src/fake-environ/uname.c

   1
   2
   3 #include <stdio.h>
   4 #include <string.h>
   5 #include <dlfcn.h>
   6 #include <stdlib.h>             /* for EXIT_FAILURE */
   7 #include <unistd.h>             /* for _exit() */
   8 #include <sys/types.h>
   9 #include <sys/stat.h>
  10 #include <fcntl.h>
  11 #include <sys/syslog.h>
  12 #include <sys/utsname.h>
  13
  14 #ifndef RTLD_NEXT
  15 #define RTLD_NEXT      ((void *) -1l)
  16 #endif
  17
  18 typedef int (*uname_t)(struct utsname * buf);
  19
  20 static void *get_libc_func(const char *funcname) {
  21         char *error;
  22
  23         void *func = dlsym(RTLD_NEXT, funcname);
  24         if ((error = dlerror()) != NULL) {
  25                 fprintf(stderr, "I can't locate libc function `%s' error: %s", funcname, error);
  26                 _exit(EXIT_FAILURE);
  27         }
  28
  29         return func;
  30 }
  31
  32 int uname(struct utsname *buf) {
  33         char *env = NULL;
  34
  35         /* Call real uname to get the information we need. */
  36         uname_t real_uname = (uname_t)get_libc_func("uname");
  37         int ret = real_uname((struct utsname *) buf);
  38
  39         /* Replace release if requested. */
  40         if ((env = getenv("UTS_RELEASE")) != NULL) {
  41                 strncpy(buf->release, env, _UTSNAME_RELEASE_LENGTH);
  42         }
  43
  44         /* Replace machine type if requested. */
  45         if ((env = getenv("UTS_MACHINE")) != NULL) {
  46                 strncpy(buf->machine, env, _UTSNAME_MACHINE_LENGTH);
  47         }
  48
  49         return ret;
  50 }