From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Teach `packet_write_gently()` to write the pkt-line header and the actual
buffer in 2 separate calls to `write_in_full()` and avoid the need for a
static buffer, thread-safe scratch space, or an excessively large stack
buffer.
Change `write_packetized_from_fd()` to allocate a temporary buffer rather
than using a static buffer to avoid similar issues here.
These changes are intended to make it easier to use pkt-line routines in
a multi-threaded context with multiple concurrent writers writing to
different streams.
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
pkt-line.c | 27 +++++++++++++++++++--------
1 file changed, 19 insertions(+), 8 deletions(-)
diff --git a/pkt-line.c b/pkt-line.c
index d633005ef746..8b3512190442 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -196,17 +196,25 @@ int packet_write_fmt_gently(int fd, const char *fmt, ...)
static int packet_write_gently(const int fd_out, const char *buf, size_t size)
{
- static char packet_write_buffer[LARGE_PACKET_MAX];
+ char header[4];
size_t packet_size;
- if (size > sizeof(packet_write_buffer) - 4)
+ if (size > LARGE_PACKET_DATA_MAX)
return error(_("packet write failed - data exceeds max packet size"));
packet_trace(buf, size, 1);
packet_size = size + 4;
- set_packet_header(packet_write_buffer, packet_size);
- memcpy(packet_write_buffer + 4, buf, size);
- if (write_in_full(fd_out, packet_write_buffer, packet_size) < 0)
+
+ set_packet_header(header, packet_size);
+
+ /*
+ * Write the header and the buffer in 2 parts so that we do not need
+ * to allocate a buffer or rely on a static buffer. This avoids perf
+ * and multi-threading issues.
+ */
+
+ if (write_in_full(fd_out, header, 4) < 0 ||
+ write_in_full(fd_out, buf, size) < 0)
return error(_("packet write failed"));
return 0;
}
@@ -244,20 +252,23 @@ void packet_buf_write_len(struct strbuf *buf, const char *data, size_t len)
int write_packetized_from_fd(int fd_in, int fd_out)
{
- static char buf[LARGE_PACKET_DATA_MAX];
+ char *buf = xmalloc(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)
+ bytes_to_write = xread(fd_in, buf, LARGE_PACKET_DATA_MAX);
+ if (bytes_to_write < 0) {
+ free(buf);
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);
+ free(buf);
return err;
}
--
gitgitgadget
