Initial import (2.0.2-6)2.0.2-6

1 files changed, 96 insertions, 0 deletions

diff --git a/reference/C/CONTRIB/OR_USING_C/c.1.c b/reference/C/CONTRIB/OR_USING_C/c.1.c
new file mode 100644
index 0000000..257f3c8
--- /dev/null
+++ b/reference/C/CONTRIB/OR_USING_C/c.1.c
@@ -0,0 +1,96 @@
+#include <sys/param.h>
+#include <sys/time.h>
+#include <sys/file.h>
+#include <nlist.h>
+#include <stdio.h>
+
+/*
+ * We declare an array of nlist structures,
+ * and initialize them to the names of the
+ * variables we want.  The last entry is
+ * to terminate the list.
+ */
+struct nlist nl[] = {
+#define X_BOOTTIME     0
+    {    "_boottime" },
+#define X_AVENRUN      1
+    {    "_avenrun"  },
+    {    0           }
+};
+
+main()
+{
+    int kmem;
+    char *ctime();
+    struct timeval boottime;
+
+    /*
+     * _avenrun is an array of three numbers.
+     * Most machines use floating point; Sun
+     * workstations use long integers.
+     */
+#ifdef sun
+    long avenrun[3];
+#else
+    double avenrun[3];
+#endif
+
+    /*
+     * Open kernel memory.
+     */
+    if ((kmem = open("/dev/kmem", O_RDONLY)) < 0) {
+        perror("/dev/kmem");
+        exit(1);
+    }
+
+    /*
+     * Read the kernel namelist.  If nl[0].n_type is
+     * 0 after this, then the call to nlist() failed.
+     */
+    if ((nlist("/vmunix", nl) < 0) || (nl[0].n_type == 0)) {
+        fprintf(stderr, "/vmunix: no namelist\n");
+        exit(1);
+    }
+
+    /*
+     * Read the _boottime variable.  We do this by
+     * seeking through memory to the address found
+     * by nlist, and then reading.
+     */
+    lseek(kmem, (long) nl[X_BOOTTIME].n_value, L_SET);
+    read(kmem, (char *) &boottime, sizeof(boottime));
+    /*
+     * Read the load averages.
+     */
+    lseek(kmem, (long) nl[X_AVENRUN].n_value, L_SET);
+    read(kmem, (char *) avenrun, sizeof(avenrun));
+
+    /*
+     * Now print the system boot time.
+     */
+    printf("System booted at %s\n", ctime(&boottime.tv_sec));
+
+    /*
+     * Print the load averages.  Sun workstations use
+     * FSCALE to convert the long integers to floating
+     * point.  The three elements of _avenrun are the
+     * load average over the past one, five, and ten
+     * minutes.
+     */
+#ifdef sun
+    printf("One minute load average:  %.2f\n",
+        (double) avenrun[0] / FSCALE);
+    printf("Five minute load average: %.2f\n",
+        (double) avenrun[1] / FSCALE);
+    printf("Ten minute load average:  %.2f\n",
+        (double) avenrun[2] / FSCALE);
+#else
+    printf("One minute load average:  %.2f\n", avenrun[0]);
+    printf("Five minute load average: %.2f\n", avenrun[1]);
+    printf("Ten minute load average:  %.2f\n", avenrun[2]);
+#endif
+
+    close(kmem);
+    exit(0);
+}
+