Hi Gerd,
On 7/1/20 5:15 PM, Gerd Hoffmann wrote:
>>> Ah, that is the problem. Yes, DT_CHR is an non-posix optimization which
>>> allows to get the file type directly, without another round-trip to the
>>> kernel. If that isn't available you can stat() the file and check
>>> ((st_mode & S_IFMT) == S_IFCHR) instead.
>>
>> Even when d_type and DT_CHR is available, there are filesystems where the
>> Linux kernel reports d_type of DT_UNKNOWN, and where you are best having
>> that code also falling back to an fstat().
>
> Given this isn't perforance critical at all it is probably simplest to
> avoid non-portable d_type altogether and just to the fstat
> unconditionally.
>
> David, does that work for haiku?
>
> take care,
> Gerd
>
> diff --git a/util/drm.c b/util/drm.c
> index a23ff2453826..a1d3520d00f2 100644
> --- a/util/drm.c
> +++ b/util/drm.c
> @@ -24,6 +24,7 @@ int qemu_drm_rendernode_open(const char *rendernode)
> {
> DIR *dir;
> struct dirent *e;
> + struct stat st;
> int r, fd;
> char *p;
>
> @@ -38,10 +39,6 @@ int qemu_drm_rendernode_open(const char *rendernode)
>
> fd = -1;
> while ((e = readdir(dir))) {
> - if (e->d_type != DT_CHR) {
> - continue;
> - }
> -
> if (strncmp(e->d_name, "renderD", 7)) {
> continue;
> }
> @@ -53,6 +50,12 @@ int qemu_drm_rendernode_open(const char *rendernode)
> g_free(p);
> continue;
> }
> + fstat(r, &st);
While preparing the formal patch, can you add a comment here explaining
we deliberately use this way for portability (not checking DT_CHR /
DT_UNKNOWN ...)?
Thanks!
> + if ((st.st_mode & S_IFMT) != S_IFCHR) {
> + close(r);
> + g_free(p);
> + continue;
> + }
> fd = r;
> g_free(p);
> break;
>
