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;
+}