1 files changed, 36 insertions, 0 deletions
diff --git a/src/data_buffer.cpp b/src/data_buffer.cpp
index 33cb0b3..c4c1d8b 100644
--- a/src/data_buffer.cpp
+++ b/src/data_buffer.cpp
@@ -4,6 +4,8 @@
 #include "data_buffer.h"
 
 #include <cassert>
+#include <cerrno>
+#include <cstdlib>
 #include <cstring>
 
 void DataBuffer::Expand(size_t new_size)
@@ -27,3 +29,37 @@ DataBuffer::~DataBuffer()
     buffer_size = 0;
     occupied_size = 0;
 }
+
+DataBuffer DataBuffer::FromStream(FILE *stream)
+{
+    DataBuffer db{};
+    assert(db.buffer && db.buffer_size >= db.kInitialSize);
+    while (1) {
+        const size_t read_size = db.buffer_size - db.occupied_size;
+        const size_t fread_ret = fread(
+                db.buffer + db.occupied_size, sizeof(*db.buffer), read_size, stream);
+        db.occupied_size += fread_ret;
+        if (fread_ret >= db.buffer_size) {
+            assert(fread_ret == db.buffer_size);
+            db.Expand(db.buffer_size * 2);
+        } else {
+            const int err = errno;
+            if (feof(stream)) {
+                break;
+            } else if (ferror(stream)) {
+                fprintf(
+                        stderr,
+                        "DataBuffer::FromStream: fread(%zu): "
+                        "Error (%d): \"%s\"\n",
+                        read_size,
+                        err,
+                        strerror(err));
+            } else if (db.buffer_size == db.occupied_size) {
+                db.Expand(db.buffer_size * 2);
+            } else {
+                assert(false);
+            }
+        }
+    }
+    return db;
+}