Improve PDF parser.

Signed-off-by: yzrh <yzrh@noema.org>

1 files changed, 26 insertions, 18 deletions

diff --git a/src/pdf_parser.c b/src/pdf_parser.c
index b4470f9..54c7fb4 100644
--- a/src/pdf_parser.c
+++ b/src/pdf_parser.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020-2022, yzrh <yzrh@noema.org>
+ * Copyright (c) 2020-2023, yzrh <yzrh@noema.org>
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -19,12 +19,12 @@ static void *
 _memmem_whitespace(const void *p0, size_t s0, const void *p1, size_t s1)
 {
 	const char whitespace[6] = {
+		' ',
 		'\r',
 		'\n',
 		'\f',
 		'\t',
-		'\0',
-		' '
+		'\0'
 	};
 
 	char tmp[s1 + 1];
@@ -34,7 +34,7 @@ _memmem_whitespace(const void *p0, size_t s0, const void *p1, size_t s1)
 
 	for (int i = 0; i < 6; i++) {
 		tmp[s1] = whitespace[i];
-		if((ret = memmem(p0, s0, tmp, s1 + 1)) != NULL)
+		if ((ret = memmem(p0, s0, tmp, s1 + 1)) != NULL)
 			return ret;
 	}
 
@@ -57,13 +57,18 @@ _locate(pdf_object_t **pdf, FILE **fp, int size_buf)
 	end = ftell(*fp);
 	fseek(*fp, cur, SEEK_SET);
 
-	int head = 0;
-	int tail = 0;
+	long head = 0;
+	long tail = 0;
 	char *pos;
 	char *tmp;
 
 	for (;;) {
-		fread(buf, size_buf, 1, *fp);
+		if (cur + size_buf < end) {
+			fread(buf, size_buf, 1, *fp);
+		} else {
+			fread(buf, end - cur, 1, *fp);
+			memset(buf + end - cur, 0, size_buf - end + cur);
+		}
 
 		if (head == 0 && (pos = _memmem_whitespace(buf, size_buf, " 0 obj", 6)) != NULL)
 			head = cur + (pos - buf) + 7;
@@ -72,8 +77,8 @@ _locate(pdf_object_t **pdf, FILE **fp, int size_buf)
 			/* We need to check if it is the object stored in stream */
 			while (memcmp(pos + 7,
 				"\r\nendstream", 11) == 0 &&
-				(tmp = _memmem_whitespace(pos + 6,
-				size_buf - (pos - buf) - 6,
+				(tmp = _memmem_whitespace(pos + 7,
+				size_buf - (pos - buf) - 7,
 				"endobj", 6)) != NULL)
 					pos = tmp;
 
@@ -102,13 +107,16 @@ _locate(pdf_object_t **pdf, FILE **fp, int size_buf)
 			ptr->address = head;
 			ptr->size = tail - head;
 
-			fseek(*fp, tail + 6, SEEK_SET);
+			fseek(*fp, tail + 7, SEEK_SET);
 			head = tail = 0;
+		} else if (head > 0 && tail > 0) {
+			fseek(*fp, head, SEEK_SET);
+			tail = 0;
 		} else {
-			fseek(*fp, -6, SEEK_CUR);
+			fseek(*fp, -7, SEEK_CUR);
 		}
 
-		if ((cur = ftell(*fp)) + 6 >= end)
+		if ((cur = ftell(*fp)) + 7 >= end)
 			break;
 	}
 
@@ -159,11 +167,11 @@ pdf_load(pdf_object_t **pdf, FILE **fp, int size_buf)
 			 * A dictionary object may have nested dictionary,
 			 * but it should not be in a stream
 			 */
-			while ((tmp = _memmem_whitespace(tail + 2,
-				ptr->size - (tail - buf) - 2,
+			while ((tmp = _memmem_whitespace(tail + 3,
+				ptr->size - (tail - buf) - 3,
 				">>", 2)) != NULL &&
-				memmem(tail + 2,
-				ptr->size - (tail - buf) - 2,
+				memmem(tail + 3,
+				ptr->size - (tail - buf) - 3,
 				"stream\r\n", 8) == NULL)
 				tail = tmp;
 
@@ -190,8 +198,8 @@ pdf_load(pdf_object_t **pdf, FILE **fp, int size_buf)
 				while (_memmem_whitespace(tail,
 					ptr->size - (tail - buf),
 					"endobj", 6) != NULL &&
-					(tmp = _memmem_whitespace(tail + 9,
-					ptr->size - (tail - buf) - 9,
+					(tmp = _memmem_whitespace(tail + 10,
+					ptr->size - (tail - buf) - 10,
 					"endstream", 9)) != NULL)
 						tail = tmp;