From 5f1b149d541ebba7cab841cb647f113248f9fb8f Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Sun, 12 Aug 2007 21:33:06 +0000 Subject: syslogd,logread: get rid of head pointer, fix logread bug in the process function old new delta logread_main 450 462 +12 syslogd_main 1246 1252 +6 shbuf - 4 +4 buf 34 30 -4 packed_usage 22729 22724 -5 log_locally 957 767 -190 ------------------------------------------------------------------------------ (add/remove: 1/0 grow/shrink: 2/3 up/down: 22/-199) Total: -177 bytes text data bss dec hex filename 773886 1116 11316 786318 bff8e busybox_old 773714 1116 11316 786146 bfee2 busybox_unstripped --- sysklogd/syslogd.c | 55 ++++++++++++------------------------------------------ 1 file changed, 12 insertions(+), 43 deletions(-) (limited to 'sysklogd/syslogd.c') diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c index 0ed16bc9e..6ecbd16f0 100644 --- a/sysklogd/syslogd.c +++ b/sysklogd/syslogd.c @@ -46,8 +46,7 @@ enum { MAX_READ = 256 }; /* Semaphore operation structures */ struct shbuf_ds { - int32_t size; /* size of data written */ - int32_t head; /* start of message list */ + int32_t size; /* size of data - 1 */ int32_t tail; /* end of message list */ char data[1]; /* data/messages */ }; @@ -212,8 +211,9 @@ static void ipcsyslog_init(void) bb_perror_msg_and_die("shmat"); } - G.shbuf->size = G.shm_size - offsetof(struct shbuf_ds, data); - G.shbuf->head = G.shbuf->tail = 0; + memset(G.shbuf, 0, G.shm_size); + G.shbuf->size = G.shm_size - offsetof(struct shbuf_ds, data) - 1; + /*G.shbuf->tail = 0;*/ // we'll trust the OS to set initial semval to 0 (let's hope) G.s_semid = semget(KEY_ID, 2, IPC_CREAT | IPC_EXCL | 1023); @@ -231,7 +231,6 @@ static void ipcsyslog_init(void) static void log_to_shmem(const char *msg, int len) { int old_tail, new_tail; - char *c; if (semop(G.s_semid, G.SMwdn, 3) == -1) { bb_perror_msg_and_die("SMwdn"); @@ -240,49 +239,20 @@ static void log_to_shmem(const char *msg, int len) /* Circular Buffer Algorithm: * -------------------------- * tail == position where to store next syslog message. - * head == position of next message to retrieve ("print"). - * if head == tail, there is no "unprinted" messages left. - * head is typically advanced by separate "reader" program, - * but if there isn't one, we have to do it ourself. - * messages are NUL-separated. + * tail's max value is (shbuf->size - 1) + * Last byte of buffer is never used and remains NUL. */ len++; /* length with NUL included */ again: old_tail = G.shbuf->tail; new_tail = old_tail + len; if (new_tail < G.shbuf->size) { - /* No need to move head if shbuf->head <= old_tail, - * else... */ - if (old_tail < G.shbuf->head && G.shbuf->head <= new_tail) { - /* ...need to move head forward */ - c = memchr(G.shbuf->data + new_tail, '\0', - G.shbuf->size - new_tail); - if (!c) /* no NUL ahead of us, wrap around */ - c = memchr(G.shbuf->data, '\0', old_tail); - if (!c) { /* still nothing? point to this msg... */ - G.shbuf->head = old_tail; - } else { - /* convert pointer to offset + skip NUL */ - G.shbuf->head = c - G.shbuf->data + 1; - } - } /* store message, set new tail */ memcpy(G.shbuf->data + old_tail, msg, len); G.shbuf->tail = new_tail; } else { - /* we need to break up the message and wrap it around */ /* k == available buffer space ahead of old tail */ - int k = G.shbuf->size - old_tail - 1; - if (G.shbuf->head > old_tail) { - /* we are going to overwrite head, need to - * move it out of the way */ - c = memchr(G.shbuf->data, '\0', old_tail); - if (!c) { /* nothing? point to this msg... */ - G.shbuf->head = old_tail; - } else { /* convert pointer to offset + skip NUL */ - G.shbuf->head = c - G.shbuf->data + 1; - } - } + int k = G.shbuf->size - old_tail; /* copy what fits to the end of buffer, and repeat */ memcpy(G.shbuf->data + old_tail, msg, k); msg += k; @@ -294,7 +264,7 @@ static void log_to_shmem(const char *msg, int len) bb_perror_msg_and_die("SMwup"); } if (DEBUG) - printf("head:%d tail:%d\n", G.shbuf->head, G.shbuf->tail); + printf("tail:%d\n", G.shbuf->tail); } #else void ipcsyslog_cleanup(void); @@ -339,11 +309,10 @@ static void log_locally(char *msg) } #if ENABLE_FEATURE_ROTATE_LOGFILE { - struct stat statf; - - G.isRegular = (fstat(G.logFD, &statf) == 0 && (statf.st_mode & S_IFREG)); - /* bug (mostly harmless): can wrap around if file > 4gb */ - G.curFileSize = statf.st_size; + struct stat statf; + G.isRegular = (fstat(G.logFD, &statf) == 0 && S_ISREG(statf.st_mode)); + /* bug (mostly harmless): can wrap around if file > 4gb */ + G.curFileSize = statf.st_size; } #endif } -- cgit v1.2.3