From 64107dc044a54ebe46348ac0fe87584be2eb3e81 Mon Sep 17 00:00:00 2001 From: Kevin Wolf Date: Mon, 8 Oct 2018 17:27:18 +0200 Subject: file-posix: Support auto-read-only option If read-only=off, but auto-read-only=on is given, open the file read-write if we have the permissions, but instead of erroring out for read-only files, just degrade to read-only. Signed-off-by: Kevin Wolf Reviewed-by: Eric Blake --- block/file-posix.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) (limited to 'block') diff --git a/block/file-posix.c b/block/file-posix.c index 2da3a76355..0c1b81ce4b 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -527,9 +527,22 @@ static int raw_open_common(BlockDriverState *bs, QDict *options, s->fd = -1; fd = qemu_open(filename, s->open_flags, 0644); - if (fd < 0) { - ret = -errno; - error_setg_errno(errp, errno, "Could not open '%s'", filename); + ret = fd < 0 ? -errno : 0; + + if (ret == -EACCES || ret == -EROFS) { + /* Try to degrade to read-only, but if it doesn't work, still use the + * normal error message. */ + if (bdrv_apply_auto_read_only(bs, NULL, NULL) == 0) { + bdrv_flags &= ~BDRV_O_RDWR; + raw_parse_flags(bdrv_flags, &s->open_flags); + assert(!(s->open_flags & O_CREAT)); + fd = qemu_open(filename, s->open_flags); + ret = fd < 0 ? -errno : 0; + } + } + + if (ret < 0) { + error_setg_errno(errp, -ret, "Could not open '%s'", filename); if (ret == -EROFS) { ret = -EACCES; } -- cgit v1.2.3