0004-linux-ttyname-_r-Make-tty-checks-consistent.patch 8.99 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270
From 2fbce9c2031e70b6bd67876accfc34b0ec492878 Mon Sep 17 00:00:00 2001
From: Luke Shumaker <lukeshu@parabola.nu>
Date: Wed, 15 Nov 2017 20:34:30 +0100
Subject: [PATCH 4/6] linux ttyname{_r}: Make tty checks consistent

In the ttyname and ttyname_r routines on Linux, at several points it needs to
check if a given TTY is the TTY we are looking for. It used to be that this
check was (to see if `maybe` is `mytty`):

       __xstat64(_STAT_VER, maybe_filename, &maybe) == 0
    #ifdef _STATBUF_ST_RDEV
       && S_ISCHR(maybe.st_mode) && maybe.st_rdev == mytty.st_rdev
    #else
       && maybe.st_ino == mytty.st_ino && maybe.st_dev == mytty.st_dev
    #endif

This check appears in several places.

Then, one of the changes made in commit 15e9a4f378c8607c2ae1aa465436af4321db0e23
was to change that check to:

       __xstat64(_STAT_VER, maybe_filename, &maybe) == 0
    #ifdef _STATBUF_ST_RDEV
       && S_ISCHR(maybe.st_mode) && maybe.st_rdev == mytty.st_rdev
    #endif
       && maybe.st_ino == mytty.st_ino && maybe.st_dev == mytty.st_dev

That is, it made the st_ino and st_dev parts of the check happen even if we have
the st_rdev member. This is an important change, because the kernel allows
multiple devpts filesystem instances to be created; a device file in one devpts
instance may share the same st_rdev with a file in another devpts instance, but
they aren't the same file.

This check appears twice in each file (ttyname.c and ttyname_r.c), once (in
ttyname and __ttyname_r) to check if a candidate file found by inspecting /proc
is the desired TTY, and once (in getttyname and getttyname_r) to check if a
candidate file found by searching /dev is the desired TTY. However, 15e9a4f
only updated the checks for files found via /proc; but the concern about
collisions between devpts instances is just as valid for files found via /dev.

So, update all 4 occurrences the check to be consistent with the version of the
check introduced in 15e9a4f. Make it easy to keep all 4 occurrences of the
check consistent by pulling it in to a static inline function, is_mytty.

Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
---
 ChangeLog                           |  7 +++++++
 sysdeps/unix/sysv/linux/ttyname.c   | 40 ++++++++----------------------------
 sysdeps/unix/sysv/linux/ttyname.h   | 12 +++++++++++
 sysdeps/unix/sysv/linux/ttyname_r.c | 41 ++++++++-----------------------------
 4 files changed, 36 insertions(+), 64 deletions(-)

--- a/sysdeps/unix/sysv/linux/ttyname.c
+++ b/sysdeps/unix/sysv/linux/ttyname.c
@@ -35,8 +35,8 @@
 char *__ttyname;
 #endif

-static char *getttyname (const char *dev, dev_t mydev,
-			 ino64_t myino, int save, int *dostat)
+static char *getttyname (const char *dev, const struct stat64 *mytty,
+			 int save, int *dostat)
      internal_function;


@@ -44,7 +44,7 @@

 static char *
 internal_function attribute_compat_text_section
-getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
+getttyname (const char *dev, const struct stat64 *mytty, int save, int *dostat)
 {
   static size_t namelen;
   struct stat64 st;
@@ -63,7 +63,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
     *((char *) __mempcpy (getttyname_name, dev, devlen - 1)) = '/';

   while ((d = __readdir64 (dirstream)) != NULL)
-    if ((d->d_fileno == myino || *dostat)
+    if ((d->d_fileno == mytty->st_ino || *dostat)
 	&& strcmp (d->d_name, "stdin")
 	&& strcmp (d->d_name, "stdout")
 	&& strcmp (d->d_name, "stderr"))
@@ -85,12 +85,7 @@ getttyname (const char *dev, dev_t mydev, ino64_t myino, int save, int *dostat)
 	  }
 	memcpy (&getttyname_name[devlen], d->d_name, dlen);
 	if (__xstat64 (_STAT_VER, getttyname_name, &st) == 0
-#ifdef _STATBUF_ST_RDEV
-	    && S_ISCHR (st.st_mode) && st.st_rdev == mydev
-#else
-	    && d->d_fileno == myino && st.st_dev == mydev
-#endif
-	   )
+	    && is_mytty (mytty, &st))
 	  {
 	    (void) __closedir (dirstream);
 #if 0
@@ -167,12 +162,7 @@ ttyname (int fd)
       /* Verify readlink result, fall back on iterating through devices.  */
       if (ttyname_buf[0] == '/'
 	  && __xstat64 (_STAT_VER, ttyname_buf, &st1) == 0
-#ifdef _STATBUF_ST_RDEV
-	  && S_ISCHR (st1.st_mode)
-	  && st1.st_rdev == st.st_rdev
-#endif
-	  && st1.st_ino == st.st_ino
-	  && st1.st_dev == st.st_dev)
+	  && is_mytty (&st, &st1))
 	return ttyname_buf;

       /* If the link doesn't exist, then it points to a device in another
@@ -186,11 +176,7 @@ ttyname (int fd)

   if (__xstat64 (_STAT_VER, "/dev/pts", &st1) == 0 && S_ISDIR (st1.st_mode))
     {
-#ifdef _STATBUF_ST_RDEV
-      name = getttyname ("/dev/pts", st.st_rdev, st.st_ino, save, &dostat);
-#else
-      name = getttyname ("/dev/pts", st.st_dev, st.st_ino, save, &dostat);
-#endif
+      name = getttyname ("/dev/pts", &st, save, &dostat);
     }
   else
     {
@@ -200,21 +186,13 @@ ttyname (int fd)

   if (!name && dostat != -1)
     {
-#ifdef _STATBUF_ST_RDEV
-      name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
-#else
-      name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
-#endif
+      name = getttyname ("/dev", &st, save, &dostat);
     }

   if (!name && dostat != -1)
     {
       dostat = 1;
-#ifdef _STATBUF_ST_RDEV
-      name = getttyname ("/dev", st.st_rdev, st.st_ino, save, &dostat);
-#else
-      name = getttyname ("/dev", st.st_dev, st.st_ino, save, &dostat);
-#endif
+      name = getttyname ("/dev", &st, save, &dostat);
     }

   return name;
diff --git a/sysdeps/unix/sysv/linux/ttyname.h b/sysdeps/unix/sysv/linux/ttyname.h
index cdaf60fb87..48181330a9 100644
--- a/sysdeps/unix/sysv/linux/ttyname.h
+++ b/sysdeps/unix/sysv/linux/ttyname.h
@@ -34,3 +34,15 @@ is_pty (struct stat64 *sb)
   return false;
 #endif
 }
+
+static inline bool
+is_mytty (const struct stat64 *mytty, const struct stat64 *maybe)
+{
+  return (maybe->st_ino == mytty->st_ino
+	  && maybe->st_dev == mytty->st_dev
+#ifdef _STATBUF_ST_RDEV
+	  && S_ISCHR (maybe->st_mode)
+	  && maybe->st_rdev == mytty->st_rdev
+#endif
+	  );
+}
diff --git a/sysdeps/unix/sysv/linux/ttyname_r.c b/sysdeps/unix/sysv/linux/ttyname_r.c
index 18f35ef2b7..58eb919c3f 100644
--- a/sysdeps/unix/sysv/linux/ttyname_r.c
+++ b/sysdeps/unix/sysv/linux/ttyname_r.c
@@ -31,12 +31,12 @@
 #include "ttyname.h"

 static int getttyname_r (char *buf, size_t buflen,
-			 dev_t mydev, ino64_t myino, int save,
+			 const struct stat64 *mytty, int save,
 			 int *dostat) internal_function;

 static int
 internal_function attribute_compat_text_section
-getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
+getttyname_r (char *buf, size_t buflen, const struct stat64 *mytty,
 	      int save, int *dostat)
 {
   struct stat64 st;
@@ -52,7 +52,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
     }

   while ((d = __readdir64 (dirstream)) != NULL)
-    if ((d->d_fileno == myino || *dostat)
+    if ((d->d_fileno == mytty->st_ino || *dostat)
 	&& strcmp (d->d_name, "stdin")
 	&& strcmp (d->d_name, "stdout")
 	&& strcmp (d->d_name, "stderr"))
@@ -72,12 +72,7 @@ getttyname_r (char *buf, size_t buflen, dev_t mydev, ino64_t myino,
 	cp[0] = '\0';

 	if (__xstat64 (_STAT_VER, buf, &st) == 0
-#ifdef _STATBUF_ST_RDEV
-	    && S_ISCHR (st.st_mode) && st.st_rdev == mydev
-#else
-	    && d->d_fileno == myino && st.st_dev == mydev
-#endif
-	   )
+	    && is_mytty (mytty, &st))
 	  {
 	    (void) __closedir (dirstream);
 	    __set_errno (save);
@@ -151,12 +146,7 @@ __ttyname_r (int fd, char *buf, size_t buflen)
       /* Verify readlink result, fall back on iterating through devices.  */
       if (buf[0] == '/'
 	  && __xstat64 (_STAT_VER, buf, &st1) == 0
-#ifdef _STATBUF_ST_RDEV
-	  && S_ISCHR (st1.st_mode)
-	  && st1.st_rdev == st.st_rdev
-#endif
-	  && st1.st_ino == st.st_ino
-	  && st1.st_dev == st.st_dev)
+	  && is_mytty (&st, &st1))
 	return 0;

       /* If the link doesn't exist, then it points to a device in another
@@ -175,13 +165,8 @@ __ttyname_r (int fd, char *buf, size_t buflen)

   if (__xstat64 (_STAT_VER, buf, &st1) == 0 && S_ISDIR (st1.st_mode))
     {
-#ifdef _STATBUF_ST_RDEV
-      ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
+      ret = getttyname_r (buf, buflen, &st, save,
 			  &dostat);
-#else
-      ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
-			  &dostat);
-#endif
     }
   else
     {
@@ -193,26 +178,16 @@ __ttyname_r (int fd, char *buf, size_t buflen)
     {
       buf[sizeof ("/dev/") - 1] = '\0';
       buflen += sizeof ("pts/") - 1;
-#ifdef _STATBUF_ST_RDEV
-      ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino, save,
-			  &dostat);
-#else
-      ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino, save,
+      ret = getttyname_r (buf, buflen, &st, save,
 			  &dostat);
-#endif
     }

   if (ret && dostat != -1)
     {
       buf[sizeof ("/dev/") - 1] = '\0';
       dostat = 1;
-#ifdef _STATBUF_ST_RDEV
-      ret = getttyname_r (buf, buflen, st.st_rdev, st.st_ino,
-			  save, &dostat);
-#else
-      ret = getttyname_r (buf, buflen, st.st_dev, st.st_ino,
+      ret = getttyname_r (buf, buflen, &st,
 			  save, &dostat);
-#endif
     }

   return ret;
--
2.14.1