Sometimes it is advantageous to be able to peek the next packet line
without consuming it (e.g. to be able to determine the protocol version
a server is speaking). In order to do that introduce 'struct
packet_reader' which is an abstraction around the normal packet reading
logic. This enables a caller to be able to peek a single line at a time
using 'packet_reader_peek()' and having a caller consume a line by
calling 'packet_reader_read()'.
Signed-off-by: Brandon Williams <bmwill@xxxxxxxxxx>
---
pkt-line.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
pkt-line.h | 58 +++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 117 insertions(+)
diff --git a/pkt-line.c b/pkt-line.c
index 08e5ba44c..6307fa4a3 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -404,3 +404,62 @@ ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out)
}
return sb_out->len - orig_len;
}
+
+/* Packet Reader Functions */
+void packet_reader_init(struct packet_reader *reader, int fd,
+ char *src_buffer, size_t src_len,
+ int options)
+{
+ memset(reader, 0, sizeof(*reader));
+
+ reader->fd = fd;
+ reader->src_buffer = src_buffer;
+ reader->src_len = src_len;
+ reader->buffer = packet_buffer;
+ reader->buffer_size = sizeof(packet_buffer);
+ reader->options = options;
+}
+
+enum packet_read_status packet_reader_read(struct packet_reader *reader)
+{
+ if (reader->line_peeked) {
+ reader->line_peeked = 0;
+ return reader->status;
+ }
+
+ reader->status = packet_read_with_status(reader->fd,
+ &reader->src_buffer,
+ &reader->src_len,
+ reader->buffer,
+ reader->buffer_size,
+ &reader->pktlen,
+ reader->options);
+
+ switch (reader->status) {
+ case PACKET_READ_EOF:
+ reader->pktlen = -1;
+ reader->line = NULL;
+ break;
+ case PACKET_READ_NORMAL:
+ reader->line = reader->buffer;
+ break;
+ case PACKET_READ_FLUSH:
+ reader->pktlen = 0;
+ reader->line = NULL;
+ break;
+ }
+
+ return reader->status;
+}
+
+enum packet_read_status packet_reader_peek(struct packet_reader *reader)
+{
+ /* Only allow peeking a single line */
+ if (reader->line_peeked)
+ return reader->status;
+
+ /* Peek a line by reading it and setting peeked flag */
+ packet_reader_read(reader);
+ reader->line_peeked = 1;
+ return reader->status;
+}
diff --git a/pkt-line.h b/pkt-line.h
index 0be691116..f2edfae9a 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -112,6 +112,64 @@ char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
*/
ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out);
+struct packet_reader {
+ /* source file descriptor */
+ int fd;
+
+ /* source buffer and its size */
+ char *src_buffer;
+ size_t src_len;
+
+ /* buffer that pkt-lines are read into and its size */
+ char *buffer;
+ unsigned buffer_size;
+
+ /* options to be used during reads */
+ int options;
+
+ /* status of the last read */
+ enum packet_read_status status;
+
+ /* length of data read during the last read */
+ int pktlen;
+
+ /* the last line read */
+ const char *line;
+
+ /* indicates if a line has been peeked */
+ int line_peeked;
+};
+
+/*
+ * Initialize a 'struct packet_reader' object which is an
+ * abstraction around the 'packet_read_with_status()' function.
+ */
+extern void packet_reader_init(struct packet_reader *reader, int fd,
+ char *src_buffer, size_t src_len,
+ int options);
+
+/*
+ * Perform a packet read and return the status of the read.
+ * The values of 'pktlen' and 'line' are updated based on the status of the
+ * read as follows:
+ *
+ * PACKET_READ_ERROR: 'pktlen' is set to '-1' and 'line' is set to NULL
+ * PACKET_READ_NORMAL: 'pktlen' is set to the number of bytes read
+ * 'line' is set to point at the read line
+ * PACKET_READ_FLUSH: 'pktlen' is set to '0' and 'line' is set to NULL
+ */
+extern enum packet_read_status packet_reader_read(struct packet_reader *reader);
+
+/*
+ * Peek the next packet line without consuming it and return the status.
+ * The next call to 'packet_reader_read()' will perform a read of the same line
+ * that was peeked, consuming the line.
+ *
+ * Peeking multiple times without calling 'packet_reader_read()' will return
+ * the same result.
+ */
+extern enum packet_read_status packet_reader_peek(struct packet_reader *reader);
+
#define DEFAULT_PACKET_MAX 1000
#define LARGE_PACKET_MAX 65520
#define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
--
2.16.2.395.g2e18187dfd-goog
