Add a snprinf wrapper which checks that the buffer was big enough

If we scale our buffer to be wide enough for the format string, we
should expect that the calculation was correct.

char_array_0() invocations are removed, since snprintf nul-terminates
the output in any case.

A similar wrapper is used for strftime calls, but only in timedatectl.c.

1 files changed, 4 insertions, 5 deletions

diff --git a/src/journal/journald-syslog.c b/src/journal/journald-syslog.c
index 21bc9679c2..ba6e3316d6 100644
--- a/src/journal/journald-syslog.c
+++ b/src/journal/journald-syslog.c
@@ -124,7 +124,8 @@ static void forward_syslog_raw(Server *s, int priority, const char *buffer, cons
 
 void server_forward_syslog(Server *s, int priority, const char *identifier, const char *message, const struct ucred *ucred, const struct timeval *tv) {
         struct iovec iovec[5];
-        char header_priority[6], header_time[64], header_pid[16];
+        char header_priority[4], header_time[64],
+             header_pid[sizeof("[]: ")-1 + DECIMAL_STR_MAX(pid_t) + 1];
         int n = 0;
         time_t t;
         struct tm *tm;
@@ -139,8 +140,7 @@ void server_forward_syslog(Server *s, int priority, const char *identifier, cons
                 return;
 
         /* First: priority field */
-        snprintf(header_priority, sizeof(header_priority), "<%i>", priority);
-        char_array_0(header_priority);
+        xsprintf(header_priority, "<%i>", priority);
         IOVEC_SET_STRING(iovec[n++], header_priority);
 
         /* Second: timestamp */
@@ -159,8 +159,7 @@ void server_forward_syslog(Server *s, int priority, const char *identifier, cons
                         identifier = ident_buf;
                 }
 
-                snprintf(header_pid, sizeof(header_pid), "["PID_FMT"]: ", ucred->pid);
-                char_array_0(header_pid);
+                xsprintf(header_pid, "["PID_FMT"]: ", ucred->pid);
 
                 if (identifier)
                         IOVEC_SET_STRING(iovec[n++], identifier);