posix: Add compat glob symbol to not follow dangling symbols

This patch follows commit 5554304f0 (posix: Allow glob to match dangling
symlinks [BZ #866]) by adding a compat symbol that follow previous
semantic of not following dangling symlinks and thus avoiding call
gl_lstat with GLOB_ALTDIRFUNC.

It avoids failure with old binaries that not set the alternate function
pointer for lstat (GNUmake for instance).  The following scenario, for
instance, fails with current GNUmake because glibc will access unitialized
memory when calling gl_lstat:

  $ cat src/t/t.c
  int main ()
  {
    return 0;
  }
  $ cat Makefile
  SRC = $(wildcard src/*/t.c)
  OBJ = $(patsubst src/%.c, obj/%.o, $(SRC))

  prog:           $(OBJ)
                  $(CC) $(CFLAGS) $(LDFLAGS) $(LIBS) $(OBJ) -o prog

  obj/%.o:        src/%.c
                  $(CC) $(CFLAGS) -c $< -o $@
  $ make

This works as expected with the patch applied.  Since it is for generic
ABI, default compat symbols are added with override for Linux due LFS.
Now we have two compat symbols for glob on Linux:

  1. sysdeps/unix/sysv/linux/oldglob.c which implements glob64 with
     the old dirent layout.  For this implementation I also set it to
     not follow dangling symlinks (which is the safest path).

  2. sysdeps/unix/sysv/linux/glob{64}-lstat-compat.c which implements
     the compat symbol for dangling symlinks.  As for generic glob,
     the implementation uses XSTAT_IS_XSTAT64 to define whether
     both __glob_lstat_compat and __glob64_lstat_compat should be
     different implementations.  For archictures that define
     XSTAT_IS_XSTAT64, __glob_lstat_compat is aliased to
     __glob64_lstat_compat.

  3. sysdeps/unix/sysv/linux/alpha/oldglob.c with a different glob_t
     layout.  As for 1. this patch changes it to not follow dangling
     symlinks.

The patch also bumps _GNU_GLOB_INTERFACE_VERSION to 2 to advertise the
new semantic.  On GNUmake, for instance, it will force to it use its
internal glob implementation instead and avoiding triggering the same
failure on builds against newer GLIBCs.

Checked on x86_64-linux-gnu and i686-linux-gnu.  I also checked
with a build against the major ABIs required to check for the abilist.

The changes should also work on gnulib (I run gnulib-tool.py check glob
and it shown no regressions).

	[BZ #22183]
	* include/gnu-versions.h (_GNU_GLOB_INTERFACE_VERSION): Increase
	version to 2.
	* posix/Makefile (routines): Add glob-lstat-compat and
	glob64-lstat-compat.
	* posix/Versions (GLIBC_2.27, glob, glob64): Add symbol version.
	* posix/glob-lstat-compat.c: New file.
	* posix/glob64-lstat-compat.c: Likewise.
	* posix/tst-glob_lstat_compat.c: Likewise.
	* sysdeps/unix/sysv/linux/glob-lstat-compat.c: Likewise.
	* sysdeps/unix/sysv/linux/alpha/glob-lstat-compat.c: Likewise.
	* sysdeps/unix/sysv/linux/glob64-lstat-compat.c: Likewise.
	* sysdeps/unix/sysv/linux/alpha/glob.c: Remove file.
	* posix/glob.c (glob_lstat): New function.
	(glob): Rename to __glob and add versioned symbol to 2.27.
	(glob_in_dir): Use glob_lstat.
	* posix/glob64.c (glob64): Add GLOB_ATTRIBUTE.
	* sysdeps/unix/sysv/linux/arm/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/glob.c (glob): Add versioned symbol for
	2.27.
	* sysdeps/unix/sysv/linux/glob64.c (glob64): Likewise.
	* sysdeps/unix/sysv/linux/oldglob.c (GLOB_NO_LSTAT): Define.
	* sysdeps/unix/sysv/linux/alpha/oldglob.c (__old_glob): Do not use
	gl_lstat on glob call.
	* sysdeps/unix/sysv/linux/aarch64/libc.abilist: Add GLIBC_2.27 glob
	and glob64 symbols.
	* sysdeps/unix/sysv/linux/alpha/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/hppa/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/i386/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/ia64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/coldfire/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/m68k/m680x0/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/microblaze/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/fpu/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips32/nofpu/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/n32/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/mips/mips64/n64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/nios2/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/fpu/libc.abilist:
	Likewise.
	* sysdeps/unix/linux/powerpc/powerpc32/nofpu/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sh/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx32/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/tile/tilegx/tilegx64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/tile/tilepro/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/64/libc.abilist: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/x32/libc.abilist: Likewise.

1 files changed, 43 insertions, 24 deletions

diff --git a/posix/glob.c b/posix/glob.c
index c699177..98122da 100644
--- a/posix/glob.c
+++ b/posix/glob.c
@@ -57,7 +57,9 @@
 # endif
 # define struct_stat64		struct stat64
 # define FLEXIBLE_ARRAY_MEMBER
+# include <shlib-compat.h>
 #else /* !_LIBC */
+# define __glob                 glob
 # define __getlogin_r(buf, len) getlogin_r (buf, len)
 # define __lstat64(fname, buf)  lstat (fname, buf)
 # define __stat64(fname, buf)   stat (fname, buf)
@@ -179,6 +181,29 @@ convert_dirent64 (const struct dirent64 *source)
     ((void) (buf), (void) (len), (void) (newlen), (void) (avar), (void *) 0)
 #endif
 
+static int
+glob_lstat (glob_t *pglob, int flags, const char *fullname)
+{
+/* Use on glob-lstat-compat.c to provide a compat symbol which does not
+   use lstat / gl_lstat.  */
+#ifdef GLOB_NO_LSTAT
+# define GL_LSTAT gl_stat
+# define LSTAT64 __stat64
+#else
+# define GL_LSTAT gl_lstat
+# define LSTAT64 __lstat64
+#endif
+
+  union
+  {
+    struct stat st;
+    struct_stat64 st64;
+  } ust;
+  return (__glibc_unlikely (flags & GLOB_ALTDIRFUNC)
+          ? pglob->GL_LSTAT (fullname, &ust.st)
+          : LSTAT64 (fullname, &ust.st64));
+}
+
 /* Set *R = A + B.  Return true if the answer is mathematically
    incorrect due to overflow; in this case, *R is the low order
    bits of the correct answer.  */
@@ -248,6 +273,9 @@ next_brace_sub (const char *cp, int flags)
   return *cp != '\0' ? cp : NULL;
 }
 
+#ifndef GLOB_ATTRIBUTE
+# define GLOB_ATTRIBUTE
+#endif
 
 /* Do glob searching for PATTERN, placing results in PGLOB.
    The bits defined above may be set in FLAGS.
@@ -258,11 +286,9 @@ next_brace_sub (const char *cp, int flags)
    If memory cannot be allocated for PGLOB, GLOB_NOSPACE is returned.
    Otherwise, 'glob' returns zero.  */
 int
-#ifdef GLOB_ATTRIBUTE
 GLOB_ATTRIBUTE
-#endif
-glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
-      glob_t *pglob)
+__glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
+	glob_t *pglob)
 {
   const char *filename;
   char *dirname = NULL;
@@ -406,9 +432,10 @@ glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	      /* Construct the new glob expression.  */
 	      mempcpy (mempcpy (alt_start, p, next - p), rest, rest_len);
 
-	      result = glob (onealt,
-			     ((flags & ~(GLOB_NOCHECK | GLOB_NOMAGIC))
-			      | GLOB_APPEND), errfunc, pglob);
+	      result = __glob (onealt,
+			       ((flags & ~(GLOB_NOCHECK | GLOB_NOMAGIC))
+				| GLOB_APPEND),
+			       errfunc, pglob);
 
 	      /* If we got an error, return it.  */
 	      if (result && result != GLOB_NOMATCH)
@@ -557,7 +584,7 @@ glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 		  flags &= ~(GLOB_NOCHECK | GLOB_NOMAGIC);
 		}
 	    }
-	  int val = glob (dirname, flags | GLOB_MARK, errfunc, pglob);
+	  int val = __glob (dirname, flags | GLOB_MARK, errfunc, pglob);
 	  if (val == 0)
 	    pglob->gl_flags = ((pglob->gl_flags & ~GLOB_MARK)
 			       | (flags & GLOB_MARK));
@@ -931,11 +958,10 @@ glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 	  dirs.gl_lstat = pglob->gl_lstat;
 	}
 
-      status = glob (dirname,
-		     ((flags & (GLOB_ERR | GLOB_NOESCAPE
-				| GLOB_ALTDIRFUNC))
-		      | GLOB_NOSORT | GLOB_ONLYDIR),
-		     errfunc, &dirs);
+      status = __glob (dirname,
+		       ((flags & (GLOB_ERR | GLOB_NOESCAPE | GLOB_ALTDIRFUNC))
+			| GLOB_NOSORT | GLOB_ONLYDIR),
+		       errfunc, &dirs);
       if (status != 0)
 	{
 	  if ((flags & GLOB_NOCHECK) == 0 || status != GLOB_NOMATCH)
@@ -1133,8 +1159,9 @@ glob (const char *pattern, int flags, int (*errfunc) (const char *, int),
 
   return retval;
 }
-#if defined _LIBC && !defined glob
-libc_hidden_def (glob)
+#if defined _LIBC && !defined __glob
+versioned_symbol (libc, __glob, glob, GLIBC_2_27);
+libc_hidden_ver (__glob, glob)
 #endif
 
 
@@ -1250,11 +1277,6 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
     }
   else if (meta == GLOBPAT_NONE)
     {
-      union
-      {
-	struct stat st;
-	struct_stat64 st64;
-      } ust;
       size_t patlen = strlen (pattern);
       size_t fullsize;
       bool alloca_fullname
@@ -1273,10 +1295,7 @@ glob_in_dir (const char *pattern, const char *directory, int flags,
       mempcpy (mempcpy (mempcpy (fullname, directory, dirlen),
 			"/", 1),
 	       pattern, patlen + 1);
-      if (((__builtin_expect (flags & GLOB_ALTDIRFUNC, 0)
-	   ? (*pglob->gl_lstat) (fullname, &ust.st)
-	    : __lstat64 (fullname, &ust.st64))
-	   == 0)
+      if (glob_lstat (pglob, flags, fullname) == 0
 	  || errno == EOVERFLOW)
 	/* We found this file to be existing.  Now tell the rest
 	   of the function to copy this name into the result.  */