From 225457f513c3f7fa66c8b494adbdd2d498e0f0f3 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Sat, 29 Jan 2022 21:13:03 +0100
Subject: [PATCH] verbose-copy

---
 verbose-copy.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 verbose-copy.c

diff --git a/verbose-copy.c b/verbose-copy.c
new file mode 100644
index 0000000..6b7c136
--- /dev/null
+++ b/verbose-copy.c
@@ -0,0 +1,96 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <linux/fs.h>
+
+// XXX: Assuming block size == 512
+
+int main(int argc, char **argv)
+{
+	if (argc != 3) {
+		fprintf(stderr, "Usage: %s <from> <to>\n", argv[0]);
+		return 1;
+	}
+
+	int fi = open(argv[1], O_RDONLY);
+	if (fi < 0) {
+		fprintf(stderr, "Cannot open source %s: %m\n", argv[1]);
+		return 1;
+	}
+
+	int fo = open(argv[2], O_WRONLY);
+	if (fo < 0) {
+		fprintf(stderr, "Cannot open destination %s: %m\n", argv[1]);
+		return 1;
+	}
+
+	struct stat sti, sto;
+	if (fstat(fi, &sti) < 0 || fstat(fo, &sto) < 0) {
+		fprintf(stderr, "Stat failed: %m\n");
+		return 1;
+	}
+	if (!S_ISBLK(sti.st_mode)) {
+		fprintf(stderr, "Input is not a block device\n");
+		return 1;
+	}
+	if (!S_ISBLK(sto.st_mode)) {
+		fprintf(stderr, "Output is not a block device\n");
+		return 1;
+	}
+
+	unsigned long leni, leno;
+	if (ioctl(fi, BLKGETSIZE, &leni) < 0 ||
+	    ioctl(fo, BLKGETSIZE, &leno) < 0) {
+		fprintf(stderr, "Cannot get device size: %m\n");
+		return 1;
+	}
+	if (leni > leno) {
+		fprintf(stderr, "Will not fit: %ld > %ld\n", leni, leno);
+		return 1;
+	}
+
+#define BUFSIZE 65536
+	char *buf = mmap(NULL, BUFSIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (buf == MAP_FAILED) {
+		fprintf(stderr, "Cannot mmap buffer: %m\n");
+		return 1;
+	}
+
+	unsigned int remi = leni;
+	int verb = 1;
+	while (remi) {
+		int s = (remi < BUFSIZE/512) ? remi : BUFSIZE/512;
+		int l = read(fi, buf, s*512);
+		if (l < 0) {
+			fprintf(stderr, "Read error: %m\n");
+			return 1;
+		}
+		if (l != s*512) {
+			fprintf(stderr, "Short read: %d of %d. Recovering.\n", l, s*512);
+		}
+		int w = write(fo, buf, l);
+		if (w < 0) {
+			fprintf(stderr, "Write error: %m\n");
+			return 1;
+		}
+		if (w != l) {
+			fprintf(stderr, "Short write: %d of %d\n", w, l);
+			return 1;
+		}
+		remi -= s;
+		if (!--verb) {
+			printf("\rCopied %d of %d MB (%d%%)...", (int)((leni-remi)/2048), (int)((leni+2047)/2048),
+				(int)((double)(leni-remi) / leni * 100));
+			verb = 64;
+		}
+	}
+
+	printf("Copied %d MB                                       \n", (int)((leni+2047)/2048));
+	close(fo);
+	close(fi);
+	return 0;
+}
-- 
2.39.5