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Re: [PATCH v4 3/6] util: add Error object for qemu_open_internal error r
From: |
Daniel P . Berrangé |
Subject: |
Re: [PATCH v4 3/6] util: add Error object for qemu_open_internal error reporting |
Date: |
Tue, 25 Aug 2020 16:36:27 +0100 |
User-agent: |
Mutt/1.14.6 (2020-07-11) |
On Tue, Aug 25, 2020 at 05:14:21PM +0200, Markus Armbruster wrote:
> Daniel P. Berrangé <berrange@redhat.com> writes:
>
> > Instead of relying on the limited information from errno, we can now
> > also provide detailed error messages.
>
> The more detailed error messages are currently always ignored, but the
> next patches will fix that.
>
> > Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
> > ---
> > util/osdep.c | 21 +++++++++++++++++++--
> > 1 file changed, 19 insertions(+), 2 deletions(-)
> >
> > diff --git a/util/osdep.c b/util/osdep.c
> > index 9ff92551e7..9c7118d3cb 100644
> > --- a/util/osdep.c
> > +++ b/util/osdep.c
> > @@ -284,7 +284,7 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t
> > len, bool exclusive)
> > * Opens a file with FD_CLOEXEC set
> > */
> > static int
> > -qemu_open_internal(const char *name, int flags, mode_t mode)
> > +qemu_open_internal(const char *name, int flags, mode_t mode, Error **errp)
> > {
> > int ret;
> >
> > @@ -298,24 +298,31 @@ qemu_open_internal(const char *name, int flags,
> > mode_t mode)
> >
> > fdset_id = qemu_parse_fdset(fdset_id_str);
> > if (fdset_id == -1) {
> > + error_setg(errp, "Could not parse fdset %s", name);
> > errno = EINVAL;
> > return -1;
> > }
> >
> > fd = monitor_fdset_get_fd(fdset_id, flags);
> > if (fd < 0) {
> > + error_setg_errno(errp, -fd, "Could not acquire FD for %s flags
> > %x",
> > + name, flags);
> > errno = -fd;
> > return -1;
> > }
> >
> > dupfd = qemu_dup_flags(fd, flags);
> > if (dupfd == -1) {
> > + error_setg_errno(errp, errno, "Could not dup FD for %s flags
> > %x",
> > + name, flags);
> > return -1;
> > }
> >
> > ret = monitor_fdset_dup_fd_add(fdset_id, dupfd);
> > if (ret == -1) {
> > close(dupfd);
> > + error_setg(errp, "Could not save FD for %s flags %x",
> > + name, flags);
>
> Can this happen?
Well there's code in monitor_fdset_dup_fd_add that can return -1.
>
> > errno = EINVAL;
> > return -1;
> > }
> > @@ -336,6 +343,16 @@ qemu_open_internal(const char *name, int flags, mode_t
> > mode)
> > }
> > #endif /* ! O_CLOEXEC */
> >
> > + if (ret == -1) {
> > + const char *action = "open";
> > + if (flags & O_CREAT) {
> > + action = "create";
> > + }
> > + error_setg_errno(errp, errno, "Could not %s '%s' flags 0x%x",
> > + action, name, flags);
>
> Not a good user experience:
>
> Could not open '/etc/shadow' flags 0x0: Permission denied
>
> Better:
>
> Could not open '/etc/shadow' for reading: Permission denied
>
> Are you sure flags other than the access mode (O_RDONLY, O_WRONLY,
> O_RDWR) must be included in the error message?
It was the flags other than access mode that I was thinking were
more important to log. I'm ambivalent htough, so can drop the
flags if it is thought to be overkill.
>
> If you must report flags in hexadecimal, then please reporting them more
> consistently. Right now you have
>
> for %s flags 0x%x
> '%s' flags %x
>
> Perhaps '%s' with flags 0x%x
>
> > + }
> > +
> > +
> > return ret;
> > }
> >
> > @@ -352,7 +369,7 @@ int qemu_open_old(const char *name, int flags, ...)
> > }
> > va_end(ap);
> >
> > - ret = qemu_open_internal(name, flags, mode);
> > + ret = qemu_open_internal(name, flags, mode, NULL);
> >
> > #ifdef O_DIRECT
> > if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {
>
>
Regards,
Daniel
--
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[PATCH v4 4/6] util: introduce qemu_open and qemu_create with error reporting, Daniel P . Berrangé, 2020/08/21
[PATCH v4 5/6] util: give a specific error message when O_DIRECT doesn't work, Daniel P . Berrangé, 2020/08/21
[PATCH v4 6/6] block/fileb: switch to use qemu_open/qemu_create for improved errors, Daniel P . Berrangé, 2020/08/21