cease inefficient /dev/urandom fiddling.

Instead of reading /dev/urandom like a file (i.e. overhead / extra
syscalls, etc.), just use getrandom(2) directly, lol.

Signed-off-by: Gediminas Jakutis <gediminas@varciai.lt>

5 files changed, 14 insertions, 32 deletions

diff --git a/src/cache.c b/src/cache.c
index fe97fef..0c99322 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -35,8 +35,8 @@ int cache_populate(struct stream * const in)
 
 	try(in->settings->access != cached, err, EINVAL, "cannot populate cache: stream is uncached");
 
-	/* if reading a chardev, fall back to the one-element-at-a-time mode */
-	if (in->type == stream_chardev) {
+	/* if reading a a randstream, fall back to the one-element-at-a-time mode */
+	if (in->type == stream_randread) {
 		for (i = 0; i < in->n && !ret; ++i) {
 			errno = 0;
 			tmp = in->get_next_element_direct(in);
diff --git a/src/datagen.c b/src/datagen.c
index 7eab23f..98a64fe 100644
--- a/src/datagen.c
+++ b/src/datagen.c
@@ -2,12 +2,9 @@
 
 /* Copyright (C) 2020 Gediminas Jakutis */
 
-#include <unistd.h>
-#include <stddef.h>
 #include <errno.h>
-#include <stdlib.h>
 #include <string.h>
-#include <sys/types.h>
+#include <sys/random.h>
 #include "datagen.h"
 #include "defs.h"
 
@@ -18,12 +15,14 @@ struct entry_l *gen_get_array(struct stream * const in)
 	struct entry_l *ret;
 	int errn;
 
-	if (read(in->fd, &buf.val, sizeof(buf.val)) == sizeof(buf.val)) {
+	(void) in; /* lol says librin, lmao */
+
+	if (getrandom(&buf.val, sizeof(buf.val), 0ul) == sizeof(buf.val)) {
 		ret = &buf;
 	} else {
 		errn = errno;
 		ret = NULL;
-		rin_err("error reading /dev/urandom: %s", strerror(errn));
+		rin_err("error reading urandom: %s", strerror(errn));
 	}
 
 	return ret;
diff --git a/src/defs.h b/src/defs.h
index a7a678d..5f1a733 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -93,7 +93,7 @@ enum streamtype {
 	stream_in,
 	stream_out,
 	stream_outlite,
-	stream_chardev
+	stream_randread
 };
 
 struct stream {
diff --git a/src/io.c b/src/io.c
index 9dae2e1..682eea2 100644
--- a/src/io.c
+++ b/src/io.c
@@ -20,7 +20,6 @@
 static int stream_open_out(struct stream * const in);
 static int stream_open_out_lite(struct stream * const in);
 static int stream_open_in(struct stream * const in);
-static int stream_open_chardev(struct stream * const in);
 static int stream_flush(struct stream * const in);
 static int stream_flush_array(struct stream * const in);
 static int stream_flush_list(struct stream * const in);
@@ -29,7 +28,7 @@ int stream_open(struct stream * const in)
 {
 	int ret = 0;
 
-	try(!in || in->fd > 0 || !in->name, err, EINVAL, "invalid argunent");
+	try(!in || in->fd > 0 || (!in->name && in->type != stream_randread), err, EINVAL, "invalid argunent");
 
 	switch (in->type) {
 	case (stream_outlite):
@@ -43,8 +42,8 @@ int stream_open(struct stream * const in)
 		try(!in->name, err, EINVAL, "no filename given");
 		ret = stream_open_in(in);
 		break;
-	case (stream_chardev):
-		ret = stream_open_chardev(in);
+	case (stream_randread):
+		; /* NOOP */
 		break;
 	default:
 		try(0, err, EINVAL, "cannot open stream: stream is invalid");
@@ -58,7 +57,7 @@ int stream_close(struct stream * const in)
 {
 	int ret = 0;
 
-	try(!in || in->fd < 0, early_err, EINVAL, "invalid argunent");
+	try(!in || (in->fd < 0 && in->type != stream_randread), early_err, EINVAL, "invalid argunent");
 
 	if (in->type != stream_out) {
 		goto out;
@@ -166,19 +165,6 @@ err:
 	return ret;
 }
 
-static int stream_open_chardev(struct stream * const in)
-{
-	struct stat st;
-	int ret = 0;
-
-	try(stat(in->name, &st), err, errno, "stat failed: %s", strerror(ret));
-	in->fd = open(in->name, O_RDONLY);
-	try(in->fd < 0, err, errno, "failed opening input file: %s", strerror(ret));
-
-err:
-	return ret;
-}
-
 int stream_flush(struct stream * const in)
 {
 	int ret = 0;
diff --git a/src/main.c b/src/main.c
index e3455d1..390be6a 100644
--- a/src/main.c
+++ b/src/main.c
@@ -13,8 +13,6 @@
 #include "cache.h"
 #include "datagen.h"
 
-static char randfile[] = "/dev/urandom";
-
 static struct settings settings = {0};
 
 static int parseargs(int argc, char **argv, struct settings * settings);
@@ -38,8 +36,7 @@ int main(int argc, char **argv)
 	try_s((ret = parseargs(argc, argv, &settings)), early_out);
 
 	if (settings.opmode == mode_generate) {
-		file_in.name = randfile;
-		file_in.type = stream_chardev;
+		file_in.type = stream_randread;
 		file_in.n = settings.to;
 	} else {
 		file_in.name = settings.filein;
@@ -188,7 +185,7 @@ int load_io_functions(struct settings const * const s, struct stream * const in)
 		} else {
 			/* TODO */
 		}
-	} else if (in->type == stream_chardev) { /* data generation streams do not support dumping nor any cache I/O beyond initial data generation */
+	} else if (in->type == stream_randread) { /* data generation streams do not support dumping nor any cache I/O beyond initial data generation */
 		if (s->format == array) {
 			in->get_next_element_direct = gen_get_array;
 			in->place_next_element_cache = cached_put_array;