Daemon(8) additional syslog logging capabilities

[grell64_gmail.com]

Summary

This patch uses the logger(1) command line utility to pass over the specified daemonized program's standard output and standard error to syslog. I use dup2 to duplicate the stderr and stdout. The option -s specifies that syslog is to be used, -h gives the user control over the facility and priority of the syslog messages, and -t allows the user to specify a custom tag. I use popen to send data to the logger command.

[bcr]

Why did you add the core team to the review? What kind of input do you need from us?

[grell64_gmail.com]

I'm not quite sure who to send it to. This is my first time submitting a
patch and I'm unsure where it should go.

[garga]

Please fix style(9)

daemon_syslog.c

212

I don't think this comment is relevant

243

This comment is also not relevant

[jhb]

One thing to consider is how to handle incorrectly formatted -p arguments. Does logger log its own error to stderr in that case? Alternatively you would need to do your own validation when parsing it.

daemon_syslog.c

218

Rather than using fixed-size strings, consider using open_memstream(). It lets you use stdio to build a dynamically-sized string. (sbuf is also an option but is in a separate library.) You would do something like this:

if (syslog) {
    FILE *fp;
    char *logger_cmd;
    size_t len;
    int fd;

    fp = open_memstream(&logger_cmd, &len);
    fprintf(fp, "logger");
    if (tag != NULL)
        fprintf(fp, " -t %s", tag);
    if (priority != NULL)
        fprintf(fp, "-p %s", priority);
    fclose(fp);
    
    fp = popen(logger_cmd, "w");
    if (fp == NULL)
        goto exit;

    fd = fileno(fp);
    dup2(fd, STDOUT_FILENO);
    dup2(fd, STDERR_FILENO);
    close(fd);
}