avformat/avio: remove 4k limit from avio_printf

We do this by switching to AVBPrint.

v2: Also set IO context error flag in case of ENOMEM.
Signed-off-by: Marton Balint <cus@passwd.hu>

doc/APIchanges

@@ -15,6 +15,9 @@ libavutil:     2017-10-21
 
 API changes, most recent first:
 
+2019-08-xx - xxxxxxxxxx - lavf 58.31.101 - avio.h
+  4K limit removed from avio_printf.
+
 2019-08-xx - xxxxxxxxxx - lavf 58.31.100 - avio.h
   Add avio_print_string_array and avio_print.
 

libavformat/avio.h

@@ -571,7 +571,10 @@ int64_t avio_size(AVIOContext *s);
  */
 int avio_feof(AVIOContext *s);
 
-/** @warning Writes up to 4 KiB per call */
+/**
+ * Writes a formatted string to the context.
+ * @return number of bytes written, < 0 on error.
+ */
 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
 
 /**

libavformat/aviobuf.c

@@ -1249,14 +1249,20 @@ int avio_closep(AVIOContext **s)
 int avio_printf(AVIOContext *s, const char *fmt, ...)
 {
     va_list ap;
-    char buf[4096]; /* update doc entry in avio.h if changed */
-    int ret;
+    AVBPrint bp;
 
+    av_bprint_init(&bp, 0, INT_MAX);
     va_start(ap, fmt);
-    ret = vsnprintf(buf, sizeof(buf), fmt, ap);
+    av_vbprintf(&bp, fmt, ap);
     va_end(ap);
-    avio_write(s, buf, strlen(buf));
-    return ret;
+    if (!av_bprint_is_complete(&bp)) {
+        av_bprint_finalize(&bp, NULL);
+        s->error = AVERROR(ENOMEM);
+        return AVERROR(ENOMEM);
+    }
+    avio_write(s, bp.str, bp.len);
+    av_bprint_finalize(&bp, NULL);
+    return bp.len;
 }
 
 void avio_print_string_array(AVIOContext *s, const char *strings[])

libavformat/version.h

@@ -33,7 +33,7 @@
 // Also please add any ticket numbers that you believe might be affected here
 #define LIBAVFORMAT_VERSION_MAJOR  58
 #define LIBAVFORMAT_VERSION_MINOR  31
-#define LIBAVFORMAT_VERSION_MICRO 100
+#define LIBAVFORMAT_VERSION_MICRO 101
 
 #define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
                                                LIBAVFORMAT_VERSION_MINOR, \