diff options
Diffstat (limited to 'login/pututline_r.c')
| -rw-r--r-- | login/pututline_r.c | 56 |
1 files changed, 45 insertions, 11 deletions
diff --git a/login/pututline_r.c b/login/pututline_r.c index 92ba8fb308..07322e5740 100644 --- a/login/pututline_r.c +++ b/login/pututline_r.c @@ -26,9 +26,29 @@ Boston, MA 02111-1307, USA. */ #include <sys/file.h> +/* XXX An alternative solution would be to call a SUID root program + which write the new value. */ + int pututline_r (const struct utmp *utmp_ptr, struct utmp_data *utmp_data) { + struct stat st; + int result = 0; + +#if _HAVE_UT_TYPE - 0 + /* Test whether ID has any of the legal types because we have to + prevent illegal entries. */ + if (id->ut_type != RUN_LVL && id->ut_type != BOOT_TIME + && id->ut_type != OLD_TIME && id->ut_type != NEW_TIME + && id->ut_type != INIT_PROCESS && id->ut_type != LOGIN_PROCESS + && id->ut_type != USER_PROCESS && id->ut_type != DEAD_PROCESS) + /* No, using '<' and '>' for the test is not possible. */ + { + errno = EINVAL; + return -1; + } +#endif + /* Open utmp file if not already done. */ if (utmp_data->ut_fd == -1) { @@ -37,12 +57,14 @@ pututline_r (const struct utmp *utmp_ptr, struct utmp_data *utmp_data) return -1; } +#if _HAVE_UT_TYPE - 0 /* Seek position to write. */ if (utmp_data->ubuf.ut_type != utmp_ptr->ut_type) { /* We must not overwrite the data in UTMP_DATA. */ struct utmp_data *data_tmp = alloca (sizeof (utmp_data)); struct utmp *dummy; + off_t new_pos; *data_tmp = *utmp_data; utmp_data = data_tmp; @@ -50,23 +72,25 @@ pututline_r (const struct utmp *utmp_ptr, struct utmp_data *utmp_data) if (getutid_r (utmp_ptr, &dummy, utmp_data) < 0) { if (errno != ESRCH) + /* Some error occured. If no entry was found, the position + pointer now is at the end of the file. */ return -1; - utmp_data->loc_utmp = lseek (utmp_data->ut_fd, 0, SEEK_END); - if (utmp_data->loc_utmp == -1) - return -1; - } + /* Set position pointer to position after adding of the record. */ + utmp_data->loc_utmp += sizeof (struct utmp); } +#endif + + /* Find out how large the file is. */ + if (fstat (utmp_data->ut_fd, &st) < 0) + return -1; /* Position file correctly. */ - if (utmp_data->loc_utmp > 0 + if (utmp_data->loc_utmp <= st.st_size && lseek (utmp_data->ut_fd, utmp_data->loc_utmp - sizeof (struct utmp), SEEK_SET) < 0) return -1; - /* XXX An alternative solution would be to call an SUID root program - which write the new value. */ - /* Try to lock the file. */ if (flock (utmp_data->ut_fd, LOCK_EX | LOCK_NB) < 0 && errno != ENOSYS) { @@ -78,12 +102,22 @@ pututline_r (const struct utmp *utmp_ptr, struct utmp_data *utmp_data) } /* Write the new data. */ - if (write (utmp_data->ut_fd, &utmp_data->ubuf, sizeof (struct utmp)) + if (write (utmp_data->ut_fd, utmp_ptr, sizeof (struct utmp)) != sizeof (struct utmp)) - return -1; + { + /* If we appended a new record this is only partially written. + Remove it. */ + if (utmp_data->loc_utmp > st.st_size) + { + (void) ftruncate (utmp_data->ut_fd, st.st_size); + utmp_data->loc_utmp = st.st_size; + } + + result = -1; + } /* And unlock the file. */ (void) flock (utmp_data->ut_fd, LOCK_UN); - return 0; + return result; } |