Fix skipping in stream inputs.

The existing test was piping input from a file, not an IPC pipe,
so wasn't a proper test. Fix the test and make skipping in pipes
work.

lib/lha_basic_reader.c

@@ -75,8 +75,10 @@ LHAFileHeader *lha_basic_reader_next_file(LHABasicReader *reader)
 		lha_file_header_free(reader->curr_file);
 		reader->curr_file = NULL;
 
-		lha_input_stream_skip(reader->stream,
-		                      reader->curr_file_remaining);
+		if (!lha_input_stream_skip(reader->stream,
+		                           reader->curr_file_remaining)) {
+			reader->eof = 1;
+		}
 	}
 
 	if (reader->eof) {

lib/lha_input_stream.c

@@ -22,6 +22,7 @@ CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
+#include <errno.h>
 
 #include "lha_arch.h"
 #include "lha_input_stream.h"
@@ -293,11 +294,51 @@ static int file_source_read(void *handle, void *buf, size_t buf_len)
 	return (int) bytes_read;
 }
 
+// "Fallback" skip for file source that uses fread(), for unseekable
+// streams.
+
+static int file_source_skip_fallback(FILE *handle, size_t bytes)
+{
+	uint8_t data[32];
+	unsigned int len;
+	int result;
+
+	while (bytes > 0) {
+		if (bytes > sizeof(data)) {
+			len = sizeof(data);
+		} else {
+			len = bytes;
+		}
+
+		result = fread(data, 1, len, handle);
+
+		if (result != (int) len) {
+			return 0;
+		}
+
+		bytes -= len;
+	}
+
+	return 1;
+}
+
 // Seek forward in a FILE * input stream.
 
-static int file_source_seek(void *handle, size_t bytes)
+static int file_source_skip(void *handle, size_t bytes)
 {
-	return fseek(handle, (long) bytes, SEEK_CUR);
+	int result;
+
+	result = fseek(handle, (long) bytes, SEEK_CUR);
+
+	if (result < 0) {
+		if (errno == EBADF || errno == ESPIPE) {
+			return file_source_skip_fallback(handle, bytes);
+		} else {
+			return 0;
+		}
+	}
+
+	return 1;
 }
 
 // Close a FILE * input stream.
@@ -312,15 +353,15 @@ static void file_source_close(void *handle)
 
 static const LHAInputStreamType file_source_owned = {
 	file_source_read,
-	file_source_seek,
+	file_source_skip,
 	file_source_close
 };
 
 // "Unowned" file source - the stream is owned by the calling code.
 
 static const LHAInputStreamType file_source_unowned = {
 	file_source_read,
-	file_source_seek,
+	file_source_skip,
 	NULL
 };
 

lib/public/lha_reader.h

@@ -49,7 +49,7 @@ typedef struct _LHAReader LHAReader;
  * Policy for extracting directories.
  *
  * When extracting a directory, some of the metadata associated with
- * it need to be set after the contents of the directory have been
+ * it needs to be set after the contents of the directory have been
  * extracted. This includes the modification time (which would
  * otherwise be reset to the current time) and the permissions (which
  * can affect the ability to extract files into the directory).

test/test-extract

@@ -250,8 +250,12 @@ test_stdin_extract() {
 
 	make_sandboxes
 
-	lha_check_output "$expected_file" e - \
-	    < $(test_arc_file "$archive_file")
+	# This is *not* a useless use of cat. If a < pipe was used,
+	# the input would come from a file handle, not a pipe. Using
+	# cat forces the data to come from a pipe.
+
+	cat $(test_arc_file "$archive_file") | \
+	    lha_check_output "$expected_file" e -
 
 	check_extracted_files "$archive_file"