1 files changed, 188 insertions, 0 deletions
diff --git a/src/pdf_writer.c b/src/pdf_writer.c
new file mode 100644
index 0000000..3cf4f7c
--- /dev/null
+++ b/src/pdf_writer.c
@@ -0,0 +1,188 @@
+/*
+ * Copyright (c) 2020, yzrh <yzrh@tuta.io>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include <openssl/md5.h>
+
+#include "pdf.h"
+
+int
+pdf_dump_obj(pdf_object_t **pdf, FILE **fp)
+{
+	if (*pdf == NULL || *fp == NULL)
+		return 1;
+
+	long cur;
+
+	pdf_object_t *ptr = (*pdf)->next;
+	while (ptr != NULL) {
+		ptr->address = cur = ftell(*fp);
+
+		fprintf(*fp, "%d 0 obj\n", ptr->id);
+
+		if (ptr->dictionary != NULL)
+			fputs(ptr->dictionary, *fp);
+		else if (ptr->object != NULL)
+			fputs(ptr->object, *fp);
+		else if (ptr->stream == NULL)
+			fputs("null\n", *fp);
+
+		if (ptr->stream != NULL) {
+			fputs("stream\r\n", *fp);
+			fwrite(ptr->stream, ptr->stream_size, 1, *fp);
+			fputs("endstream\n", *fp);
+		}
+
+		fputs("endobj\n", *fp);
+
+		ptr->size = ftell(*fp) - cur;
+
+		ptr = ptr->next;
+	}
+
+	return 0;
+}
+
+int
+pdf_dump_header(pdf_object_t **pdf, FILE **fp)
+{
+	if (*pdf == NULL || *fp == NULL)
+		return 1;
+
+	fputs("%PDF-1.7\n", *fp);
+
+	const unsigned char bin[4] = {
+		0xf6,
+		0xe4,
+		0xfc,
+		0xdf,
+	};
+
+	fputs("%", *fp);
+	fwrite(bin, 4, 1, *fp);
+	fputs("\n", *fp);
+
+	return 0;
+}
+
+int
+pdf_dump_xref(pdf_object_t **pdf, FILE **fp)
+{
+	if (*pdf == NULL || *fp == NULL)
+		return 1;
+
+	fputs("xref\n", *fp);
+
+	pdf_object_t *ptr = *pdf;
+
+	pdf_object_t *start = ptr;
+	int count = 1;
+
+	while (ptr != NULL) {
+		if (ptr->next == NULL ||
+			(ptr->next != NULL && ptr->next->id != ptr->id + 1)) {
+			fprintf(*fp, "%d %d\n", start->id, count);
+
+			for (; count > 0; count--) {
+				fprintf(*fp, "%010d %05d %s\r\n",
+					start->address,
+					start->address > 0 ? 0 : 65535,
+					start->size > 0 ? "n" : "f");
+				start = start->next;
+			}
+
+			if (ptr->next != NULL)
+				start = ptr->next;
+		}
+
+		ptr = ptr->next;
+		count++;
+	}
+
+	return 0;
+}
+
+int
+pdf_dump_trailer(pdf_object_t **pdf, FILE **fp, int xref)
+{
+	if (*pdf == NULL || *fp == NULL)
+		return 1;
+
+	fputs("trailer\n", *fp);
+
+	fputs("<<\n", *fp);
+
+	/*
+	 * File identifiers should be generated using
+	 * (a) Current time
+	 * (b) File path
+	 * (c) Size of file
+	 * (d) Values of all entries in the
+	 * file's document information dictionary
+	 *
+	 * It is recommended to be computed according to RFC 1321
+	 */
+
+	time_t timestamp = time(NULL);
+	int size = pdf_get_size(pdf);
+
+	int buf_size;
+	char buf[64];
+
+	buf_size = snprintf(buf, 64, "%lx%x", timestamp, size);
+
+	unsigned char str[64];
+	memcpy(str, buf, 64);
+
+	unsigned char fid[MD5_DIGEST_LENGTH];
+	MD5(str, buf_size, fid);
+
+	pdf_object_t *ptr = *pdf;
+	while (ptr->next != NULL)
+		ptr = ptr->next;
+
+	/*
+	 * TODO: Document information dictionary
+	 * `"/Producer (Melon)"'
+	 * `"/CreationDate (D:YYYYMMDDHHmmSS+00'00')"'
+	 *
+	 * Trailer dictionary
+	 * `"/Info %d 0 R"'
+	 */
+	fprintf(*fp,
+		"/Size %d\n/Root %d 0 R\n",
+		ptr->id + 1,
+		pdf_get_catalog_id(pdf));
+
+	fputs("/ID [", *fp);
+
+	for (int i = 0; i < 2; i++) {
+		fputs("<", *fp);
+
+		for (int j = 0; j < MD5_DIGEST_LENGTH; j++)
+			fprintf(*fp, "%02x", fid[j]);
+
+		fputs(">", *fp);
+
+		if (i < 1)
+			fputs(" ", *fp);
+	}
+
+	fputs("]\n", *fp);
+
+	fputs(">>\n", *fp);
+
+	fputs("startxref\n", *fp);
+
+	fprintf(*fp, "%d\n", xref);
+
+	fputs("%%EOF\n", *fp);
+
+	return 0;
+}