libbb: factor out common code from mpstat/iostat

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

2 files changed, 50 insertions, 0 deletions

diff --git a/libbb/Kbuild.src b/libbb/Kbuild.src
index 5c567000a..6081ebe4b 100644
--- a/libbb/Kbuild.src
+++ b/libbb/Kbuild.src
@@ -157,6 +157,9 @@ lib-$(CONFIG_MOUNT) += find_mount_point.o
 lib-$(CONFIG_HWCLOCK) += rtc.o
 lib-$(CONFIG_RTCWAKE) += rtc.o
 
+lib-$(CONFIG_IOSTAT) += get_cpu_count.o
+lib-$(CONFIG_MPSTAT) += get_cpu_count.o
+
 # We shouldn't build xregcomp.c if we don't need it - this ensures we don't
 # require regex.h to be in the include dir even if we don't need it thereby
 # allowing us to build busybox even if uclibc regex support is disabled.
diff --git a/libbb/get_cpu_count.c b/libbb/get_cpu_count.c
new file mode 100644
index 000000000..a0dcb45f5
--- /dev/null
+++ b/libbb/get_cpu_count.c
@@ -0,0 +1,47 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * Factored out of mpstat/iostat.
+ *
+ * Copyright (C) 2010 Marek Polacek <mmpolacek@gmail.com>
+ *
+ * Licensed under GPLv2, see file License in this tarball for details.
+ */
+#include "libbb.h"
+
+/* Does str start with "cpu"? */
+int FAST_FUNC starts_with_cpu(const char *str)
+{
+        return ((str[0] - 'c') | (str[1] - 'p') | (str[2] - 'u')) == 0;
+}
+
+/*
+ * Get number of processors. Uses /proc/stat.
+ * Return value 0 means one CPU and non SMP kernel.
+ * Otherwise N means N processor(s) and SMP kernel.
+ */
+unsigned FAST_FUNC get_cpu_count(void)
+{
+        FILE *fp;
+        char line[256];
+        int proc_nr = -1;
+
+        fp = xfopen_for_read("/proc/stat");
+        while (fgets(line, sizeof(line), fp)) {
+                if (!starts_with_cpu(line)) {
+                        if (proc_nr >= 0)
+                                break; /* we are past "cpuN..." lines */
+                        continue;
+                }
+                if (line[3] != ' ') { /* "cpuN" */
+                        int num_proc;
+                        if (sscanf(line + 3, "%u", &num_proc) == 1
+                         && num_proc > proc_nr
+                        ) {
+                                proc_nr = num_proc;
+                        }
+                }
+        }
+
+        fclose(fp);
+        return proc_nr + 1;
+}