lib/pwdutils.c

   1 #include <stdlib.h>
   2
   3 #include "c.h"
   4 #include "pwdutils.h"
   5 #include "xalloc.h"
   6
   7 /* Returns allocated passwd and allocated pwdbuf to store passwd strings
   8  * fields. In case of error returns NULL and set errno, for unknown user set
   9  * errno to EINVAL
  10  */
  11 struct passwd *xgetpwnam(const char *username, char **pwdbuf)
  12 {
  13         struct passwd *pwd = NULL, *res = NULL;
  14         int rc;
  15
  16         if (!pwdbuf || !username)
  17                 return NULL;
  18
  19         *pwdbuf = xmalloc(UL_GETPW_BUFSIZ);
  20         pwd = xcalloc(1, sizeof(struct passwd));
  21
  22         errno = 0;
  23         rc = getpwnam_r(username, pwd, *pwdbuf, UL_GETPW_BUFSIZ, &res);
  24         if (rc != 0) {
  25                 errno = rc;
  26                 goto failed;
  27         }
  28         if (!res) {
  29                 errno = EINVAL;
  30                 goto failed;
  31         }
  32         return pwd;
  33 failed:
  34         free(pwd);
  35         free(*pwdbuf);
  36         return NULL;
  37 }
  38
  39 char *xgetlogin(void)
  40 {
  41         struct passwd *pw = NULL;
  42         uid_t ruid;
  43         char *user;
  44
  45         user = getlogin();
  46         if (user)
  47                 return xstrdup(user);
  48
  49         /* GNU Hurd implementation has an extension where a process can exist in a
  50          * non-conforming environment, and thus be outside the realms of POSIX
  51          * process identifiers; on this platform, getuid() fails with a status of
  52          * (uid_t)(-1) and sets errno if a program is run from a non-conforming
  53          * environment.
  54          *
  55          * http://austingroupbugs.net/view.php?id=511
  56          */
  57         errno = 0;
  58         ruid = getuid();
  59
  60         if (errno == 0)
  61                 pw = getpwuid(ruid);
  62         if (pw && pw->pw_name && *pw->pw_name)
  63                 return xstrdup(pw->pw_name);
  64
  65         return NULL;
  66 }
  67
  68 #ifdef TEST_PROGRAM
  69 int main(int argc, char *argv[])
  70 {
  71         char *buf = NULL;
  72         struct passwd *pwd = NULL;
  73
  74         if (argc != 2) {
  75                 fprintf(stderr, "usage: %s <username>\n", argv[0]);
  76                 return EXIT_FAILURE;
  77         }
  78
  79         pwd = xgetpwnam(argv[1], &buf);
  80         if (!pwd)
  81                 err(EXIT_FAILURE, "failed to get %s pwd entry", argv[1]);
  82
  83         printf("Username: %s\n", pwd->pw_name);
  84         printf("UID:      %d\n", pwd->pw_uid);
  85         printf("HOME:     %s\n", pwd->pw_dir);
  86         printf("GECO:     %s\n", pwd->pw_gecos);
  87
  88         free(pwd);
  89         free(buf);
  90
  91         printf("Current:  %s\n", (buf = xgetlogin()));
  92         free(buf);
  93
  94         return EXIT_SUCCESS;
  95 }
  96 #endif /* TEST_PROGRAM */