| Message ID | abcc11027eb2a9364c7ba8f6b7ea2d3688ef8f09.1675920064.git.deborah.brouwer@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | v4l2-tracer: misc fixes | expand |
On 09/02/2023 07:06, Deborah Brouwer wrote: > Put the trace file into valid JSON format by removing the trailing comma > from the trace file array. > > Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com> > --- > utils/v4l2-tracer/v4l2-tracer.cpp | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/utils/v4l2-tracer/v4l2-tracer.cpp b/utils/v4l2-tracer/v4l2-tracer.cpp > index ae6f68e4..7adbe04e 100644 > --- a/utils/v4l2-tracer/v4l2-tracer.cpp > +++ b/utils/v4l2-tracer/v4l2-tracer.cpp > @@ -346,7 +346,7 @@ int tracer(int argc, char *argv[], bool retrace) > > /* Close the json-array and the trace file. */ > trace_file = fopen(trace_filename.c_str(), "a"); > - fseek(trace_file, 0L, SEEK_END); > + ftruncate(fileno(trace_file), lseek(fileno(trace_file), 0, SEEK_END) - 2); > fputs("\n]\n", trace_file); ftruncate seems overkill to me. Wouldn't it be enough to just do fseek(trace_file, -2, SEEK_END); since the fputs afterwards will overwrite those last two characters anyway? (I think it is -2 for SEEK_END, I'm not 100% certain though, it could be 2) Regards, Hans > fclose(trace_file); >
On Wed, Feb 22, 2023 at 08:26:33PM +0100, Hans Verkuil wrote: > On 09/02/2023 07:06, Deborah Brouwer wrote: > > Put the trace file into valid JSON format by removing the trailing comma > > from the trace file array. > > > > Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com> > > --- > > utils/v4l2-tracer/v4l2-tracer.cpp | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/utils/v4l2-tracer/v4l2-tracer.cpp b/utils/v4l2-tracer/v4l2-tracer.cpp > > index ae6f68e4..7adbe04e 100644 > > --- a/utils/v4l2-tracer/v4l2-tracer.cpp > > +++ b/utils/v4l2-tracer/v4l2-tracer.cpp > > @@ -346,7 +346,7 @@ int tracer(int argc, char *argv[], bool retrace) > > > > /* Close the json-array and the trace file. */ > > trace_file = fopen(trace_filename.c_str(), "a"); > > - fseek(trace_file, 0L, SEEK_END); > > + ftruncate(fileno(trace_file), lseek(fileno(trace_file), 0, SEEK_END) - 2); > > fputs("\n]\n", trace_file); > > ftruncate seems overkill to me. Wouldn't it be enough to just do > > fseek(trace_file, -2, SEEK_END); > > since the fputs afterwards will overwrite those last two characters anyway? > > (I think it is -2 for SEEK_END, I'm not 100% certain though, it could be 2) It took me a while to remember why I didn't use this simpler method, but it's because the trace file is opened in append mode "a" in write_json_object_to_json_file() and so fputs() stubbornly ignores the file position indicator set by fseek. > > Regards, > > Hans > > > fclose(trace_file); > > >
diff --git a/utils/v4l2-tracer/v4l2-tracer.cpp b/utils/v4l2-tracer/v4l2-tracer.cpp index ae6f68e4..7adbe04e 100644 --- a/utils/v4l2-tracer/v4l2-tracer.cpp +++ b/utils/v4l2-tracer/v4l2-tracer.cpp @@ -346,7 +346,7 @@ int tracer(int argc, char *argv[], bool retrace) /* Close the json-array and the trace file. */ trace_file = fopen(trace_filename.c_str(), "a"); - fseek(trace_file, 0L, SEEK_END); + ftruncate(fileno(trace_file), lseek(fileno(trace_file), 0, SEEK_END) - 2); fputs("\n]\n", trace_file); fclose(trace_file);
Put the trace file into valid JSON format by removing the trailing comma from the trace file array. Signed-off-by: Deborah Brouwer <deborah.brouwer@collabora.com> --- utils/v4l2-tracer/v4l2-tracer.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)