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| author | Corinna Vinschen <corinna@vinschen.de> | 2025-03-30 20:42:07 +0200 |
|---|---|---|
| committer | Corinna Vinschen <corinna@vinschen.de> | 2025-03-30 20:52:34 +0200 |
| commit | 1c4fc31c48a0c7cc6de122c50e25e618c169c343 (patch) | |
| tree | 5ecda04e4d337a5c072673353dbed635a53d6bbc | |
| parent | 82b31085f6ad23c3aaf5a928bd56fe06cbe63df5 (diff) | |
| download | newlib-1c4fc31c48a0c7cc6de122c50e25e618c169c343.zip newlib-1c4fc31c48a0c7cc6de122c50e25e618c169c343.tar.gz newlib-1c4fc31c48a0c7cc6de122c50e25e618c169c343.tar.bz2 | |
Cygwin: dlfcn: fix dlopen refcounting for DLLs loaded with RTLD_NODELETE
Refcounting is performed even if the DLL is loaded at least once
with RTLD_NODELETE. In that case we must not decrement the count
on dlclose, even if FreeLibrary will never unload the DLL.
Use INT_MAX as dll count if RTLD_NODELETE has been used at least once.
Skip any further refcounting and make sure the DLL is still pinned
in memory after fork.
Fixes: 33297d810d90 ("Cygwin: dlfcn: Fix reference counting")
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
| -rw-r--r-- | winsup/cygwin/dlfcn.cc | 15 | ||||
| -rw-r--r-- | winsup/cygwin/dll_init.cc | 16 | ||||
| -rw-r--r-- | winsup/cygwin/release/3.6.1 | 2 |
3 files changed, 26 insertions, 7 deletions
diff --git a/winsup/cygwin/dlfcn.cc b/winsup/cygwin/dlfcn.cc index f98c7db..a1e121f 100644 --- a/winsup/cygwin/dlfcn.cc +++ b/winsup/cygwin/dlfcn.cc @@ -278,7 +278,13 @@ dlopen (const char *name, int flags) { dll *d = dlls.find (ret, true); if (d) - ++d->count; + { + /* count == INT_MIN is used to specify RTLD_NODELETE */ + if (d->count == INT_MIN || gmheflags) + d->count = INT_MIN; + else + ++d->count; + } } if (ret && gmheflags) @@ -348,14 +354,15 @@ dlclose (void *handle) int ret = 0; if (handle != GetModuleHandle (NULL)) { - /* reference counting */ + /* Reference counting. + count == INT_MIN is used to specify RTLD_NODELETE */ dll *d = dlls.find (handle, true); - if (!d || d->count <= 0) + if (!d || (d->count <= 0 && d->count != INT_MIN)) { errno = ENOENT; ret = -1; } - else + else if (d->count != INT_MIN) { --d->count; if (!FreeLibrary ((HMODULE) handle)) diff --git a/winsup/cygwin/dll_init.cc b/winsup/cygwin/dll_init.cc index c6fb94a..aab11d1 100644 --- a/winsup/cygwin/dll_init.cc +++ b/winsup/cygwin/dll_init.cc @@ -782,9 +782,19 @@ void dll_list::load_after_fork_impl (HANDLE parent, dll* d, int retries) if (h != d->handle) fabort ("unable to map %W (using %W) to same address as parent: %p != %p", d->ntname, buffered_shortname (d->forkedntname ()), d->handle, h); - /* Fix OS reference count. */ - for (int cnt = 1; cnt < d->count; ++cnt) - LoadLibraryW (buffered_shortname (d->forkedntname ())); + /* Fix OS reference count. + count == INT_MIN is used to specify RTLD_NODELETE. If so, we don't + have to call LoadLibraryW count times, just mark the DLL as pinned. */ + if (d->count == INT_MIN) /* RTLD_NODELETE */ + { + HMODULE hm; + GetModuleHandleExW (GET_MODULE_HANDLE_EX_FLAG_PIN, + buffered_shortname (d->forkedntname ()), + &hm); + } + else + for (int cnt = 1; cnt < d->count; ++cnt) + LoadLibraryW (buffered_shortname (d->forkedntname ())); } } diff --git a/winsup/cygwin/release/3.6.1 b/winsup/cygwin/release/3.6.1 index 85c3f6c..c1dbbfb 100644 --- a/winsup/cygwin/release/3.6.1 +++ b/winsup/cygwin/release/3.6.1 @@ -18,3 +18,5 @@ Fixes: - Fix reference counting when dlopen/dlclose is called on the Cygwin DLL. Addresses: https://cygwin.com/pipermail/cygwin/2025-March/257783.html + +- Fix reference counting when dlopen/dlclose a DLL with RTLD_NODELETE. |