From 645ae7d88e5393a2a67ebe325f4456ecd49e33e5 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Fri, 1 Feb 2019 20:29:14 +0100 Subject: [PATCH] block: bdrv_get_full_backing_filename_from_...'s ret. val. Make bdrv_get_full_backing_filename_from_filename() return an allocated string instead of placing the result in a caller-provided buffer. Signed-off-by: Max Reitz Message-id: 20190201192935.18394-11-mreitz@redhat.com Signed-off-by: Max Reitz --- block.c | 53 ++++++++++++++++++++++++++++++------------- block/vmdk.c | 10 ++++---- include/block/block.h | 7 +++--- qemu-img.c | 12 ++++------ 4 files changed, 49 insertions(+), 33 deletions(-) diff --git a/block.c b/block.c index 91859a928d..466d7887cc 100644 --- a/block.c +++ b/block.c @@ -312,20 +312,29 @@ fail: return -EACCES; } -void bdrv_get_full_backing_filename_from_filename(const char *backed, - const char *backing, - char *dest, size_t sz, - Error **errp) +/* + * If @backing is empty, this function returns NULL without setting + * @errp. In all other cases, NULL will only be returned with @errp + * set. + * + * Therefore, a return value of NULL without @errp set means that + * there is no backing file; if @errp is set, there is one but its + * absolute filename cannot be generated. + */ +char *bdrv_get_full_backing_filename_from_filename(const char *backed, + const char *backing, + Error **errp) { - if (backing[0] == '\0' || path_has_protocol(backing) || - path_is_absolute(backing)) - { - pstrcpy(dest, sz, backing); + if (backing[0] == '\0') { + return NULL; + } else if (path_has_protocol(backing) || path_is_absolute(backing)) { + return g_strdup(backing); } else if (backed[0] == '\0' || strstart(backed, "json:", NULL)) { error_setg(errp, "Cannot use relative backing file names for '%s'", backed); + return NULL; } else { - path_combine_deprecated(dest, sz, backed, backing); + return path_combine(backed, backing); } } @@ -333,12 +342,24 @@ void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz, Error **errp) { char *backed; + char *full_name; + Error *local_error = NULL; bdrv_refresh_filename(bs); backed = bs->exact_filename[0] ? bs->exact_filename : bs->filename; - bdrv_get_full_backing_filename_from_filename(backed, bs->backing_file, - dest, sz, errp); + + full_name = bdrv_get_full_backing_filename_from_filename(backed, + bs->backing_file, + &local_error); + if (full_name) { + pstrcpy(dest, sz, full_name); + g_free(full_name); + } else if (local_error) { + error_propagate(errp, local_error); + } else if (sz > 0) { + *dest = '\0'; + } } void bdrv_register(BlockDriver *bdrv) @@ -5179,17 +5200,17 @@ void bdrv_img_create(const char *filename, const char *fmt, size = qemu_opt_get_size(opts, BLOCK_OPT_SIZE, img_size); if (backing_file && !(flags & BDRV_O_NO_BACKING)) { BlockDriverState *bs; - char *full_backing = g_new0(char, PATH_MAX); + char *full_backing; int back_flags; QDict *backing_options = NULL; - bdrv_get_full_backing_filename_from_filename(filename, backing_file, - full_backing, PATH_MAX, - &local_err); + full_backing = + bdrv_get_full_backing_filename_from_filename(filename, backing_file, + &local_err); if (local_err) { - g_free(full_backing); goto out; } + assert(full_backing); /* backing files always opened read-only */ back_flags = flags; diff --git a/block/vmdk.c b/block/vmdk.c index 32e4e7589a..81c506cb69 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -2078,16 +2078,16 @@ static int coroutine_fn vmdk_co_do_create(int64_t size, if (backing_file) { BlockBackend *backing; - char *full_backing = g_new0(char, PATH_MAX); - bdrv_get_full_backing_filename_from_filename(blk_bs(blk)->filename, backing_file, - full_backing, PATH_MAX, - &local_err); + char *full_backing = + bdrv_get_full_backing_filename_from_filename(blk_bs(blk)->filename, + backing_file, + &local_err); if (local_err) { - g_free(full_backing); error_propagate(errp, local_err); ret = -ENOENT; goto exit; } + assert(full_backing); backing = blk_new_open(full_backing, NULL, NULL, BDRV_O_NO_BACKING, errp); diff --git a/include/block/block.h b/include/block/block.h index e233372a3a..5f1650304d 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -489,10 +489,9 @@ void bdrv_get_backing_filename(BlockDriverState *bs, char *filename, int filename_size); void bdrv_get_full_backing_filename(BlockDriverState *bs, char *dest, size_t sz, Error **errp); -void bdrv_get_full_backing_filename_from_filename(const char *backed, - const char *backing, - char *dest, size_t sz, - Error **errp); +char *bdrv_get_full_backing_filename_from_filename(const char *backed, + const char *backing, + Error **errp); int path_has_protocol(const char *path); int path_is_absolute(const char *path); diff --git a/qemu-img.c b/qemu-img.c index d2fc28c987..ae0025926c 100644 --- a/qemu-img.c +++ b/qemu-img.c @@ -3343,18 +3343,14 @@ static int img_rebase(int argc, char **argv) bdrv_refresh_filename(bs); overlay_filename = bs->exact_filename[0] ? bs->exact_filename : bs->filename; - out_real_path = g_malloc(PATH_MAX); - - bdrv_get_full_backing_filename_from_filename(overlay_filename, - out_baseimg, - out_real_path, - PATH_MAX, - &local_err); + out_real_path = + bdrv_get_full_backing_filename_from_filename(overlay_filename, + out_baseimg, + &local_err); if (local_err) { error_reportf_err(local_err, "Could not resolve backing filename: "); ret = -1; - g_free(out_real_path); goto out; }