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linux: implement ttyname as a wrapper around ttyname_r. 

Big win in binary size and avoids duplicating the logic in multiple
places.

On x86_64, dropped from 1883206 to 1881790, a 1416 byte decrease.

Also changed logic to track if ttyname_buf has been allocated by
checking if it's NULL instead of tracking buflen as an additional
variable.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Érico Nogueira 2021-05-03 22:51:52 -03:00 committed by Adhemerval Zanella
parent 0fb3dadca2
commit 05ae46ee7a
3 changed files with 15 additions and 161 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/unistd.h
View File

@ -134,8 +134,8 @@ libc_hidden_proto (__setresuid)
libc_hidden_proto (__setresgid)
extern __pid_t __vfork (void);
libc_hidden_proto (__vfork)
extern int __ttyname_r (int __fd, char *__buf, size_t __buflen)
attribute_hidden;
extern int __ttyname_r (int __fd, char *__buf, size_t __buflen);
libc_hidden_proto (__ttyname_r)
extern int __isatty (int __fd) attribute_hidden;
extern int __link (const char *__from, const char *__to);
extern int __symlink (const char *__from, const char *__to);

170
sysdeps/unix/sysv/linux/ttyname.c
View File

@ -17,188 +17,42 @@
#include <errno.h>
#include <limits.h>
#include <stddef.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <termios.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <_itoa.h>
#include "ttyname.h"
#if 0
/* Is this used anywhere? It is not exported. */
char *__ttyname;
#endif
static char *ttyname_buf = NULL;
static char *getttyname (const char *dev, const struct stat64 *mytty,
int save, int *dostat);
libc_freeres_ptr (static char *getttyname_name);
static char *
attribute_compat_text_section
getttyname (const char *dev, const struct stat64 *mytty, int save, int *dostat)
libc_freeres_fn (free_mem)
{
static size_t namelen;
struct stat64 st;
DIR *dirstream;
struct dirent64 *d;
size_t devlen = strlen (dev) + 1;
dirstream = __opendir (dev);
if (dirstream == NULL)
{
*dostat = -1;
return NULL;
}
/* Prepare for the loop. If we already have a buffer copy the directory
name we look at into it. */
if (devlen < namelen)
*((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';
while ((d = __readdir64 (dirstream)) != NULL)
if ((d->d_fileno == mytty->st_ino || *dostat)
&& strcmp (d->d_name, "stdin")
&& strcmp (d->d_name, "stdout")
&& strcmp (d->d_name, "stderr"))
{
size_t dlen = _D_ALLOC_NAMLEN (d);
if (devlen + dlen > namelen)
{
free (getttyname_name);
namelen = 2 * (devlen + dlen); /* Big enough. */
getttyname_name = malloc (namelen);
if (! getttyname_name)
{
*dostat = -1;
/* Perhaps it helps to free the directory stream buffer. */
(void) __closedir (dirstream);
return NULL;
}
*((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';
}
memcpy (&getttyname_name[devlen], d->d_name, dlen);
if (__stat64 (getttyname_name, &st) == 0
&& is_mytty (mytty, &st))
{
(void) __closedir (dirstream);
#if 0
__ttyname = getttyname_name;
#endif
__set_errno (save);
return getttyname_name;
}
}
(void) __closedir (dirstream);
__set_errno (save);
return NULL;
free (ttyname_buf);
}
/* Static buffer in `ttyname'. */
libc_freeres_ptr (static char *ttyname_buf);
/* Return the pathname of the terminal FD is open on, or NULL on errors.
The returned storage is good only until the next call to this function. */
char *
ttyname (int fd)
{
static size_t buflen;
char procname[30];
struct stat64 st, st1;
int dostat = 0;
int doispty = 0;
char *name;
int save = errno;
struct termios term;
/* isatty check, tcgetattr is used because it sets the correct
errno (EBADF resp. ENOTTY) on error. */
errno (EBADF resp. ENOTTY) on error. Fast error path to avoid the
allocation */
struct termios term;
if (__glibc_unlikely (__tcgetattr (fd, &term) < 0))
return NULL;
if (__fstat64 (fd, &st) < 0)
return NULL;
/* We try using the /proc filesystem. */
*_fitoa_word (fd, __stpcpy (procname, "/proc/self/fd/"), 10, 0) = '\0';
if (buflen == 0)
if (ttyname_buf == NULL)
{
buflen = 4095;
ttyname_buf = (char *) malloc (buflen + 1);
ttyname_buf = malloc (PATH_MAX);
if (ttyname_buf == NULL)
{
buflen = 0;
return NULL;
}
}
ssize_t len = __readlink (procname, ttyname_buf, buflen);
if (__glibc_likely (len != -1))
{
if ((size_t) len >= buflen)
return NULL;
#define UNREACHABLE_LEN strlen ("(unreachable)")
if (len > UNREACHABLE_LEN
&& memcmp (ttyname_buf, "(unreachable)", UNREACHABLE_LEN) == 0)
{
memmove (ttyname_buf, ttyname_buf + UNREACHABLE_LEN,
len - UNREACHABLE_LEN);
len -= UNREACHABLE_LEN;
}
/* readlink need not terminate the string. */
ttyname_buf[len] = '\0';
/* Verify readlink result, fall back on iterating through devices. */
if (ttyname_buf[0] == '/'
&& __stat64 (ttyname_buf, &st1) == 0
&& is_mytty (&st, &st1))
return ttyname_buf;
doispty = 1;
}
if (__stat64 ("/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
int result = __ttyname_r (fd, ttyname_buf, PATH_MAX);
if (result != 0)
{
name = getttyname ("/dev/pts", &st, save, &dostat);
}
else
{
__set_errno (save);
name = NULL;
}
if (!name && dostat != -1)
{
name = getttyname ("/dev", &st, save, &dostat);
}
if (!name && dostat != -1)
{
dostat = 1;
name = getttyname ("/dev", &st, save, &dostat);
}
if (!name && doispty && is_pty (&st))
{
/* We failed to figure out the TTY's name, but we can at least
signal that we did verify that it really is a PTY slave.
This happens when we have inherited the file descriptor from
a different mount namespace. */
__set_errno (ENODEV);
__set_errno (result);
return NULL;
}
return name;
return ttyname_buf;
}

2
sysdeps/unix/sysv/linux/ttyname_r.c
View File

@ -194,5 +194,5 @@ __ttyname_r (int fd, char *buf, size_t buflen)
return ret;
}
libc_hidden_def (__ttyname_r)
weak_alias (__ttyname_r, ttyname_r)