fix: use u64 to represent the number of bytes in backup files

src/imex.rs

@@ -25,7 +25,8 @@ use crate::pgp;
 use crate::qr::DCBACKUP_VERSION;
 use crate::sql;
 use crate::tools::{
-    TempPathGuard, create_folder, delete_file, get_filesuffix_lc, read_file, time, write_file,
+    TempPathGuard, create_folder, delete_file, get_filesuffix_lc, read_file, time, usize_to_u64,
+    write_file,
 };
 
 mod key_transfer;
@@ -263,11 +264,11 @@ struct ProgressReader<R> {
     inner: R,
 
     /// Number of bytes successfully read from the internal reader.
-    read: usize,
+    read: u64,
 
     /// Total size of the backup .tar file expected to be read from the reader.
     /// Used to calculate the progress.
-    file_size: usize,
+    file_size: u64,
 
     /// Last progress emitted to avoid emitting the same progress value twice.
     last_progress: usize,
@@ -281,7 +282,7 @@ impl<R> ProgressReader<R> {
         Self {
             inner: r,
             read: 0,
-            file_size: file_size as usize,
+            file_size,
             last_progress: 1,
             context,
         }
@@ -301,9 +302,11 @@ where
         let before = buf.filled().len();
         let res = this.inner.poll_read(cx, buf);
         if let std::task::Poll::Ready(Ok(())) = res {
-            *this.read = this.read.saturating_add(buf.filled().len() - before);
+            *this.read = this
+                .read
+                .saturating_add(usize_to_u64(buf.filled().len() - before));
 
-            let progress = std::cmp::min(1000 * *this.read / *this.file_size, 999);
+            let progress = std::cmp::min(1000 * *this.read / *this.file_size, 999) as usize;
             if progress > *this.last_progress {
                 this.context.emit_event(EventType::ImexProgress(progress));
                 *this.last_progress = progress;
@@ -490,11 +493,11 @@ struct ProgressWriter<W> {
     inner: W,
 
     /// Number of bytes successfully written into the internal writer.
-    written: usize,
+    written: u64,
 
     /// Total size of the backup .tar file expected to be written into the writer.
     /// Used to calculate the progress.
-    file_size: usize,
+    file_size: u64,
 
     /// Last progress emitted to avoid emitting the same progress value twice.
     last_progress: usize,
@@ -508,7 +511,7 @@ impl<W> ProgressWriter<W> {
         Self {
             inner: w,
             written: 0,
-            file_size: file_size as usize,
+            file_size,
             last_progress: 1,
             context,
         }
@@ -527,9 +530,9 @@ where
         let this = self.project();
         let res = this.inner.poll_write(cx, buf);
         if let std::task::Poll::Ready(Ok(written)) = res {
-            *this.written = this.written.saturating_add(written);
+            *this.written = this.written.saturating_add(usize_to_u64(written));
 
-            let progress = std::cmp::min(1000 * *this.written / *this.file_size, 999);
+            let progress = std::cmp::min(1000 * *this.written / *this.file_size, 999) as usize;
             if progress > *this.last_progress {
                 this.context.emit_event(EventType::ImexProgress(progress));
                 *this.last_progress = progress;

src/tools.rs

@@ -798,6 +798,26 @@ pub(crate) fn inc_and_check<T: PrimInt + AddAssign + std::fmt::Debug>(
     Ok(())
 }
 
+/// Converts usize to u64 without using `as`.
+///
+/// This is needed for example to convert in-memory buffer sizes
+/// to u64 type used for counting all the bytes written.
+///
+/// On 32-bit systems it is possible to have files
+/// larger than 4 GiB or write more than 4 GiB to network connection,
+/// in which case we need a 64-bit total counter,
+/// but use 32-bit usize for buffer sizes.
+///
+/// This can only break if usize has more than 64 bits
+/// and this is not the case as of 2025 and is
+/// unlikely to change for general purpose computers.
+/// See <https://github.com/rust-lang/rust/issues/30495>
+/// and <https://users.rust-lang.org/t/cant-convert-usize-to-u64/6243>
+/// and <https://github.com/rust-lang/rust/issues/106050>.
+pub(crate) fn usize_to_u64(v: usize) -> u64 {
+    u64::try_from(v).unwrap_or(u64::MAX)
+}
+
 /// Returns early with an error if a condition is not satisfied.
 /// In non-optimized builds, panics instead if so.
 #[macro_export]