avformat/{aviobuf,avio_internal}: add ff_read_string_to_bprint_overwrite

For now, same as ff_read_line_to_bprint_overwrite, but reads until
the end of a null-terminated string.

Signed-off-by: Jan Ekström <jan.ekstrom@24i.com>

libavformat/avio_internal.h

@@ -245,4 +245,16 @@ struct AVBPrint;
  */
 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.
+ *
+ * @param s the read-only AVIOContext
+ * @param bp the AVBPrint buffer
+ * @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);
+
 #endif /* AVFORMAT_AVIO_INTERNAL_H */

libavformat/aviobuf.c

@@ -863,6 +863,11 @@ int64_t ff_read_line_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp)
     return read_string_to_bprint_overwrite(s, bp, FFBPrintReadLine);
 }
 
+int64_t ff_read_string_to_bprint_overwrite(AVIOContext *s, AVBPrint *bp)
+{
+    return read_string_to_bprint_overwrite(s, bp, FFBPrintReadString);
+}
+
 int avio_get_str(AVIOContext *s, int maxlen, char *buf, int buflen)
 {
     int i;