[PATCH 08/20] trace-cmd library: Add local helper function for data compression

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

The newly added helper functions read data from a file and compress it,
before writing into the trace file. The trace data is compressed in
chunks, which are page aligned. A new local define is introduced:
  PAGES_IN_CHUNK
which can be used to tune how big a compression chunk is.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 lib/trace-cmd/trace-output.c | 71 +++++++++++++++++++++++++++++++++---
 1 file changed, 65 insertions(+), 6 deletions(-)

diff --git a/lib/trace-cmd/trace-output.c b/lib/trace-cmd/trace-output.c
index 1c6e9728..c69d6d4f 100644
--- a/lib/trace-cmd/trace-output.c
+++ b/lib/trace-cmd/trace-output.c
@@ -283,18 +283,27 @@ static unsigned long get_size(const char *file)
 	return size;
 }
 
-static tsize_t copy_file_fd(struct tracecmd_output *handle, int fd)
+static tsize_t copy_file_fd(struct tracecmd_output *handle, int fd, unsigned long long max)
 {
+	tsize_t rsize = BUFSIZ;
 	tsize_t size = 0;
 	char buf[BUFSIZ];
 	stsize_t r;
 
 	do {
-		r = read(fd, buf, BUFSIZ);
+		if (max && rsize > max)
+			rsize = max;
+
+		r = read(fd, buf, rsize);
 		if (r > 0) {
 			size += r;
 			if (do_write_check(handle, buf, r))
 				return 0;
+			if (max) {
+				max -= r;
+				if (!max)
+					break;
+			}
 		}
 	} while (r > 0);
 
@@ -312,12 +321,62 @@ static tsize_t copy_file(struct tracecmd_output *handle,
 		tracecmd_warning("Can't read '%s'", file);
 		return 0;
 	}
-	size = copy_file_fd(handle, fd);
+	size = copy_file_fd(handle, fd, 0);
 	close(fd);
 
 	return size;
 }
 
+#define PAGES_IN_CHUNK 10
+__hidden unsigned long long out_copy_fd_compress(struct tracecmd_output *handle,
+						 int fd, unsigned long long max,
+						 unsigned long long *write_size)
+{
+	unsigned long long rsize = 0;
+	unsigned long long wsize = 0;
+	unsigned long long size;
+	int ret;
+
+	if (handle->compress) {
+		rsize = max;
+		ret = tracecmd_compress_copy_from(handle->compress, fd,
+						  PAGES_IN_CHUNK * handle->page_size,
+						  &rsize, &wsize);
+		if (ret < 0)
+			return 0;
+
+		size = rsize;
+		if (write_size)
+			*write_size = wsize;
+	} else {
+		size = copy_file_fd(handle, fd, max);
+		if (write_size)
+			*write_size = size;
+	}
+
+	return size;
+}
+
+static tsize_t copy_file_compress(struct tracecmd_output *handle,
+				  const char *file, unsigned long long *write_size)
+{
+	int ret;
+	int fd;
+
+	fd = open(file, O_RDONLY);
+	if (fd < 0) {
+		tracecmd_warning("Can't read '%s'", file);
+		return 0;
+	}
+
+	ret = out_copy_fd_compress(handle, fd, 0, write_size);
+	if (!ret)
+		tracecmd_warning("Can't compress '%s'", file);
+
+	close(fd);
+	return ret;
+}
+
 /*
  * Finds the path to the debugfs/tracing
  * Allocates the string and stores it.
@@ -513,7 +572,7 @@ static int read_header_files(struct tracecmd_output *handle, bool compress)
 	endian8 = convert_endian_8(handle, size);
 	if (do_write_check(handle, &endian8, 8))
 		goto out_close;
-	check_size = copy_file_fd(handle, fd);
+	check_size = copy_file_fd(handle, fd, 0);
 	close(fd);
 	if (size != check_size) {
 		tracecmd_warning("wrong size for '%s' size=%lld read=%lld", path, size, check_size);
@@ -539,7 +598,7 @@ static int read_header_files(struct tracecmd_output *handle, bool compress)
 	endian8 = convert_endian_8(handle, size);
 	if (do_write_check(handle, &endian8, 8))
 		goto out_close;
-	check_size = copy_file_fd(handle, fd);
+	check_size = copy_file_fd(handle, fd, 0);
 	close(fd);
 	if (size != check_size) {
 		tracecmd_warning("wrong size for '%s'", path);
@@ -2177,7 +2236,7 @@ __hidden int out_write_cpu_data(struct tracecmd_output *handle,
 		if (lseek64(data[i].fd, data[i].offset, SEEK_SET) == (off64_t)-1)
 			goto out_free;
 		if (data[i].size) {
-			read_size = copy_file_fd(handle, data[i].fd);
+			read_size = copy_file_fd(handle, data[i].fd, data[i].size);
 			if (read_size != data_files[i].file_size) {
 				errno = EINVAL;
 				tracecmd_warning("did not match size of %lld to %lld",
-- 
2.31.1