在码头容器中运行FlexLM许可证服务器

Question

我试图在一个码头容器中运行一个FlexLM许可证服务器。我以前做过这件事没有任何问题。但是现在我有了一个供应商(Synopsys)守护进程(snpslmd)，它似乎不适合Docker。守护进程抱怨无法打开它的锁文件：/var/tmp/locksnpslmd，但是/var/tmp存在并且是可写的。

下面是来自Docker容器中供应商守护进程的strace：

munmap(0x7fa322830000, 167936)          = 0
setsid()                                = 64
openat(AT_FDCWD, "/", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3
getdents(3, /* 22 entries */, 32768)    = 568
getdents(3, /* 0 entries */, 32768)     = 0
close(3)                                = 0
write(1, "17:35:24 (snpslmd) Cannot open d"..., 4817:35:24 (snpslmd) Cannot open daemon lock file
) = 48
write(1, "17:35:24 (snpslmd) EXITING DUE T"..., 5817:35:24 (snpslmd) EXITING DUE TO SIGNAL 41 Exit reason 9
) = 58
exit_group(41)                          = ?
+++ exited with 41 +++**

下面是来自通常在容器外运行的供应商守护进程的相同的strace段：

munmap(0x7f25da4db000, 4096)            = 0
setsid()                                = 15808
openat(AT_FDCWD, "/", O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC) = 3
getdents(3, /* 23 entries */, 32768)    = 584
getdents(3, /* 0 entries */, 32768)     = 0
close(3)                                = 0
open("/var/tmp/locksnpslmd", O_RDWR|O_CREAT, 0666) = 3
fcntl(3, F_SETLK, {l_type=F_WRLCK, l_whence=SEEK_CUR, l_start=0, l_len=0}) = 0
stat("/var/tmp/locksnpslmd", {st_mode=S_IFREG|0644, st_size=0, ...}) = 0

有什么想法吗？

Answer 1

之所以会发生这种情况，是因为get申根()返回“”的不同inode编号。还有“.”"/“的子目录。可以使用LD_PRELOAD hack对snpslmd进行修复。

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <dlfcn.h>
#include <string.h>

static int is_root = 0;
static int d_ino = -1;

static DIR *(*orig_opendir)(const char *name);
static int (*orig_closedir)(DIR *dirp);
static struct dirent *(*orig_readdir)(DIR *dirp);

DIR *opendir(const char *name) {
  if (strcmp(name, "/") == 0) {
    is_root = 1;
  }

  return orig_opendir(name);
}


int closedir(DIR *dirp) {
  is_root = 0;
  return orig_closedir(dirp);
}

struct dirent *readdir(DIR *dirp) {
  struct dirent *r = orig_readdir(dirp);
  if (is_root && r) {
    if (strcmp(r->d_name, ".") == 0) {
      r->d_ino = d_ino;
    } else if (strcmp(r->d_name, "..") == 0) {
      r->d_ino = d_ino;
    }
  }
  return r;
}

static __attribute__((constructor)) void init_methods() {
  orig_opendir = dlsym(RTLD_NEXT, "opendir");
  orig_closedir = dlsym(RTLD_NEXT, "closedir");
  orig_readdir = dlsym(RTLD_NEXT, "readdir");
  DIR *d = orig_opendir("/");
  struct dirent *e = orig_readdir(d);
  while (e) {
    if (strcmp(e->d_name, ".") == 0) {
      d_ino = e->d_ino;
      break;
    }
    e = orig_readdir(d);
  }
  orig_closedir(d);
  if (d_ino == -1) {
    puts("Failed to determine root directory inode number");
    exit(EXIT_FAILURE);
  }
}

使用

gcc -ldl -shared -fPIC snpslmd-hack.c -o snpslmd-hack.so

使用包装脚本而不是原始snpslmd：

#!/bin/sh
export LD_PRELOAD=snpslmd-hack.so
exec /usr/bin/snpslmd_bin "$@"