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Re: [PATCH v2 2/3] util: support detailed error reporting for qemu_open
From: |
Markus Armbruster |
Subject: |
Re: [PATCH v2 2/3] util: support detailed error reporting for qemu_open |
Date: |
Wed, 08 Jul 2020 08:55:26 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) |
Daniel P. Berrangé <berrange@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 <berrange@redhat.com>
> ---
> include/qemu/osdep.h | 2 ++
> util/osdep.c | 66 +++++++++++++++++++++++++++++++++++---------
> 2 files changed, 55 insertions(+), 13 deletions(-)
>
> diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
> index 0d26a1b9bd..8506a978fa 100644
> --- a/include/qemu/osdep.h
> +++ b/include/qemu/osdep.h
> @@ -483,6 +483,8 @@ 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);
>
> +/* This is preferred over qemu_open for its improved error reporting */
> +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);
I still think renaming qemu_open() to something like
qemu_open_with_useless_errors() is the way to go.
> diff --git a/util/osdep.c b/util/osdep.c
> index e2b7507ee2..3de8bee463 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, "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);
> 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
> @@ -342,21 +346,57 @@ int qemu_open(const char *name, int flags, ...)
> }
> #endif
>
> + if (ret == -1) {
> + const char *action = "open";
> + if (flags & O_CREAT) {
> + action = "create";
> + }
I'd prefer the more concise single assignment
const char *action = flags & O_CREAT ? "create" : "open";
I'd also put it right at the beginning of the function.
> #ifdef O_DIRECT
> - if (ret == -1 && errno == EINVAL && (flags & O_DIRECT)) {
> - int newflags = flags & ~O_DIRECT;
> - ret = open(name, newflags, mode);
> - if (ret != -1) {
> - close(ret);
> - error_report("file system does not support O_DIRECT");
> - errno = EINVAL;
> + if (errno == EINVAL && (flags & O_DIRECT)) {
> + int newflags = flags & ~O_DIRECT;
> + ret = open(name, newflags, mode);
> + if (ret != -1) {
> + close(ret);
> + error_setg(errp, "Could not %s '%s' flags 0x%x: "
> + "filesystem does not support O_DIRECT",
> + action, name, flags);
> + errno = EINVAL;
> + return -1;
> + }
> }
> - }
> #endif /* O_DIRECT */
> + error_setg_errno(errp, errno, "Could not %s '%s' flags 0x%x",
> + action, name, flags);
> + }
> +
Swapping with PATCH 1 will reduce churn here.
>
> 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;
> +}
> +
> int qemu_close(int fd)
> {
> int64_t fdset_id;
Preferably with suggested improvements:
Reviewed-by: Markus Armbruster <armbru@redhat.com>