Besides being safe for arbitrary path lengths, after some follow-up patches all callers will want a freshly allocated buffer anyway.
In the meantime, path_combine_deprecated() is added which has the same interface as path_combine() had before this patch. All callers to that function will be converted in follow-up patches. Signed-off-by: Max Reitz <mre...@redhat.com> Reviewed-by: Alberto Garcia <be...@igalia.com> --- block.c | 81 +++++++++++++++++++++++++++++---------------------- block/vmdk.c | 3 +- include/block/block.h | 4 +-- 3 files changed, 48 insertions(+), 40 deletions(-) diff --git a/block.c b/block.c index f7a287a..28ce42c 100644 --- a/block.c +++ b/block.c @@ -148,48 +148,59 @@ int path_is_absolute(const char *path) #endif } -/* if filename is absolute, just copy it to dest. Otherwise, build a +/* if filename is absolute, just return its duplicate. Otherwise, build a path to it by considering it is relative to base_path. URL are supported. */ -void path_combine(char *dest, int dest_size, - const char *base_path, - const char *filename) +char *path_combine(const char *base_path, const char *filename) { const char *p, *p1; + char *result; int len; - if (dest_size <= 0) - return; if (path_is_absolute(filename)) { - pstrcpy(dest, dest_size, filename); + return g_strdup(filename); + } + + p = strchr(base_path, ':'); + if (p) { + p++; } else { - p = strchr(base_path, ':'); - if (p) - p++; - else - p = base_path; - p1 = strrchr(base_path, '/'); + p = base_path; + } + p1 = strrchr(base_path, '/'); #ifdef _WIN32 - { - const char *p2; - p2 = strrchr(base_path, '\\'); - if (!p1 || p2 > p1) - p1 = p2; + { + const char *p2; + p2 = strrchr(base_path, '\\'); + if (!p1 || p2 > p1) { + p1 = p2; } + } #endif - if (p1) - p1++; - else - p1 = base_path; - if (p1 > p) - p = p1; - len = p - base_path; - if (len > dest_size - 1) - len = dest_size - 1; - memcpy(dest, base_path, len); - dest[len] = '\0'; - pstrcat(dest, dest_size, filename); + if (p1) { + p1++; + } else { + p1 = base_path; + } + if (p1 > p) { + p = p1; } + len = p - base_path; + + result = g_malloc(len + strlen(filename) + 1); + memcpy(result, base_path, len); + strcpy(result + len, filename); + + return result; +} + +static void path_combine_deprecated(char *dest, int dest_size, + const char *base_path, + const char *filename) +{ + char *combined = path_combine(base_path, filename); + pstrcpy(dest, dest_size, combined); + g_free(combined); } void bdrv_get_full_backing_filename_from_filename(const char *backed, @@ -205,7 +216,7 @@ void bdrv_get_full_backing_filename_from_filename(const char *backed, error_setg(errp, "Cannot use relative backing file names for '%s'", backed); } else { - path_combine(dest, sz, backed, backing); + path_combine_deprecated(dest, sz, backed, backing); } } @@ -3177,8 +3188,8 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, } else { /* If not an absolute filename path, make it relative to the current * image's filename path */ - path_combine(filename_tmp, PATH_MAX, curr_bs->filename, - backing_file); + path_combine_deprecated(filename_tmp, PATH_MAX, curr_bs->filename, + backing_file); /* We are going to compare absolute pathnames */ if (!realpath(filename_tmp, filename_full)) { @@ -3187,8 +3198,8 @@ BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, /* We need to make sure the backing filename we are comparing against * is relative to the current image filename (or absolute) */ - path_combine(filename_tmp, PATH_MAX, curr_bs->filename, - curr_bs->backing_file); + path_combine_deprecated(filename_tmp, PATH_MAX, curr_bs->filename, + curr_bs->backing_file); if (!realpath(filename_tmp, backing_file_full)) { continue; diff --git a/block/vmdk.c b/block/vmdk.c index a11c27a..aad2d7d 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -846,8 +846,7 @@ static int vmdk_parse_extents(const char *desc, BlockDriverState *bs, return -EINVAL; } - extent_path = g_malloc0(PATH_MAX); - path_combine(extent_path, PATH_MAX, desc_file_path, fname); + extent_path = path_combine(desc_file_path, fname); ret = snprintf(extent_opt_prefix, 32, "extents.%d", s->num_extents); assert(ret < 32); diff --git a/include/block/block.h b/include/block/block.h index 49bb0b2..6e5d4b2 100644 --- a/include/block/block.h +++ b/include/block/block.h @@ -444,9 +444,7 @@ void bdrv_get_full_backing_filename_from_filename(const char *backed, int path_has_protocol(const char *path); int path_is_absolute(const char *path); -void path_combine(char *dest, int dest_size, - const char *base_path, - const char *filename); +char *path_combine(const char *base_path, const char *filename); int bdrv_readv_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); int bdrv_writev_vmstate(BlockDriverState *bs, QEMUIOVector *qiov, int64_t pos); -- 2.10.2