From 137f0076c2986306109d637599b885bdaf92cd58 Mon Sep 17 00:00:00 2001 From: FRIGN Date: Tue, 23 Aug 2016 01:45:46 +0200 Subject: [PATCH] Refactor dontkillme() - Use file pointers instead of raw I/O, inspired by Kernel code. - Use OOM_SCORE_ADJ_MIN from linux/oom.h instead of working with magic values. - Stricter error checking and descriptive error messages. The reasoning for using the constant rather than magic values lies in the fact that this ensures people get the message. With "-1000", a code reviewer would question if that is really the lowest possible number or just an arbitrary value. The kernel ABI probably won't change, but even in the case, we wouldn't have to modify the code. The OOM killer only is guaranteed to not kill you if you have OOM_SCORE_ADJ_MIN. --- slock.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/slock.c b/slock.c index 3e2ab8f..9ec2f71 100644 --- a/slock.c +++ b/slock.c @@ -65,19 +65,27 @@ die(const char *errstr, ...) #ifdef __linux__ #include +#include static void dontkillme(void) { - int fd; + FILE *f; + const char oomfile[] = "/proc/self/oom_score_adj"; - fd = open("/proc/self/oom_score_adj", O_WRONLY); - if (fd < 0 && errno == ENOENT) { - return; + if (!(f = fopen(oomfile, "w"))) { + if (errno == ENOENT) + return; + die("slock: fopen %s: %s\n", oomfile, strerror(errno)); } - if (fd < 0 || write(fd, "-1000\n", (sizeof("-1000\n") - 1)) != - (sizeof("-1000\n") - 1) || close(fd) != 0) { - die("can't tame the oom-killer. is suid or sgid set?\n"); + fprintf(f, "%d", OOM_SCORE_ADJ_MIN); + if (fclose(f)) { + if (errno == EACCES) + die("slock: unable to disable OOM killer. " + "suid or sgid set?\n"); + else + die("slock: fclose %s: %s\n", oomfile, + strerror(errno)); } } #endif -- 2.39.2