provide KVM guest count and limit info message (C implementation) (#1014731)

2 files changed, 151 insertions, 1 deletions

diff --git a/src/Makefile b/src/Makefile
index 07d1f1f9..f2842152 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2,7 +2,7 @@ CFLAGS+=$(RPM_OPT_FLAGS) -Wall -D_GNU_SOURCE
 LDFLAGS+=$(RPM_LD_FLAGS)
 
 PROGS=usernetctl netreport usleep ipcalc brandbot \
-	ppp-watch consoletype genhostid rename_device
+	ppp-watch consoletype genhostid rename_device udev-kvm-check
 PPPWATCH_OBJS=ppp-watch.o shvar.o
 BRANDBOT_OBJS=brandbot.o shvar.o
 CONSOLE_INIT_OBJS=console_init.o shvar.o
@@ -30,6 +30,7 @@ install:
 	install -m 755 sushell $(ROOT)/usr/sbin/sushell
 	install -m 755 brandbot $(ROOT)/usr/sbin/brandbot
 	install -m 755 rename_device $(ROOT)/usr/lib/udev/rename_device
+	install -m 755 udev-kvm-check $(ROOT)/usr/lib/udev/udev-kvm-check
 	install -m 644 genhostid.1 $(ROOT)$(mandir)/man1
 	install -m 644 netreport.1 $(ROOT)$(mandir)/man1
 	install -m 644 usleep.1 $(ROOT)$(mandir)/man1
@@ -77,3 +78,6 @@ ppp-watch.o: ppp-watch.c
 rename_device: rename_device.c
 	$(CC) $(CFLAGS) `pkg-config glib-2.0 --cflags` -o $@ $< `pkg-config glib-2.0 --libs`
 
+udev-kvm-check: udev-kvm-check.c
+	$(CC) $(CFLAGS) -o $@ $<
+
diff --git a/src/udev-kvm-check.c b/src/udev-kvm-check.c
new file mode 100644
index 00000000..43cb9d93
--- /dev/null
+++ b/src/udev-kvm-check.c
@@ -0,0 +1,146 @@
+#include <ctype.h>
+#include <syslog.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DEFAULT 0
+#define FACILITY "kvm"
+#define SYSCONFIG_KVM "/etc/sysconfig/kvm"
+
+#define COUNT_MSG \
+    "%d %s now active"
+
+#define SUBSCRIPTION_MSG \
+    "%d %s now active; your Red Hat Enterprise Linux subscription" \
+    " limit is %d guests. Please review your Red Hat Enterprise Linux" \
+    " subscription agreement or contact your Red Hat" \
+    " support representative for more information. You" \
+    " may review the Red Hat Enterprise subscription" \
+    " limits at http://www.redhat.com/rhel-virt-limits"
+
+int get_threshold_from_file(FILE *fp)
+{
+    static const char key[] = "THRESHOLD=";
+    int pos = 0;
+    int thres;
+    char ch;
+
+start:
+    /* State START - at beginning of line, search for beginning of "THRESHOLD="
+     * string.
+     */
+    ch = getc(fp);
+    if (ch == EOF) {
+        return DEFAULT;
+    }
+    if (isspace(ch)) {
+        goto start;
+    }
+    if (ch == 'T') {
+        pos = 1;
+        goto key;
+    }
+    goto eol;
+
+eol:
+    /* State EOL - loop until end of line */
+    ch = getc(fp);
+    if (ch == EOF) {
+        return DEFAULT;
+    }
+    if (ch == '\n') {
+        goto start;
+    }
+    goto eol;
+
+key:
+    /* State KEY - match "THRESHOLD=" string, go to THRESHOLD if found */
+    ch = getc(fp);
+    if (ch == EOF) {
+        return DEFAULT;
+    }
+    if (ch == key[pos]) {
+        pos++;
+        if (key[pos] == 0) {
+            goto threshold;
+        } else {
+            goto key;
+        }
+    }
+    goto eol;
+
+threshold:
+    /* State THRESHOLD - parse number using fscanf, expect comment or space
+     * or EOL.
+     */
+    ch = getc(fp);
+    if (ch == EOF) {
+        return DEFAULT;
+    }
+    if (!isdigit(ch)) {
+        goto eol;
+    }
+    ungetc(ch, fp);
+    if (fscanf(fp, "%d", &thres) != 1) {
+        return DEFAULT;
+    }
+    ch = getc(fp);
+    if (ch == '#' || ch == EOF || ch == '\n' || isspace(ch)) {
+        return thres;
+    }
+    goto eol;
+}
+
+int get_threshold()
+{
+    FILE *fp = fopen(SYSCONFIG_KVM, "r");
+    int val = get_threshold_from_file(fp);
+
+    fclose (fp);
+    return val;
+}
+
+const char *guest(int count)
+{
+    return (count == 1 ? "guest" : "guests");
+}
+
+void emit_count_message(int count)
+{
+    openlog(FACILITY, LOG_CONS, LOG_USER);
+    syslog(LOG_INFO, COUNT_MSG, count, guest(count));
+    closelog();
+}
+
+void emit_subscription_message(int count, int threshold)
+{
+    openlog(FACILITY, LOG_CONS, LOG_USER);
+    syslog(LOG_WARNING, SUBSCRIPTION_MSG, count, guest(count), threshold);
+    closelog();
+}
+
+int main(int argc, char **argv)
+{
+    int count, threshold;
+
+    if (argc < 3)
+        exit(1);
+
+    count = atoi(argv[1]);
+    threshold = get_threshold();
+
+    if (!strcmp(argv[2], "create")) {
+        if (threshold == 0) {
+            emit_count_message(count);
+        } else if (count > threshold) {
+            emit_subscription_message(count, threshold);
+        }
+    } else {
+        if (count >= threshold) {
+            emit_count_message(count);
+        }
+    }
+
+    return 0;
+}