Avoid using any globals in language detection.

ep.c

@@ -4,7 +4,7 @@
  * configuring existing ones.
  *
  * Liberties taken:
- *   - will crash with segfault if allocations fail; NULL is special only when meaningful beyond allocation
+ *   - might crash with segfault if some allocations fail; NULL is special only when meaningful beyond allocation
  *   - assumes stdio is reasonably buffered, so multiple fputs calls aren't expensive
  */
 
@@ -78,9 +78,19 @@ int main(int argc, char **argv)
 	print_git();
 
 	/* programming languages */
-	pthread_join(pwd_lang_handle, NULL);
-	if (root_lang_task.launched) pthread_join(root_lang_task.handle, NULL);
-	print_lang();
+	uint64_t pwd_langs = 0, root_langs = 0;
+	void *tmp_mask;
+	pthread_join(pwd_lang_handle, &tmp_mask);
+	/* if thread returned NULL, assume no language */
+	#define read_mask() (tmp_mask ? *(uint64_t *)tmp_mask : 0)
+	pwd_langs = read_mask();
+	/* safe to check for launched here because we joined git_handle above */
+	if (root_lang_task.launched) {
+		pthread_join(root_lang_task.handle, &tmp_mask);
+		root_langs = read_mask();
+	}
+	#undef read_mask
+	print_lang(pwd_langs | root_langs);
 
 	/* print currently active shell jobs */
 	if (shell_jobs) {

ep.h

@@ -2,6 +2,7 @@
 #define EP_H
 
 #include <stdio.h>
+#include <stdint.h>
 #include <pthread.h>
 #include <signal.h>
 
@@ -32,6 +33,6 @@ void print_git(void);
 
 /* from lang.c */
 void *lang_thread(void *);
-void print_lang(void);
+void print_lang(uint64_t);
 
 #endif

lang.c

@@ -1,4 +1,5 @@
 #include <dirent.h>
+#include <stdlib.h>
 #include <stdint.h>
 #include <fnmatch.h>
 
@@ -18,16 +19,12 @@ struct lang_check {
 	char display[8];
 };
 
-struct lang_check l[] = {
+const struct lang_check l[] = {
 	[c_lang] = { .check = c_lang_check, .display = " C" },
 };
 
 /* bitmap of 1<<lang_index */
-static uint64_t pwd_langs, root_langs;
-
-void print_lang(void) {
-	uint64_t mask = pwd_langs | root_langs;
-
+void print_lang(uint64_t mask) {
 	for (int i = 0; i < lang_index_n; i++) {
 		if (mask & (1 << i)) {
 			p(l[i].display);
@@ -37,9 +34,11 @@ void print_lang(void) {
 
 void *lang_thread(void *arg)
 {
-	/* scan current dir or received root of project */
+	/* scan current dir if arg is NULL */
 	char *path = arg ? arg : ".";
-	uint64_t *mask = arg ? &root_langs : &pwd_langs;
+	uint64_t *mask = calloc(1, sizeof(mask));
+	if (!mask)
+		return NULL;
 
 	DIR *d = opendir(path);
 	if (!d)
@@ -56,7 +55,7 @@ void *lang_thread(void *arg)
 		}
 	}
 
-	return NULL;
+	return mask;
 }
 
 static inline int isfile(unsigned char t) { return t & (DT_REG | DT_LNK); }