[PATCH 1/8] pkt-line: remove buffer arg from write_packetized_from_fd_no_flush()

["Jeff Hostetler via GitGitGadget" <gitgitgadget@gmail.com>]

From: Jeff Hostetler <jeffhost@microsoft.com>

Remove the scratch buffer argument from `write_packetized_from_fd_no_flush()`
and allocate a temporary buffer within the function.

In 3e4447f1ea (pkt-line: eliminate the need for static buffer in
packet_write_gently(), 2021-02-13) we added the argument in order to
get rid of a static buffer to make the routine safe in multi-threaded
contexts and to avoid putting a very large buffer on the stack.  This
delegated the problem to the caller who has more knowledge of the use
case and can best decide the most efficient way to provide such a
buffer.

However, in practice, the (currently, only) caller just created the
buffer on the stack, so we might as well just allocate it within the
function and restore the original API.

Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
---
 convert.c  |  7 +++----
 pkt-line.c | 19 +++++++++++--------
 pkt-line.h |  6 +-----
 3 files changed, 15 insertions(+), 17 deletions(-)

diff --git a/convert.c b/convert.c
index 9f44f00d841f..516f1095b06e 100644
--- a/convert.c
+++ b/convert.c
@@ -883,10 +883,9 @@ static int apply_multi_file_filter(const char *path, const char *src, size_t len
 	if (err)
 		goto done;
 
-	if (fd >= 0) {
-		struct packet_scratch_space scratch;
-		err = write_packetized_from_fd_no_flush(fd, process->in, &scratch);
-	} else
+	if (fd >= 0)
+		err = write_packetized_from_fd_no_flush(fd, process->in);
+	else
 		err = write_packetized_from_buf_no_flush(src, len, process->in);
 	if (err)
 		goto done;
diff --git a/pkt-line.c b/pkt-line.c
index 18ecad65e08c..c933bb95586d 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -250,22 +250,25 @@ void packet_buf_write_len(struct strbuf *buf, const char *data, size_t len)
 	packet_trace(data, len, 1);
 }
 
-int write_packetized_from_fd_no_flush(int fd_in, int fd_out,
-				      struct packet_scratch_space *scratch)
+int write_packetized_from_fd_no_flush(int fd_in, int fd_out)
 {
 	int err = 0;
 	ssize_t bytes_to_write;
+	char *buf = xmalloc(LARGE_PACKET_DATA_MAX);
 
 	while (!err) {
-		bytes_to_write = xread(fd_in, scratch->buffer,
-				       sizeof(scratch->buffer));
-		if (bytes_to_write < 0)
-			return COPY_READ_ERROR;
+		bytes_to_write = xread(fd_in, buf, LARGE_PACKET_DATA_MAX);
+		if (bytes_to_write < 0) {
+			err = COPY_READ_ERROR;
+			break;
+		}
 		if (bytes_to_write == 0)
 			break;
-		err = packet_write_gently(fd_out, scratch->buffer,
-					  bytes_to_write);
+		err = packet_write_gently(fd_out, buf, bytes_to_write);
 	}
+
+	free(buf);
+
 	return err;
 }
 
diff --git a/pkt-line.h b/pkt-line.h
index e347fe46832a..54eec72dc0af 100644
--- a/pkt-line.h
+++ b/pkt-line.h
@@ -8,10 +8,6 @@
 #define LARGE_PACKET_MAX 65520
 #define LARGE_PACKET_DATA_MAX (LARGE_PACKET_MAX - 4)
 
-struct packet_scratch_space {
-	char buffer[LARGE_PACKET_DATA_MAX]; /* does not include header bytes */
-};
-
 /*
  * Write a packetized stream, where each line is preceded by
  * its length (including the header) as a 4-byte hex number.
@@ -39,7 +35,7 @@ void packet_buf_write(struct strbuf *buf, const char *fmt, ...) __attribute__((f
 void packet_buf_write_len(struct strbuf *buf, const char *data, size_t len);
 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_no_flush(int fd_in, int fd_out, struct packet_scratch_space *scratch);
+int write_packetized_from_fd_no_flush(int fd_in, int fd_out);
 int write_packetized_from_buf_no_flush(const char *src_in, size_t len, int fd_out);
 
 /*
-- 
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