[PATCH v2 05/14] Warn when attempting to log in a signal unsafe manner from signal context

[Peter Hutterer]

On Mon, Apr 09, 2012 at 11:17:31AM -0700, Chase Douglas wrote:
> Also, print out the offending message format. This will hopefully help
> developers track down unsafe logging.
> 
> Signed-off-by: Chase Douglas <chase.douglas at canonical.com>
> ---
>  os/log.c |   31 +++++++++++++++++++++++++++++++
>  1 files changed, 31 insertions(+), 0 deletions(-)
> 
> diff --git a/os/log.c b/os/log.c
> index 2583fe8..8a59306 100644
> --- a/os/log.c
> +++ b/os/log.c
> @@ -288,6 +288,21 @@ LogVWrite(int verb, const char *f, va_list args)
>      int len = 0;
>      static Bool newline = TRUE;
>  
> +    if (inSignalContext) {
> +        static const char warning[] = "Warning: attempting to log data in a "
> +                                      "signal unsafe manner while in signal "
> +                                      "context. Please update to check "
> +                                      "inSignalContext and/or use "
> +                                      "LogMessageVerbSigSafe(). The offending "
> +                                      "log format message is:\n";
> +
> +        write(logFileFd, warning, sizeof(warning) - 1);
> +
> +        write(logFileFd, f, strlen_sigsafe(f));
> +
> +        return;
> +    }
> +

can we use a BUG_WARN derivative (BUG_WARN_SIGSAFE?) here?

Cheers,
  Peter

>      if (newline) {
>          sprintf(tmpBuffer, "[%10.3f] ", GetTimeInMillis() / 1000.0);
>          len = strlen(tmpBuffer);
> @@ -457,6 +472,22 @@ LogVHdrMessageVerb(MessageType type, int verb, const char *msg_format,
>      char *p;
>      int left;
>  
> +    if (inSignalContext) {
> +        static const char warning[] = "Warning: attempting to log data in a "
> +                                      "signal unsafe manner while in signal "
> +                                      "context. Please update to check "
> +                                      "inSignalContext and/or use "
> +                                      "LogMessageVerbSigSafe(). The offending "
> +                                      "header and log message formats are:\n";
> +
> +        write(logFileFd, warning, sizeof(warning) - 1);
> +
> +        write(logFileFd, hdr_format, strlen_sigsafe(hdr_format));
> +        write(logFileFd, msg_format, strlen_sigsafe(msg_format));
> +
> +        return;
> +    }
> +
>      type_str = LogMessageTypeVerbString(type, verb);
>      if (!type_str)
>          return;
> -- 
> 1.7.9.1
>