src/nofail_setfacl.c

   1 /*
   2  * gcc -D _GNU_SOURCE -shared -fPIC -o nofail_setfacl.so nofail_setfacl.c
   3  *
   4  */
   5
   6 #include <dlfcn.h>
   7 #include <stdlib.h>
   8 #include <stdio.h>
   9 #include <unistd.h>
  10 #include <string.h>
  11 #include <errno.h>
  12 #include <err.h>
  13 #include <limits.h>
  14
  15 #define XATTRNAME "system.posix_acl_access"
  16 #define NOTICEMSG "%s: Could not set acl"
  17 #define NOTICEMSGFD (NOTICEMSG + 4)
  18 #define SUCCESS 0
  19 #define MIN(a,b) (((a)<(b))?(a):(b))
  20
  21 int setxattr (const char *path, const char *name, const void *value, size_t size, int flags)
  22 {
  23         int (*orig_setxattr)(const char*, const char*, const void*, size_t, int) = dlsym(RTLD_NEXT, __func__);
  24         int result = orig_setxattr(path, name, value, size, flags);
  25
  26         if(result < 0 && errno == EOPNOTSUPP)
  27         {
  28                 if(strcmp(name, XATTRNAME)==0)
  29                 {
  30                         warnx(NOTICEMSG, path);
  31                         result = SUCCESS;
  32                 }
  33         }
  34         return result;
  35 }
  36
  37 int lsetxattr (const char *path, const char *name, const void *value, size_t size, int flags)
  38 {
  39         int (*orig_lsetxattr)(const char*, const char*, const void*, size_t, int) = dlsym(RTLD_NEXT, __func__);
  40         int result = orig_lsetxattr(path, name, value, size, flags);
  41
  42         if(result < 0 && errno == EOPNOTSUPP)
  43         {
  44                 if(strcmp(name, XATTRNAME)==0)
  45                 {
  46                         warnx(NOTICEMSG, path);
  47                         result = SUCCESS;
  48                 }
  49         }
  50         return result;
  51 }
  52
  53 int fsetxattr (int fd, const char *name, const void *value, size_t size, int flags)
  54 {
  55         int (*orig_fsetxattr)(int, const char*, const void*, size_t, int) = dlsym(RTLD_NEXT, __func__);
  56         int result = orig_fsetxattr(fd, name, value, size, flags);
  57
  58         if(result < 0 && errno == EOPNOTSUPP)
  59         {
  60                 if(strcmp(name, XATTRNAME)==0)
  61                 {
  62                         char linkpath[PATH_MAX];
  63                         char path[PATH_MAX];
  64                         sprintf(linkpath, "/proc/self/fd/%d", fd);
  65                         ssize_t sz = readlink(linkpath, path, PATH_MAX);
  66                         path[MIN(sz, PATH_MAX-1)] = '\0';
  67                         warnx(NOTICEMSG, path);
  68                         result = SUCCESS;
  69                 }
  70         }
  71         return result;
  72 }