From: Eric Wong <e@80x24.org>
To: mwrap-public@80x24.org
Subject: [PATCH 09/19] resolve real_malloc earlier for C++ programs
Date: Mon, 16 Jul 2018 21:19:23 +0000 [thread overview]
Message-ID: <20180716211933.5835-10-e@80x24.org> (raw)
In-Reply-To: <20180716211933.5835-1-e@80x24.org>
cmake (as run by the Ruby test suite for RubyGems) uses libjson
and libtasn1, which respectively call malloc (via `new') and
free before our constructor can even fire. Apparently, C++
variable initialization may call "new" outside of any functions;
and those run before any functions with the GCC constructor
attribute.
Disclaimer: I don't know C++
---
ext/mwrap/mwrap.c | 34 ++++++++++++++++++++++++----------
test/test_mwrap.rb | 16 ++++++++++++++++
2 files changed, 40 insertions(+), 10 deletions(-)
diff --git a/ext/mwrap/mwrap.c b/ext/mwrap/mwrap.c
index d08ebf0..73d5a80 100644
--- a/ext/mwrap/mwrap.c
+++ b/ext/mwrap/mwrap.c
@@ -42,12 +42,11 @@ void *__malloc(size_t);
void __free(void *);
static void *(*real_malloc)(size_t) = __malloc;
static void (*real_free)(void *) = __free;
-static const int ready = 1;
#else
-static int ready;
static void *(*real_malloc)(size_t);
static void (*real_free)(void *);
#endif /* !FreeBSD */
+static int resolving_malloc;
/*
* we need to fake an OOM condition while dlsym is running,
@@ -55,7 +54,7 @@ static void (*real_free)(void *);
* symbol for the jemalloc calloc, yet
*/
# define RETURN_IF_NOT_READY() do { \
- if (!ready) { \
+ if (!real_malloc) { \
errno = ENOMEM; \
return NULL; \
} \
@@ -93,14 +92,16 @@ __attribute__((constructor)) static void resolve_malloc(void)
int err;
#ifndef __FreeBSD__
- real_malloc = dlsym(RTLD_NEXT, "malloc");
+ if (!real_malloc) {
+ resolving_malloc = 1;
+ real_malloc = dlsym(RTLD_NEXT, "malloc");
+ }
real_free = dlsym(RTLD_NEXT, "free");
if (!real_malloc || !real_free) {
fprintf(stderr, "missing malloc/aligned_alloc/free\n"
"\t%p %p\n", real_malloc, real_free);
_exit(1);
}
- ready = 1;
#endif
totals = lfht_new();
if (!totals)
@@ -343,6 +344,8 @@ void free(void *p)
{
if (p) {
struct alloc_hdr *h = ptr2hdr(p);
+
+ if (!real_free) return; /* oh well, leak a little */
if (h->as.live.loc) {
h->size = 0;
mutex_lock(h->as.live.loc->mtx);
@@ -400,7 +403,7 @@ internal_memalign(void **pp, size_t alignment, size_t size, uintptr_t caller)
size_t d = alignment / sizeof(void*);
size_t r = alignment % sizeof(void*);
- if (!ready) return ENOMEM;
+ if (!real_malloc) return ENOMEM;
if (r != 0 || d == 0 || !is_power_of_two(d))
return EINVAL;
@@ -498,11 +501,19 @@ void *malloc(size_t size)
size_t asize;
void *p;
- if (__builtin_add_overflow(size, sizeof(struct alloc_hdr), &asize)) {
- errno = ENOMEM;
- return 0;
+ if (__builtin_add_overflow(size, sizeof(struct alloc_hdr), &asize))
+ goto enomem;
+
+ /*
+ * Needed for C++ global declarations using "new",
+ * which happens before our constructor
+ */
+ if (!real_malloc) {
+ if (resolving_malloc) goto enomem;
+ resolving_malloc = 1;
+ real_malloc = dlsym(RTLD_NEXT, "malloc");
}
- RETURN_IF_NOT_READY();
+
rcu_read_lock();
l = update_stats_rcu(size, RETURN_ADDRESS(0));
p = h = real_malloc(asize);
@@ -513,6 +524,9 @@ void *malloc(size_t size)
rcu_read_unlock();
if (caa_unlikely(!p)) errno = ENOMEM;
return p;
+enomem:
+ errno = ENOMEM;
+ return 0;
}
void *calloc(size_t nmemb, size_t size)
diff --git a/test/test_mwrap.rb b/test/test_mwrap.rb
index d76e4da..d0af0f7 100644
--- a/test/test_mwrap.rb
+++ b/test/test_mwrap.rb
@@ -61,6 +61,22 @@ class TestMwrap < Test::Unit::TestCase
end
end
+ def test_cmake
+ begin
+ exp = `cmake -h`
+ rescue Errno::ENOENT
+ warn 'cmake missing'
+ return
+ end
+ assert_not_predicate exp.strip, :empty?
+ env = @@env.merge('MWRAP' => 'dump_fd:1')
+ out = IO.popen(env, %w(cmake -h), &:read)
+ assert out.start_with?(exp), 'original help exists'
+ assert_not_equal exp, out, 'includes dump output'
+ dump = out.delete_prefix(exp)
+ assert_match(/\b0x[a-f0-9]+\b/s, dump, 'dump output has addresses')
+ end
+
def test_clear
cmd = @@cmd + %w(
-e ("0"*10000).clear
--
EW
next prev parent reply other threads:[~2018-07-16 21:19 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-16 21:19 [PATCH 0/19] the heavy version of mwrap Eric Wong
2018-07-16 21:19 ` [PATCH 01/19] support per-allocation headers for per-alloc tracking Eric Wong
2018-07-16 21:19 ` [PATCH 02/19] mwrap: use malloc to do our own memalign Eric Wong
2018-07-16 21:19 ` [PATCH 03/19] hold RCU read lock to insert each allocation Eric Wong
2018-07-16 21:19 ` [PATCH 04/19] realloc: do not copy if allocation failed Eric Wong
2018-07-16 21:19 ` [PATCH 05/19] internal_memalign: do not assume real_malloc succeeds Eric Wong
2018-07-16 21:19 ` [PATCH 06/19] ensure ENOMEM is preserved in errno when appropriate Eric Wong
2018-07-16 21:19 ` [PATCH 07/19] memalign: check alignment on all public functions Eric Wong
2018-07-16 21:19 ` [PATCH 08/19] reduce stack usage from file names Eric Wong
2018-07-16 21:19 ` Eric Wong [this message]
2018-07-16 21:19 ` [PATCH 10/19] allow analyzing live allocations via Mwrap[location] Eric Wong
2018-07-16 21:19 ` [PATCH 11/19] alias Mwrap.clear to Mwrap.reset Eric Wong
2018-07-16 21:19 ` [PATCH 12/19] implement accessors for SourceLocation Eric Wong
2018-07-16 21:19 ` [PATCH 13/19] mwrap_aref: quiet -Wshorten-64-to-32 warning Eric Wong
2018-07-16 21:19 ` [PATCH 14/19] fixes for FreeBSD 11.1 Eric Wong
2018-07-16 21:19 ` [PATCH 15/19] use memrchr to extract address under glibc Eric Wong
2018-07-16 21:19 ` [PATCH 16/19] do not track allocations for constructor and Init_ Eric Wong
2018-07-16 21:19 ` [PATCH 17/19] disable memalign tracking by default Eric Wong
2018-07-16 21:19 ` [PATCH 18/19] support Mwrap.quiet to temporarily disable allocation tracking Eric Wong
2018-07-16 21:19 ` [PATCH 19/19] mwrap_rack: Rack app to track live allocations Eric Wong
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