[Libguestfs] [nbdkit PATCH v2 2/3] blocksize: Defer per-handle initialization to .prepare

Now that we can track block size constraints per handle, it makes more sense to initialize parameters during .prepare (where the next patch will also take into consideration next->block_size values), than it is to supply values for unspecified globals during .config. This has no logical change, but is intentionally separate from the renaming churn of the previous patch. --- filters/blocksize/blocksize.c | 39 ++++++++++++++++++++++++----------- 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/filters/blocksize/blocksize.c b/filters/blocksize/blocksize.c index e0420409..bca9fb73 100644 --- a/filters/blocksize/blocksize.c +++ b/filters/blocksize/blocksize.c @@ -66,7 +66,7 @@ static unsigned int config_minblock; static unsigned int config_maxdata; static unsigned int config_maxlen; -/* Per-handle values set during .open */ +/* Per-handle values set during .prepare */ struct blocksize_handle { uint32_t minblock; uint32_t maxdata; @@ -122,28 +122,20 @@ blocksize_config_complete (nbdkit_next_config_complete *next, return -1; } } - else - config_minblock = 1; - if (config_maxdata) { + if (config_maxdata && config_minblock) { if (config_maxdata & (config_minblock - 1)) { nbdkit_error ("maxdata must be a multiple of %u", config_minblock); return -1; } } - else if (config_maxlen) - config_maxdata = MIN (config_maxlen, 64 * 1024 * 1024); - else - config_maxdata = 64 * 1024 * 1024; - if (config_maxlen) { + if (config_maxlen && config_minblock) { if (config_maxlen & (config_minblock - 1)) { nbdkit_error ("maxlen must be a multiple of %u", config_minblock); return -1; } } - else - config_maxlen = -config_minblock; nbdkit_debug ("configured values minblock=%u maxdata=%u maxlen=%u", config_minblock, config_maxdata, config_maxlen); @@ -173,9 +165,31 @@ blocksize_open (nbdkit_next_open *next, nbdkit_context *nxdata, h->minblock = config_minblock; h->maxdata = config_maxdata; h->maxlen = config_maxlen; + return h; +} + +static int +blocksize_prepare (nbdkit_next *next, void *handle, + int readonly) +{ + struct blocksize_handle *h = handle; + + if (h->minblock == 0) + h->minblock = 1; + + if (h->maxdata == 0) { + if (h->maxlen) + h->maxdata = MIN (h->maxlen, 64 * 1024 * 1024); + else + h->maxdata = 64 * 1024 * 1024; + } + + if (h->maxlen == 0) + h->maxlen = -h->minblock; + nbdkit_debug ("handle values minblock=%u maxdata=%u maxlen=%u", h->minblock, h->maxdata, h->maxlen); - return h; + return 0; } /* Round size down to avoid issues at end of file. */ @@ -501,6 +515,7 @@ static struct nbdkit_filter filter = { .config_complete = blocksize_config_complete, .config_help = blocksize_config_help, .open = blocksize_open, + .prepare = blocksize_prepare, .close = free, .get_size = blocksize_get_size, .block_size = blocksize_block_size, -- 2.35.1