emo/shadow
1
0
Fork 0
Code Issues Pull Requests Packages Releases Activity

Simplify is_my_tty()

Browse Source 
This commit will serve to document why we shouldn't worry about the
truncation in the call to strlcpy(3).  Since we have one more byte in
tmptty than in full_tty, truncation will produce a string that is at
least one byte longer than full_tty.  Such a string could never compare
equal, so we're actually handling the truncation in a clever way.  Maybe
too clever, but that's why I'm documenting it here.

Now, about the simplification itself:

Since we made sure that both full_tty and tmptty are null-terminated, we
can call strcmp(3) instead of strncmp(3).  We can also simplify the
return logic avoiding one branch.

Cc: Paul Eggert <eggert@cs.ucla.edu>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Reviewed-by: Iker Pedrosa <ipedrosa@redhat.com>
This commit is contained in:
Alejandro Colomar 2023-03-13 00:59:22 +01:00 committed by Iker Pedrosa
parent e27ca53091
commit 1d7d94ed7d
1 changed files with 4 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
libmisc/utmp.c
View File

@ -42,17 +42,15 @@ static bool is_my_tty (const char tty[UT_LINESIZE])
if ('\0' == tmptty[0]) { if ('\0' == tmptty[0]) {
const char *tname = ttyname (STDIN_FILENO); const char *tname = ttyname (STDIN_FILENO);
if (NULL != tname) if (NULL != tname)
(void) strlcpy (tmptty, tname, sizeof tmptty); (void) strlcpy (tmptty, tname, sizeof(tmptty));
} }
if ('\0' == tmptty[0]) { if ('\0' == tmptty[0]) {
(void) puts (_("Unable to determine your tty name.")); (void) puts (_("Unable to determine your tty name."));
exit (EXIT_FAILURE); exit (EXIT_FAILURE);
} else if (strncmp (full_tty, tmptty, sizeof (tmptty)) != 0) {
return false;
} else {
return true;
} }
return strcmp (full_tty, tmptty) == 0;
} }
/* /*