sign_custom.c

Example use of custom interface callbacks for document signing.

#include "tools.h"
 
void print_sign_custom_help() {
    printf("Usage: sign_custom -s [source file] -d [destination file] -l [license file]");
}
 
// Custom callbacks
typedef struct {
    BufferHandle* data;
} SignatureData;
 
error_type sign_init(void* user_data, MessageDigestAlgorithmType algorithm) {
    SignatureData* signature_data = (SignatureData*) user_data;
 
    const char SAMPLE_DATA[] = "Hello world!";
 
    UNUSED(algorithm);
 
    RETURN_ERROR_IF_NOT_SUCCESS(Buffer_Create(&signature_data->data));
    RETURN_ERROR_IF_NOT_SUCCESS(Buffer_SetData(signature_data->data, SAMPLE_DATA, sizeof(SAMPLE_DATA)));
 
    return VANILLAPDF_ERROR_SUCCESS;
}
 
error_type sign_update(void* user_data, const BufferHandle* data) {
    SignatureData* signature_data = (SignatureData*) user_data;
    string_type buffer_data = NULL;
    size_type buffer_size = 0;
 
    RETURN_ERROR_IF_NOT_SUCCESS(Buffer_GetData(data, &buffer_data, &buffer_size));
 
    // Calculate signature
 
    UNUSED(signature_data);
 
    return VANILLAPDF_ERROR_SUCCESS;
}
 
error_type sign_final(void* user_data, BufferHandle** result) {
    SignatureData* signature_data = (SignatureData*) user_data;
 
    *result = signature_data->data;
 
    return VANILLAPDF_ERROR_SUCCESS;
}
 
error_type sign_cleanup(void* user_data) {
    SignatureData* signature_data = (SignatureData*) user_data;
 
    RETURN_ERROR_IF_NOT_SUCCESS(Buffer_Release(signature_data->data));
 
    return VANILLAPDF_ERROR_SUCCESS;
}
 
int process_sign_custom(int argc, char *argv[]) {
    string_type license_file = NULL;
    string_type source_document_path = NULL;
    string_type destination_file_path = NULL;
 
    DocumentHandle* source_document = NULL;
    FileHandle* destination_file = NULL;
 
    DocumentSignatureSettingsHandle* signature_settings = NULL;
    SigningKeyHandle* signing_key = NULL;
    SignatureData user_data = {0};
 
    integer_type i = 0;
 
    for (i = 0; i < argc; ++i) {
 
        // source document path
        if (strcmp(argv[i], "-s") == 0 && (i + 1 < argc)) {
            source_document_path = argv[i + 1];
            i++;
 
        // destination file path
        } else if (strcmp(argv[i], "-d") == 0 && (i + 1 < argc)) {
            destination_file_path = argv[i + 1];
            i++;
 
        // license
        } else if (strcmp(argv[i], "-l") == 0 && (i + 1 < argc)) {
            license_file = argv[i + 1];
            i++;
 
        } else {
            print_sign_custom_help();
            return VANILLAPDF_TOOLS_ERROR_INVALID_PARAMETERS;
        }
    }
 
    if (source_document_path == NULL || destination_file_path == NULL) {
        print_sign_custom_help();
        return VANILLAPDF_TOOLS_ERROR_INVALID_PARAMETERS;
    }
 
    if (license_file != NULL) {
        RETURN_ERROR_IF_NOT_SUCCESS(LicenseInfo_SetLicenseFile(license_file));
    }
 
    RETURN_ERROR_IF_NOT_SUCCESS(SigningKey_CreateCustom(&sign_init, &sign_update, &sign_final, &sign_cleanup, &user_data, &signing_key));
 
    RETURN_ERROR_IF_NOT_SUCCESS(DocumentSignatureSettings_Create(&signature_settings));
    RETURN_ERROR_IF_NOT_SUCCESS(DocumentSignatureSettings_SetSigningKey(signature_settings, signing_key));
    RETURN_ERROR_IF_NOT_SUCCESS(DocumentSignatureSettings_SetDigest(signature_settings, MessageDigestAlgorithmType_SHA256));
 
    RETURN_ERROR_IF_NOT_SUCCESS(File_Create(destination_file_path, &destination_file));
    RETURN_ERROR_IF_NOT_SUCCESS(Document_Open(source_document_path, &source_document));
    RETURN_ERROR_IF_NOT_SUCCESS(Document_Sign(source_document, destination_file, signature_settings));
    RETURN_ERROR_IF_NOT_SUCCESS(Document_Release(source_document));
    RETURN_ERROR_IF_NOT_SUCCESS(File_Release(destination_file));
 
    RETURN_ERROR_IF_NOT_SUCCESS(DocumentSignatureSettings_Release(signature_settings));
    RETURN_ERROR_IF_NOT_SUCCESS(SigningKey_Release(signing_key));
 
    return VANILLAPDF_TOOLS_ERROR_SUCCESS;
}