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-rw-r--r--fs/romfs/storage.c261
1 files changed, 261 insertions, 0 deletions
diff --git a/fs/romfs/storage.c b/fs/romfs/storage.c
new file mode 100644
index 000000000000..7e3e1e12a081
--- /dev/null
+++ b/fs/romfs/storage.c
@@ -0,0 +1,261 @@
+/* RomFS storage access routines
+ *
+ * Copyright © 2007 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/fs.h>
+#include <linux/mtd/super.h>
+#include <linux/buffer_head.h>
+#include "internal.h"
+
+#if !defined(CONFIG_ROMFS_ON_MTD) && !defined(CONFIG_ROMFS_ON_BLOCK)
+#error no ROMFS backing store interface configured
+#endif
+
+#ifdef CONFIG_ROMFS_ON_MTD
+#define ROMFS_MTD_READ(sb, ...) ((sb)->s_mtd->read((sb)->s_mtd, ##__VA_ARGS__))
+
+/*
+ * read data from an romfs image on an MTD device
+ */
+static int romfs_mtd_read(struct super_block *sb, unsigned long pos,
+ void *buf, size_t buflen)
+{
+ size_t rlen;
+ int ret;
+
+ ret = ROMFS_MTD_READ(sb, pos, buflen, &rlen, buf);
+ return (ret < 0 || rlen != buflen) ? -EIO : 0;
+}
+
+/*
+ * determine the length of a string in a romfs image on an MTD device
+ */
+static ssize_t romfs_mtd_strnlen(struct super_block *sb,
+ unsigned long pos, size_t maxlen)
+{
+ ssize_t n = 0;
+ size_t segment;
+ u_char buf[16], *p;
+ size_t len;
+ int ret;
+
+ /* scan the string up to 16 bytes at a time */
+ while (maxlen > 0) {
+ segment = min_t(size_t, maxlen, 16);
+ ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
+ if (ret < 0)
+ return ret;
+ p = memchr(buf, 0, len);
+ if (p)
+ return n + (p - buf);
+ maxlen -= len;
+ pos += len;
+ n += len;
+ }
+
+ return n;
+}
+
+/*
+ * compare a string to one in a romfs image on MTD
+ * - return 1 if matched, 0 if differ, -ve if error
+ */
+static int romfs_mtd_strncmp(struct super_block *sb, unsigned long pos,
+ const char *str, size_t size)
+{
+ u_char buf[16];
+ size_t len, segment;
+ int ret;
+
+ /* scan the string up to 16 bytes at a time */
+ while (size > 0) {
+ segment = min_t(size_t, size, 16);
+ ret = ROMFS_MTD_READ(sb, pos, segment, &len, buf);
+ if (ret < 0)
+ return ret;
+ if (memcmp(buf, str, len) != 0)
+ return 0;
+ size -= len;
+ pos += len;
+ str += len;
+ }
+
+ return 1;
+}
+#endif /* CONFIG_ROMFS_ON_MTD */
+
+#ifdef CONFIG_ROMFS_ON_BLOCK
+/*
+ * read data from an romfs image on a block device
+ */
+static int romfs_blk_read(struct super_block *sb, unsigned long pos,
+ void *buf, size_t buflen)
+{
+ struct buffer_head *bh;
+ unsigned long offset;
+ size_t segment;
+
+ /* copy the string up to blocksize bytes at a time */
+ while (buflen > 0) {
+ offset = pos & (ROMBSIZE - 1);
+ segment = min_t(size_t, buflen, ROMBSIZE - offset);
+ bh = sb_bread(sb, pos >> ROMBSBITS);
+ if (!bh)
+ return -EIO;
+ memcpy(buf, bh->b_data + offset, segment);
+ brelse(bh);
+ buflen -= segment;
+ pos += segment;
+ }
+
+ return 0;
+}
+
+/*
+ * determine the length of a string in romfs on a block device
+ */
+static ssize_t romfs_blk_strnlen(struct super_block *sb,
+ unsigned long pos, size_t limit)
+{
+ struct buffer_head *bh;
+ unsigned long offset;
+ ssize_t n = 0;
+ size_t segment;
+ u_char *buf, *p;
+
+ /* scan the string up to blocksize bytes at a time */
+ while (limit > 0) {
+ offset = pos & (ROMBSIZE - 1);
+ segment = min_t(size_t, limit, ROMBSIZE - offset);
+ bh = sb_bread(sb, pos >> ROMBSBITS);
+ if (!bh)
+ return -EIO;
+ buf = bh->b_data + offset;
+ p = memchr(buf, 0, segment);
+ brelse(bh);
+ if (p)
+ return n + (p - buf);
+ limit -= segment;
+ pos += segment;
+ n += segment;
+ }
+
+ return n;
+}
+
+/*
+ * compare a string to one in a romfs image on a block device
+ * - return 1 if matched, 0 if differ, -ve if error
+ */
+static int romfs_blk_strncmp(struct super_block *sb, unsigned long pos,
+ const char *str, size_t size)
+{
+ struct buffer_head *bh;
+ unsigned long offset;
+ size_t segment;
+ bool x;
+
+ /* scan the string up to 16 bytes at a time */
+ while (size > 0) {
+ offset = pos & (ROMBSIZE - 1);
+ segment = min_t(size_t, size, ROMBSIZE - offset);
+ bh = sb_bread(sb, pos >> ROMBSBITS);
+ if (!bh)
+ return -EIO;
+ x = (memcmp(bh->b_data + offset, str, segment) != 0);
+ brelse(bh);
+ if (x)
+ return 0;
+ size -= segment;
+ pos += segment;
+ str += segment;
+ }
+
+ return 1;
+}
+#endif /* CONFIG_ROMFS_ON_BLOCK */
+
+/*
+ * read data from the romfs image
+ */
+int romfs_dev_read(struct super_block *sb, unsigned long pos,
+ void *buf, size_t buflen)
+{
+ size_t limit;
+
+ limit = romfs_maxsize(sb);
+ if (pos >= limit)
+ return -EIO;
+ if (buflen > limit - pos)
+ buflen = limit - pos;
+
+#ifdef CONFIG_ROMFS_ON_MTD
+ if (sb->s_mtd)
+ return romfs_mtd_read(sb, pos, buf, buflen);
+#endif
+#ifdef CONFIG_ROMFS_ON_BLOCK
+ if (sb->s_bdev)
+ return romfs_blk_read(sb, pos, buf, buflen);
+#endif
+ return -EIO;
+}
+
+/*
+ * determine the length of a string in romfs
+ */
+ssize_t romfs_dev_strnlen(struct super_block *sb,
+ unsigned long pos, size_t maxlen)
+{
+ size_t limit;
+
+ limit = romfs_maxsize(sb);
+ if (pos >= limit)
+ return -EIO;
+ if (maxlen > limit - pos)
+ maxlen = limit - pos;
+
+#ifdef CONFIG_ROMFS_ON_MTD
+ if (sb->s_mtd)
+ return romfs_mtd_strnlen(sb, pos, limit);
+#endif
+#ifdef CONFIG_ROMFS_ON_BLOCK
+ if (sb->s_bdev)
+ return romfs_blk_strnlen(sb, pos, limit);
+#endif
+ return -EIO;
+}
+
+/*
+ * compare a string to one in romfs
+ * - return 1 if matched, 0 if differ, -ve if error
+ */
+int romfs_dev_strncmp(struct super_block *sb, unsigned long pos,
+ const char *str, size_t size)
+{
+ size_t limit;
+
+ limit = romfs_maxsize(sb);
+ if (pos >= limit)
+ return -EIO;
+ if (size > ROMFS_MAXFN)
+ return -ENAMETOOLONG;
+ if (size > limit - pos)
+ return -EIO;
+
+#ifdef CONFIG_ROMFS_ON_MTD
+ if (sb->s_mtd)
+ return romfs_mtd_strncmp(sb, pos, str, size);
+#endif
+#ifdef CONFIG_ROMFS_ON_BLOCK
+ if (sb->s_bdev)
+ return romfs_blk_strncmp(sb, pos, str, size);
+#endif
+ return -EIO;
+}
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