[v2,50/87] trace-cmd library: Read compression header

Commit Message

Tzvetomir Stoyanov (VMware) July 29, 2021, 5:09 a.m. UTC

Trace file version 7 introduced new mandatory compression header,
storing information about the compression algorithm used to compress the
trace file. Added code to read that header and to initialize compression
context according to it.

Signed-off-by: Tzvetomir Stoyanov (VMware) <[e-mail]>
---
 lib/trace-cmd/trace-input.c | 35 +++++++++++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

Comments

Steven Rostedt Aug. 19, 2021, 7:15 p.m. UTC | #1

On Thu, 29 Jul 2021 08:09:22 +0300
"Tzvetomir Stoyanov (VMware)" <[e-mail]> wrote:

> @@ -3752,11 +3755,38 @@ struct tracecmd_input *tracecmd_alloc_fd(int fd, int flags)
>  	handle->total_file_size = lseek64(handle->fd, 0, SEEK_END);
>  	lseek64(handle->fd, offset, SEEK_SET);
>  
> +	if (handle->file_version >= 7) {

In the next version, remove all comparisons to 7, and create feature
flags. Then in one place, where the version is decided on, it will set
the feature flags that are supported by that version. And everyplace
else, references the features, not the number. Because 7 is really
meaningless, and years from now, will just cause more confusion.

-- Steve


> +		zname = read_string(handle);
> +		if (!zname)
> +			goto failed_read;
> +		zver = read_string(handle);
> +		if (!zver)
> +			goto failed_read;
> +		if (strcmp(zname, "none")) {

Patch

diff --git a/lib/trace-cmd/trace-input.c b/lib/trace-cmd/trace-input.c
index 9ab20d64..520d611f 100644
--- a/lib/trace-cmd/trace-input.c
+++ b/lib/trace-cmd/trace-input.c
@@ -3684,7 +3684,9 @@  struct tracecmd_input *tracecmd_alloc_fd(int fd, int flags)
 	char test[] = TRACECMD_MAGIC;
 	unsigned int page_size;
 	size_t offset;
-	char *version;
+	char *version = NULL;
+	char *zver = NULL;
+	char *zname = NULL;
 	char buf[BUFSIZ];
 	unsigned long ver;
 
@@ -3723,6 +3725,7 @@  struct tracecmd_input *tracecmd_alloc_fd(int fd, int flags)
 	}
 	handle->file_version = ver;
 	free(version);
+	version = NULL;
 
 	if (do_read_check(handle, buf, 1))
 		goto failed_read;
@@ -3752,11 +3755,38 @@  struct tracecmd_input *tracecmd_alloc_fd(int fd, int flags)
 	handle->total_file_size = lseek64(handle->fd, 0, SEEK_END);
 	lseek64(handle->fd, offset, SEEK_SET);
 
+	if (handle->file_version >= 7) {
+		zname = read_string(handle);
+		if (!zname)
+			goto failed_read;
+		zver = read_string(handle);
+		if (!zver)
+			goto failed_read;
+		if (strcmp(zname, "none")) {
+			handle->compress = tracecmd_compress_alloc(zname, zver,
+								   handle->fd,
+								   handle->pevent, NULL);
+			if (!handle->compress) {
+				tracecmd_warning("Unsupported file compression %s %s", zname, zver);
+				goto failed_read;
+			}
+		}
+		if (read8(handle, &(handle->options_start))) {
+			tracecmd_warning("Filed to read the offset of the first option section");
+			goto failed_read;
+		}
+		free(zname);
+		free(zver);
+	}
+
 	handle->file_state = TRACECMD_FILE_INIT;
 
 	return handle;
 
  failed_read:
+	free(version);
+	free(zname);
+	free(zver);
 	free(handle);
 
 	return NULL;
@@ -3952,7 +3982,8 @@  void tracecmd_close(struct tracecmd_input *handle)
 	if (handle->flags & TRACECMD_FL_BUFFER_INSTANCE)
 		tracecmd_close(handle->parent);
 	else {
-		/* Only main handle frees plugins and pevent */
+		/* Only main handle frees plugins, pevent and compression context */
+		tracecmd_compress_destroy(handle->compress);
 		tep_unload_plugins(handle->plugin_list, handle->pevent);
 		tep_free(handle->pevent);
 	}