Daniel P. Berrangé <berra...@redhat.com> writes:
> Create a "qemu_open_err" method which does the same as "qemu_open",
> but with a "Error **errp" for error reporting. There should be no
> behavioural difference for existing callers at this stage.
>
> Signed-off-by: Daniel P. Berrangé <berra...@redhat.com>
> ---
> include/qemu/osdep.h | 1 +
> util/osdep.c | 71 +++++++++++++++++++++++++++++++++++---------
> 2 files changed, 58 insertions(+), 14 deletions(-)
>
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index 0d26a1b9bd..e41701a308 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -483,6 +483,7 @@ int qemu_madvise(void *addr, size_t len, int advice);
> int qemu_mprotect_rwx(void *addr, size_t size);
> int qemu_mprotect_none(void *addr, size_t size);
>
> +int qemu_open_err(const char *name, int flags, Error **errp, ...);
> int qemu_open(const char *name, int flags, ...);
> int qemu_close(int fd);
> int qemu_unlink(const char *name);
> diff --git a/util/osdep.c b/util/osdep.c
> index 4bdbe81cec..450b3a5da3 100644
> --- a/util/osdep.c
> +++ b/util/osdep.c
> @@ -22,6 +22,7 @@
> * THE SOFTWARE.
> */
> #include "qemu/osdep.h"
> +#include "qapi/error.h"
>
> /* Needed early for CONFIG_BSD etc. */
>
> @@ -282,7 +283,7 @@ int qemu_lock_fd_test(int fd, int64_t start, int64_t len,
> bool exclusive)
> /*
> * Opens a file with FD_CLOEXEC set
> */
> -int qemu_open(const char *name, int flags, ...)
> +static int qemu_openv(const char *name, int flags, Error **errp, va_list ap)
> {
> int ret;
> int mode = 0;
> @@ -297,24 +298,31 @@ int qemu_open(const char *name, int flags, ...)
>
> fdset_id = qemu_parse_fdset(fdset_id_str);
> if (fdset_id == -1) {
> + error_setg(errp, "Unable to parse fdset %s", name);
> errno = EINVAL;
> return -1;
> }
>
> fd = monitor_fdset_get_fd(fdset_id, flags);
> if (fd < 0) {
> + error_setg_errno(errp, -fd, "Unable 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, "Unable 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, "Unable save FD for %s flags %x",
> + name, flags);
> errno = EINVAL;
> return -1;
> }
> @@ -324,11 +332,7 @@ int qemu_open(const char *name, int flags, ...)
> #endif
>
> if (flags & O_CREAT) {
> - va_list ap;
> -
> - va_start(ap, flags);
> mode = va_arg(ap, int);
> - va_end(ap);
> }
>
> #ifdef O_CLOEXEC
> @@ -340,25 +344,64 @@ int qemu_open(const char *name, int flags, ...)
> }
> #endif
>
> + if (ret == -1) {
> + const char *action = "open";
> + if (flags & O_CREAT) {
> + action = "create";
> + }
> #ifdef O_DIRECT
> - if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {
> - int newflags = flags & ~O_DIRECT;
> + if (errno == EINVAL && (flags & O_DIRECT)) {
> + int newflags = flags & ~O_DIRECT;
> # ifdef O_CLOEXEC
> - ret = open(name, newflags | O_CLOEXEC, mode);
> + ret = open(name, newflags | O_CLOEXEC, mode);
> # else
> - ret = open(name, newflags, mode);
> + ret = open(name, newflags, mode);
> # endif
> - if (ret != -1) {
> - close(ret);
> - error_report("file system does not support O_DIRECT");
> - errno = EINVAL;
> + if (ret != -1) {
> + close(ret);
> + error_setg(errp, "Unable to %s '%s' flags 0x%x: "
> + "filesystem does not support O_DIRECT",
> + action, name, flags);
> + if (!errp) {
If the caller ignores errors, ...
> + error_report("file system does not support O_DIRECT");
... we report this error to stderr (but not any of the other ones).
This is weird. I figure you do it here to reproduce the weirdness of
qemu_open() before the patch. Goes back to
commit a5813077aac7865f69b7ee46a594f3705429f7cd
Author: Stefan Hajnoczi <stefa...@redhat.com>
Date: Thu Aug 22 11:29:03 2013 +0200
osdep: warn if open(O_DIRECT) on fails with EINVAL
Print a warning when opening a file O_DIRECT fails with EINVAL. This
saves users a lot of time trying to figure out the EINVAL error, which
is typical when attempting to open a file O_DIRECT on Linux tmpfs.
Reported-by: Deepak C Shetty <deepa...@linux.vnet.ibm.com>
Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
Reviewed-by: Eric Blake <ebl...@redhat.com>
The message isn't phrased as a warning, though. Should it use
warn_report()? Stefan?
Regardless, since use of error_report() in a function that returns
errors through its Error ** parameter is an anti-pattern, this use needs
a comment. I'd make it a TODO comment: convert all callers where the
warning is wanted to qemu_open_err(), then drop it.
> + }
> + errno = EINVAL;
> + return -1;
> + }
> }
> - }
> #endif /* O_DIRECT */
> + error_setg_errno(errp, errno, "Unable to %s '%s' flags 0x%x",
> + action, name, flags);
> + }
> +
>
> return ret;
> }
>
> +int qemu_open_err(const char *name, int flags, Error **errp, ...)
> +{
> + va_list ap;
> + int rv;
> +
> + va_start(ap, errp);
> + rv = qemu_openv(name, flags, errp, ap);
> + va_end(ap);
> +
> + return rv;
> +}
> +
> +int qemu_open(const char *name, int flags, ...)
> +{
> + va_list ap;
> + int rv;
> +
> + va_start(ap, flags);
> + rv = qemu_openv(name, flags, NULL, ap);
> + va_end(ap);
> +
> + return rv;
> +}
I'd rename this to qemu_open_with_bad_error_messages().
For better ones, callers can use
if (qemu_open_err(name, flags, &err) < 0) {
error_report_err(err);
...
}
or, where the error is fatal
qemu_open_err(name, flags, &error_fatal);
If you prefer not to rename it now, please add a comment why it should
not be used in new code, and existing uses should be converted.
If you rename, call the new one qemu_open().
> +
> int qemu_close(int fd)
> {
> int64_t fdset_id;
