l2md: bump open file limit for repos with lots of pack files

Bump the limit to avoid bailing out in git_revwalk_next() without
having walked any commits. This happens when the repo has a lot of
pack files where we otherwise surpass the open file limit with the
default.

Ideally doing an equivalent of ...

  git repack -a -d -f --depth=250 --window=250

... out of libgit2 would be best and solve this issue, but given
GH issue [0], it's not there yet (if ever).

  [0] https://github.com/libgit2/libgit2/issues/3247

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 29 insertions, 0 deletions

diff --git a/config.c b/config.c
index d8d55da..3abf25b 100644
--- a/config.c
+++ b/config.c
@@ -8,6 +8,8 @@
 #include <wordexp.h>
 #include <stdbool.h>
 
+#include <sys/resource.h>
+
 #include "l2md.h"
 
 enum {
@@ -153,6 +155,31 @@ static void config_set_defaults(struct config *cfg, const char *homedir)
 	cfg->ops->set_defaults(cfg);
 }
 
+static void config_ulimits(void)
+{
+	struct rlimit limit;
+	int ret;
+
+	ret = getrlimit(RLIMIT_NOFILE, &limit);
+	if (ret < 0)
+		panic("Cannot retrieve rlimit!\n");
+
+	/* The git repos we're dealing with can have a lot of
+	 * pack files potentially, hence increase open file limit
+	 * to help libgit2's revwalk.
+	 *
+	 * If there is a better API supported by native libgit2
+	 * for doing repack, we should use that instead:
+	 *
+	 * https://github.com/libgit2/libgit2/issues/3247
+	 */
+	limit.rlim_cur = limit.rlim_max;
+
+	ret = setrlimit(RLIMIT_NOFILE, &limit);
+	if (ret < 0)
+		panic("Cannot set rlimit!\n");
+}
+
 void config_uninit(struct config *cfg)
 {
 	struct config_repo *repo;
@@ -190,6 +217,8 @@ struct config *config_init(int argc, char **argv)
 	if (!fp)
 		panic("Cannot open config %s: %s\n", tmp, strerror(errno));
 
+	config_ulimits();
+
 	cfg = xzmalloc(sizeof(*cfg));
 	config_set_defaults(cfg, homedir);