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(pututline_r): If not located after any entry don't use UTMP_DATA->ubuf, and seek to the end before adding. Lock the file before stating.

This commit is contained in:
Miles Bader 1996-07-01 19:19:08 +00:00
parent 4bbb963eb4
commit e81bd562d5
1 changed files with 34 additions and 24 deletions
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58
login/pututline_r.c
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@ -60,7 +60,8 @@ pututline_r (const struct utmp *id, struct utmp_data *utmp_data)
#if _HAVE_UT_TYPE - 0
/* Seek position to write. */
if (utmp_data->ubuf.ut_type != id->ut_type)
if (utmp_data->loc_utmp >= sizeof (utmp)
&& utmp_data->ubuf.ut_type != id->ut_type)
{
/* We must not overwrite the data in UTMP_DATA. */
struct utmp_data *data_tmp = alloca (sizeof (*data_tmp));
@ -82,16 +83,6 @@ pututline_r (const struct utmp *id, struct utmp_data *utmp_data)
}
#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 <= st.st_size
&& lseek (utmp_data->ut_fd, utmp_data->loc_utmp - sizeof (struct utmp),
SEEK_SET) < 0)
return -1;
/* Try to lock the file. */
if (flock (utmp_data->ut_fd, LOCK_EX | LOCK_NB) < 0 && errno != ENOSYS)
{
@ -102,20 +93,39 @@ pututline_r (const struct utmp *id, struct utmp_data *utmp_data)
(void) flock (utmp_data->ut_fd, LOCK_EX | LOCK_NB);
}
/* Write the new data. */
if (write (utmp_data->ut_fd, id, sizeof (struct utmp))
!= sizeof (struct utmp))
{
/* 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;
}
/* Find out how large the file is. */
result = fstat (utmp_data->ut_fd, &st);
result = -1;
}
if (result == 0)
/* Position file correctly. */
if (utmp_data->loc_utmp < sizeof (struct utmp))
/* Not located at any valid entry. Add at the end. */
{
result = lseek (utmp_data->ut_fd, 0L, SEEK_END);
if (result == 0)
/* Where we'll be if the write succeeds. */
utmp_data->loc_utmp = st.st_size + sizeof (struct utmp);
}
else if (utmp_data->loc_utmp <= st.st_size)
result =
lseek (utmp_data->ut_fd, utmp_data->loc_utmp - sizeof (struct utmp),
SEEK_SET);
if (result == 0)
/* Write the new data. */
if (write (utmp_data->ut_fd, id, sizeof (struct utmp))
!= sizeof (struct utmp))
{
/* 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);