[PATCH weston,v2] refactor configuration API of fbdev-backend
Benoit Gschwind
gschwind at gnu-log.net
Wed Apr 27 20:04:25 UTC 2016
Hello Pekka,
I was too confident when I submitted my patch, while I fixing the memory
corruption that you pointed out I found another issue:
composite-fbdev.c:504
section = weston_config_get_section(backend->compositor->config,
"output", "name",
output->base.name);
Thus I will investigate to fix this issue, and submit again the patch :)
Thanks again for your reviews
Best regards
Le 27/04/2016 09:59, Pekka Paalanen a écrit :
> On Tue, 26 Apr 2016 21:10:55 +0200
> Benoit Gschwind <gschwind at gnu-log.net> wrote:
>
>> Implement a "well" defined API to configure the fbdev backend.
>> Following and according to discution about libweston API
>> ---
>> Signed-off-by: Benoit Gschwind <gschwind at gnu-log.net>
>
> This S-o-b is on the wrong side of the '---'. git-am will drop if it is
> below the '---'.
>
>>
>> v1:
>> - add src/compositor-fbdev.h in the Makefile.am
>> - fix typo
>>
>> Makefile.am | 3 ++-
>> src/compositor-fbdev.c | 45 +++++++++++++++++++++++----------------------
>> src/compositor-fbdev.h | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
>> src/main.c | 33 +++++++++++++++++++++++++++++++--
>> 4 files changed, 105 insertions(+), 25 deletions(-)
>> create mode 100644 src/compositor-fbdev.h
>
> Hi Benoit,
>
> would have been nice to rebase this on upstream master branch, but I
> handled the conflicts for now to review it.
>
>>
>> diff --git a/Makefile.am b/Makefile.am
>> index c042c68..d319786 100644
>> --- a/Makefile.am
>> +++ b/Makefile.am
>> @@ -72,7 +72,8 @@ weston_SOURCES = \
>> src/log.c \
>> src/compositor.c \
>> src/compositor.h \
>> - src/compositor-headless.h \
>> + src/compositor-headless.h \
>> + src/compositor-fbdev.h \
>> src/input.c \
>> src/data-device.c \
>> src/screenshooter.c \
>
> Makefile.am is still missing the other two places to add
> compositor-fbdev.h to.
>
>> diff --git a/src/compositor-fbdev.c b/src/compositor-fbdev.c
>> index 19c5e3b..d0597a6 100644
>> --- a/src/compositor-fbdev.c
>> +++ b/src/compositor-fbdev.c
>> @@ -44,6 +44,7 @@
>>
>> #include "shared/helpers.h"
>> #include "compositor.h"
>> +#include "compositor-fbdev.h"
>> #include "launcher-util.h"
>> #include "pixman-renderer.h"
>> #include "libinput-seat.h"
>> @@ -93,12 +94,6 @@ struct fbdev_output {
>> uint8_t depth;
>> };
>>
>> -struct fbdev_parameters {
>> - int tty;
>> - char *device;
>> - int use_gl;
>> -};
>> -
>> struct gl_renderer_interface *gl_renderer;
>>
>> static const char default_seat[] = "seat0";
>> @@ -744,7 +739,7 @@ fbdev_restore(struct weston_compositor *compositor)
>> static struct fbdev_backend *
>> fbdev_backend_create(struct weston_compositor *compositor, int *argc, char *argv[],
>> struct weston_config *config,
>> - struct fbdev_parameters *param)
>> + struct weston_fbdev_backend_config *param)
>> {
>> struct fbdev_backend *backend;
>> const char *seat_id = default_seat;
>> @@ -827,29 +822,35 @@ out_compositor:
>> return NULL;
>> }
>>
>> +static void
>> +config_init_to_defaults(struct weston_fbdev_backend_config *config)
>> +{
>> + /* TODO: Ideally, available frame buffers should be enumerated using
>> + * udev, rather than passing a device node in as a parameter. */
>> + config->tty = 0; /* default to current tty */
>> + config->device = "/dev/fb0"; /* default frame buffer */
>> + config->use_gl = 0;
>> +}
>> +
>> WL_EXPORT int
>> backend_init(struct weston_compositor *compositor, int *argc, char *argv[],
>> - struct weston_config *config,
>> + struct weston_config *wc,
>> struct weston_backend_config *config_base)
>> {
>> struct fbdev_backend *b;
>> - /* TODO: Ideally, available frame buffers should be enumerated using
>> - * udev, rather than passing a device node in as a parameter. */
>> - struct fbdev_parameters param = {
>> - .tty = 0, /* default to current tty */
>> - .device = "/dev/fb0", /* default frame buffer */
>> - .use_gl = 0,
>> - };
>> + struct weston_fbdev_backend_config config = {{ 0, }};
>>
>> - const struct weston_option fbdev_options[] = {
>> - { WESTON_OPTION_INTEGER, "tty", 0, ¶m.tty },
>> - { WESTON_OPTION_STRING, "device", 0, ¶m.device },
>> - { WESTON_OPTION_BOOLEAN, "use-gl", 0, ¶m.use_gl },
>> - };
>> + if (config_base == NULL ||
>> + config_base->struct_version != WESTON_FBDEV_BACKEND_CONFIG_VERSION ||
>> + config_base->struct_size > sizeof(struct weston_fbdev_backend_config)) {
>> + weston_log("fbdev backend config structure is invalid\n");
>> + return -1;
>> + }
>>
>> - parse_options(fbdev_options, ARRAY_LENGTH(fbdev_options), argc, argv);
>> + config_init_to_defaults(&config);
>> + memcpy(&config, config_base, config_base->struct_size);
>>
>> - b = fbdev_backend_create(compositor, argc, argv, config, ¶m);
>> + b = fbdev_backend_create(compositor, argc, argv, wc, &config);
>
> I am quoting the exact same comment I gave the last time:
>
>> There is a small issue with config.device. It is ok for
>> config_init_to_defaults() to use a statically allocated const string
>> for it, because the pointer gets overwritten with a pointer from
>> main.c. However, fbdev_output_create() is storing the pointer instead
>> of calling strdup(). When main.c after init frees the pointer,
>> fbdev_output::device will contain a stale pointer.
>>
>> Could you send a preparation patch that makes fbdev_output_create() use
>> strdup() for the device string, please?
>>
>> I think it might have leaked the device string allocated by
>> parse_options() before your patch.
>
> What we talked about in IRC was the other comment, not this one.
>
> Please, look again at the call chain after applying your patch:
>
> main.c:
> - load_fbdev_backend():
> The config.device string is malloc'd, and passed in to
> load_backend_new().
>
> compositor-fbdev.c:
> - backend_init(): Just copies the pointer, does not reallocate the string.
> - fbdev_backend_create(): Calls fbdev_output_create().
> - fbdev_output_create(): stores the string pointer in struct
> fbdev_output::device *without* copying.
>
> main.c:
> - load_fbdev_backend(): calls free() on the pointer.
>
> This results in struct fbdev_output::device containing a pointer to
> freed memory.
>
>> if (b == NULL)
>> return -1;
>> return 0;
>
>
> Thanks,
> pq
>
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