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-rw-r--r--login/login.c71
1 files changed, 63 insertions, 8 deletions
diff --git a/login/login.c b/login/login.c
index 446b6b927b..ede02d7938 100644
--- a/login/login.c
+++ b/login/login.c
@@ -21,27 +21,79 @@ Boston, MA 02111-1307, USA. */
#include <limits.h>
#include <string.h>
#include <unistd.h>
+#include <stdlib.h>
#include <utmp.h>
+
+/* Return the result of ttyname in the buffer pointed to by TTY, which should
+ be of length BUF_LEN. If it is too long to fit in this buffer, a
+ sufficiently long buffer is allocated using malloc, and returned in TTY.
+ 0 is returned upon success, -1 otherwise. */
+static int
+tty_name (int fd, char **tty, size_t buf_len)
+{
+ int rv; /* Return value. 0 = success. */
+ char *buf = *tty; /* Buffer for ttyname, initially the user's. */
-/* XXX used for tty name array in login. */
-#ifndef PATH_MAX
-#define PATH_MAX 1024
-#endif
+ for (;;)
+ {
+ char *new_buf;
+
+ if (buf_len)
+ {
+ rv = ttyname_r (fd, buf, buf_len);
+
+ if (rv < 0 || memchr (buf, '\0', buf_len))
+ /* We either got an error, or we succeeded and the returned name fit
+ in the buffer. */
+ break;
+ /* Try again with a longer buffer. */
+ buf_len += buf_len; /* Double it */
+ }
+ else
+ /* No initial buffer; start out by mallocing one. */
+ buf_len = 128; /* First time guess. */
+
+ if (buf != *tty)
+ /* We've already malloced another buffer at least once. */
+ new_buf = realloc (buf, buf_len);
+ else
+ new_buf = malloc (buf_len);
+ if (! new_buf)
+ {
+ rv = -1;
+ errno = ENOMEM;
+ break;
+ }
+ }
+
+ if (rv == 0)
+ *tty = buf; /* Return buffer to the user. */
+ else if (buf != *tty)
+ free (buf); /* Free what we malloced when returning an error. */
+
+ return rv;
+}
+
void
login (const struct utmp *ut)
{
- char tty[PATH_MAX + UT_LINESIZE];
+#ifdef PATH_MAX
+ char _tty[PATH_MAX + UT_LINESIZE];
+#else
+ char _tty[512 + UT_LINESIZE];
+#endif
+ char *tty = _tty;
int found_tty;
const char *ttyp;
struct utmp_data data;
/* Seek tty. */
- found_tty = ttyname_r (STDIN_FILENO, tty, sizeof tty);
+ found_tty = tty_name (STDIN_FILENO, &tty, sizeof (_tty));
if (found_tty < 0)
- found_tty = ttyname_r (STDOUT_FILENO, tty, sizeof tty);
+ found_tty = tty_name (STDOUT_FILENO, &tty, sizeof (_tty));
if (found_tty < 0)
- found_tty = ttyname_r (STDERR_FILENO, tty, sizeof tty);
+ found_tty = tty_name (STDERR_FILENO, &tty, sizeof (_tty));
if (found_tty >= 0)
{
@@ -78,6 +130,9 @@ login (const struct utmp *ut)
/* Close UTMP file. */
endutent_r (&data);
}
+
+ if (tty != _tty)
+ free (tty); /* Free buffer malloced by tty_name. */
}
/* Update the WTMP file. Here we have to add a new entry. */