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authorDenis Vlasenko2007-08-12 21:33:06 +0000
committerDenis Vlasenko2007-08-12 21:33:06 +0000
commit5f1b149d541ebba7cab841cb647f113248f9fb8f (patch)
treee7f962fba89b6e201b4c857e32d85c9671b3db0d /sysklogd/syslogd.c
parent1b9064d5355b5c26676e8447a1900116066e42e4 (diff)
downloadbusybox-5f1b149d541ebba7cab841cb647f113248f9fb8f.zip
busybox-5f1b149d541ebba7cab841cb647f113248f9fb8f.tar.gz
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
Diffstat (limited to 'sysklogd/syslogd.c')
-rw-r--r--sysklogd/syslogd.c55
1 files changed, 12 insertions, 43 deletions
diff --git a/sysklogd/syslogd.c b/sysklogd/syslogd.c
index 0ed16bc..6ecbd16 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
}