Add io_pread().

It will be used by --list.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/xz/file_io.h b/src/xz/file_io.h
index 58bf7b5e..94d4c174 100644
--- a/src/xz/file_io.h
+++ b/src/xz/file_io.h
@@ -23,6 +23,7 @@
 /// Use an union to make sure that the buffer is properly aligned.
 typedef union {
 	uint8_t u8[IO_BUFFER_SIZE];
+	uint32_t u32[IO_BUFFER_SIZE / sizeof(uint32_t)];
 	uint64_t u64[IO_BUFFER_SIZE / sizeof(uint64_t)];
 } io_buf;
 
@@ -97,6 +98,22 @@ extern void io_close(file_pair *pair, bool success);
 extern size_t io_read(file_pair *pair, io_buf *buf, size_t size);
 
 
+/// \brief      Read from source file from given offset to a buffer
+///
+/// This is remotely similar to standard pread(). This uses lseek() though,
+/// so the read offset is changed on each call.
+///
+/// \param      pair    Seekable source file
+/// \param      buf     Destination buffer
+/// \param      size    Amount of data to read
+/// \param      pos     Offset relative to the beginning of the file,
+///                     from which the data should be read.
+///
+/// \return     On success, false is returned. On error, error message
+///             is printed and true is returned.
+extern bool io_pread(file_pair *pair, io_buf *buf, size_t size, off_t pos);
+
+
 /// \brief      Writes a buffer to the destination file
 ///
 /// \param      pair    File pair having the destination file open for writing