1 files changed, 61 insertions, 0 deletions
diff --git a/oom_score_adj.c b/oom_score_adj.c
new file mode 100644
index 000000000000..3fc91dd06a5d
--- /dev/null
+++ b/oom_score_adj.c
@@ -0,0 +1,61 @@
+/* OOM killer adjustment, meant to protect running processes via a small
+ * setuid-ed "wrapper". */
+
+/* (c) 2018 Alexander Kobel <a-kobel@a-kobel.de> */
+/* Published under the WTFPL; see LICENSE. */
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <linux/oom.h>
+
+int usage (char **argv) {
+  fprintf (stderr,
+           "Adjust the out-of-memory killer score for a process; "
+           "see man proc(5).\n"
+           "\n"
+           "Usage:\t%s <pid> <oom_score_adj>\n"
+           "\n"
+           "  <pid>\n"
+           "\tprocess id\n"
+           "  <oom_score_adj>\n"
+           "\tinteger between %d and %d inclusive.\n"
+           "\t(oom_score_adj = %d disables oom killing for this process)\n",
+           argv[0], OOM_SCORE_ADJ_MIN, OOM_SCORE_ADJ_MAX, OOM_SCORE_ADJ_MIN);
+  return EINVAL;
+}
+
+int main (int argc, char **argv) {
+  char *endptr;
+  long pid;
+  long oom_score_adj;
+  char fn[PATH_MAX];
+  int n;
+  FILE *f;
+
+  if (argc != 3)
+    return usage (argv);
+
+  pid = strtol (argv[1], &endptr, 10);
+  if (errno == ERANGE || *endptr != 0 || pid < 1)
+    return usage (argv);
+
+  oom_score_adj = strtol (argv[2], &endptr, 10);
+  if (errno == ERANGE || *endptr != 0
+      || oom_score_adj < OOM_SCORE_ADJ_MIN
+      || oom_score_adj > OOM_SCORE_ADJ_MAX)
+    return usage (argv);
+
+  n = snprintf (fn, PATH_MAX, "/proc/%ld/oom_score_adj", pid);
+  if (n < 0 && n > PATH_MAX)
+    return ENAMETOOLONG;
+  f = fopen (fn, "w");
+  if (f == NULL)
+    return EPERM;
+  fprintf (f, "%ld", oom_score_adj);
+  fclose (f);
+
+  return 0;
+}