new libbb func: xmalloc_realpath (+ use it where makes sense)

syslogd, logread: add debugging code (disabled)
syslogs: drastically smaller bss; fix "-C n" behaviour

1 files changed, 65 insertions, 75 deletions

diff --git a/sysklogd/logread.c b/sysklogd/logread.c
index 745f97629..4427cf37e 100644
--- a/sysklogd/logread.c
+++ b/sysklogd/logread.c
@@ -9,46 +9,48 @@
  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
  */
 
-
 #include "busybox.h"
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
 #include <sys/ipc.h>
-#include <sys/types.h>
+//#include <sys/types.h>
 #include <sys/sem.h>
 #include <sys/shm.h>
-#include <signal.h>
-#include <setjmp.h>
-#include <unistd.h>
+//#include <signal.h>
+//#include <setjmp.h>
+
+#define DEBUG 0
 
-static const long KEY_ID = 0x414e4547; /*"GENA"*/
+static const long KEY_ID = 0x414e4547; /* "GENA" */
 
 static struct shbuf_ds {
-        int size;               // size of data written
-        int head;               // start of message list
-        int tail;               // end of message list
+        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 = NULL;                  // shared memory pointer
+} *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 jmp_buf  jmp_env;
+static int log_shmid = -1;      // ipc shared memory id
+static int log_semid = -1;      // ipc semaphore id
 
-static void error_exit(const char *str);
-static void interrupted(int sig);
+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);
+        bb_perror_msg_and_die(str);
+}
 
 /*
  * sem_up - up()'s a semaphore.
  */
 static void sem_up(int semid)
 {
-        if ( semop(semid, SMrup, 1) == -1 )
+        if (semop(semid, SMrup, 1) == -1)
                 error_exit("semop[SMrup]");
 }
 
@@ -57,52 +59,59 @@ static void sem_up(int semid)
  */
 static void sem_down(int semid)
 {
-        if ( semop(semid, SMrdn, 2) == -1 )
+        if (semop(semid, SMrdn, 2) == -1)
                 error_exit("semop[SMrdn]");
 }
 
+static void interrupted(int sig)
+{
+        signal(SIGINT, SIG_IGN);
+        shmdt(buf);
+        exit(0);
+}
+
 int logread_main(int argc, char **argv)
 {
-        int i;
-        int follow=0;
+        int cur;
+        int follow = 1;
 
-        if (argc == 2 && argv[1][0]=='-' && argv[1][1]=='f') {
-                follow = 1;
-        } else {
+        if (argc != 2 || argv[1][0]!='-' || argv[1][1]!='f' ) {
+                follow = 0;
                 /* no options, no getopt */
                 if (argc > 1)
                         bb_show_usage();
         }
 
-        // handle interrupt signal
-        if (setjmp(jmp_env)) goto output_end;
-
-        // attempt to redefine ^C signal
-        signal(SIGINT, interrupted);
-
-        if ( (log_shmid = shmget(KEY_ID, 0, 0)) == -1)
-                error_exit("Can't find circular buffer");
+        log_shmid = shmget(KEY_ID, 0, 0);
+        if (log_shmid == -1)
+                error_exit("can't find circular buffer");
 
         // Attach shared memory to our char*
-        if ( (buf = shmat(log_shmid, NULL, SHM_RDONLY)) == NULL)
-                error_exit("Can't get access to circular buffer from syslogd");
+        buf = shmat(log_shmid, NULL, SHM_RDONLY);
+        if (buf == NULL)
+                error_exit("can't get access to syslogd buffer");
+
+        log_semid = semget(KEY_ID, 0, 0);
+        if (log_semid == -1)
+                error_exit("can't get access to semaphores for syslogd buffer");
 
-        if ( (log_semid = semget(KEY_ID, 0, 0)) == -1)
-                error_exit("Can't get access to semaphore(s) for circular buffer from syslogd");
+        // attempt to redefine ^C signal
+        signal(SIGINT, interrupted);
 
         // Suppose atomic memory move
-        i = follow ? buf->tail : buf->head;
+        cur = follow ? buf->tail : buf->head;
 
         do {
 #ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
                 char *buf_data;
-                int log_len,j;
+                int log_len, j;
 #endif
-
                 sem_down(log_semid);
 
-                //printf("head: %i tail: %i size: %i\n",buf->head,buf->tail,buf->size);
-                if (buf->head == buf->tail || i==buf->tail) {
+                if (DEBUG)
+                        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 */
@@ -114,58 +123,39 @@ int logread_main(int argc, char **argv)
 
                 // Read Memory
 #ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
-                log_len = buf->tail - i;
+                log_len = buf->tail - cur;
                 if (log_len < 0)
                         log_len += buf->size;
                 buf_data = xmalloc(log_len);
 
-                if (buf->tail < i) {
-                        memcpy(buf_data, buf->data+i, buf->size-i);
-                        memcpy(buf_data+buf->size-i, buf->data, buf->tail);
+                if (buf->tail >= cur) {
+                        memcpy(buf_data, buf->data + cur, log_len);
                 } else {
-                        memcpy(buf_data, buf->data+i, buf->tail-i);
+                        memcpy(buf_data, buf->data + cur, buf->size - cur);
+                        memcpy(buf_data + buf->size - cur, buf->data, buf->tail);
                 }
-                i = buf->tail;
-
+                cur = buf->tail;
 #else
-                while ( i != buf->tail) {
-                        printf("%s", buf->data+i);
-                        i+= strlen(buf->data+i) + 1;
-                        if (i >= buf->size )
-                                i=0;
+                while (cur != buf->tail) {
+                        fputs(buf->data + cur, stdout);
+                        cur += strlen(buf->data + cur) + 1;
+                        if (cur >= buf->size)
+                                cur = 0;
                 }
 #endif
                 // release the lock on the log chain
                 sem_up(log_semid);
 
 #ifdef CONFIG_FEATURE_LOGREAD_REDUCED_LOCKING
-                for (j=0; j < log_len; j+=strlen(buf_data+j)+1) {
-                        printf("%s", buf_data+j);
-                        if (follow)
-                                fflush(stdout);
+                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);
 
-output_end:
-        if (log_shmid != -1)
-                shmdt(buf);
+        shmdt(buf);
 
         return EXIT_SUCCESS;
 }
-
-static void interrupted(int sig){
-        signal(SIGINT, SIG_IGN);
-        longjmp(jmp_env, 1);
-}
-
-static void error_exit(const char *str){
-        bb_perror_msg(str);
-        //release all acquired resources
-        if (log_shmid != -1)
-                shmdt(buf);
-
-        exit(1);
-}