From 9019a184494e6fc220bcc1eb8f47f33fe0f3e506 Mon Sep 17 00:00:00 2001
From: yzrh <yzrh@noema.org>
Date: Sun, 1 Jan 2023 10:44:27 +0000
Subject: Split md5 function.

Signed-off-by: yzrh <yzrh@noema.org>
---
 src/Makefile     |  4 ++--
 src/md5.c        | 24 ++++++++++++++++++++++++
 src/md5.h        |  9 +++++++++
 src/pdf_writer.c | 16 ++++++++--------
 4 files changed, 43 insertions(+), 10 deletions(-)
 create mode 100644 src/md5.c
 create mode 100644 src/md5.h

diff --git a/src/Makefile b/src/Makefile
index 74aff8e..b2346a7 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -4,11 +4,11 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 
-src =	melon.c iconv.c zlib.c jbig2.c jpeg.c jp2.c \
+src =	melon.c iconv.c zlib.c jbig2.c jpeg.c jp2.c md5.c \
 	cnki_caj.c cnki_hn.c cnki_kdh.c cnki_outline_tree.c cnki_pdf.c \
 	cnki_zlib.c cnki_jbig.c cnki_jbig_dec.c cnki_jbig2.c cnki.c \
 	pdf_cnki.c pdf_get.c pdf_parser.c pdf_writer.c pdf.c
-inc =	extern.h version.h iconv.h zlib.h jbig2.h jpeg.h jp2.h \
+inc =	extern.h version.h iconv.h zlib.h jbig2.h jpeg.h jp2.h md5.h \
 	cnki.h pdf_cnki.h cnki_jbig.h cnki_jbig_dec.h pdf.h
 
 obj = ${src:.c=.o}
diff --git a/src/md5.c b/src/md5.c
new file mode 100644
index 0000000..e5ab95e
--- /dev/null
+++ b/src/md5.c
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2023, yzrh <yzrh@noema.org>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <stdlib.h>
+
+#include <openssl/md5.h>
+
+int
+strmd5(unsigned char **dst, int *dst_size,
+	const unsigned char * restrict src, int src_size)
+{
+	*dst_size = MD5_DIGEST_LENGTH;
+	*dst = malloc(*dst_size);
+
+	if (*dst == NULL)
+		return 1;
+
+	MD5(src, src_size, *dst);
+
+	return 0;
+}
diff --git a/src/md5.h b/src/md5.h
new file mode 100644
index 0000000..9c1745d
--- /dev/null
+++ b/src/md5.h
@@ -0,0 +1,9 @@
+/*
+ * Copyright (c) 2023, yzrh <yzrh@noema.org>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+int
+strmd5(unsigned char **dst, int *dst_size,
+	const unsigned char * restrict src, int src_size);
diff --git a/src/pdf_writer.c b/src/pdf_writer.c
index be64e49..465d26b 100644
--- a/src/pdf_writer.c
+++ b/src/pdf_writer.c
@@ -5,11 +5,9 @@
  */
 
 #include <stdlib.h>
-#include <string.h>
 #include <time.h>
 
-#include <openssl/md5.h>
-
+#include "md5.h"
 #include "pdf.h"
 
 int
@@ -144,11 +142,11 @@ pdf_dump_trailer(pdf_object_t **pdf, FILE **fp, int xref)
 	buf_size = snprintf(buf, 64, "%lx%x", timestamp, size);
 #endif
 
-	unsigned char str[64];
-	memcpy(str, buf, 64);
+	int fid_size;
+	unsigned char *fid;
 
-	unsigned char fid[MD5_DIGEST_LENGTH];
-	MD5(str, buf_size, fid);
+	if (strmd5(&fid, &fid_size, (unsigned char *) buf, buf_size) != 0)
+		return 1;
 
 	pdf_object_t *ptr = *pdf;
 	while (ptr->next != NULL)
@@ -172,7 +170,7 @@ pdf_dump_trailer(pdf_object_t **pdf, FILE **fp, int xref)
 	for (int i = 0; i < 2; i++) {
 		fputs("<", *fp);
 
-		for (int j = 0; j < MD5_DIGEST_LENGTH; j++)
+		for (int j = 0; j < fid_size; j++)
 			fprintf(*fp, "%02x", fid[j]);
 
 		fputs(">", *fp);
@@ -191,5 +189,7 @@ pdf_dump_trailer(pdf_object_t **pdf, FILE **fp, int xref)
 
 	fputs("%%EOF\n", *fp);
 
+	free(fid);
+
 	return 0;
 }
-- 
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