From 2ec68c51e4599b8493a2e103793f571451d872d3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomas=20H=C3=A4rdin?= <git@haerdin.se>
Date: Thu, 28 Mar 2024 20:30:37 +0100
Subject: [PATCH 1/2] lavf/subtitles: Add ff_text_peek_r16(), only accept \r,
 \n, \r\n and \r\r\n line endings

---
 libavformat/subtitles.c | 53 +++++++++++++++++++++++++++++++++++++----
 libavformat/subtitles.h |  5 ++++
 2 files changed, 53 insertions(+), 5 deletions(-)

diff --git a/libavformat/subtitles.c b/libavformat/subtitles.c
index 3413763c7b..01187df6ab 100644
--- a/libavformat/subtitles.c
+++ b/libavformat/subtitles.c
@@ -22,6 +22,7 @@
 #include "subtitles.h"
 #include "avio_internal.h"
 #include "libavutil/avstring.h"
+#include "libavutil/intreadwrite.h"
 
 void ff_text_init_avio(void *s, FFTextReader *r, AVIOContext *pb)
 {
@@ -106,6 +107,42 @@ int ff_text_peek_r8(FFTextReader *r)
     return c;
 }
 
+int ff_text_peek_r16(FFTextReader *r)
+{
+    int c1, c2;
+    if (r->buf_pos < r->buf_len - 1)
+        return AV_RB16(&r->buf[r->buf_pos]);
+
+    // missing one or two bytes
+    c1 = ff_text_r8(r);
+    if (avio_feof(r->pb))
+        return 0;
+
+    if (r->buf_pos == r->buf_len - 1) {
+        // missing one byte
+        r->buf[0] = r->buf[r->buf_pos];
+        r->buf[1] = c1;
+        r->buf_pos = 0;
+        r->buf_len = 2;
+        return AV_RB16(r->buf);
+    }
+
+    // missing two bytes
+    c2 = ff_text_r8(r);
+    if (avio_feof(r->pb)) {
+        r->buf[0] = c1;
+        r->buf_pos = 0;
+        r->buf_len = 1;
+        return 0;
+    }
+
+    r->buf[0] = c1;
+    r->buf[1] = c2;
+    r->buf_pos = 0;
+    r->buf_len = 2;
+    return AV_RB16(r->buf);
+}
+
 AVPacket *ff_subtitles_queue_insert(FFDemuxSubtitlesQueue *q,
                                     const uint8_t *event, size_t len, int merge)
 {
@@ -446,11 +483,12 @@ int ff_subtitles_read_chunk(AVIOContext *pb, AVBPrint *buf)
 ptrdiff_t ff_subtitles_read_line(FFTextReader *tr, char *buf, size_t size)
 {
     size_t cur = 0;
+    unsigned char c;
     if (!size)
         return 0;
     buf[0] = '\0';
     while (cur + 1 < size) {
-        unsigned char c = ff_text_r8(tr);
+        c = ff_text_r8(tr);
         if (!c)
             return ff_text_eof(tr) ? cur : AVERROR_INVALIDDATA;
         if (c == '\r' || c == '\n')
@@ -458,9 +496,14 @@ ptrdiff_t ff_subtitles_read_line(FFTextReader *tr, char *buf, size_t size)
         buf[cur++] = c;
         buf[cur] = '\0';
     }
-    while (ff_text_peek_r8(tr) == '\r')
-        ff_text_r8(tr);
-    if (ff_text_peek_r8(tr) == '\n')
-        ff_text_r8(tr);
+    if (c == '\r') {
+        if (ff_text_peek_r8(tr) == '\n')
+            ff_text_r8(tr);
+        else if (ff_text_peek_r16(tr) == AV_RB16("\r\n")) {
+            // ticket5032-rrn.srt has \r\r\n
+            ff_text_r8(tr);
+            ff_text_r8(tr);
+        }
+    }
     return cur;
 }
diff --git a/libavformat/subtitles.h b/libavformat/subtitles.h
index 88665663c5..2a92044976 100644
--- a/libavformat/subtitles.h
+++ b/libavformat/subtitles.h
@@ -94,6 +94,11 @@ int ff_text_eof(FFTextReader *r);
  */
 int ff_text_peek_r8(FFTextReader *r);
 
+/**
+ * Like ff_text_peek_r8(), but peek two bytes and return them as a big-endian number.
+ */
+int ff_text_peek_r16(FFTextReader *r);
+
 /**
  * Read the given number of bytes (in UTF-8). On error or EOF, \0 bytes are
  * written.
-- 
2.39.2