Add hook for a client-provided progress callback to be invoked

during lengthy extract operations.

lib/libarchive/archive.h

@@ -200,6 +200,8 @@ ssize_t		 archive_read_data_into_fd(struct archive *, int fd);
 
 int		 archive_read_extract(struct archive *, struct archive_entry *,
 		     int flags);
+void		 archive_read_extract_set_progress_callback(struct archive *,
+		     void (*_progress_func)(void *), void *_user_data);
 
 /* Close the file, release any resources, and destroy the object. */
 void		 archive_read_finish(struct archive *);

lib/libarchive/archive.h.in

@@ -200,6 +200,8 @@ ssize_t		 archive_read_data_into_fd(struct archive *, int fd);
 
 int		 archive_read_extract(struct archive *, struct archive_entry *,
 		     int flags);
+void		 archive_read_extract_set_progress_callback(struct archive *,
+		     void (*_progress_func)(void *), void *_user_data);
 
 /* Close the file, release any resources, and destroy the object. */
 void		 archive_read_finish(struct archive *);

lib/libarchive/archive_private.h

@@ -192,6 +192,8 @@ struct archive {
 	 */
 	struct archive_string			 extract_mkdirpath;
 	struct archive_extract_dir_entry	*archive_extract_dir_list;
+	void			(*extract_progress)(void *);
+	void			 *extract_progress_user_data;
 	void			(*cleanup_archive_extract)(struct archive *);
 
 	int		  archive_error_number;

lib/libarchive/archive_read.3

@@ -47,6 +47,7 @@
 .Nm archive_read_data_into_buffer ,
 .Nm archive_read_data_into_file ,
 .Nm archive_read_extract ,
+.Nm archive_read_extract_set_progress_callback ,
 .Nm archive_read_finish
 .Nd functions for reading tar archives
 .Sh SYNOPSIS
@@ -90,6 +91,8 @@
 .Ft int
 .Fn archive_read_extract "struct archive *" "int flags"
 .Ft void
+.Fn archive_read_extract_set_progress_callback "struct archive *" "void (*func)(void *)" "void *user_data"
+.Ft void
 .Fn archive_read_finish "struct archive *"
 .Sh DESCRIPTION
 These functions provide a complete API for reading streaming archives.
@@ -202,6 +205,15 @@ By default, existing files are truncated and rewritten, but
 the file is not recreated.
 In particular, the default behavior does not break existing hard links.
 .El
+.It Fn archive_read_extract_set_progress_callback
+Sets a pointer to a user-defined callback that can be used
+for updating progress displays during extraction.
+The progress function will be invoked during the extraction of large
+regular files.
+The progress function will be invoked with the pointer provided to this call.
+Generally, the data pointed to should include a reference to the archive
+object and the archive_entry object so that various statistics
+can be retrieved for the progress display.
 .It Fn archive_read_finish
 Complete the archive, invoke the close callback, and release
 all resources.

lib/libarchive/archive_read_data_into_fd.c

@@ -44,12 +44,16 @@ archive_read_data_into_fd(struct archive *a, int fd)
 
 	total_written = 0;
 	while (a->entry_bytes_remaining > 0) {
-		bytes_read = (a->compression_read_ahead)(a, &buff,
+		/* Remember: '1' here is minimum, not maximum. */
-		    a->entry_bytes_remaining);
+		/* Read-ahead function will return as much as is convenient. */
+		bytes_read = (a->compression_read_ahead)(a, &buff, 1);
 		if (bytes_read < 0)
 			return (-1);
 		if (bytes_read > a->entry_bytes_remaining)
 			bytes_read = (ssize_t)a->entry_bytes_remaining;
+		/* Don't copy more than 1 megabyte at a time. */
+		if (bytes_read > (1024*1024))
+			bytes_read = 1024*1024;
 
 		bytes_written = write(fd, buff, bytes_read);
 		if (bytes_written < 0)
@@ -57,6 +61,8 @@ archive_read_data_into_fd(struct archive *a, int fd)
 		(a->compression_read_consume)(a, bytes_written);
 		total_written += bytes_written;
 		a->entry_bytes_remaining -= bytes_written;
+		if (a->extract_progress != NULL)
+			(*a->extract_progress)(a->extract_progress_user_data);
 	}
 	return (total_written);
 }

lib/libarchive/archive_read_extract.c

@@ -1078,3 +1078,11 @@ lookup_uid(struct archive *a, const char *uname, uid_t uid)
 	}
 	return (uid);
 }
+
+void
+archive_read_extract_set_progress_callback(struct archive *a,
+    void (*progress_func)(void *), void *user_data)
+{
+	a->extract_progress = progress_func;
+	a->extract_progress_user_data = user_data;
+}