pkt-line: add functions to read/write flush terminated packet streams

write_packetized_from_fd() and write_packetized_from_buf() write a
stream of packets. All content packets use the maximal packet size
except for the last one. After the last content packet a `flush` control
packet is written.

read_packetized_to_strbuf() reads arbitrary sized packets until it
detects a `flush` packet.

Signed-off-by: Lars Schneider <larsxschneider@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/pkt-line.c b/pkt-line.c
index fef1059..d4b6bfe 100644 (file)
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -197,6 +197,46 @@ void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
        va_end(args);
 }
 
+int write_packetized_from_fd(int fd_in, int fd_out)
+{
+       static char buf[LARGE_PACKET_DATA_MAX];
+       int err = 0;
+       ssize_t bytes_to_write;
+
+       while (!err) {
+               bytes_to_write = xread(fd_in, buf, sizeof(buf));
+               if (bytes_to_write < 0)
+                       return COPY_READ_ERROR;
+               if (bytes_to_write == 0)
+                       break;
+               err = packet_write_gently(fd_out, buf, bytes_to_write);
+       }
+       if (!err)
+               err = packet_flush_gently(fd_out);
+       return err;
+}
+
+int write_packetized_from_buf(const char *src_in, size_t len, int fd_out)
+{
+       int err = 0;
+       size_t bytes_written = 0;
+       size_t bytes_to_write;
+
+       while (!err) {
+               if ((len - bytes_written) > LARGE_PACKET_DATA_MAX)
+                       bytes_to_write = LARGE_PACKET_DATA_MAX;
+               else
+                       bytes_to_write = len - bytes_written;
+               if (bytes_to_write == 0)
+                       break;
+               err = packet_write_gently(fd_out, src_in + bytes_written, bytes_to_write);
+               bytes_written += bytes_to_write;
+       }
+       if (!err)
+               err = packet_flush_gently(fd_out);
+       return err;
+}
+
 static int get_packet_data(int fd, char **src_buf, size_t *src_size,
                           void *dst, unsigned size, int options)
 {
@@ -287,3 +327,35 @@ char *packet_read_line_buf(char **src, size_t *src_len, int *dst_len)
 {
        return packet_read_line_generic(-1, src, src_len, dst_len);
 }
+
+ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out)
+{
+       int packet_len;
+
+       size_t orig_len = sb_out->len;
+       size_t orig_alloc = sb_out->alloc;
+
+       for (;;) {
+               strbuf_grow(sb_out, LARGE_PACKET_DATA_MAX);
+               packet_len = packet_read(fd_in, NULL, NULL,
+                       /* strbuf_grow() above always allocates one extra byte to
+                        * store a '\0' at the end of the string. packet_read()
+                        * writes a '\0' extra byte at the end, too. Let it know
+                        * that there is already room for the extra byte.
+                        */
+                       sb_out->buf + sb_out->len, LARGE_PACKET_DATA_MAX+1,
+                       PACKET_READ_GENTLE_ON_EOF);
+               if (packet_len <= 0)
+                       break;
+               sb_out->len += packet_len;
+       }
+
+       if (packet_len < 0) {
+               if (orig_alloc == 0)
+                       strbuf_release(sb_out);
+               else
+                       strbuf_setlen(sb_out, orig_len);
+               return packet_len;
+       }
+       return sb_out->len - orig_len;
+}

diff --git a/pkt-line.h b/pkt-line.h
index 3fa0899..18eac64 100644 (file)
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -25,6 +25,8 @@ void packet_buf_flush(struct strbuf *buf);
 void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
 int packet_flush_gently(int fd);
 int packet_write_fmt_gently(int fd, const char *fmt, ...) __attribute__((format (printf, 2, 3)));
+int write_packetized_from_fd(int fd_in, int fd_out);
+int write_packetized_from_buf(const char *src_in, size_t len, int fd_out);
 
 /*
  * Read a packetized line into the buffer, which must be at least size bytes
@@ -77,8 +79,14 @@ char *packet_read_line(int fd, int *size);
  */
 char *packet_read_line_buf(char **src_buf, size_t *src_len, int *size);
 
+/*
+ * Reads a stream of variable sized packets until a flush packet is detected.
+ */
+ssize_t read_packetized_to_strbuf(int fd_in, struct strbuf *sb_out);
+
 #define DEFAULT_PACKET_MAX 1000
 #define LARGE_PACKET_MAX 65520
+#define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
 extern char packet_buffer[LARGE_PACKET_MAX];
 
 #endif