Handy little tool that increases the amount of max open file descriptors

and then runs a given command line.

diff --git a/hiper/ulimiter.c b/hiper/ulimiter.c
new file mode 100644 (file)
index 0000000..cb22732
--- /dev/null
+++ b/hiper/ulimiter.c
@@ -0,0 +1,101 @@
+/*****************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * $Id$
+ *
+ * Little tool to raise the amount of maximum file descriptor and then run the
+ * given command line (using the hard-coded uid/gid).
+ *
+ */
+
+#include <stdio.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <unistd.h>
+#include <errno.h>
+#include <string.h> /* for errno translation */
+
+/* ulimiter
+ *
+ * Source code inspiration from:
+ *  http://www.cs.wisc.edu/condor/condorg/linux_scalability.html
+ */
+
+#define UID 1000 /* the user who must run this */
+
+#define GID 1000 /* group id to run the program as */
+
+/* Number of open files to increase to */
+#define NEW_MAX 10000
+
+int main(int argc, char *argv[])
+{
+  int ret;
+  struct rlimit rl;
+  char *brgv[20];
+  int brgc=argc-1;
+  int i;
+
+  for(i=1; i< argc; i++)
+    brgv[i-1]=argv[i];
+  brgv[i-1]=NULL; /* terminate the list */
+
+  if(getuid() != UID) {
+    fprintf(stderr, "Only uid %d is allowed to run this\n", UID);
+    return 1;
+  }
+
+  ret = getrlimit(RLIMIT_NOFILE, &rl);
+  if(ret != 0) {
+    fprintf(stderr, "Unable to read open file limit.\n"
+            "(getrlimit(RLIMIT_NOFILE, &rl) failed)\n"
+            "(%d, %s)", errno, strerror(errno));
+    return 1;
+  }
+
+  fprintf(stderr, "Limit was %d (max %d), setting to %d\n",
+          rl.rlim_cur, rl.rlim_max, NEW_MAX);
+
+  rl.rlim_cur = rl.rlim_max = NEW_MAX;
+  ret = setrlimit(RLIMIT_NOFILE, &rl);
+  if(ret != 0) {
+    fprintf(stderr, "Unable to set open file limit.\n"
+            "(setrlimit(RLIMIT_NOFILE, &rl) failed)\n"
+            "(%d, %s)", errno, strerror(errno));
+    return 1;
+  }
+
+  ret = getrlimit(RLIMIT_NOFILE, &rl);
+  if(ret != 0) {
+    fprintf(stderr, "Unable to read new open file limit.\n"
+            "(getrlimit(RLIMIT_NOFILE, &rl) failed)\n"
+            "(%d, %s)", errno, strerror(errno));
+    return 1;
+  }
+  if(rl.rlim_cur < NEW_MAX) {
+    fprintf(stderr, "Failed to set new open file limit.\n"
+            "Limit is %d, expected %d\n",
+            rl.rlim_cur, NEW_MAX);
+    return 1;
+  }
+
+  if(setgid(GID) != 0) {
+    fprintf(stderr, "setgid failed (%d, %s)\n", errno, strerror(errno));
+    return 1;
+  }
+  if(setuid(UID) != 0) {
+    fprintf(stderr, "setuid failed (%d, %s)\n", errno, strerror(errno));
+    return 1;
+  }
+
+  ret = execv(brgv[0], brgv);
+
+  fprintf(stderr, "execl returned, failure\n"
+          "returned %d, errno is %d (%s)\n",
+          ret, errno, strerror(errno));
+  return 1;
+}