[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] libxl: Make an internal function explicitly check existence of expected paths
# HG changeset patch # User George Dunlap <george.dunlap@xxxxxxxxxxxxx> # Date 1353686127 0 # Node ID 85552b648b3cabebd4f5bfb484ab329fe2bb290d # Parent 54d1bcd211d14cfbae0782f2bf04f8942c2eb726 libxl: Make an internal function explicitly check existence of expected paths libxl__device_disk_from_xs_be() was failing without error for some missing xenstore nodes in a backend, while assuming (without checking) that other nodes were valid, causing a crash when another internal error wrote these nodes in the wrong place. Make this function consistent by: * Checking the existence of all nodes before using * Choosing a default only when the node is not written in device_disk_add() * Failing with log msg if any node written by device_disk_add() is not present * Returning an error on failure Also make the callers of the function pay attention to the error and behave appropriately. Signed-off-by: George Dunlap <george.dunlap@xxxxxxxxxxxxx> diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c --- a/tools/libxl/libxl.c +++ b/tools/libxl/libxl.c @@ -2168,9 +2168,9 @@ void libxl__device_disk_add(libxl__egc * device_disk_add(egc, domid, disk, aodev, NULL, NULL); } -static void libxl__device_disk_from_xs_be(libxl__gc *gc, - const char *be_path, - libxl_device_disk *disk) +static int libxl__device_disk_from_xs_be(libxl__gc *gc, + const char *be_path, + libxl_device_disk *disk) { libxl_ctx *ctx = libxl__gc_owner(gc); unsigned int len; @@ -2178,6 +2178,7 @@ static void libxl__device_disk_from_xs_b libxl_device_disk_init(disk); + /* "params" may not be present; but everything else must be. */ tmp = xs_read(ctx->xsh, XBT_NULL, libxl__sprintf(gc, "%s/params", be_path), &len); if (tmp && strchr(tmp, ':')) { @@ -2186,21 +2187,40 @@ static void libxl__device_disk_from_xs_b } else { disk->pdev_path = tmp; } - libxl_string_to_backend(ctx, - libxl__xs_read(gc, XBT_NULL, - libxl__sprintf(gc, "%s/type", be_path)), - &(disk->backend)); + + + tmp = libxl__xs_read(gc, XBT_NULL, + libxl__sprintf(gc, "%s/type", be_path)); + if (!tmp) { + LIBXL__LOG(ctx, LIBXL__LOG_ERROR, + "Internal error: Missing xenstore node %s/type", be_path); + return ERROR_FAIL; + } + libxl_string_to_backend(ctx, tmp, &(disk->backend)); + disk->vdev = xs_read(ctx->xsh, XBT_NULL, libxl__sprintf(gc, "%s/dev", be_path), &len); + if (!disk->vdev) { + LIBXL__LOG(ctx, LIBXL__LOG_ERROR, + "Internal error: Missing xenstore node %s/dev", be_path); + return ERROR_FAIL; + } + tmp = libxl__xs_read(gc, XBT_NULL, libxl__sprintf (gc, "%s/removable", be_path)); - - if (tmp) - disk->removable = atoi(tmp); - else - disk->removable = 0; + if (!tmp) { + LIBXL__LOG(ctx, LIBXL__LOG_ERROR, + "Internal error: Missing xenstore node %s/removable", be_path); + return ERROR_FAIL; + } + disk->removable = atoi(tmp); tmp = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, "%s/mode", be_path)); + if (!tmp) { + LIBXL__LOG(ctx, LIBXL__LOG_ERROR, + "Internal error: Missing xenstore node %s/mode", be_path); + return ERROR_FAIL; + } if (!strcmp(tmp, "w")) disk->readwrite = 1; else @@ -2208,9 +2228,16 @@ static void libxl__device_disk_from_xs_b tmp = libxl__xs_read(gc, XBT_NULL, libxl__sprintf(gc, "%s/device-type", be_path)); + if (!tmp) { + LIBXL__LOG(ctx, LIBXL__LOG_ERROR, + "Internal error: Missing xenstore node %s/device-type", be_path); + return ERROR_FAIL; + } disk->is_cdrom = !strcmp(tmp, "cdrom"); disk->format = LIBXL_DISK_FORMAT_UNKNOWN; + + return 0; } int libxl_vdev_to_device_disk(libxl_ctx *ctx, uint32_t domid, @@ -2236,9 +2263,7 @@ int libxl_vdev_to_device_disk(libxl_ctx if (!path) goto out; - libxl__device_disk_from_xs_be(gc, path, disk); - - rc = 0; + rc = libxl__device_disk_from_xs_be(gc, path, disk); out: GC_FREE; return rc; @@ -2255,6 +2280,7 @@ static int libxl__append_disk_list_of_ty char **dir = NULL; unsigned int n = 0; libxl_device_disk *pdisk = NULL, *pdisk_end = NULL; + int rc=0; be_path = libxl__sprintf(gc, "%s/backend/%s/%d", libxl__xs_get_dompath(gc, 0), type, domid); @@ -2271,7 +2297,8 @@ static int libxl__append_disk_list_of_ty for (; pdisk < pdisk_end; pdisk++, dir++) { const char *p; p = libxl__sprintf(gc, "%s/%s", be_path, *dir); - libxl__device_disk_from_xs_be(gc, p, pdisk); + if ((rc=libxl__device_disk_from_xs_be(gc, p, pdisk))) + return rc; pdisk->backend_domid = 0; } } _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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