[Feature #18249] Implement ABI checking

Header file include/ruby/internal/abi.h contains RUBY_ABI_VERSION which
is the ABI version. This value should be bumped whenever an ABI
incompatible change is introduced.

When loading dynamic libraries, Ruby will compare its own
`ruby_abi_version` and the `ruby_abi_version` of the loaded library. If
these two values don't match it will raise a `LoadError`. This feature
can also be turned off by setting the environment variable
`RUBY_RUBY_ABI_CHECK=0`.

This feature will prevent cases where previously installed native gems
fail in unexpected ways due to incompatibility of changes in header
files. This will force the developer to recompile their gems to use the
same header files as the built Ruby.

In Ruby, the ABI version is exposed through
`RbConfig::CONFIG["ruby_abi_version"]`.

1 files changed, 17 insertions, 0 deletions

diff --git a/dln.c b/dln.c
index 3ebce48a45..a38ff7341d 100644
--- a/dln.c
+++ b/dln.c
@@ -426,12 +426,29 @@ dln_sym(void *handle, const char *symbol)
 }
 #endif
 
+#if RUBY_DLN_CHECK_ABI
+static bool
+abi_check_enabled_p(void)
+{
+    const char *val = getenv("RUBY_ABI_CHECK");
+    return val == NULL || !(val[0] == '0' && val[1] == '\0');
+}
+#endif
+
 void *
 dln_load(const char *file)
 {
 #if defined(_WIN32) || defined(USE_DLN_DLOPEN)
     void *handle = dln_open(file);
 
+#if RUBY_DLN_CHECK_ABI
+    unsigned long long (*abi_version_fct)(void) = (unsigned long long(*)(void))dln_sym(handle, "ruby_abi_version");
+    unsigned long long binary_abi_version = (*abi_version_fct)();
+    if (binary_abi_version != ruby_abi_version() && abi_check_enabled_p()) {
+        dln_loaderror("ABI version of binary is incompatible with this Ruby. Try rebuilding this binary.");
+    }
+#endif
+
     char *init_fct_name;
     init_funcname(&init_fct_name, file);
     void (*init_fct)(void) = (void(*)(void))dln_sym(handle, init_fct_name);