syslogd: start using bb_common_bufsiz1 instead of stack/malloc

logger: optimize, also use bb_common_bufsiz1 (~40 bytes)
tested to eat arbitrarily-sized input at high speed - ok

1 files changed, 35 insertions, 28 deletions

diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 7edce7a0a..fbb85338a 100644
--- a/sysklogd/syslogd.c
+++ b/sysklogd/syslogd.c
@@ -56,13 +56,23 @@ static int remoteFD = -1;
 static struct sockaddr_in remoteAddr;
 #endif
 
-
-/* NB: we may need 2x this amount on stack... */
-enum { MAX_READ = 1024 };
-
-
-/* options */
-/* Correct regardless of combination of CONFIG_xxx */
+/* We are using bb_common_bufsiz1 for buffering: */
+enum { MAX_READ = (BUFSIZ/6) & ~0xf };
+/* We recv into this... (size: MAX_READ ~== BUFSIZ/6) */
+#define RECVBUF  bb_common_bufsiz1
+/* ...then copy here, escaping control chars */
+/* (can grow x2 + 1 max ~== BUFSIZ/3) */
+#define PARSEBUF (bb_common_bufsiz1 + MAX_READ)
+/* ...then sprintf into this, adding timestamp (15 chars),
+ * host (64), fac.prio (20) to the message */
+/* (growth by: 15 + 64 + 20 + delims = ~110) */
+#define PRINTBUF (bb_common_bufsiz1 + 3*MAX_READ + 0x10)
+/* totals: BUFSIZ/6 + BUFSIZ/3 + BUFSIZ/3 = BUFSIZ - BUFSIZ/6
+ * -- we have BUFSIZ/6 extra at the ent of PRINTBUF
+ * which covers needed ~110 extra bytes (and much more) */
+
+
+/* Options */
 enum {
         OPTBIT_mark = 0, // -m
         OPTBIT_nofork, // -n
@@ -175,11 +185,12 @@ static void ipcsyslog_init(void)
         }
 }
 
-/* write message to buffer */
+/* Write message to shared mem buffer */
 static void log_to_shmem(const char *msg, int len)
 {
-        static /*const*/ struct sembuf SMwup[1] = { {1, -1, IPC_NOWAIT} };
-        static /*const*/ struct sembuf SMwdn[3] = { {0, 0}, {1, 0}, {1, +1} };
+        /* Why libc insists on these being rw? */
+        static struct sembuf SMwup[1] = { {1, -1, IPC_NOWAIT} };
+        static struct sembuf SMwdn[3] = { {0, 0}, {1, 0}, {1, +1} };
 
         int old_tail, new_tail;
         char *c;
@@ -362,9 +373,9 @@ static void parse_fac_prio_20(int pri, char *res20)
         }
 }
 
-/* len parameter is used only for "is there a timestamp?" check
+/* len parameter is used only for "is there a timestamp?" check.
  * NB: some callers cheat and supply 0 when they know
- * that there is no timestamp, short-cutting the test */
+ * that there is no timestamp, short-cutting the test. */
 static void timestamp_and_log(int pri, char *msg, int len)
 {
         time_t now;
@@ -385,31 +396,29 @@ static void timestamp_and_log(int pri, char *msg, int len)
         if (!ENABLE_FEATURE_REMOTE_LOG || (option_mask32 & OPT_locallog)) {
                 if (LOG_PRI(pri) < logLevel) {
                         if (option_mask32 & OPT_small)
-                                msg = xasprintf("%s %s\n", timestamp, msg);
+                                sprintf(PRINTBUF, "%s %s\n", timestamp, msg);
                         else {
                                 char res[20];
                                 parse_fac_prio_20(pri, res);
-                                msg = xasprintf("%s %s %s %s\n", timestamp, localHostName, res, msg);
+                                sprintf(PRINTBUF, "%s %s %s %s\n", timestamp, localHostName, res, msg);
                         }
-                        log_locally(msg);
-                        free(msg);
+                        log_locally(PRINTBUF);
                 }
         }
 }
 
 static void split_escape_and_log(char *tmpbuf, int len)
 {
-        char line[len * 2 + 1]; /* gcc' cheap alloca */
         char *p = tmpbuf;
 
         tmpbuf += len;
         while (p < tmpbuf) {
                 char c;
-                char *q = line;
+                char *q = PARSEBUF;
                 int pri = (LOG_USER | LOG_NOTICE);
 
                 if (*p == '<') {
-                        /* Parse the magic priority number. */
+                        /* Parse the magic priority number */
                         pri = bb_strtou(p + 1, &p, 10);
                         if (*p == '>') p++;
                         if (pri & ~(LOG_FACMASK | LOG_PRIMASK)) {
@@ -427,8 +436,8 @@ static void split_escape_and_log(char *tmpbuf, int len)
                         *q++ = c;
                 }
                 *q = '\0';
-                /* now log it */
-                timestamp_and_log(pri, line, q - line);
+                /* Now log it */
+                timestamp_and_log(pri, PARSEBUF, q - PARSEBUF);
         }
 }
 
@@ -509,11 +518,10 @@ static void do_syslogd(void)
 
                 if (FD_ISSET(sock_fd, &fds)) {
                         int i;
-#define tmpbuf bb_common_bufsiz1
-                        i = recv(sock_fd, tmpbuf, MAX_READ, 0);
+                        i = recv(sock_fd, RECVBUF, MAX_READ - 1, 0);
                         if (i <= 0)
                                 bb_perror_msg_and_die("UNIX socket error");
-                        /* TODO: maybe supress duplicates? */
+                        /* TODO: maybe suppress duplicates? */
 #if ENABLE_FEATURE_REMOTE_LOG
                         /* We are not modifying log messages in any way before send */
                         /* Remote site cannot trust _us_ anyway and need to do validation again */
@@ -523,15 +531,14 @@ static void do_syslogd(void)
                                 }
                                 if (-1 != remoteFD) {
                                         /* send message to remote logger, ignore possible error */
-                                        sendto(remoteFD, tmpbuf, i, MSG_DONTWAIT,
+                                        sendto(remoteFD, RECVBUF, i, MSG_DONTWAIT,
                                                 (struct sockaddr *) &remoteAddr,
                                                 sizeof(remoteAddr));
                                 }
                         }
 #endif
-                        tmpbuf[i] = '\0';
-                        split_escape_and_log(tmpbuf, i);
-#undef tmpbuf
+                        RECVBUF[i] = '\0';
+                        split_escape_and_log(RECVBUF, i);
                 } /* FD_ISSET() */
         } /* for */
 }