Hi Daniel,
> When using syslog() directly we are in danger to deadlock
> when syslog() is already been called by normal code
> and the signal kicks in. With using a socket to "/dev/log"
> we are safe even in the signal handler to log messages.
> ---
> src/log.c | 153
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
> 1 files changed, 143 insertions(+), 10 deletions(-)
so we wanna just use /dev/log from all of our logging calls. Is this to
unify things a bit further or is this fixing a real bug as well. I was
thinking of keep using syslog() and only open /dev/log from the signal
handler.
> diff --git a/src/log.c b/src/log.c
> index 04e61f3..63f1df3 100644
> --- a/src/log.c
> +++ b/src/log.c
> @@ -32,12 +32,92 @@
> #include <syslog.h>
> #include <execinfo.h>
> #include <dlfcn.h>
> +#include <sys/socket.h>
> +#include <sys/un.h>
> +#include <errno.h>
>
> #include "connman.h"
>
> static const char *program_exec;
> static const char *program_path;
>
> +static int log_option;
Maybe we can a bit smarter in just always have to check the log_option.
> +static int syslog_fd;
> +
> +static char *program_str;
> +static char *pid_str;
> +static const char * const level_str[] = { "<0>", "<1>", "<2>", "<3>",
> + "<4>", "<5>", "<6>", "<7>" };
There is a double const here ;)
> +
> +#define IOVEC_SET_STRING(i, s) \
> + do { \
> + struct iovec *_i = &(i); \
> + char *_s = (char *)(s); \
> + _i->iov_base = _s; \
> + _i->iov_len = strlen(_s); \
> + } while (0);
> +
> +static int write_to_syslog(unsigned int level, const char *buffer)
> +{
> + struct iovec iovec[4];
> + struct msghdr msghdr;
> +
> + if (level > LOG_DEBUG)
> + level = LOG_DEBUG;
> +
> + memset(iovec, 0, sizeof(iovec));
> + IOVEC_SET_STRING(iovec[0], level_str[level]);
> + IOVEC_SET_STRING(iovec[1], program_str);
> + IOVEC_SET_STRING(iovec[2], pid_str);
> + IOVEC_SET_STRING(iovec[3], buffer);
> +
> + memset(&msghdr, 0, sizeof(msghdr));
> + msghdr.msg_iov = iovec;
> + msghdr.msg_iovlen = 4;
> +
> + if (writev(syslog_fd, iovec, 4) < 0)
> + return -errno;
> +
> + return 0;
> +}
> +
> +static int write_to_console(const char *buffer)
> +{
> + struct iovec iovec[4];
> + struct msghdr msghdr;
> +
> + memset(iovec, 0, sizeof(iovec));
> + IOVEC_SET_STRING(iovec[0], program_str);
> + IOVEC_SET_STRING(iovec[1], pid_str);
> + IOVEC_SET_STRING(iovec[2], buffer);
> + IOVEC_SET_STRING(iovec[3], "\n");
> +
> + memset(&msghdr, 0, sizeof(msghdr));
> + msghdr.msg_iov = iovec;
> + msghdr.msg_iovlen = 4;
> +
> + if (writev(STDERR_FILENO, iovec, 4) < 0)
> + return -errno;
> +
> + return 0;
> +}
To optimize this, we might be able to create only one iovec and just
call writev with an offset to it. I don't see a need to allocate an
iovec twice.
> +
> +static void log_dispatch(unsigned int level, const char *format, va_list ap)
> +{
> + char name[16], pid[16];
> + char *buffer;
> + int len;
So who is using name, pid and len (and more important why the compiler
did not complain loudly).
> +
> + len = vasprintf(&buffer, format, ap);
> +
> + write_to_syslog(level, buffer);
> +
> + if ((log_option & LOG_PERROR) == LOG_PERROR)
> + write_to_console(buffer);
> +
> + free(buffer);
> +}
> +
> /**
> * connman_info:
> * @format: format string
> @@ -51,7 +131,7 @@ void connman_info(const char *format, ...)
>
> va_start(ap, format);
>
> - vsyslog(LOG_INFO, format, ap);
> + log_dispatch(LOG_INFO, format, ap);
>
> va_end(ap);
> }
> @@ -69,7 +149,7 @@ void connman_warn(const char *format, ...)
>
> va_start(ap, format);
>
> - vsyslog(LOG_WARNING, format, ap);
> + log_dispatch(LOG_WARNING, format, ap);
>
> va_end(ap);
> }
> @@ -87,7 +167,7 @@ void connman_error(const char *format, ...)
>
> va_start(ap, format);
>
> - vsyslog(LOG_ERR, format, ap);
> + log_dispatch(LOG_ERR, format, ap);
>
> va_end(ap);
> }
> @@ -105,7 +185,7 @@ void connman_debug(const char *format, ...)
>
> va_start(ap, format);
>
> - vsyslog(LOG_DEBUG, format, ap);
> + log_dispatch(LOG_DEBUG, format, ap);
>
> va_end(ap);
> }
> @@ -238,6 +318,37 @@ static void signal_setup(sighandler_t handler)
> sigaction(SIGPIPE, &sa, NULL);
> }
>
> +static int open_syslog(void)
> +{
> + union {
> + struct sockaddr sa;
> + struct sockaddr_un un;
> + } sa;
Please don't do that. Just cast it in connect() call.
> + memset(&sa, 0, sizeof(sa));
> + sa.un.sun_family = AF_UNIX;
> + strncpy(sa.un.sun_path, "/dev/log", sizeof(sa.un.sun_path));
You could just use strcpy since we know how long the string is.
> +
> + syslog_fd = socket(AF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0);
> + if (syslog_fd < 0)
> + return -errno;
> +
> + if (connect(syslog_fd, &sa.sa, sizeof(sa)) < 0) {
> + close(syslog_fd);
> + return -errno;
> + }
> +
> + return 0;
> +}
> +
> +static void close_syslog(void)
> +{
> + if (syslog_fd <= 0)
> + return;
> +
> + close(syslog_fd);
> +}
> +
For open_syslog and close_syslog we might be better do it directly in
init and exit functions of src/log.c here. No need trying to emulate
syslog.
> extern struct connman_debug_desc __start___debug[];
> extern struct connman_debug_desc __stop___debug[];
>
> @@ -320,6 +431,7 @@ int __connman_log_init(const char *program, const char
> *debug,
> {
> static char path[PATH_MAX];
> int option = LOG_NDELAY | LOG_PID;
> + int err;
>
> program_exec = program;
> program_path = getcwd(path, sizeof(path));
> @@ -329,25 +441,46 @@ int __connman_log_init(const char *program, const char
> *debug,
>
> __connman_log_enable(__start___debug, __stop___debug);
>
> + if (asprintf(&program_str, "%s", basename(program_exec)) < 0) {
> + err = -errno;
> + goto err;
> + }
> +
> + if (asprintf(&pid_str, "[%lu]: ", (unsigned long)getpid()) < 0) {
> + err = -errno;
> + goto err;
> + }
> +
> + err = open_syslog();
> + if (err < 0)
> + goto err;
> +
> if (detach == FALSE)
> - option |= LOG_PERROR;
> + log_option |= LOG_PERROR;
>
> signal_setup(signal_handler);
>
> - openlog(basename(program), option, LOG_DAEMON);
> -
> - syslog(LOG_INFO, "Connection Manager version %s", VERSION);
> + connman_info("Connection Manager version %s", VERSION);
>
> return 0;
> +
> +err:
> + g_free(program_str);
> + g_free(pid_str);
> +
> + return err;
> }
>
> void __connman_log_cleanup(void)
> {
> - syslog(LOG_INFO, "Exit");
> + connman_info("Exit");
>
> - closelog();
> + close_syslog();
>
> signal_setup(SIG_DFL);
>
> + g_free(program_str);
> + g_free(pid_str);
> +
We could just have static strings here. We know what the max will be.
> g_strfreev(enabled);
> }
Regards
Marcel
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