nsslist.c

   1 /* list users for a particular nss module
   2  */
   3
   4 #include <stdio.h>
   5 #include <nss.h>
   6 #include <dlfcn.h>
   7 #include <pwd.h>
   8 #include <grp.h>
   9
  10 typedef enum nss_status NSS_STATUS;
  11
  12 static char *nss_name;
  13 static int nss_errno;
  14 static NSS_STATUS last_error;
  15 static int total_errors;
  16
  17 static void *find_fn(const char *name)
  18 {
  19         char *so_path, *s;
  20         static void *h;
  21         void *res;
  22
  23         asprintf(&s, "_nss_%s_%s", nss_name, name);
  24         asprintf(&so_path, "/lib/libnss_%s.so.2", nss_name);
  25
  26         if (!h) {
  27                 h = dlopen(so_path, RTLD_LAZY);
  28         }
  29         if (!h) {
  30                 printf("Can't open shared library %s\n", so_path);
  31                 exit(1);
  32         }
  33         res = dlsym(h, s);
  34         if (!res) {
  35                 printf("Can't find function %s\n", s);
  36                 return NULL;
  37         }
  38         free(so_path);
  39         free(s);
  40         return res;
  41 }
  42
  43 static void report_nss_error(const char *who, NSS_STATUS status)
  44 {
  45         last_error = status;
  46         total_errors++;
  47         printf("ERROR %s: NSS_STATUS=%d  %d (nss_errno=%d)\n",
  48                who, status, NSS_STATUS_SUCCESS, nss_errno);
  49 }
  50
  51 static struct passwd *nss_getpwent(void)
  52 {
  53         NSS_STATUS (*_nss_getpwent_r)(struct passwd *, char *,
  54                                       size_t , int *) = find_fn("getpwent_r");
  55         static struct passwd pwd;
  56         static char buf[1000];
  57         NSS_STATUS status;
  58
  59         status = _nss_getpwent_r(&pwd, buf, sizeof(buf), &nss_errno);
  60         if (status == NSS_STATUS_NOTFOUND) {
  61                 return NULL;
  62         }
  63         if (status != NSS_STATUS_SUCCESS) {
  64                 report_nss_error("getpwent", status);
  65                 return NULL;
  66         }
  67         return &pwd;
  68 }
  69
  70 static void nss_setpwent(void)
  71 {
  72         NSS_STATUS (*_nss_setpwent)(void) = find_fn("setpwent");
  73         NSS_STATUS status;
  74         status = _nss_setpwent();
  75         if (status != NSS_STATUS_SUCCESS) {
  76                 report_nss_error("setpwent", status);
  77         }
  78 }
  79
  80 static void nss_endpwent(void)
  81 {
  82         NSS_STATUS (*_nss_endpwent)(void) = find_fn("endpwent");
  83         NSS_STATUS status;
  84         status = _nss_endpwent();
  85         if (status != NSS_STATUS_SUCCESS) {
  86                 report_nss_error("endpwent", status);
  87         }
  88 }
  89
  90 static void list_users(void)
  91 {
  92         struct passwd *pwd;
  93
  94         nss_setpwent();
  95         /* loop over all users */
  96         while ((pwd = nss_getpwent())) {
  97                 printf("%s\n", pwd->pw_name);
  98         }
  99         nss_endpwent();
 100 }
 101
 102 static void usage(void)
 103 {
 104         printf("nsslist <nsstype>\n");
 105 }
 106
 107 int main(int argc, char *argv[])
 108 {
 109         if (argc < 2) {
 110                 usage();
 111                 exit(1);
 112         }
 113
 114         nss_name = argv[1];
 115
 116         list_users();
 117
 118         return 0;
 119 }