qpdf/include/qpdf/qpdf-c.h

/* Copyright (c) 2005-2017 Jay Berkenbilt
 *
 * This file is part of qpdf.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * Versions of qpdf prior to version 7 were released under the terms
 * of version 2.0 of the Artistic License. At your option, you may
 * continue to consider qpdf to be licensed under those terms. Please
 * see the manual for additional information.
 */

#ifndef __QPDF_C_H__
#define __QPDF_C_H__

/*
 * This file defines a basic "C" API for qpdf.  It provides access to
 * a subset of the QPDF library's capabilities to make them accessible
 * to callers who can't handle calling C++ functions or working with
 * C++ classes.  This may be especially useful to Windows users who
 * are accessing the qpdf DLL directly or to other people programming
 * in non-C/C++ languages that can call C code but not C++ code.
 *
 * There are several things to keep in mind when using the C API.
 *
 *     The C API is not as rich as the C++ API.  For any operations
 *     that involve actually manipulating PDF objects, you must use
 *     the C++ API.  The C API is primarily useful for doing basic
 *     transformations on PDF files similar to what you might do with
 *     the qpdf command-line tool.
 *
 *     These functions store their state in a qpdf_data object.
 *     Individual instances of qpdf_data are not thread-safe: although
 *     you may access different qpdf_data objects from different
 *     threads, you may not access one qpdf_data simultaneously from
 *     multiple threads.
 *
 *     All dynamic memory, except for that of the qpdf_data object
 *     itself, is managed by the library.  You must create a qpdf_data
 *     object using qpdf_init and free it using qpdf_cleanup.
 *
 *     Many functions return char*.  In all cases, the char* values
 *     returned are pointers to data inside the qpdf_data object.  As
 *     such, they are always freed by qpdf_cleanup.  In most cases,
 *     strings returned by functions here may be invalidated by
 *     subsequent function calls, sometimes even to different
 *     functions.  If you want a string to last past the next qpdf
 *     call or after a call to qpdf_cleanup, you should make a copy of
 *     it.
 *
 *     Many functions defined here merely set parameters and therefore
 *     never return error conditions.  Functions that may cause PDF
 *     files to be read or written may return error conditions.  Such
 *     functions return an error code.  If there were no errors or
 *     warnings, they return QPDF_SUCCESS.  If there were warnings,
 *     the return value has the QPDF_WARNINGS bit set.  If there
 *     errors, the QPDF_ERRORS bit is set.  In other words, if there
 *     are both warnings and errors, then the return status will be
 *     QPDF_WARNINGS | QPDF_ERRORS.  You may also call the
 *     qpdf_more_warnings and qpdf_more_errors functions to test
 *     whether there are unseen warning or error conditions.  By
 *     default, warnings are written to stderr when detected, but this
 *     behavior can be suppressed.  In all cases, errors and warnings
 *     may be retrieved by calling qpdf_next_warning and
 *     qpdf_next_error.  All exceptions thrown by the C++ interface
 *     are caught and converted into error messages by the C
 *     interface.
 *
 *     Most functions defined here have obvious counterparts that are
 *     methods to either QPDF or QPDFWriter.  Please see comments in
 *     QPDF.hh and QPDFWriter.hh for details on their use.  In order
 *     to avoid duplication of information, comments here focus
 *     primarily on differences between the C and C++ API.
 */

#include <qpdf/DLL.h>
#include <qpdf/Types.h>
#include <qpdf/Constants.h>
#include <string.h>

#ifdef __cplusplus
extern "C" {
#endif

    typedef struct _qpdf_data* qpdf_data;
    typedef struct _qpdf_error* qpdf_error;

    /* Many functions return an integer error code.  Codes are defined
     * below.  See comments at the top of the file for details.  Note
     * that the values below can be logically orred together.
     */
    typedef int QPDF_ERROR_CODE;
#   define QPDF_SUCCESS 0
#   define QPDF_WARNINGS 1 << 0
#   define QPDF_ERRORS 1 << 1

    typedef int QPDF_BOOL;
#   define QPDF_TRUE 1
#   define QPDF_FALSE 0

    /* Returns the version of the qpdf software */
    QPDF_DLL
    char const* qpdf_get_qpdf_version();

    /* Returns dynamically allocated qpdf_data pointer; must be freed
     * by calling qpdf_cleanup.
     */
    QPDF_DLL
    qpdf_data qpdf_init();

    /* Pass a pointer to the qpdf_data pointer created by qpdf_init to
     * clean up resources.
     */
    QPDF_DLL
    void qpdf_cleanup(qpdf_data* qpdf);

    /* ERROR REPORTING */

    /* Returns 1 if there is an error condition.  The error condition
     * can be retrieved by a single call to qpdf_get_error.
     */
    QPDF_DLL
    QPDF_BOOL qpdf_has_error(qpdf_data qpdf);

    /* Returns the error condition, if any.  The return value is a
     * pointer to data that will become invalid after the next call to
     * this function, qpdf_next_warning, or qpdf_destroy.  After this
     * function is called, qpdf_has_error will return QPDF_FALSE until
     * the next error condition occurs.  If there is no error
     * condition, this function returns a null pointer.
     */
    QPDF_DLL
    qpdf_error qpdf_get_error(qpdf_data qpdf);

    /* Returns 1 if there are any unretrieved warnings, and zero
     * otherwise.
     */
    QPDF_DLL
    QPDF_BOOL qpdf_more_warnings(qpdf_data qpdf);

    /* If there are any warnings, returns a pointer to the next
     * warning.  Otherwise returns a null pointer.
     */
    QPDF_DLL
    qpdf_error qpdf_next_warning(qpdf_data qpdf);

    /* Extract fields of the error. */

    /* Use this function to get a full error message suitable for
     * showing to the user. */
    QPDF_DLL
    char const* qpdf_get_error_full_text(qpdf_data q, qpdf_error e);

    /* Use these functions to extract individual fields from the
     * error; see QPDFExc.hh for details. */
    QPDF_DLL
    enum qpdf_error_code_e qpdf_get_error_code(qpdf_data q, qpdf_error e);
    QPDF_DLL
    char const* qpdf_get_error_filename(qpdf_data q, qpdf_error e);
    QPDF_DLL
    unsigned long long qpdf_get_error_file_position(qpdf_data q, qpdf_error e);
    QPDF_DLL
    char const* qpdf_get_error_message_detail(qpdf_data q, qpdf_error e);

    /* By default, warnings are written to stderr.  Passing true to
     * this function will prevent warnings from being written to
     * stderr.  They will still be available by calls to
     * qpdf_next_warning.
     */
    QPDF_DLL
    void qpdf_set_suppress_warnings(qpdf_data qpdf, QPDF_BOOL value);

    /* READ FUNCTIONS */

    /* READ PARAMETER FUNCTIONS -- must be called before qpdf_read */

    QPDF_DLL
    void qpdf_set_ignore_xref_streams(qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_attempt_recovery(qpdf_data qpdf, QPDF_BOOL value);

    /* Calling qpdf_read causes processFile to be called in the C++
     * API.  Basic parsing is performed, but data from the file is
     * only read as needed.  For files without passwords, pass a null
     * pointer as the password.
     */
    QPDF_DLL
    QPDF_ERROR_CODE qpdf_read(qpdf_data qpdf, char const* filename,
			      char const* password);

    /* Calling qpdf_read_memory causes processMemoryFile to be called
     * in the C++ API.  Otherwise, it behaves in the same way as
     * qpdf_read.  The description argument will be used in place of
     * the file name in any error or warning messages generated by the
     * library.
     */
    QPDF_DLL
    QPDF_ERROR_CODE qpdf_read_memory(qpdf_data qpdf,
				     char const* description,
				     char const* buffer,
				     unsigned long long size,
				     char const* password);

    /* Read functions below must be called after qpdf_read or
     * qpdf_read_memory. */

    /*
     * NOTE: Functions that return char* are returning a pointer to an
     * internal buffer that will be reused for each call to a function
     * that returns a char*.  You must use or copy the value before
     * calling any other qpdf library functions.
     */

    /* Return the version of the PDF file.  See warning above about
     * functions that return char*. */
    QPDF_DLL
    char const* qpdf_get_pdf_version(qpdf_data qpdf);

    /* Return the extension level of the PDF file. */
    QPDF_DLL
    int qpdf_get_pdf_extension_level(qpdf_data qpdf);

    /* Return the user password.  If the file is opened using the
     * owner password, the user password may be retrieved using this
     * function.  If the file is opened using the user password, this
     * function will return that user password.  See warning above
     * about functions that return char*.
     */
    QPDF_DLL
    char const* qpdf_get_user_password(qpdf_data qpdf);

    /* Return the string value of a key in the document's Info
     * dictionary.  The key parameter should include the leading
     * slash, e.g. "/Author".  If the key is not present or has a
     * non-string value, a null pointer is returned.  Otherwise, a
     * pointer to an internal buffer is returned.  See warning above
     * about functions that return char*.
     */
    QPDF_DLL
    char const* qpdf_get_info_key(qpdf_data qpdf, char const* key);

    /* Set a value in the info dictionary, possibly replacing an
     * existing value.  The key must include the leading slash
     * (e.g. "/Author").  Passing a null pointer as a value will
     * remove the key from the info dictionary.  Otherwise, a copy
     * will be made of the string that is passed in.
     */
    QPDF_DLL
    void qpdf_set_info_key(qpdf_data qpdf, char const* key, char const* value);

    /* Indicate whether the input file is linearized. */
    QPDF_DLL
    QPDF_BOOL qpdf_is_linearized(qpdf_data qpdf);

    /* Indicate whether the input file is encrypted. */
    QPDF_DLL
    QPDF_BOOL qpdf_is_encrypted(qpdf_data qpdf);

    QPDF_DLL
    QPDF_BOOL qpdf_allow_accessibility(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_extract_all(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_print_low_res(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_print_high_res(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_modify_assembly(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_modify_form(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_modify_annotation(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_modify_other(qpdf_data qpdf);
    QPDF_DLL
    QPDF_BOOL qpdf_allow_modify_all(qpdf_data qpdf);

    /* WRITE FUNCTIONS */

    /* Set up for writing.  No writing is actually performed until the
     * call to qpdf_write().
     */

    /* Supply the name of the file to be written and initialize the
     * qpdf_data object to handle writing operations.  This function
     * also attempts to create the file.  The PDF data is not written
     * until the call to qpdf_write.  qpdf_init_write may be called
     * multiple times for the same qpdf_data object.  When
     * qpdf_init_write is called, all information from previous calls
     * to functions that set write parameters (qpdf_set_linearization,
     * etc.) is lost, so any write parameter functions must be called
     * again.
     */
    QPDF_DLL
    QPDF_ERROR_CODE qpdf_init_write(qpdf_data qpdf, char const* filename);

    /* Initialize for writing but indicate that the PDF file should be
     * written to memory.  Call qpdf_get_buffer_length and
     * qpdf_get_buffer to retrieve the resulting buffer.  The memory
     * containing the PDF file will be destroyed when qpdf_cleanup is
     * called.
     */
    QPDF_DLL
    QPDF_ERROR_CODE qpdf_init_write_memory(qpdf_data qpdf);

    /* Retrieve the buffer used if the file was written to memory.
     * qpdf_get_buffer returns a null pointer if data was not written
     * to memory.  The memory is freed when qpdf_cleanup is called or
     * if a subsequent call to qpdf_init_write or
     * qpdf_init_write_memory is called. */
    QPDF_DLL
    size_t qpdf_get_buffer_length(qpdf_data qpdf);
    QPDF_DLL
    unsigned char const* qpdf_get_buffer(qpdf_data qpdf);

    QPDF_DLL
    void qpdf_set_object_stream_mode(qpdf_data qpdf,
				     enum qpdf_object_stream_e mode);

    QPDF_DLL
    void qpdf_set_stream_data_mode(qpdf_data qpdf,
				   enum qpdf_stream_data_e mode);

    QPDF_DLL
    void qpdf_set_compress_streams(qpdf_data qpdf, QPDF_BOOL value);


    QPDF_DLL
    void qpdf_set_decode_level(qpdf_data qpdf,
                               enum qpdf_stream_decode_level_e level);

    QPDF_DLL
    void qpdf_set_preserve_unreferenced_objects(
        qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_newline_before_endstream(qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_content_normalization(qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_qdf_mode(qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_deterministic_ID(qpdf_data qpdf, QPDF_BOOL value);

    /* Never use qpdf_set_static_ID except in test suites to suppress
     * generation of a random /ID.  See also qpdf_set_deterministic_ID.
     */
    QPDF_DLL
    void qpdf_set_static_ID(qpdf_data qpdf, QPDF_BOOL value);

    /* Never use qpdf_set_static_aes_IV except in test suites to
     * create predictable AES encrypted output.
     */
    QPDF_DLL
    void qpdf_set_static_aes_IV(qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_suppress_original_object_IDs(
	qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_preserve_encryption(qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_r2_encryption_parameters(
	qpdf_data qpdf, char const* user_password, char const* owner_password,
	QPDF_BOOL allow_print, QPDF_BOOL allow_modify,
	QPDF_BOOL allow_extract, QPDF_BOOL allow_annotate);

    QPDF_DLL
    void qpdf_set_r3_encryption_parameters(
	qpdf_data qpdf, char const* user_password, char const* owner_password,
	QPDF_BOOL allow_accessibility, QPDF_BOOL allow_extract,
	enum qpdf_r3_print_e print, enum qpdf_r3_modify_e modify);

    QPDF_DLL
    void qpdf_set_r4_encryption_parameters(
	qpdf_data qpdf, char const* user_password, char const* owner_password,
	QPDF_BOOL allow_accessibility, QPDF_BOOL allow_extract,
	enum qpdf_r3_print_e print, enum qpdf_r3_modify_e modify,
	QPDF_BOOL encrypt_metadata, QPDF_BOOL use_aes);

    QPDF_DLL
    void qpdf_set_r5_encryption_parameters(
	qpdf_data qpdf, char const* user_password, char const* owner_password,
	QPDF_BOOL allow_accessibility, QPDF_BOOL allow_extract,
	enum qpdf_r3_print_e print, enum qpdf_r3_modify_e modify,
	QPDF_BOOL encrypt_metadata);

    QPDF_DLL
    void qpdf_set_r6_encryption_parameters(
	qpdf_data qpdf, char const* user_password, char const* owner_password,
	QPDF_BOOL allow_accessibility, QPDF_BOOL allow_extract,
	enum qpdf_r3_print_e print, enum qpdf_r3_modify_e modify,
	QPDF_BOOL encrypt_metadata);

    QPDF_DLL
    void qpdf_set_linearization(qpdf_data qpdf, QPDF_BOOL value);

    QPDF_DLL
    void qpdf_set_minimum_pdf_version(qpdf_data qpdf, char const* version);

    QPDF_DLL
    void qpdf_set_minimum_pdf_version_and_extension(
        qpdf_data qpdf, char const* version, int extension_level);

    QPDF_DLL
    void qpdf_force_pdf_version(qpdf_data qpdf, char const* version);

    QPDF_DLL
    void qpdf_force_pdf_version_and_extension(
        qpdf_data qpdf, char const* version, int extension_level);

    /* Do actual write operation. */
    QPDF_DLL
    QPDF_ERROR_CODE qpdf_write(qpdf_data qpdf);

#ifdef __cplusplus
}
#endif


#endif /* __QPDF_C_H__ */