code shrinkage by Bernhard Fischer <rep.nop@aon.at>

1 files changed, 31 insertions, 49 deletions

diff --git a/sysklogd/logread.c b/sysklogd/logread.c
index 4427cf3..d092056 100644
--- a/sysklogd/logread.c
+++ b/sysklogd/logread.c
@@ -11,37 +11,30 @@
 
 #include "busybox.h"
 #include <sys/ipc.h>
-//#include <sys/types.h>
 #include <sys/sem.h>
 #include <sys/shm.h>
-//#include <signal.h>
-//#include <setjmp.h>
 
 #define DEBUG 0
 
-static const long KEY_ID = 0x414e4547; /* "GENA" */
+enum { KEY_ID = 0x414e4547 }; /* "GENA" */
 
 static struct shbuf_ds {
-	int32_t size;		// size of data written
-	int32_t head;		// start of message list
-	int32_t tail;		// end of message list
-	char data[1];		// data/messages
-} *buf;				// shared memory pointer
-
+	int32_t size;           // size of data written
+	int32_t head;           // start of message list
+	int32_t tail;           // end of message list
+	char data[1];           // data/messages
+} *buf;                         // shared memory pointer
 
 // Semaphore operation structures
 static struct sembuf SMrup[1] = {{0, -1, IPC_NOWAIT | SEM_UNDO}}; // set SMrup
 static struct sembuf SMrdn[2] = {{1, 0}, {0, +1, SEM_UNDO}}; // set SMrdn
 
-static int log_shmid = -1;	// ipc shared memory id
-static int log_semid = -1;	// ipc semaphore id
 
 static void error_exit(const char *str) ATTRIBUTE_NORETURN;
 static void error_exit(const char *str)
 {
 	//release all acquired resources
-	if (log_shmid != -1)
-		shmdt(buf);
+	shmdt(buf);
 	bb_perror_msg_and_die(str);
 }
 
@@ -54,16 +47,7 @@ static void sem_up(int semid)
 		error_exit("semop[SMrup]");
 }
 
-/*
- * sem_down - down()'s a semaphore
- */
-static void sem_down(int semid)
-{
-	if (semop(semid, SMrdn, 2) == -1)
-		error_exit("semop[SMrdn]");
-}
-
-static void interrupted(int sig)
+static void interrupted(int sig ATTRIBUTE_UNUSED)
 {
 	signal(SIGINT, SIG_IGN);
 	shmdt(buf);
@@ -73,23 +57,18 @@ static void interrupted(int sig)
 int logread_main(int argc, char **argv)
 {
 	int cur;
-	int follow = 1;
-
-	if (argc != 2 || argv[1][0]!='-' || argv[1][1]!='f' ) {
-		follow = 0;
-		/* no options, no getopt */
-		if (argc > 1)
-			bb_show_usage();
-	}
+	int log_semid; /* ipc semaphore id */
+	int log_shmid; /* ipc shared memory id */
+	smallint follow = getopt32(argc, argv, "f");
 
 	log_shmid = shmget(KEY_ID, 0, 0);
 	if (log_shmid == -1)
-		error_exit("can't find circular buffer");
+		bb_perror_msg_and_die("can't find syslogd buffer");
 
 	// Attach shared memory to our char*
 	buf = shmat(log_shmid, NULL, SHM_RDONLY);
 	if (buf == NULL)
-		error_exit("can't get access to syslogd buffer");
+		bb_perror_msg_and_die("can't access syslogd buffer");
 
 	log_semid = semget(KEY_ID, 0, 0);
 	if (log_semid == -1)
@@ -102,38 +81,42 @@ int logread_main(int argc, char **argv)
 	cur = follow ? buf->tail : buf->head;
 
 	do {
-#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
 		char *buf_data;
 		int log_len, j;
 #endif
-		sem_down(log_semid);
+		if (semop(log_semid, SMrdn, 2) == -1)
+			error_exit("semop[SMrdn]");
 
 		if (DEBUG)
-			printf("head:%i cur:%d tail:%i size:%i\n", buf->head, cur, buf->tail, buf->size);
+			printf("head:%i cur:%d tail:%i size:%i\n",
+					buf->head, cur, buf->tail, buf->size);
 
 		if (buf->head == buf->tail || cur == buf->tail) {
 			if (follow) {
 				sem_up(log_semid);
-				sleep(1);	/* TODO: replace me with a sleep_on */
+				fflush(stdout);
+				sleep(1); /* TODO: replace me with a sleep_on */
 				continue;
-			} else {
-				printf("<empty syslog>\n");
 			}
+			puts("<empty syslog>");
 		}
 
 		// Read Memory
-#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
 		log_len = buf->tail - cur;
 		if (log_len < 0)
 			log_len += buf->size;
 		buf_data = xmalloc(log_len);
 
-		if (buf->tail >= cur) {
-			memcpy(buf_data, buf->data + cur, log_len);
-		} else {
-			memcpy(buf_data, buf->data + cur, buf->size - cur);
+		if (buf->tail >= cur)
+			j = log_len;
+		else
+			j = buf->size - cur;
+		memcpy(buf_data, buf->data + cur, j);
+
+		if (buf->tail < cur)
 			memcpy(buf_data + buf->size - cur, buf->data, buf->tail);
-		}
 		cur = buf->tail;
 #else
 		while (cur != buf->tail) {
@@ -146,16 +129,15 @@ int logread_main(int argc, char **argv)
 		// release the lock on the log chain
 		sem_up(log_semid);
 
-#ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
+#if ENABLE_FEATURE_LOGREAD_REDUCED_LOCKING
 		for (j = 0; j < log_len; j += strlen(buf_data+j) + 1) {
 			fputs(buf_data + j, stdout);
 		}
 		free(buf_data);
 #endif
-		fflush(stdout);
 	} while (follow);
 
 	shmdt(buf);
 
-	return EXIT_SUCCESS;
+	fflush_stdout_and_exit(EXIT_SUCCESS);
 }