Make have_proc_stat an ordinary function

Removes a mutable global variable.

src/builtin_jobs.cpp

@@ -54,7 +54,7 @@ static void builtin_jobs_print(const job_t *j, int mode, int header, io_streams_
             if (header) {
                 // Print table header before first job.
                 streams.out.append(_(L"Job\tGroup\t"));
-                if (have_proc_stat) {
+                if (have_proc_stat()) {
                     streams.out.append(_(L"CPU\t"));
                 }
                 streams.out.append(_(L"State\tCommand\n"));
@@ -62,7 +62,7 @@ static void builtin_jobs_print(const job_t *j, int mode, int header, io_streams_
 
             streams.out.append_format(L"%d\t%d\t", j->job_id, j->pgid);
 
-            if (have_proc_stat) {
+            if (have_proc_stat()) {
                 streams.out.append_format(L"%d%%\t", cpu_use(j));
             }
 

src/env.cpp

@@ -219,10 +219,6 @@ void misc_init() {
         fflush(stdout);
         setvbuf(stdout, NULL, _IONBF, 0);
     }
-    // Check for /proc/self/stat to see if we are running with Linux-style procfs
-    if (access("/proc/self/stat", R_OK) == 0) {
-        have_proc_stat = true;
-    }
 }
 
 /// Ensure the content of the magic path env vars is reasonable. Specifically, that empty path

src/proc.cpp

@@ -59,7 +59,12 @@ bool is_breakpoint = false;
 bool is_login = false;
 int is_event = 0;
 int no_exec = 0;
-bool have_proc_stat = false;
+
+bool have_proc_stat() {
+    // Check for /proc/self/stat to see if we are running with Linux-style procfs.
+    static const bool s_result = (access("/proc/self/stat", R_OK) == 0);
+    return s_result;
+}
 
 static relaxed_atomic_t<job_control_t> job_control_mode{job_control_t::interactive};
 
@@ -623,7 +628,7 @@ bool job_reap(parser_t &parser, bool allow_interactive) {
 
 /// Get the CPU time for the specified process.
 unsigned long proc_get_jiffies(process_t *p) {
-    if (!have_proc_stat) return 0;
+    if (!have_proc_stat()) return 0;
     if (p->pid <= 0) return 0;
 
     wchar_t fn[FN_SIZE];

src/proc.h

@@ -517,6 +517,6 @@ void add_disowned_pgid(pid_t pgid);
 ///   function
 enum { INVALID_PID = -2 };
 
-extern bool have_proc_stat;
+bool have_proc_stat();
 
 #endif

src/reader.cpp

@@ -1963,7 +1963,7 @@ void reader_run_command(parser_t &parser, const wcstring &cmd) {
     // For compatibility with fish 2.0's $_, now replaced with `status current-command`
     parser.vars().set_one(L"_", ENV_GLOBAL, program_name);
 
-    if (have_proc_stat) {
+    if (have_proc_stat()) {
         proc_update_jiffies(parser);
     }
 }