jau::io::read_stream(): Guarantee consumer_fn() is called with `is_final=true` once at the end, even if input stream has zero size

2 files changed, 12 insertions, 3 deletions

diff --git a/include/jau/io_util.hpp b/include/jau/io_util.hpp
index 3d48a90..ad91a42 100644
--- a/include/jau/io_util.hpp
+++ b/include/jau/io_util.hpp
@@ -97,6 +97,9 @@ namespace jau::io {
      *
      * To abort streaming, user may return `false` from the given `consumer_func`.
      *
+     * It is guaranteed that consumer_fn() is called with `is_final=true` once at the end,
+     * even if `input_file` stream has zero size.
+     *
      * @param input_file input file name path, `-` denotes std::stdin.
      * @param buffer secure std::vector buffer, passed down to consumer_fn
      * @param consumer_fn StreamConsumerFunc consumer for each received heap of bytes, returning true to continue stream of false to abort.
@@ -113,6 +116,9 @@ namespace jau::io {
      *
      * To abort streaming, user may return `false` from the given `consumer_func`.
      *
+     * It is guaranteed that consumer_fn() is called with `is_final=true` once at the end,
+     * even input stream has zero size.
+     *
      * @param in the input byte stream to read from
      * @param buffer secure std::vector buffer, passed down to consumer_fn
      * @param consumer_fn StreamConsumerFunc consumer for each received heap of bytes, returning true to continue stream of false to abort.
@@ -127,6 +133,9 @@ namespace jau::io {
      *
      * To abort streaming, user may return `false` from the given `consumer_func`.
      *
+     * It is guaranteed that consumer_fn() is called with `is_final=true` once at the end,
+     * even if input stream has zero size.
+     *
      * Implementation reads one buffer ahead in respect to consumer_fn(). <br/>
      * If reading zero bytes on the next buffer,
      * it propagates the end-of-file (EOF) to the previous buffer which will be send via consumer_fn() next.<br/>
diff --git a/src/io_util.cpp b/src/io_util.cpp
index 724e51e..7b43520 100644
--- a/src/io_util.cpp
+++ b/src/io_util.cpp
@@ -61,8 +61,8 @@ uint64_t jau::io::read_stream(ByteInStream& in,
                               secure_vector<uint8_t>& buffer,
                               StreamConsumerFunc consumer_fn) noexcept {
     uint64_t total = 0;
-    bool has_more = !in.end_of_data();
-    while( has_more ) {
+    bool has_more;
+    do {
         if( in.check_available(1) ) { // at least one byte to stream ..
             buffer.resize(buffer.capacity());
             const uint64_t got = in.read(buffer.data(), buffer.capacity());
@@ -83,7 +83,7 @@ uint64_t jau::io::read_stream(ByteInStream& in,
             buffer.resize(0);
             consumer_fn(buffer, true); // forced final, zero size
         }
-    }
+    } while( has_more );
     return total;
 }