デーモンの作成中にforkが失敗する

Question

私は可変引数で呼び出されるCプログラムを持っています。このプログラムは、引数を使用してコマンドを作成し、次にフォークを使用して子プロセスを作成します。しかし、プログラムへの引数の数が多いほどfork()コマンドが失敗することがわかります。

これがどうして起こるのか？

int main(int argc, char *argv[]) 
{ 
    FILE *logfile; 
    int other=0; 
    int i, pid; 
    char *conn="conntrack -E"; 
    char *logger="logger -t log-conntrack -p daemon.notice"; 
    char *fother="grep -vE 'tcp|udp|icmp'"; 
    char cmd[1024]; 
    int length = 0; 
    char * temp_cmd = cmd; 

    for (i=1; i<argc; i++) { 
    printf("for loop\n"); 
     switch(argv[i][1]) { 
     case 'p': if (i+1 < argc && argv[i+1][0] != '-') { 
          if (strncmp(argv[i+1], "other", 
             strlen(argv[i+1])) == 0) { 
            other=1; 
            snprintf(cmd, sizeof (cmd), "%s", conn); 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } else if ((strncmp(argv[i+1], "tcp", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "udp", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "icmp", 
              strlen(argv[i+1])) == 0)) { 
            snprintf(cmd, sizeof (cmd), "%s%s%s", conn, " -p ", argv[i+1]); 
            other=0; 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } 
        } 
        break; 
case 'e': 
        if (i+1 < argc && argv[i+1][0] != '-') { 
          if ((strncmp(argv[i+1], "NEW", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "UPDATES", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "DESTROY", 
              strlen(argv[i+1])) == 0)) { 
            if (other == 1) { 
             snprintf(temp_cmd, sizeof (cmd) - length, "%s%s%s%s%s%s%s", " -e ", argv[i+1], " -o id", " | ", fother, " | ", logger); 
             cmds[pcounter] = malloc(strlen+1); 
             strcpy(cmds[pcounter],cmd); 
             pcounter++; 
            } else if ((strncmp(argv[i-1], "tcp",strlen(argv[i-1]))==0) && 
               (strncmp(argv[i+1], "UPDATES",strlen(argv[i+1])) == 0)){ 
             snprintf(temp_cmd, sizeof (cmd) - length, "%s%s", " -e ", argv[i+1]); 
            } else { 
             snprintf(temp_cmd, sizeof (cmd) - length, "%s%s%s%s%s", " -e ", argv[i+1], " -o id", " | ", logger); 
             cmds[pcounter] = malloc(strlen+1); 
             strcpy(cmds[pcounter],cmd); 
             pcounter++; 
            } 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } 
        } 
        break; 
     case 's': if (i+1 < argc && argv[i+1][0] != '-') { 
          if ((strncmp(argv[i+1], "SYN_RECV", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "ESTABLISHED", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "FIN_WAIT", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "CLOSE_WAIT", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "LAST_ACK", 
              strlen(argv[i+1])) == 0) || 
             (strncmp(argv[i+1], "TIME_WAIT", 
              strlen(argv[i+1])) == 0)) { 
            snprintf(temp_cmd, sizeof (cmd) - length, "%s%s%s%s%s", " --state ", argv[i+1], " -o id", " | ", logger); 
            cmds[pcounter] = malloc(strlen+1); 
            strcpy(cmds[pcounter],cmd); 
            pcounter++; 
            length = strlen (cmd); 
            temp_cmd = cmd + length; 
            i++; 
          } 
        } 
        break; 
    } 
    } 
    daemonize(); 
} 

のulimit -aの出力である -

ulimit -a 
core file size   (blocks, -c) 0 
data seg size   (kbytes, -d) unlimited 
scheduling priority    (-e) 0 
file size    (blocks, -f) unlimited 
pending signals     (-i) 16382 
max locked memory  (kbytes, -l) 64 
max memory size   (kbytes, -m) unlimited 
open files      (-n) 1024 
pipe size   (512 bytes, -p) 8 
POSIX message queues  (bytes, -q) 819200 
real-time priority    (-r) 0 
stack size    (kbytes, -s) 8192 
cpu time    (seconds, -t) unlimited 
max user processes    (-u) unlimited 
virtual memory   (kbytes, -v) unlimited 
file locks      (-x) unlimited 


free -m 
      total  used  free  shared buffers  cached 
Mem:   502  123  379   0   19   72 
-/+ buffers/cache:   31  471 
Swap:   0   0   0 

Answer 1

ここでの問題は、フォークは子プロセスに割り当てるための十分なメモリを持っていなかったです。私はプログラムを実行していたVMのメモリを増やしていました。