From 2e55bedc45e836899a18ea7f4a488f50597afad5 Mon Sep 17 00:00:00 2001
From: Mattias Andrée <maandree@kth.se>
Date: Sat, 21 Sep 2024 19:31:16 +0200
Subject: misc
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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Signed-off-by: Mattias Andrée <maandree@kth.se>
---
 ask.c | 115 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)
 create mode 100644 ask.c

(limited to 'ask.c')

diff --git a/ask.c b/ask.c
new file mode 100644
index 0000000..bb8fa50
--- /dev/null
+++ b/ask.c
@@ -0,0 +1,115 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+#if defined(__linux__)
+# include <sys/sysmacros.h>
+#endif
+
+
+int
+confirm(const char *device, off_t off, off_t len, off_t end)
+{
+	char buf[1024];
+	int ttyfd = -1;
+	int need_close;
+	int ret = 1;
+	int custom_section = (off >= 0 || len >= 0 || end >= 0);
+	const char *type;
+	ssize_t i, r;
+	int confirm_state = 0;
+	struct stat st;
+
+	if (isatty(STDIN_FILENO)) {
+		ttyfd = STDIN_FILENO;
+		need_close = 0;
+	} else {
+		ttyfd = open("/dev/tty", O_RDWR);
+		if (ttyfd < 0)
+			return 1;
+		need_close = 1;
+	}
+
+	if (getpgrp() != tcgetpgrp(ttyfd))
+		goto out;
+
+	if (custom_section) {
+		if (off < 0)
+			off = 0;
+		if (end >= 0)
+			len = end - off;
+		else if (len >= 0)
+			end = off + len;
+		else if (off == 0)
+			custom_section = 0;
+		if (end >= 0 && end < off)
+			eprintf("the value of -e option is lower than value of -o option");
+	}
+
+	if (stat(device, &st))
+		eprintf("stat %s:", device);
+	switch (st.st_mode & S_IFMT) {
+	case S_IFREG:
+		type = "file";
+		break;
+	case S_IFBLK:
+		type = "device";
+		break;
+	default:
+		eprintf("%s: not a regular file or block device", device);
+	}
+
+	if (dprintf(ttyfd, "Are you sure you want to erase the contents of %s?\n", device) < 0)
+		goto printerror;
+
+	if (S_ISREG(st.st_mode)) {
+		if (dprintf(ttyfd, "\nThe file is %s large.\n", exact_and_human_size(st.st_size, buf, 1)) < 0)
+			goto printerror;
+#if defined(__linux__)
+	} else if (S_ISBLK(st.st_mode)) {
+		char *devname = get_device_name(major(st.st_rdev), minor(st.st_rdev));
+		if (devname) {
+			/* TODO display device identity and size (look in /sys/class/block/<devname>/) */
+		}
+#endif
+	}
+
+	if (custom_section) {
+		if (dprintf(ttyfd, "\nYou have requested to only erase part of the %s:\n", type) < 0 ||
+		    (off >= 0 && dprintf(ttyfd, "\tFirst byte: %s\n", exact_and_human_size(off, buf, 0)) < 0) ||
+		    (len >= 0 && dprintf(ttyfd, "\tNumber of bytes: %s\n", exact_and_human_size(len, buf, 0)) < 0) ||
+		    (end >= 0 && dprintf(ttyfd, "\tEnd of overwrite: %s\n", exact_and_human_size(end, buf, 1)) < 0))
+			goto printerror;
+	}
+
+	if (dprintf(ttyfd, "\nAffirm by entering 'yes' in majuscule without quotes.\n") < 0)
+		goto printerror;
+
+	ret = 0;
+	for (;;) {
+		r = read(ttyfd, buf, sizeof(buf));
+		if (!r) {
+			goto out;
+		} else if (r < 0) {
+			if (errno == EINTR)
+				continue;
+			eprintf("read %s:", need_close ? "/dev/tty" : "<stdin>");
+		}
+		for (i = 0; i < r; i++) {
+			if (buf[i] != "YES\n"[confirm_state++])
+				goto out;
+			if (buf[i] == '\n') {
+				ret = 1;
+				goto out;
+			}
+		}
+	}
+
+out:
+	if (need_close)
+		close(ttyfd);
+	if (dprintf(ttyfd, "%s\n", ret ? "" : "User did not affirm action. Aborting...") < 0)
+		goto printerror;
+	return ret;
+
+printerror:
+	eprintf("dprintf %s:", need_close ? "/dev/tty" : "<stdin>");
+}
-- 
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