libio: Remove the usage of __libc_IO_vtables

Instead of using a special ELF section along with a linker script
directive to put the IO vtables within the RELRO section, the libio
vtables are all moved to an array marked as data.relro (so linker
will place in the RELRO segment without the need of extra directives).

To avoid static linking namespace issues and including all vtable
referenced objects, all required function pointers are set to weak alias.

Checked on x86_64-linux-gnu, i686-linux-gnu, and aarch64-linux-gnu.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>

1 files changed, 6 insertions, 54 deletions

diff --git a/libio/iofopncook.c b/libio/iofopncook.c
index d6a06c5acb..5511c07c18 100644
--- a/libio/iofopncook.c
+++ b/libio/iofopncook.c
@@ -30,7 +30,7 @@
 #include <shlib-compat.h>
 #include <pointer_guard.h>
 
-static ssize_t
+ssize_t
 _IO_cookie_read (FILE *fp, void *buf, ssize_t size)
 {
   struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
@@ -43,7 +43,7 @@ _IO_cookie_read (FILE *fp, void *buf, ssize_t size)
   return read_cb (cfile->__cookie, buf, size);
 }
 
-static ssize_t
+ssize_t
 _IO_cookie_write (FILE *fp, const void *buf, ssize_t size)
 {
   struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
@@ -63,7 +63,7 @@ _IO_cookie_write (FILE *fp, const void *buf, ssize_t size)
   return n;
 }
 
-static off64_t
+off64_t
 _IO_cookie_seek (FILE *fp, off64_t offset, int dir)
 {
   struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
@@ -77,7 +77,7 @@ _IO_cookie_seek (FILE *fp, off64_t offset, int dir)
 	  ? _IO_pos_BAD : offset);
 }
 
-static int
+int
 _IO_cookie_close (FILE *fp)
 {
   struct _IO_cookie_file *cfile = (struct _IO_cookie_file *) fp;
@@ -91,7 +91,7 @@ _IO_cookie_close (FILE *fp)
 }
 
 
-static off64_t
+off64_t
 _IO_cookie_seekoff (FILE *fp, off64_t offset, int dir, int mode)
 {
   /* We must force the fileops code to always use seek to determine
@@ -100,31 +100,6 @@ _IO_cookie_seekoff (FILE *fp, off64_t offset, int dir, int mode)
   return _IO_file_seekoff (fp, offset, dir, mode);
 }
 
-
-static const struct _IO_jump_t _IO_cookie_jumps libio_vtable = {
-  JUMP_INIT_DUMMY,
-  JUMP_INIT(finish, _IO_file_finish),
-  JUMP_INIT(overflow, _IO_file_overflow),
-  JUMP_INIT(underflow, _IO_file_underflow),
-  JUMP_INIT(uflow, _IO_default_uflow),
-  JUMP_INIT(pbackfail, _IO_default_pbackfail),
-  JUMP_INIT(xsputn, _IO_file_xsputn),
-  JUMP_INIT(xsgetn, _IO_default_xsgetn),
-  JUMP_INIT(seekoff, _IO_cookie_seekoff),
-  JUMP_INIT(seekpos, _IO_default_seekpos),
-  JUMP_INIT(setbuf, _IO_file_setbuf),
-  JUMP_INIT(sync, _IO_file_sync),
-  JUMP_INIT(doallocate, _IO_file_doallocate),
-  JUMP_INIT(read, _IO_cookie_read),
-  JUMP_INIT(write, _IO_cookie_write),
-  JUMP_INIT(seek, _IO_cookie_seek),
-  JUMP_INIT(close, _IO_cookie_close),
-  JUMP_INIT(stat, _IO_default_stat),
-  JUMP_INIT(showmanyc, _IO_default_showmanyc),
-  JUMP_INIT(imbue, _IO_default_imbue),
-};
-
-
 /* Copy the callbacks from SOURCE to *TARGET, with pointer
    mangling.  */
 static void
@@ -209,7 +184,7 @@ versioned_symbol (libc, _IO_fopencookie, fopencookie, GLIBC_2_2);
 
 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_2)
 
-static off64_t
+off64_t
 attribute_compat_text_section
 _IO_old_cookie_seek (FILE *fp, off64_t offset, int dir)
 {
@@ -226,29 +201,6 @@ _IO_old_cookie_seek (FILE *fp, off64_t offset, int dir)
   return (ret == -1) ? _IO_pos_BAD : ret;
 }
 
-static const struct _IO_jump_t _IO_old_cookie_jumps libio_vtable = {
-  JUMP_INIT_DUMMY,
-  JUMP_INIT(finish, _IO_file_finish),
-  JUMP_INIT(overflow, _IO_file_overflow),
-  JUMP_INIT(underflow, _IO_file_underflow),
-  JUMP_INIT(uflow, _IO_default_uflow),
-  JUMP_INIT(pbackfail, _IO_default_pbackfail),
-  JUMP_INIT(xsputn, _IO_file_xsputn),
-  JUMP_INIT(xsgetn, _IO_default_xsgetn),
-  JUMP_INIT(seekoff, _IO_cookie_seekoff),
-  JUMP_INIT(seekpos, _IO_default_seekpos),
-  JUMP_INIT(setbuf, _IO_file_setbuf),
-  JUMP_INIT(sync, _IO_file_sync),
-  JUMP_INIT(doallocate, _IO_file_doallocate),
-  JUMP_INIT(read, _IO_cookie_read),
-  JUMP_INIT(write, _IO_cookie_write),
-  JUMP_INIT(seek, _IO_old_cookie_seek),
-  JUMP_INIT(close, _IO_cookie_close),
-  JUMP_INIT(stat, _IO_default_stat),
-  JUMP_INIT(showmanyc, _IO_default_showmanyc),
-  JUMP_INIT(imbue, _IO_default_imbue),
-};
-
 FILE *
 attribute_compat_text_section
 _IO_old_fopencookie (void *cookie, const char *mode,