Add xcount_cpus()

3 files changed, 23 insertions, 19 deletions

diff --git a/lib/lib.h b/lib/lib.h
index 90f44dcb..04e81e8a 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -136,6 +136,7 @@ void xpidfile(char *name);
 void xregcomp(regex_t *preg, char *rexec, int cflags);
 char *xtzset(char *new);
 void xsignal(int signal, void *handler);
+unsigned xcount_cpus(void);
 
 // lib.c
 void verror_msg(char *msg, int err, va_list va);
diff --git a/lib/xwrap.c b/lib/xwrap.c
index 4880bbe0..69f891b9 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -723,3 +723,21 @@ void xsignal(int signal, void *handler)
 
   if (sigaction(signal, sa, 0)) perror_exit("xsignal %d", signal);
 }
+
+unsigned xcount_cpus(void)
+{
+  int len = 0, i, fd = xopen("/proc/stat", O_RDONLY);
+  unsigned cpus = 0;
+
+  for (;;) {
+    if (1>(i = xread(fd, libbuf, sizeof(libbuf)-len))) break;
+    len += i;
+    // Each cpu# line has data after it, so last 5 bytes of file can't match
+    for (i = 0; i<len-5; i++)
+      if (!strncmp(libbuf+i, "\ncpu", 4) && isdigit(libbuf[i+4])) cpus++;
+    memmove(libbuf, libbuf+i, 5);
+  }
+  close(fd);
+
+  return cpus;
+}
diff --git a/toys/other/taskset.c b/toys/other/taskset.c
index 4ade5f10..29ce3173 100644
--- a/toys/other/taskset.c
+++ b/toys/other/taskset.c
@@ -40,10 +40,6 @@ config TASKSET
 #define sched_getaffinity(pid, size, cpuset) \
   syscall(__NR_sched_getaffinity, (pid_t)pid, (size_t)size, (void *)cpuset)
 
-GLOBALS(
-  int nproc;
-)
-
 // mask is an array of long, which makes the layout a bit weird on big
 // endian systems but as long as it's consistent...
 
@@ -120,29 +116,18 @@ void taskset_main(void)
   }
 }
 
-static int do_nproc(struct dirtree *new)
-{
-  if (!new->parent) return DIRTREE_RECURSE;
-  if (!strncmp(new->name, "cpu", 3) && isdigit(new->name[3])) TT.nproc++;
-
-  return 0;
-}
-
 void nproc_main(void)
 {
-  int i, j;
+  unsigned i, j, nproc = 0;
 
   // This can only detect 32768 processors. Call getaffinity and count bits.
   if (!toys.optflags && -1!=sched_getaffinity(getpid(), 4096, toybuf)) {
     for (i = 0; i<4096; i++)
-      if (toybuf[i])
-        for (j=0; j<8; j++)
-          if (toybuf[i]&(1<<j))
-            TT.nproc++;
+      if (toybuf[i]) for (j=0; j<8; j++) if (toybuf[i]&(1<<j)) nproc++;
   }
 
   // If getaffinity failed or --all, count cpu entries in proc
-  if (!TT.nproc) dirtree_read("/sys/devices/system/cpu", do_nproc);
+  if (!nproc) nproc = xcount_cpus();
 
-  xprintf("%d\n", TT.nproc);
+  xprintf("%u\n", nproc);
 }