From: Thomas Weißschuh <thomas@t-8ch.de>
Date: Fri, 28 Apr 2023 18:42:01 +0000 (+0200)
Subject: mkswap: implement --offset
X-Git-Tag: v2.40-rc1~467^2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=84ec6f99f7927e5dc05a20f133b21f5870923ff1;p=thirdparty%2Futil-linux.git

mkswap: implement --offset

Addresses #2166

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---

diff --git a/bash-completion/mkswap b/bash-completion/mkswap
index 61157ef13e..33b0a70ceb 100644
--- a/bash-completion/mkswap
+++ b/bash-completion/mkswap
@@ -21,13 +21,17 @@ _mkswap_module()
 			COMPREPLY=( $(compgen -W "$(uuidgen -r)" -- $cur) )
 			return 0
 			;;
+		'-o'|'--offset')
+			COMPREPLY=( $(compgen -W "bytes" -- $cur) )
+			return 0
+			;;
 		'-h'|'--help'|'-V'|'--version')
 			return 0
 			;;
 	esac
 	case $cur in
 		-*)
-			OPTS="--check --force --pagesize --lock --label --swapversion --uuid --verbose --version --help"
+			OPTS="--check --force --pagesize --lock --label --swapversion --uuid --offset --verbose --version --help"
 			COMPREPLY=( $(compgen -W "${OPTS[*]}" -- $cur) )
 			return 0
 			;;
diff --git a/disk-utils/mkswap.8.adoc b/disk-utils/mkswap.8.adoc
index 904467d772..ad48c99e08 100644
--- a/disk-utils/mkswap.8.adoc
+++ b/disk-utils/mkswap.8.adoc
@@ -73,6 +73,9 @@ generate a new time-based UUID
 *-e*, *--endianness* _ENDIANNESS_::
 Specify the _ENDIANNESS_ to use, valid arguments are *native*, *little* or *big*. The default is *native*.
 
+*-o*, *--offset* _offset_::
+Specify the _offset_ to write the swap area to.
+
 *-v*, *--swapversion 1*::
 Specify the swap-space version. (This option is currently pointless, as the old *-v 0* option has become obsolete and now only *-v 1* is supported. The kernel has not supported v0 swap-space format since 2.5.22 (June 2002). The new version v1 is supported since 2.1.117 (August 1998).)
 
diff --git a/disk-utils/mkswap.c b/disk-utils/mkswap.c
index bd02301774..b6deadf38a 100644
--- a/disk-utils/mkswap.c
+++ b/disk-utils/mkswap.c
@@ -76,6 +76,7 @@ struct mkswap_control {
 
 	int			user_pagesize;	/* --pagesize */
 	int			pagesize;	/* final pagesize used for the header */
+	off_t			offset;         /* offset of the header in the target */
 
 	char			*opt_label;	/* LABEL as specified on command line */
 	unsigned char		*uuid;		/* UUID parsed by libbuuid */
@@ -194,6 +195,7 @@ static void __attribute__((__noreturn__)) usage(void)
 	fprintf(out,
 	      _(" -e, --endianness=<value>  specify the endianness to use "
 	                                    "(%s, %s or %s)\n"), "native", "little", "big");
+	fputs(_(" -o, --offset OFFSET       specify the offset in the device\n"), out);
 	fputs(_("     --verbose             verbose output\n"), out);
 
 	fprintf(out,
@@ -347,6 +349,9 @@ static unsigned long long get_size(const struct mkswap_control *ctl)
 		err(EXIT_FAILURE, _("cannot open %s"), ctl->devname);
 	if (blkdev_get_size(fd, &size) < 0)
 		err(EXIT_FAILURE, _("cannot determine size of %s"), ctl->devname);
+	if ((unsigned long long) ctl->offset > size)
+		errx(EXIT_FAILURE, _("offset larger than file size"));
+	size -= ctl->offset;
 	size /= ctl->pagesize;
 
 	close(fd);
@@ -465,11 +470,15 @@ static void wipe_device(struct mkswap_control *ctl)
 
 static void write_header_to_device(struct mkswap_control *ctl)
 {
+	off_t offset;
+
 	assert(ctl);
 	assert(ctl->fd > -1);
 	assert(ctl->signature_page);
 
-	if (lseek(ctl->fd, SIGNATURE_OFFSET, SEEK_SET) != SIGNATURE_OFFSET)
+	offset = SIGNATURE_OFFSET + ctl->offset;
+
+	if (lseek(ctl->fd, offset, SEEK_SET) != offset)
 		errx(EXIT_FAILURE, _("unable to rewind swap-device"));
 
 	if (write_all(ctl->fd, (char *) ctl->signature_page + SIGNATURE_OFFSET,
@@ -503,6 +512,7 @@ int main(int argc, char **argv)
 		{ "swapversion", required_argument, NULL, 'v' },
 		{ "uuid",        required_argument, NULL, 'U' },
 		{ "endianness",  required_argument, NULL, 'e' },
+		{ "offset",      required_argument, NULL, 'o' },
 		{ "version",     no_argument,       NULL, 'V' },
 		{ "help",        no_argument,       NULL, 'h' },
 		{ "lock",        optional_argument, NULL, OPT_LOCK },
@@ -521,7 +531,7 @@ int main(int argc, char **argv)
 	textdomain(PACKAGE);
 	close_stdout_atexit();
 
-	while((c = getopt_long(argc, argv, "cfp:qL:v:U:e:Vh", longopts, NULL)) != -1) {
+	while((c = getopt_long(argc, argv, "cfp:qL:v:U:e:o:Vh", longopts, NULL)) != -1) {
 
 		err_exclusive_options(c, longopts, excl, excl_st);
 
@@ -567,6 +577,10 @@ int main(int argc, char **argv)
 					_("invalid endianness %s is not supported"), optarg);
 			}
 			break;
+		case 'o':
+			ctl.offset = str2unum_or_err(optarg,
+					10, _("Invalid offset"), SINT_MAX(off_t));
+			break;
 		case 'V':
 			print_version(EXIT_SUCCESS);
 			break;
diff --git a/tests/ts/mkswap/mkswap b/tests/ts/mkswap/mkswap
index bed7941899..c4fdce4f03 100755
--- a/tests/ts/mkswap/mkswap
+++ b/tests/ts/mkswap/mkswap
@@ -63,4 +63,28 @@ for PAGESIZE in 4096 8192; do
 	done
 done
 
+ts_init_subtest offset
+
+offset=10000
+outimg="$TS_OUTDIR/offset.img"
+
+rm -f "$outimg"
+truncate -s $(( 4096 * 10 )) "$outimg" > $TS_ERRLOG 2>&1
+
+rm -f "$outimg.offset"
+truncate -s $(( 4096 * 10 + $offset )) "$outimg.offset" > $TS_ERRLOG 2>&1
+
+"$TS_CMD_MKSWAP" -q -U "$UUID" -p 4096 "$outimg" \
+	>> "$TS_OUTPUT" 2>/dev/null \
+	|| ts_log "mkswap failed"
+
+"$TS_CMD_MKSWAP" -q -U "$UUID" -p 4096 -o "$offset" "$outimg.offset" \
+	>> "$TS_OUTPUT" 2>/dev/null \
+	|| ts_log "mkswap -o failed"
+
+cmp -n "$offset" "$outimg.offset" /dev/zero >> "$TS_ERRLOG" 2>&1
+cmp "$outimg" "$outimg.offset" 0 "$offset" >> "$TS_ERRLOG" 2>&1
+
+ts_finalize_subtest
+
 ts_finalize