commit 4dc228e35bbedb6f451a621db4a756ead9560a76 Author: Nick Mathewson nickm@torproject.org Date: Thu Jan 25 17:04:12 2018 -0500

Remove workaround code for systems where free(NULL) is busted.

Add an autoconf test to make sure we won't regret it.

Closes ticket 24484. --- changes/bug24484 | 4 ++++ configure.ac | 15 +++++++++++++++ src/common/util.h | 18 +++++++----------- 3 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/changes/bug24484 b/changes/bug24484 new file mode 100644 index 000000000..35a204492 --- /dev/null +++ b/changes/bug24484 @@ -0,0 +1,4 @@ + o Code simplification and refactoring: + - Since Tor requires C99, remove our old workaround code for libc + implementations where free(NULL) doesn't work. Closes ticket 24484. + diff --git a/configure.ac b/configure.ac index 3cb187b0e..3795faddc 100644 --- a/configure.ac +++ b/configure.ac @@ -615,6 +615,21 @@ fi AM_CONDITIONAL(BUILD_READPASSPHRASE_C, test "x$ac_cv_func_readpassphrase" = "xno" && test "$bwin32" = "false")

+AC_MSG_CHECKING([whether free(NULL) works]) +AC_RUN_IFELSE([AC_LANG_PROGRAM([ + #include <stdlib.h> +], [ +char *p = NULL; +free(p); +])], +[free_null_ok=true; AC_MSG_RESULT(yes)], +[free_null_ok=false; AC_MSG_RESULT(no)], +[free_null_ok=cross; AC_MSG_RESULT(cross)]) + +if test "$free_null_ok" = "false"; then + AC_MSG_ERROR([Your libc implementation doesn't allow free(NULL), as required by C99.]) +fi + dnl ------------------------------------------------------ dnl Where do you live, libevent? And how do we call you?

diff --git a/src/common/util.h b/src/common/util.h index 2ee0ea28c..653c154ab 100644 --- a/src/common/util.h +++ b/src/common/util.h @@ -73,9 +73,9 @@ extern int dmalloc_free(const char *file, const int line, void *pnt, } \ STMT_END #else /* !(defined(USE_DMALLOC)) */ -/** Release memory allocated by tor_malloc, tor_realloc, tor_strdup, etc. - * Unlike the free() function, tor_free() will still work on NULL pointers, - * and it sets the pointer value to NULL after freeing it. +/** Release memory allocated by tor_malloc, tor_realloc, tor_strdup, + * etc. Unlike the free() function, the tor_free() macro sets the + * pointer value to NULL after freeing it. * * This is a macro. If you need a function pointer to release memory from * tor_malloc(), use tor_free_(). @@ -88,17 +88,13 @@ extern int dmalloc_free(const char *file, const int line, void *pnt, #ifdef __GNUC__ #define tor_free(p) STMT_BEGIN \ typeof(&(p)) tor_free__tmpvar = &(p); \ - if (PREDICT_LIKELY((*tor_free__tmpvar)!=NULL)) { \ - raw_free(*tor_free__tmpvar); \ - *tor_free__tmpvar=NULL; \ - } \ + raw_free(*tor_free__tmpvar); \ + *tor_free__tmpvar=NULL; \ STMT_END #else #define tor_free(p) STMT_BEGIN \ - if (PREDICT_LIKELY((p)!=NULL)) { \ - raw_free(p); \ - (p)=NULL; \ - } \ + raw_free(p); \ + (p)=NULL; \ STMT_END #endif #endif /* defined(USE_DMALLOC) */