.mem.len = 0;
+                out->method.mem.size = 0;
+                LOGMEM(NULL);
+                return LY_EMEM;
+            }
+            *out->method.mem.buf = aux;
+            out->method.mem.size = out->method.mem.len + written + 1;
+        }
+        memcpy(&(*out->method.mem.buf)[out->method.mem.len], msg, written);
+        out->method.mem.len += written;
+        (*out->method.mem.buf)[out->method.mem.len] = '\0';
+        free(msg);
+        break;
+    case LY_OUT_CALLBACK:
+        if ((written = vasprintf(&msg, format, ap)) < 0) {
+            break;
+        }
+        written = out->method.clb.func(out->method.clb.arg, msg, written);
+        free(msg);
+        break;
+    case LY_OUT_ERROR:
+        LOGINT(NULL);
+        return LY_EINT;
+    }
+
+    if (written < 0) {
+        LOGERR(NULL, LY_ESYS, "%s: writing data failed (%s).", __func__, strerror(errno));
+        written = 0;
+        ret = LY_ESYS;
+    } else {
+        if (out->type == LY_OUT_FDSTREAM) {
+            /* move the original file descriptor to the end of the output file */
+            lseek(out->method.fdstream.fd, 0, SEEK_END);
+        }
+        ret = LY_SUCCESS;
+    }
+
+    out->printed += written;
+    out->func_printed += written;
+    return ret;
+}
+
+LY_ERR
+ly_print_(struct ly_out *out, const char *format, ...)
+{
+    LY_ERR ret;
+    va_list ap;
+
+    va_start(ap, format);
+    ret = ly_vprint_(out, format, ap);
+    va_end(ap);
+
+    return ret;
+}
+
+API LY_ERR
+ly_print(struct ly_out *out, const char *format, ...)
+{
+    LY_ERR ret;
+    va_list ap;
+
+    out->func_printed = 0;
+
+    va_start(ap, format);
+    ret = ly_vprint_(out, format, ap);
+    va_end(ap);
+
+    return ret;
+}
+
+API void
+ly_print_flush(struct ly_out *out)
+{
+    switch (out->type) {
+    case LY_OUT_FDSTREAM:
+        /* move the original file descriptor to the end of the output file */
+        lseek(out->method.fdstream.fd, 0, SEEK_END);
+        fflush(out->method.fdstream.f);
+        break;
+    case LY_OUT_FILEPATH:
+    case LY_OUT_FILE:
+        fflush(out->method.f);
+        break;
+    case LY_OUT_FD:
+        fsync(out->method.fd);
+        break;
+    case LY_OUT_MEMORY:
+    case LY_OUT_CALLBACK:
+        /* nothing to do */
+        break;
+    case LY_OUT_ERROR:
+        LOGINT(NULL);
+    }
+
+    free(out->buffered);
+    out->buf_size = out->buf_len = 0;
+}
+
+LY_ERR
+ly_write_(struct ly_out *out, const char *buf, size_t len)
+{
+    LY_ERR ret = LY_SUCCESS;
+    size_t written = 0;
+
+    if (out->hole_count) {
+        /* we are buffering data after a hole */
+        if (out->buf_len + len > out->buf_size) {
+            out->buffered = ly_realloc(out->buffered, out->buf_len + len);
+            if (!out->buffered) {
+                out->buf_len = 0;
+                out->buf_size = 0;
+                LOGMEM(NULL);
+                return LY_EMEM;
+            }
+            out->buf_size = out->buf_len + len;
+        }
+
+        memcpy(&out->buffered[out->buf_len], buf, len);
+        out->buf_len += len;
+
+        out->printed += len;
+        out->func_printed += len;
+        return LY_SUCCESS;
+    }
+
+repeat:
+    switch (out->type) {
+    case LY_OUT_MEMORY:
+        if (out->method.mem.len + len + 1 > out->method.mem.size) {
+            *out->method.mem.buf = ly_realloc(*out->method.mem.buf, out->method.mem.len + len + 1);
+            if (!*out->method.mem.buf) {
+                out->method.mem.len = 0;
+                out->method.mem.size = 0;
+                LOGMEM(NULL);
+                return LY_EMEM;
+            }
+            out->method.mem.size = out->method.mem.len + len + 1;
+        }
+        memcpy(&(*out->method.mem.buf)[out->method.mem.len], buf, len);
+        out->method.mem.len += len;
+        (*out->method.mem.buf)[out->method.mem.len] = '\0';
+
+        written = len;
+        break;
+    case LY_OUT_FD: {
+        ssize_t r;
+        r = write(out->method.fd, buf, len);
+        if (r < 0) {
+            ret = LY_ESYS;
+        } else {
+            written = (size_t)r;
+        }
+        break;
+    }
+    case LY_OUT_FDSTREAM:
+    case LY_OUT_FILEPATH:
+    case LY_OUT_FILE:
+        written = fwrite(buf, sizeof *buf, len, out->method.f);
+        if (written != len) {
+            ret = LY_ESYS;
+        }
+        break;
+    case LY_OUT_CALLBACK: {
+        ssize_t r;
+        r = out->method.clb.func(out->method.clb.arg, buf, len);
+        if (r < 0) {
+            ret = LY_ESYS;
+        } else {
+            written = (size_t)r;
+        }
+        break;
+    }
+    case LY_OUT_ERROR:
+        LOGINT(NULL);
+        return LY_EINT;
+    }
+
+    if (ret) {
+        if ((errno == EAGAIN) || (errno == EWOULDBLOCK)) {
+            ret = LY_SUCCESS;
+            goto repeat;
+        }
+        LOGERR(NULL, LY_ESYS, "%s: writing data failed (%s).", __func__, strerror(errno));
+        written = 0;
+    } else if ((size_t)written != len) {
+        LOGERR(NULL, LY_ESYS, "%s: writing data failed (unable to write %u from %u data).", __func__,
+                len - (size_t)written, len);
+        ret = LY_ESYS;
+    } else {
+        if (out->type == LY_OUT_FDSTREAM) {
+            /* move the original file descriptor to the end of the output file */
+            lseek(out->method.fdstream.fd, 0, SEEK_END);
+        }
+        ret = LY_SUCCESS;
+    }
+
+    out->printed += written;
+    out->func_printed += written;
+    return ret;
+}
+
+API LY_ERR
+ly_write(struct ly_out *out, const char *buf, size_t len)
+{
+    out->func_printed = 0;
+
+    return ly_write_(out, buf, len);
+}
+
+API size_t
+ly_out_printed(const struct ly_out *out)
+{
+    return out->func_printed;
+}
+
+LY_ERR
+ly_write_skip(struct ly_out *out, size_t count, size_t *position)
+{
+    switch (out->type) {
+    case LY_OUT_MEMORY:
+        if (out->method.mem.len + count > out->method.mem.size) {
+            *out->method.mem.buf = ly_realloc(*out->method.mem.buf, out->method.mem.len + count);
+            if (!(*out->method.mem.buf)) {
+                out->method.mem.len = 0;
+                out->method.mem.size = 0;
+                LOGMEM(NULL);
+                return LY_EMEM;
+            }
+            out->method.mem.size = out->method.mem.len + count;
+        }
+
+        /* save the current position */
+        *position = out->method.mem.len;
+
+        /* skip the memory */
+        out->method.mem.len += count;
+        break;
+    case LY_OUT_FD:
+    case LY_OUT_FDSTREAM:
+    case LY_OUT_FILEPATH:
+    case LY_OUT_FILE:
+    case LY_OUT_CALLBACK:
+        /* buffer the hole */
+        if (out->buf_len + count > out->buf_size) {
+            out->buffered = ly_realloc(out->buffered, out->buf_len + count);
+            if (!out->buffered) {
+                out->buf_len = 0;
+                out->buf_size = 0;
+                LOGMEM(NULL);
+                return LY_EMEM;
+            }
+            out->buf_size = out->buf_len + count;
+        }
+
+        /* save the current position */
+        *position = out->buf_len;
+
+        /* skip the memory */
+        out->buf_len += count;
+
+        /* increase hole counter */
+        ++out->hole_count;
+        break;
+    case LY_OUT_ERROR:
+        LOGINT(NULL);
+        return LY_EINT;
+    }
+
+    /* update printed bytes counter despite we actually printed just a hole */
+    out->printed += count;
+    out->func_printed += count;
+    return LY_SUCCESS;
+}
+
+LY_ERR
+ly_write_skipped(struct ly_out *out, size_t position, const char *buf, size_t count)
+{
+    LY_ERR ret = LY_SUCCESS;
+
+    switch (out->type) {
+    case LY_OUT_MEMORY:
+        /* write */
+        memcpy(&(*out->method.mem.buf)[position], buf, count);
+        break;
+    case LY_OUT_FD:
+    case LY_OUT_FDSTREAM:
+    case LY_OUT_FILEPATH:
+    case LY_OUT_FILE:
+    case LY_OUT_CALLBACK:
+        if (out->buf_len < position + count) {
+            LOGMEM(NULL);
+            return LY_EMEM;
+        }
+
+        /* write into the hole */
+        memcpy(&out->buffered[position], buf, count);
+
+        /* decrease hole counter */
+        --out->hole_count;
+
+        if (!out->hole_count) {
+            /* all holes filled, we can write the buffer,
+             * printed bytes counter is updated by ly_write_() */
+            ret = ly_write_(out, out->buffered, out->buf_len);
+            out->buf_len = 0;
+        }
+        break;
+    case LY_OUT_ERROR:
+        LOGINT(NULL);
+        return LY_EINT;
+    }
+
+    if (out->type == LY_OUT_FILEPATH) {
+        /* move the original file descriptor to the end of the output file */
+        lseek(out->method.fdstream.fd, 0, SEEK_END);
+    }
+    return ret;
+}