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authorJan Ekström <jan.ekstrom@24i.com>2021-09-20 14:51:42 +0300
committerJan Ekström <jeebjp@gmail.com>2021-10-04 17:13:21 +0300
commit847fd8de7c13abe41ca59464014f17c56555ef7b (patch)
tree1e1c3c197fa8e41e2315880daa26ec670a9f80f2
parent151f46e84ddce557aace102a9f86f72d37e1cdbf (diff)
downloadffmpeg-847fd8de7c13abe41ca59464014f17c56555ef7b.tar.gz
avformat/{aviobuf,avio_internal}: add max_len argument to ff_read_string_to_bprint_overwrite
This is especially useful when reading things such as null-terminated strings from MOV/MP4-likes, where the size of the box is known, but not the exact size of the string. Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>
-rw-r--r--libavformat/avio_internal.h13
-rw-r--r--libavformat/aviobuf.c23
2 files changed, 25 insertions, 11 deletions
diff --git a/libavformat/avio_internal.h b/libavformat/avio_internal.h
index 238b007396..eded38759b 100644
--- a/libavformat/avio_internal.h
+++ b/libavformat/avio_internal.h
@@ -247,14 +247,21 @@ int64_t ff_read_line_to_bprint_overwrite(AVIOContext *s, struct AVBPrint *bp);
/**
* Read a whole null-terminated string of text from AVIOContext to an AVBPrint
- * buffer overwriting its contents. Stop reading after reaching a \\0 or
- * EOF.
+ * buffer overwriting its contents. Stop reading after reaching the maximum
+ * length, a \\0 or EOF.
*
* @param s the read-only AVIOContext
* @param bp the AVBPrint buffer
+ * @param max_len the maximum length to be read from the AVIOContext.
+ * Negative (< 0) values signal that there is no known maximum
+ * length applicable. A maximum length of zero means that the
+ * AVIOContext is not touched, and the function returns
+ * with a read length of zero. In all cases the AVBprint
+ * is cleared.
* @return the length of the read string not including the terminating null,
* negative on error, or if the buffer becomes truncated.
*/
-int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp);
+int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, struct AVBPrint *bp,
+ int64_t max_len);
#endif /* AVFORMAT_AVIO_INTERNAL_H */
diff --git a/libavformat/aviobuf.c b/libavformat/aviobuf.c
index 6ec20e33d2..3d87d66091 100644
--- a/libavformat/aviobuf.c
+++ b/libavformat/aviobuf.c
@@ -809,13 +809,17 @@ typedef enum FFBPrintReadStringMode {
} FFBPrintReadStringMode;
static int64_t read_string_to_bprint(AVIOContext *s, AVBPrint *bp,
- FFBPrintReadStringMode mode)
+ FFBPrintReadStringMode mode,
+ int64_t max_len)
{
int len, end;
int64_t read = 0;
char tmp[1024];
char c;
+ if (!max_len)
+ return 0;
+
do {
len = 0;
do {
@@ -824,10 +828,11 @@ static int64_t read_string_to_bprint(AVIOContext *s, AVBPrint *bp,
c == '\0');
if (!end)
tmp[len++] = c;
- } while (!end && len < sizeof(tmp));
+ } while (!end && len < sizeof(tmp) &&
+ ((max_len < 0) || (read + len < max_len)));
av_bprint_append_data(bp, tmp, len);
read += len;
- } while (!end);
+ } while (!end && ((max_len < 0) || (read < max_len)));
if (mode == FFBPrintReadLine &&
c == '\r' && avio_r8(s) != '\n' && !avio_feof(s))
@@ -843,12 +848,13 @@ static int64_t read_string_to_bprint(AVIOContext *s, AVBPrint *bp,
}
static int64_t read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp,
- FFBPrintReadStringMode mode)
+ FFBPrintReadStringMode mode,
+ int64_t max_len)
{
int64_t ret;
av_bprint_clear(bp);
- ret = read_string_to_bprint(s, bp, mode);
+ ret = read_string_to_bprint(s, bp, mode, max_len);
if (ret < 0)
return ret;
@@ -860,12 +866,13 @@ static int64_t read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp,
int64_t ff_read_line_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp)
{
- return read_string_to_bprint_overwrite(s, bp, FFBPrintReadLine);
+ return read_string_to_bprint_overwrite(s, bp, FFBPrintReadLine, -1);
}
-int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp)
+int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp,
+ int64_t max_len)
{
- return read_string_to_bprint_overwrite(s, bp, FFBPrintReadString);
+ return read_string_to_bprint_overwrite(s, bp, FFBPrintReadString, max_len);
}
int avio_get_str(AVIOContext *s, int maxlen, char *buf, int buflen)