fixes existing data races

rdar://75568341

Author: QuietMisdreavus

extensions/core-extensions.c

@@ -1,3 +1,5 @@
+#include <pthread.h>
+
 #include "cmark-gfm-core-extensions.h"
 #include "autolink.h"
 #include "strikethrough.h"
@@ -7,21 +9,28 @@
 #include "registry.h"
 #include "plugin.h"
 
+pthread_mutex_t extensions_lock;
+
 static int core_extensions_registration(cmark_plugin *plugin) {
+  pthread_mutex_lock(&extensions_lock);
   cmark_plugin_register_syntax_extension(plugin, create_table_extension());
   cmark_plugin_register_syntax_extension(plugin,
                                          create_strikethrough_extension());
   cmark_plugin_register_syntax_extension(plugin, create_autolink_extension());
   cmark_plugin_register_syntax_extension(plugin, create_tagfilter_extension());
   cmark_plugin_register_syntax_extension(plugin, create_tasklist_extension());
+  pthread_mutex_unlock(&extensions_lock);
   return 1;
 }
 
-void cmark_gfm_core_extensions_ensure_registered(void) {
-  static int registered = 0;
+pthread_mutex_t registered_lock;
+static _Atomic int registered = 0;
 
+void cmark_gfm_core_extensions_ensure_registered(void) {
+  pthread_mutex_lock(&registered_lock);
   if (!registered) {
     cmark_register_plugin(core_extensions_registration);
     registered = 1;
   }
+  pthread_mutex_unlock(&registered_lock);
 }

src/inlines.c

@@ -1,6 +1,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
+#include <pthread.h>
 
 #include "cmark_ctype.h"
 #include "cmark-gfm_config.h"
@@ -64,7 +65,7 @@ typedef struct subject{
 } subject;
 
 // Extensions may populate this.
-static int8_t SKIP_CHARS[256];
+static _Atomic int8_t SKIP_CHARS[256];
 
 static CMARK_INLINE bool S_is_line_end_char(char c) {
   return (c == '\n' || c == '\r');
@@ -1321,7 +1322,7 @@ static cmark_node *handle_newline(subject *subj) {
 }
 
 // "\r\n\\`&_*[]<!"
-static int8_t SPECIAL_CHARS[256] = {
+static _Atomic int8_t SPECIAL_CHARS[256] = {
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0,
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
@@ -1349,6 +1350,8 @@ static char SMART_PUNCT_CHARS[] = {
       0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 };
 
+pthread_mutex_t chars_lock;
+
 static bufsize_t subject_find_special_char(subject *subj, int options) {
   bufsize_t n = subj->pos + 1;
 
@@ -1364,15 +1367,19 @@ static bufsize_t subject_find_special_char(subject *subj, int options) {
 }
 
 void cmark_inlines_add_special_character(unsigned char c, bool emphasis) {
+  pthread_mutex_lock(&chars_lock);
   SPECIAL_CHARS[c] = 1;
   if (emphasis)
     SKIP_CHARS[c] = 1;
+  pthread_mutex_unlock(&chars_lock);
 }
 
 void cmark_inlines_remove_special_character(unsigned char c, bool emphasis) {
+  pthread_mutex_lock(&chars_lock);
   SPECIAL_CHARS[c] = 0;
   if (emphasis)
     SKIP_CHARS[c] = 0;
+  pthread_mutex_unlock(&chars_lock);
 }
 
 static cmark_node *try_extensions(cmark_parser *parser,