Rename dlopen() to cosmo_dlopen()

examples/dlopen.c

@@ -17,7 +17,7 @@
 /**
  * @fileoverview cosmopolitan dynamic runtime linking demo
  *
- * Our dlopen() interface currently supports:
+ * Our cosmo_dlopen() interface currently supports:
  *
  * - x86-64 Linux w/ Glibc
  * - x86-64 Linux w/ Musl Libc
@@ -31,16 +31,16 @@
 int main(int argc, char **argv, char **envp) {
 
   // open the host system's zlib library
-  void *libc = dlopen("libz.so", RTLD_LAZY);
+  void *libc = cosmo_dlopen("libz.so", RTLD_LAZY);
   if (!libc) {
-    tinyprint(2, dlerror(), "\n", NULL);
+    tinyprint(2, cosmo_dlerror(), "\n", NULL);
     exit(1);
   }
 
   // load crc() function address
-  unsigned (*crc32)(unsigned, void *, int) = dlsym(libc, "crc32");
+  unsigned (*crc32)(unsigned, void *, int) = cosmo_dlsym(libc, "crc32");
   if (!crc32) {
-    tinyprint(2, dlerror(), "\n", NULL);
+    tinyprint(2, cosmo_dlerror(), "\n", NULL);
     exit(1);
   }
 
@@ -50,6 +50,6 @@ int main(int argc, char **argv, char **envp) {
   tinyprint(1, "crc(hi) = ", ibuf, "\n", NULL);
 
   // mop up
-  dlclose(libc);
+  cosmo_dlclose(libc);
   exit(0);
 }

libc/dlopen/dlfcn.h

@@ -18,6 +18,14 @@ void *dlsym(void *, const char *);
 int dlclose(void *);
 int dl_iterate_phdr(int (*)(void *, size_t, void *), void *);
 
+#ifdef _COSMO_SOURCE
+char *cosmo_dlerror(void);
+void *cosmo_dlopen(const char *, int);
+void *cosmo_dlsym(void *, const char *);
+int cosmo_dlclose(void *);
+int cosmo_dl_iterate_phdr(int (*)(void *, size_t, void *), void *);
+#endif
+
 COSMOPOLITAN_C_END_
 #endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
 #endif /* COSMOPOLITAN_LIBC_DLFCN_H_ */

libc/dlopen/dlopen.c

@@ -19,6 +19,7 @@
 #include "libc/atomic.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/internal.h"
+#include "libc/calls/struct/sigset.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/calls/syscall_support-nt.internal.h"
 #include "libc/cosmo.h"
@@ -77,6 +78,7 @@ __static_yoink(".dlopen.aarch64.glibc.elf");
 
 #define BEGIN_FOREIGN                         \
   {                                           \
+    BLOCK_SIGNALS;                            \
     struct CosmoTib *cosmo_tib = __get_tls(); \
     pthread_mutex_lock(&foreign.lock);        \
     __set_tls(foreign.tib)
@@ -84,6 +86,7 @@ __static_yoink(".dlopen.aarch64.glibc.elf");
 #define END_FOREIGN                    \
   __set_tls(cosmo_tib);                \
   pthread_mutex_unlock(&foreign.lock); \
+  ALLOW_SIGNALS;                       \
   }
 
 struct loaded {
@@ -478,6 +481,27 @@ static void *dlopen_silicon(const char *path, int mode) {
  * this wrapper will automatically change it to `.dll` or `.dylib` to
  * increase its chance of successfully loading.
  *
+ * WARNING: This isn't supported on MacOS x86-64, OpenBSD, and NetBSD.
+ *
+ * WARNING: This dlopen() implementation is highly limited. Cosmo
+ * binaries are always statically linked. You can import functions from
+ * dynamic shared objects, but you can't export any. This dlopen() won't
+ * work for language plugins, but might help you access GUI and GPU DRM.
+ *
+ * WARNING: Do not expect this dlopen() is in any way safe to use. It's
+ * mostly due to thread local storage. On Windows it should be safe. On
+ * Apple Silicon it should be safe so long as foreign functions don't
+ * issue callbacks. On libre OSes we currently only make dlopen() APIs
+ * safe to use. In order for it to be safe, four system calls need to be
+ * issued for every dlopen() related API call, and that's assuming this
+ * API is only used from the main of your program. Most importantly
+ * there are no safeguards added around imported functions, since it'd
+ * make them go 1000x slower. It's the responsibility of the caller to
+ * ensure that imported functions never touch TLS, don't install signal
+ * handlers, will never spawn threads, and don't issue callbacks. Care
+ * should also be taken on all platforms, to ensure dynamic memory is
+ * being passed to the correct malloc() and free() implementations.
+ *
  * @param mode is a bitmask that can contain:
  *     - `RTLD_LOCAL` (default)
  *     - `RTLD_GLOBAL` (not supported on Windows)
@@ -485,7 +509,7 @@ static void *dlopen_silicon(const char *path, int mode) {
  *     - `RTLD_NOW`
  * @return dso handle, or NULL w/ dlerror()
  */
-void *dlopen(const char *path, int mode) {
+void *cosmo_dlopen(const char *path, int mode) {
   void *res;
   if (IsWindows()) {
     res = dlopen_nt(path, mode);
@@ -514,7 +538,7 @@ void *dlopen(const char *path, int mode) {
  * @param handle was opened by dlopen()
  * @return address of symbol, or NULL w/ dlerror()
  */
-void *dlsym(void *handle, const char *name) {
+void *cosmo_dlsym(void *handle, const char *name) {
   void *res;
   if (IsWindows()) {
     res = dlsym_nt(handle, name);
@@ -540,7 +564,7 @@ void *dlsym(void *handle, const char *name) {
  * @param handle was opened by dlopen()
  * @return 0 on success, or -1 w/ dlerror()
  */
-int dlclose(void *handle) {
+int cosmo_dlclose(void *handle) {
   int res;
   if (IsWindows()) {
     res = dlclose_nt(handle);
@@ -563,7 +587,7 @@ int dlclose(void *handle) {
 /**
  * Returns string describing last dlopen/dlsym/dlclose error.
  */
-char *dlerror(void) {
+char *cosmo_dlerror(void) {
   char *res;
   if (IsXnuSilicon()) {
     res = __syslib->__dlerror();

libc/dlopen/stubs.c

@@ -0,0 +1,39 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/dlopen/dlfcn.h"
+
+char *dlerror(void) {
+  return "dlopen() isn't supported by cosmo";
+}
+
+void *dlopen(const char *, int) {
+  return 0;
+}
+
+void *dlsym(void *, const char *) {
+  return 0;
+}
+
+int dlclose(void *) {
+  return -1;
+}
+
+int dl_iterate_phdr(int (*)(void *, size_t, void *), void *) {
+  return -1;
+}