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Label reading/writing code.
Not tested the filter yet.
This commit is contained in:
Patrick Caulfield
parent
db73838ca4
commit
3dd5cbe54f
304
lib/label/label.c
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304
lib/label/label.c
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@ -0,0 +1,304 @@
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/*
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* Copyright (C) 2001 Sistina Software
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*
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* This file is released under the LGPL.
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*/
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "device.h"
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#include "dev-cache.h"
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#include "log.h"
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#include "filter.h"
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#include "label.h"
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#include "pool.h"
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#include "xlate.h"
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/* Label Magic is "LnXl" - error: imagination failure */
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#define LABEL_MAGIC 0x6c586e4c
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/* Our memory pool */
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static void *label_pool = NULL;
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/* This is just the "struct label" with the data pointer removed */
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struct label_ondisk
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{
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uint32_t magic;
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uint32_t format_type;
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uint32_t checksum;
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uint16_t datalen;
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uint16_t pad;
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};
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struct filter_private
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{
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void *mem;
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uint32_t format_type;
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};
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/* Calculate checksum */
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static uint32_t calc_checksum(struct label *label)
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{
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uint32_t csum = 0;
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int i;
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csum += label->magic;
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csum += label->format_type;
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csum += label->datalen;
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for (i=0; i<label->datalen; i++)
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{
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csum += label->data[i];
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}
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return csum;
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}
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int label_read(struct device *dev, struct label *label)
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{
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uint64_t size;
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uint32_t sectsize;
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char *block;
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struct label_ondisk *ondisk;
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int status;
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int iter;
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if (!dev_get_size(dev, &size))
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return 0;
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if (!dev_get_sectsize(dev, §size))
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return 0;
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if (dev_open(dev, O_RDWR))
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return 0;
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if (label_pool == NULL)
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label_pool = pool_create(512);
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block = pool_alloc(label_pool, sectsize);
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if (!block)
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{
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stack;
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return 1;
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}
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ondisk = (struct label_ondisk *)block;
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status = dev_read(dev, sectsize*2, sectsize, block);
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/* If the first label is bad then use the second */
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for (iter = 0; iter <= 1; iter++)
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{
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if (iter == 0)
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status = dev_read(dev, sectsize*2, sectsize, block);
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else
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status = dev_read(dev, size*512 - sectsize, sizeof(struct label_ondisk) + label->datalen, block);
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if (!status)
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{
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struct label incore;
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/* Copy and convert endianness */
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incore.magic = xlate32(ondisk->magic);
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incore.checksum = xlate32(ondisk->checksum);
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incore.datalen = xlate16(ondisk->datalen);
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incore.data = block + sizeof(struct label_ondisk);
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if (incore.magic != LABEL_MAGIC)
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continue;
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/* Check Checksum */
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if (incore.checksum != calc_checksum(&incore))
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{
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log_error("Checksum %d does not match\n", iter);
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continue;
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}
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*label = incore;
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label->data = pool_alloc(label_pool, incore.datalen);
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if (!label->data)
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{
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stack;
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return 1;
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}
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label->pool = label_pool;
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if (label->data) memcpy(label->data, incore.data, incore.datalen);
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pool_free(label_pool, block);
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dev_close(dev);
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return 1;
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}
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}
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pool_free(label_pool, block);
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dev_close(dev);
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return 0;
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}
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int label_write(struct device *dev, struct label *label)
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{
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uint64_t size;
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uint32_t sectsize;
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char *block;
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struct label_ondisk *ondisk;
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int status1, status2;
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if (!dev_get_size(dev, &size))
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return 0;
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if (!dev_get_sectsize(dev, §size))
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return 0;
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/* Can the metata fit in the remaining space ? */
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if (label->datalen > sectsize - sizeof(struct label_ondisk))
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return 0;
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if (label_pool == NULL)
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label_pool = pool_create(512);
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block = pool_alloc(label_pool, sizeof(struct label_ondisk) + label->datalen);
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if (!block)
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{
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stack;
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return 1;
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}
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ondisk = (struct label_ondisk *)block;
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/* Make into ondisk format */
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ondisk->magic = xlate32(LABEL_MAGIC);
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ondisk->format_type = xlate32(label->format_type);
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ondisk->datalen = xlate16(label->datalen);
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ondisk->checksum = xlate32(calc_checksum(label));
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memcpy(block+sizeof(struct label_ondisk), label->data, label->datalen);
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/* Write metadata to disk */
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if (!dev_open(dev, O_RDWR))
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{
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pool_free(label_pool, block);
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return 0;
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}
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status1 = dev_write(dev, sectsize*2, sizeof(struct label_ondisk) + label->datalen, block);
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/* Write another at the end of the device */
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status2 = dev_write(dev, size*512 - sectsize, sizeof(struct label_ondisk) + label->datalen, block);
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pool_free(label_pool, block);
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dev_close(dev);
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return ((status1 != 0) && (status2 != 0));
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}
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/* Return 1 for Yes, 0 for No */
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int is_labelled(struct device *dev)
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{
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struct label l;
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int status;
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status = label_read(dev, &l);
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pool_free(l.pool, l.data);
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return 1-status;
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}
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/* Check the device is labelled and has the right format_type */
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static int _accept_format(struct dev_filter *f, struct device *dev)
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{
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struct label l;
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int status;
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status = label_read(dev, &l);
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pool_free(l.pool, l.data);
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if (status && l.format_type == (uint32_t)f->private)
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return 1;
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else
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return 0;
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}
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/* We just want to know if it's labelled or not */
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static int _accept_label(struct dev_filter *f, struct device *dev)
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{
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return is_labelled(dev);
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}
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static void _destroy(struct dev_filter *f)
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{
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struct filter_private *fp = (struct filter_private *) f->private;
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pool_destroy(fp->mem);
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}
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/* A filter to find devices with a particular label type on them */
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struct dev_filter *label_format_filter_create(uint32_t format_type)
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{
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struct pool *mem = pool_create(10 * 1024);
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struct filter_private *fp;
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struct dev_filter *f;
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if (!mem) {
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stack;
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return NULL;
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}
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if (!(f = pool_zalloc(mem, sizeof(*f)))) {
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stack;
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goto bad;
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}
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if (!(fp = pool_zalloc(mem, sizeof(*fp)))) {
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stack;
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goto bad;
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}
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fp->mem = mem;
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fp->format_type = format_type;
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f->passes_filter = _accept_format;
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f->destroy = _destroy;
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f->private = fp;
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return f;
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bad:
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pool_destroy(mem);
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return NULL;
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}
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/* A filter to find devices with any label on them */
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struct dev_filter *label_filter_create()
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{
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struct pool *mem = pool_create(10 * 1024);
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struct filter_private *fp;
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struct dev_filter *f;
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if (!mem) {
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stack;
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return NULL;
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}
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if (!(f = pool_zalloc(mem, sizeof(*f)))) {
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stack;
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goto bad;
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}
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if (!(fp = pool_zalloc(mem, sizeof(*fp)))) {
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stack;
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goto bad;
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}
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fp->mem = mem;
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f->passes_filter = _accept_label;
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f->destroy = _destroy;
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f->private = fp;
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return f;
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bad:
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pool_destroy(mem);
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return NULL;
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}
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24
lib/label/label.h
Normal file
24
lib/label/label.h
Normal file
@ -0,0 +1,24 @@
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/*
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* Copyright (C) 2001 Sistina Software (UK) Limited.
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*
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* This file is released under the GPL.
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*/
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struct label
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{
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uint32_t magic;
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uint32_t format_type;
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uint32_t checksum;
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uint16_t datalen;
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char *data;
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void *pool; /* Pool that data is allocated from */
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};
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extern int label_write(struct device *dev, struct label *label);
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extern int label_read(struct device *dev, struct label *label);
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extern int is_labelled(struct device *dev);
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extern struct dev_filter *label_filter_create();
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extern struct dev_filter *label_format_filter_create(uint32_t format_type);
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