[PATCH 03/20] trace-cmd library: Internal helpers for uncompressing data

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

New library internal helper functions are introduced, to add compression
functionality to the input trace handler.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@xxxxxxxxx>
---
 lib/trace-cmd/include/trace-cmd-local.h |  3 ++
 lib/trace-cmd/trace-input.c             | 49 ++++++++++++++++++++++---
 2 files changed, 46 insertions(+), 6 deletions(-)

diff --git a/lib/trace-cmd/include/trace-cmd-local.h b/lib/trace-cmd/include/trace-cmd-local.h
index 304bec49..14223a08 100644
--- a/lib/trace-cmd/include/trace-cmd-local.h
+++ b/lib/trace-cmd/include/trace-cmd-local.h
@@ -45,6 +45,9 @@ void out_compression_reset(struct tracecmd_output *handle, bool compress);
 unsigned long long out_copy_fd_compress(struct tracecmd_output *handle,
 					int fd, unsigned long long max,
 					unsigned long long *write_size);
+void in_uncompress_reset(struct tracecmd_input *handle);
+int in_uncompress_block(struct tracecmd_input *handle);
+
 unsigned long long
 out_write_section_header(struct tracecmd_output *handle, unsigned short header_id,
 			 char *description, enum tracecmd_section_flags flags, bool option);
diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index b7d78a3a..25d376f7 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -155,6 +155,9 @@ struct tracecmd_input {
 	long long		ts_offset;
 	struct tsc2nsec		tsc_calc;
 
+	bool			read_compress;
+	struct tracecmd_compression *compress;
+
 	struct host_trace_info	host;
 	double			ts2secs;
 	unsigned int		cpustats_size;
@@ -262,13 +265,13 @@ static const char *show_records(struct page **pages, int nr_pages)
 
 static int init_cpu(struct tracecmd_input *handle, int cpu);
 
-static ssize_t do_read(struct tracecmd_input *handle, void *data, size_t size)
+static ssize_t do_read_fd(int fd, void *data, size_t size)
 {
 	ssize_t tot = 0;
 	ssize_t r;
 
 	do {
-		r = read(handle->fd, data + tot, size - tot);
+		r = read(fd, data + tot, size - tot);
 		tot += r;
 
 		if (!r)
@@ -280,6 +283,22 @@ static ssize_t do_read(struct tracecmd_input *handle, void *data, size_t size)
 	return tot;
 }
 
+static inline int do_lseek(struct tracecmd_input *handle, int offset, int whence)
+{
+	if (handle->read_compress)
+		return tracecmd_compress_lseek(handle->compress, offset, whence);
+	else
+		return lseek(handle->fd, offset, whence);
+}
+
+static inline ssize_t do_read(struct tracecmd_input *handle, void *data, size_t size)
+{
+	if (handle->read_compress)
+		return tracecmd_compress_read(handle->compress, data, size);
+	else
+		return do_read_fd(handle->fd, data, size);
+}
+
 static ssize_t
 do_read_check(struct tracecmd_input *handle, void *data, size_t size)
 {
@@ -304,9 +323,7 @@ static char *read_string(struct tracecmd_input *handle)
 
 	for (;;) {
 		r = do_read(handle, buf, BUFSIZ);
-		if (r < 0)
-			goto fail;
-		if (!r)
+		if (r <= 0)
 			goto fail;
 
 		for (i = 0; i < r; i++) {
@@ -332,7 +349,7 @@ static char *read_string(struct tracecmd_input *handle)
 	}
 
 	/* move the file descriptor to the end of the string */
-	r = lseek(handle->fd, -(r - (i+1)), SEEK_CUR);
+	r = do_lseek(handle, -(r - (i+1)), SEEK_CUR);
 	if (r < 0)
 		goto fail;
 
@@ -396,6 +413,26 @@ static int read8(struct tracecmd_input *handle, unsigned long long *size)
 	return 0;
 }
 
+__hidden void in_uncompress_reset(struct tracecmd_input *handle)
+{
+	if (handle->compress) {
+		handle->read_compress = false;
+		tracecmd_compress_reset(handle->compress);
+	}
+}
+
+__hidden int in_uncompress_block(struct tracecmd_input *handle)
+{
+	int ret = 0;
+
+	if (handle->compress) {
+		ret = tracecmd_uncompress_block(handle->compress);
+		if (!ret)
+			handle->read_compress = true;
+	}
+	return ret;
+}
+
 static struct file_section *section_get(struct tracecmd_input *handle, int id)
 {
 	struct file_section *sec;
-- 
2.31.1