mtrace: Wean away from malloc hooks

Wean mtrace away from the malloc hooks and move them into the debug
DSO.  Split the API away from the implementation so that we can add
the API to libc.so as well as libc_malloc_debug.so, with the libc
implementations being empty.

Update localplt data since memalign no longer has any callers after
this change.

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

1 files changed, 12 insertions, 302 deletions

diff --git a/malloc/mtrace.c b/malloc/mtrace.c
index fb58413d39..c1c836a740 100644
--- a/malloc/mtrace.c
+++ b/malloc/mtrace.c
@@ -1,4 +1,4 @@
-/* More debugging hooks for `malloc'.
+/* mtrace API for `malloc'.
    Copyright (C) 1991-2021 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
                  Written April 2, 1991 by John Gilmore of Cygnus Support.
@@ -18,40 +18,14 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
-#ifndef _MALLOC_INTERNAL
-# define _MALLOC_INTERNAL
-# include <malloc.h>
-# include <mcheck.h>
-# include <malloc-internal.h>
-# include <libc-lock.h>
+#if !IS_IN (libc)
+# include "mtrace-impl.c"
+#else
+# include <shlib-compat.h>
+# include <libc-symbols.h>
 #endif
 
-#include <dlfcn.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
-
-#include <_itoa.h>
-
-#include <libc-internal.h>
-#include <dso_handle.h>
-
-#include <libio/iolibio.h>
-#define setvbuf(s, b, f, l) _IO_setvbuf (s, b, f, l)
-#define fwrite(buf, size, count, fp) _IO_fwrite (buf, size, count, fp)
-
-#include <kernel-features.h>
-
-#define TRACE_BUFFER_SIZE 512
-
-static FILE *mallstream;
-static const char mallenv[] = "MALLOC_TRACE";
-static char *malloc_trace_buffer;
-
-__libc_lock_define_initialized (static, lock);
-
-#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_34)
+#if IS_IN (libc) && SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_34)
 /* Compatibility symbols that were introduced to help break at allocation sites
    for specific memory allocations.  This is unusable with ASLR, although gdb
    may allow predictable allocation addresses.  Even then, gdb has watchpoint
@@ -71,282 +45,18 @@ compat_symbol (libc, tr_break, tr_break, GLIBC_2_0);
 #endif
 
 
-/* Old hook values.  */
-static void (*tr_old_free_hook) (void *ptr, const void *);
-static void *(*tr_old_malloc_hook) (size_t size, const void *);
-static void *(*tr_old_realloc_hook) (void *ptr, size_t size,
-				     const void *);
-static void *(*tr_old_memalign_hook) (size_t __alignment, size_t __size,
-				      const void *);
-
-static void
-tr_where (const void *caller, Dl_info *info)
-{
-  if (caller != NULL)
-    {
-      if (info != NULL)
-        {
-          char *buf = (char *) "";
-          if (info->dli_sname != NULL)
-            {
-              size_t len = strlen (info->dli_sname);
-              buf = alloca (len + 6 + 2 * sizeof (void *));
-
-              buf[0] = '(';
-              __stpcpy (_fitoa (caller >= (const void *) info->dli_saddr
-                                ? caller - (const void *) info->dli_saddr
-                                : (const void *) info->dli_saddr - caller,
-                                __stpcpy (__mempcpy (buf + 1, info->dli_sname,
-                                                     len),
-                                          caller >= (void *) info->dli_saddr
-                                          ? "+0x" : "-0x"),
-                                16, 0),
-                        ")");
-            }
-
-          fprintf (mallstream, "@ %s%s%s[%p] ",
-                   info->dli_fname ? : "", info->dli_fname ? ":" : "",
-                   buf, caller);
-        }
-      else
-        fprintf (mallstream, "@ [%p] ", caller);
-    }
-}
-
-static Dl_info *
-lock_and_info (const void *caller, Dl_info *mem)
-{
-  if (caller == NULL)
-    return NULL;
-
-  Dl_info *res = _dl_addr (caller, mem, NULL, NULL) ? mem : NULL;
-
-  __libc_lock_lock (lock);
-
-  return res;
-}
-
-static void tr_freehook (void *, const void *);
-static void * tr_mallochook (size_t, const void *);
-static void * tr_reallochook (void *, size_t, const void *);
-static void * tr_memalignhook (size_t, size_t, const void *);
-
-/* Set all the default non-trace hooks.  */
-static __always_inline void
-set_default_hooks (void)
-{
-  __free_hook = tr_old_free_hook;
-  __malloc_hook = tr_old_malloc_hook;
-  __realloc_hook = tr_old_realloc_hook;
-  __memalign_hook = tr_old_memalign_hook;
-}
-
-/* Set all of the tracing hooks used for mtrace.  */
-static __always_inline void
-set_trace_hooks (void)
-{
-  __free_hook = tr_freehook;
-  __malloc_hook = tr_mallochook;
-  __realloc_hook = tr_reallochook;
-  __memalign_hook = tr_memalignhook;
-}
-
-/* Save the current set of hooks as the default hooks.  */
-static __always_inline void
-save_default_hooks (void)
-{
-  tr_old_free_hook = __free_hook;
-  tr_old_malloc_hook = __malloc_hook;
-  tr_old_realloc_hook = __realloc_hook;
-  tr_old_memalign_hook = __memalign_hook;
-}
-
-static void
-tr_freehook (void *ptr, const void *caller)
-{
-  if (ptr == NULL)
-    return;
-
-  Dl_info mem;
-  Dl_info *info = lock_and_info (caller, &mem);
-  tr_where (caller, info);
-  /* Be sure to print it first.  */
-  fprintf (mallstream, "- %p\n", ptr);
-  set_default_hooks ();
-  if (tr_old_free_hook != NULL)
-    (*tr_old_free_hook)(ptr, caller);
-  else
-    free (ptr);
-  set_trace_hooks ();
-  __libc_lock_unlock (lock);
-}
-
-static void *
-tr_mallochook (size_t size, const void *caller)
-{
-  void *hdr;
-
-  Dl_info mem;
-  Dl_info *info = lock_and_info (caller, &mem);
-
-  set_default_hooks ();
-  if (tr_old_malloc_hook != NULL)
-    hdr = (void *) (*tr_old_malloc_hook)(size, caller);
-  else
-    hdr = (void *) malloc (size);
-  set_trace_hooks ();
-
-  tr_where (caller, info);
-  /* We could be printing a NULL here; that's OK.  */
-  fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
-
-  __libc_lock_unlock (lock);
-
-  return hdr;
-}
-
-static void *
-tr_reallochook (void *ptr, size_t size, const void *caller)
-{
-  void *hdr;
-
-  Dl_info mem;
-  Dl_info *info = lock_and_info (caller, &mem);
-
-  set_default_hooks ();
-  if (tr_old_realloc_hook != NULL)
-    hdr = (void *) (*tr_old_realloc_hook)(ptr, size, caller);
-  else
-    hdr = (void *) realloc (ptr, size);
-  set_trace_hooks ();
-
-  tr_where (caller, info);
-  if (hdr == NULL)
-    {
-      if (size != 0)
-        /* Failed realloc.  */
-        fprintf (mallstream, "! %p %#lx\n", ptr, (unsigned long int) size);
-      else
-        fprintf (mallstream, "- %p\n", ptr);
-    }
-  else if (ptr == NULL)
-    fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
-  else
-    {
-      fprintf (mallstream, "< %p\n", ptr);
-      tr_where (caller, info);
-      fprintf (mallstream, "> %p %#lx\n", hdr, (unsigned long int) size);
-    }
-
-  __libc_lock_unlock (lock);
-
-  return hdr;
-}
-
-static void *
-tr_memalignhook (size_t alignment, size_t size, const void *caller)
-{
-  void *hdr;
-
-  Dl_info mem;
-  Dl_info *info = lock_and_info (caller, &mem);
-
-  set_default_hooks ();
-  if (tr_old_memalign_hook != NULL)
-    hdr = (void *) (*tr_old_memalign_hook)(alignment, size, caller);
-  else
-    hdr = (void *) memalign (alignment, size);
-  set_trace_hooks ();
-
-  tr_where (caller, info);
-  /* We could be printing a NULL here; that's OK.  */
-  fprintf (mallstream, "+ %p %#lx\n", hdr, (unsigned long int) size);
-
-  __libc_lock_unlock (lock);
-
-  return hdr;
-}
-
-
-#ifdef _LIBC
-
-/* This function gets called to make sure all memory the library
-   allocates get freed and so does not irritate the user when studying
-   the mtrace output.  */
-static void __libc_freeres_fn_section
-release_libc_mem (void)
-{
-  /* Only call the free function if we still are running in mtrace mode.  */
-  if (mallstream != NULL)
-    __libc_freeres ();
-}
-#endif
-
-
-/* We enable tracing if the environment variable MALLOC_TRACE is set.  */
-
 void
 mtrace (void)
 {
-#ifdef _LIBC
-  static int added_atexit_handler;
+#if !IS_IN (libc)
+  do_mtrace ();
 #endif
-  char *mallfile;
-
-  /* Don't panic if we're called more than once.  */
-  if (mallstream != NULL)
-    return;
-
-#ifdef _LIBC
-  /* When compiling the GNU libc we use the secure getenv function
-     which prevents the misuse in case of SUID or SGID enabled
-     programs.  */
-  mallfile = __libc_secure_getenv (mallenv);
-#else
-  mallfile = getenv (mallenv);
-#endif
-  if (mallfile != NULL)
-    {
-      char *mtb = malloc (TRACE_BUFFER_SIZE);
-      if (mtb == NULL)
-        return;
-
-      mallstream = fopen (mallfile != NULL ? mallfile : "/dev/null", "wce");
-      if (mallstream != NULL)
-        {
-          /* Be sure it doesn't malloc its buffer!  */
-          malloc_trace_buffer = mtb;
-          setvbuf (mallstream, malloc_trace_buffer, _IOFBF, TRACE_BUFFER_SIZE);
-          fprintf (mallstream, "= Start\n");
-	  save_default_hooks ();
-	  set_trace_hooks ();
-#ifdef _LIBC
-          if (!added_atexit_handler)
-            {
-              added_atexit_handler = 1;
-              __cxa_atexit ((void (*)(void *))release_libc_mem, NULL,
-			    __dso_handle);
-            }
-#endif
-        }
-      else
-        free (mtb);
-    }
 }
 
 void
 muntrace (void)
 {
-  if (mallstream == NULL)
-    return;
-
-  /* Do the reverse of what done in mtrace: first reset the hooks and
-     MALLSTREAM, and only after that write the trailer and close the
-     file.  */
-  FILE *f = mallstream;
-  mallstream = NULL;
-  set_default_hooks ();
-
-  fprintf (f, "= End\n");
-  fclose (f);
+#if !IS_IN (libc)
+  do_muntrace ();
+#endif
 }