Re: [PATCH v3 17/20] util: add support for formatting a workload name in messages

["Dr. David Alan Gilbert" <dave@treblig.org>]

* Daniel P. Berrangé (berrange@redhat.com) wrote:
> The error_report function can include the guest name in any
> messages it prints. The qemu_log function has no equivalent
> behaviour.
> 
> This introduces support for a "workload name" in the new
> messages API, which in the case of system emulators will
> be the guest name. The possibility of defining a workload
> name for other binaries is left as an exercise for the
> future.
> 
> This change has no impact on the output of the error_report
> function, but will change the qemu_log function. This can
> be easily seen with the 'log' trace backend, and how it is
> now more closely matching error_report output.
> 
> Before:
> 
>   # qemu-system-x86_64 -msg guest-name=on -name blah -object tls-creds-x509,id=t0,dir=fish -d 'trace:qcrypto*'
>   qcrypto_tls_creds_x509_load TLS creds x509 load creds=0x55b3af3fd870 dir=fish
>   qcrypto_tls_creds_get_path TLS creds path creds=0x55b3af3fd870 filename=ca-cert.pem path=<none>
>   blah qemu-system-x86_64: Unable to access credentials fish/ca-cert.pem: No such file or directory
> 
> After:
> 
>   # qemu-system-x86_64 -msg guest-name=on -name blah -object tls-creds-x509,id=t0,dir=fish -d 'trace:qcrypto*'
>   blah qcrypto_tls_creds_x509_load TLS creds x509 load creds=0x55b3af3fd870 dir=fish
>   blah qcrypto_tls_creds_get_path TLS creds path creds=0x55b3af3fd870 filename=ca-cert.pem path=<none>
>   blah qemu-system-x86_64: Unable to access credentials fish/ca-cert.pem: No such file or directory
> 
> Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Are you going to want to escape that? I see later you're adding []'s around it,
which makes it feel like you want to end up with it parsable, but if some nasty
person does:

-name ']})🐧({['

then things get confusing; I guess you're hoping that whoever calls qemu will
be careful not to allow that.

Dave

> ---
>  include/qemu/error-report.h |  3 ---
>  include/qemu/message.h      | 10 ++++++++++
>  system/vl.c                 |  6 ++++--
>  util/error-report.c         |  7 -------
>  util/message.c              | 12 +++++++++++-
>  5 files changed, 25 insertions(+), 13 deletions(-)
> 
> diff --git a/include/qemu/error-report.h b/include/qemu/error-report.h
> index c8000778ec..ffc305f828 100644
> --- a/include/qemu/error-report.h
> +++ b/include/qemu/error-report.h
> @@ -70,7 +70,4 @@ void error_init(const char *argv0);
>                                fmt, ##__VA_ARGS__);      \
>      })
>  
> -extern bool error_with_guestname;
> -extern const char *error_guest_name;
> -
>  #endif
> diff --git a/include/qemu/message.h b/include/qemu/message.h
> index 0a06421f77..cfc3c92648 100644
> --- a/include/qemu/message.h
> +++ b/include/qemu/message.h
> @@ -5,6 +5,7 @@
>  
>  enum QMessageFormatFlags {
>      QMESSAGE_FORMAT_TIMESTAMP = (1 << 0),
> +    QMESSAGE_FORMAT_WORKLOAD_NAME = (1 << 1),
>  };
>  
>  /**
> @@ -16,6 +17,15 @@ enum QMessageFormatFlags {
>   */
>  void qmessage_set_format(int flags);
>  
> +/**
> + * qmessage_set_workload_name:
> + * @name: the name of the workload
> + *
> + * Set the workload name, which for a system emulator
> + * will be the guest VM name.
> + */
> +void qmessage_set_workload_name(const char *name);
> +
>  /**
>   * qmessage_context_print:
>   * @fp: file to emit the prefix on
> diff --git a/system/vl.c b/system/vl.c
> index 696dd92669..fee6fdf7b1 100644
> --- a/system/vl.c
> +++ b/system/vl.c
> @@ -818,7 +818,9 @@ static void configure_msg(QemuOpts *opts)
>      if (qemu_opt_get_bool(opts, "timestamp", false)) {
>          flags |= QMESSAGE_FORMAT_TIMESTAMP;
>      }
> -    error_with_guestname = qemu_opt_get_bool(opts, "guest-name", false);
> +    if (qemu_opt_get_bool(opts, "guest-name", false)) {
> +        flags |= QMESSAGE_FORMAT_WORKLOAD_NAME;
> +    }
>      qmessage_set_format(flags);
>  }
>  
> @@ -3520,7 +3522,7 @@ void qemu_init(int argc, char **argv)
>                      exit(1);
>                  }
>                  /* Capture guest name if -msg guest-name is used later */
> -                error_guest_name = qemu_opt_get(opts, "guest");
> +                qmessage_set_workload_name(qemu_opt_get(opts, "guest"));
>                  break;
>              case QEMU_OPTION_prom_env:
>                  if (nb_prom_envs >= MAX_PROM_ENVS) {
> diff --git a/util/error-report.c b/util/error-report.c
> index 719f059494..c40cdf3bb3 100644
> --- a/util/error-report.c
> +++ b/util/error-report.c
> @@ -25,8 +25,6 @@ typedef enum {
>      REPORT_TYPE_INFO,
>  } report_type;
>  
> -bool error_with_guestname;
> -const char *error_guest_name;
>  
>  typedef void (*error_print_func)(void *opaque, const char *fmt, ...);
>  typedef void (*error_print_vfunc)(void *opaque, const char *fmt, va_list ap);
> @@ -218,11 +216,6 @@ static void vreport(report_type type, const char *fmt, va_list ap)
>          qmessage_context_print(stderr);
>      }
>  
> -    /* Only prepend guest name if -msg guest-name and -name guest=... are set */
> -    if (error_with_guestname && error_guest_name && !cur) {
> -        print_func(print_opaque, "%s ", error_guest_name);
> -    }
> -
>      print_loc(!!cur, print_func, print_opaque);
>  
>      switch (type) {
> diff --git a/util/message.c b/util/message.c
> index ef70e08c5f..a91c008e08 100644
> --- a/util/message.c
> +++ b/util/message.c
> @@ -6,18 +6,28 @@
>  #include "monitor/monitor.h"
>  
>  static int message_format;
> +static char *message_workloadname;
>  
>  void qmessage_set_format(int flags)
>  {
>      message_format = flags;
>  }
>  
> -void qmessage_context_print(FILE *fp)
> +void qmessage_set_workload_name(const char *name)
>  {
> +    message_workloadname = g_strdup(name);
> +}
>  
> +void qmessage_context_print(FILE *fp)
> +{
>      if (message_format & QMESSAGE_FORMAT_TIMESTAMP) {
>          g_autoptr(GDateTime) dt = g_date_time_new_now_utc();
>          g_autofree char *timestr = g_date_time_format_iso8601(dt);
>          fprintf(fp, "%s ", timestr);
>      }
> +
> +    if ((message_format & QMESSAGE_FORMAT_WORKLOAD_NAME) &&
> +        message_workloadname) {
> +        fprintf(fp, "%s ", message_workloadname);
> +    }
>  }
> -- 
> 2.50.1
> 
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\        dave @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/