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unix_io: check for read-only devices when opening R/W
[tools/e2fsprogs.git] / lib / ext2fs / unix_io.c
index b2deb70..797fce8 100644 (file)
@@ -4,7 +4,7 @@
  *
  * Implements a one-block write-through cache.
  *
- * Includes support for Windows NT support under Cygwin. 
+ * Includes support for Windows NT support under Cygwin.
  *
  * Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001,
  *     2002 by Theodore Ts'o.
 #ifdef __linux__
 #include <sys/utsname.h>
 #endif
+#ifdef HAVE_SYS_IOCTL_H
+#include <sys/ioctl.h>
+#endif
+#ifdef HAVE_SYS_MOUNT_H
+#include <sys/mount.h>
+#endif
 #if HAVE_SYS_STAT_H
 #include <sys/stat.h>
 #endif
 #include <sys/resource.h>
 #endif
 
+#if defined(__linux__) && defined(_IO) && !defined(BLKGETSIZE)
+#define BLKROGET   _IO(0x12, 94) /* Get read-only status (0 = read_write).  */
+#endif
+
 #include "ext2_fs.h"
 #include "ext2fs.h"
 
@@ -55,8 +65,8 @@ struct unix_cache {
        char            *buf;
        unsigned long   block;
        int             access_time;
-       int             dirty:1;
-       int             in_use:1;
+       unsigned        dirty:1;
+       unsigned        in_use:1;
 };
 
 #define CACHE_SIZE 8
@@ -68,7 +78,9 @@ struct unix_private_data {
        int     dev;
        int     flags;
        int     access_time;
+       ext2_loff_t offset;
        struct unix_cache cache[CACHE_SIZE];
+       struct struct_io_stats io_stats;
 };
 
 static errcode_t unix_open(const char *name, int flags, io_channel *channel);
@@ -81,9 +93,24 @@ static errcode_t unix_write_blk(io_channel channel, unsigned long block,
 static errcode_t unix_flush(io_channel channel);
 static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
                                int size, const void *data);
-
+static errcode_t unix_set_option(io_channel channel, const char *option,
+                                const char *arg);
+static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
+;
 static void reuse_cache(io_channel channel, struct unix_private_data *data,
-                struct unix_cache *cache, unsigned long block);
+                struct unix_cache *cache, unsigned long long block);
+static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
+                              int count, void *data);
+static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
+                               int count, const void *data);
+
+/* __FreeBSD_kernel__ is defined by GNU/kFreeBSD - the FreeBSD kernel
+ * does not know buffered block devices - everything is raw. */
+#if defined(__CYGWIN__) || defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#define NEED_BOUNCE_BUFFER
+#else
+#undef NEED_BOUNCE_BUFFER
+#endif
 
 static struct struct_io_manager struct_unix_manager = {
        EXT2_ET_MAGIC_IO_MANAGER,
@@ -94,31 +121,52 @@ static struct struct_io_manager struct_unix_manager = {
        unix_read_blk,
        unix_write_blk,
        unix_flush,
-#ifdef __CYGWIN__
-       0
+#ifdef NEED_BOUNCE_BUFFER
+       0,
 #else
-       unix_write_byte
+       unix_write_byte,
 #endif
+       unix_set_option,
+       unix_get_stats,
+       unix_read_blk64,
+       unix_write_blk64,
 };
 
 io_manager unix_io_manager = &struct_unix_manager;
 
+static errcode_t unix_get_stats(io_channel channel, io_stats *stats)
+{
+       errcode_t       retval = 0;
+
+       struct unix_private_data *data;
+
+       EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+       data = (struct unix_private_data *) channel->private_data;
+       EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+       if (stats)
+               *stats = &data->io_stats;
+
+       return retval;
+}
+
 /*
  * Here are the raw I/O functions
  */
-#ifndef __CYGWIN__
+#ifndef NEED_BOUNCE_BUFFER
 static errcode_t raw_read_blk(io_channel channel,
                              struct unix_private_data *data,
-                             unsigned long block,
+                             unsigned long long block,
                              int count, void *buf)
 {
        errcode_t       retval;
-       size_t          size;
+       ssize_t         size;
        ext2_loff_t     location;
        int             actual = 0;
 
        size = (count < 0) ? -count : count * channel->block_size;
-       location = (ext2_loff_t) block * channel->block_size;
+       data->io_stats.bytes_read += size;
+       location = ((ext2_loff_t) block * channel->block_size) + data->offset;
        if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
                retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
                goto error_out;
@@ -131,7 +179,7 @@ static errcode_t raw_read_blk(io_channel channel,
                goto error_out;
        }
        return 0;
-       
+
 error_out:
        memset((char *) buf+actual, 0, size-actual);
        if (channel->read_error)
@@ -139,9 +187,9 @@ error_out:
                                               size, actual, retval);
        return retval;
 }
-#else /* __CYGWIN__ */
+#else /* NEED_BOUNCE_BUFFER */
 /*
- * Windows block devices only allow sector alignment IO in offset and size
+ * Windows and FreeBSD block devices only allow sector alignment IO in offset and size
  */
 static errcode_t raw_read_blk(io_channel channel,
                              struct unix_private_data *data,
@@ -156,10 +204,11 @@ static errcode_t raw_read_blk(io_channel channel,
        char            sector[BLOCKALIGN];
 
        size = (count < 0) ? -count : count * channel->block_size;
-       location = (ext2_loff_t) block * channel->block_size;
+       data->io_stats.bytes_read += size;
+       location = ((ext2_loff_t) block * channel->block_size) + data->offset;
 #ifdef DEBUG
-       printf("count=%d, size=%d, block=%d, blk_size=%d, location=%lx\n",
-                       count, size, block, channel->block_size, location);
+       printf("count=%d, size=%d, block=%lu, blk_size=%d, location=%llx\n",
+                       count, size, block, channel->block_size, (long long)location);
 #endif
        if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
                retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
@@ -196,10 +245,10 @@ error_out:
 
 static errcode_t raw_write_blk(io_channel channel,
                               struct unix_private_data *data,
-                              unsigned long block,
+                              unsigned long long block,
                               int count, const void *buf)
 {
-       size_t          size;
+       ssize_t         size;
        ext2_loff_t     location;
        int             actual = 0;
        errcode_t       retval;
@@ -212,20 +261,21 @@ static errcode_t raw_write_blk(io_channel channel,
                else
                        size = count * channel->block_size;
        }
+       data->io_stats.bytes_written += size;
 
-       location = (ext2_loff_t) block * channel->block_size;
+       location = ((ext2_loff_t) block * channel->block_size) + data->offset;
        if (ext2fs_llseek(data->dev, location, SEEK_SET) != location) {
                retval = errno ? errno : EXT2_ET_LLSEEK_FAILED;
                goto error_out;
        }
-       
+
        actual = write(data->dev, buf, size);
        if (actual != size) {
                retval = EXT2_ET_SHORT_WRITE;
                goto error_out;
        }
        return 0;
-       
+
 error_out:
        if (channel->write_error)
                retval = (channel->write_error)(channel, block, count, buf,
@@ -245,7 +295,7 @@ static errcode_t alloc_cache(io_channel channel,
        errcode_t               retval;
        struct unix_cache       *cache;
        int                     i;
-       
+
        data->access_time = 0;
        for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
                cache->block = 0;
@@ -253,19 +303,18 @@ static errcode_t alloc_cache(io_channel channel,
                cache->dirty = 0;
                cache->in_use = 0;
                if ((retval = ext2fs_get_mem(channel->block_size,
-                                            (void **) &cache->buf)))
+                                            &cache->buf)))
                        return retval;
        }
        return 0;
 }
 
 /* Free the cache buffers */
-static void free_cache(io_channel channel, 
-                      struct unix_private_data *data)
+static void free_cache(struct unix_private_data *data)
 {
        struct unix_cache       *cache;
        int                     i;
-       
+
        data->access_time = 0;
        for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
                cache->block = 0;
@@ -273,7 +322,7 @@ static void free_cache(io_channel channel,
                cache->dirty = 0;
                cache->in_use = 0;
                if (cache->buf)
-                       ext2fs_free_mem((void **) &cache->buf);
+                       ext2fs_free_mem(&cache->buf);
                cache->buf = 0;
        }
 }
@@ -284,14 +333,13 @@ static void free_cache(io_channel channel,
  * eldest is a non-zero pointer, then fill in eldest with the cache
  * entry to that should be reused.
  */
-static struct unix_cache *find_cached_block(io_channel channel,
-                                           struct unix_private_data *data,
-                                           unsigned long block,
+static struct unix_cache *find_cached_block(struct unix_private_data *data,
+                                           unsigned long long block,
                                            struct unix_cache **eldest)
 {
        struct unix_cache       *cache, *unused_cache, *oldest_cache;
        int                     i;
-       
+
        unused_cache = oldest_cache = 0;
        for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
                if (!cache->in_use) {
@@ -316,7 +364,7 @@ static struct unix_cache *find_cached_block(io_channel channel,
  * Reuse a particular cache entry for another block.
  */
 static void reuse_cache(io_channel channel, struct unix_private_data *data,
-                struct unix_cache *cache, unsigned long block)
+                struct unix_cache *cache, unsigned long long block)
 {
        if (cache->dirty && cache->in_use)
                raw_write_blk(channel, data, cache->block, 1, cache->buf);
@@ -338,18 +386,18 @@ static errcode_t flush_cached_blocks(io_channel channel,
        struct unix_cache       *cache;
        errcode_t               retval, retval2;
        int                     i;
-       
+
        retval2 = 0;
        for (i=0, cache = data->cache; i < CACHE_SIZE; i++, cache++) {
                if (!cache->in_use)
                        continue;
-               
+
                if (invalidate)
                        cache->in_use = 0;
-               
+
                if (!cache->dirty)
                        continue;
-               
+
                retval = raw_write_blk(channel, data,
                                       cache->block, 1, cache->buf);
                if (retval)
@@ -374,19 +422,17 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
 
        if (name == 0)
                return EXT2_ET_BAD_DEVICE_NAME;
-       retval = ext2fs_get_mem(sizeof(struct struct_io_channel),
-                               (void **) &io);
+       retval = ext2fs_get_mem(sizeof(struct struct_io_channel), &io);
        if (retval)
                return retval;
        memset(io, 0, sizeof(struct struct_io_channel));
        io->magic = EXT2_ET_MAGIC_IO_CHANNEL;
-       retval = ext2fs_get_mem(sizeof(struct unix_private_data),
-                               (void **) &data);
+       retval = ext2fs_get_mem(sizeof(struct unix_private_data), &data);
        if (retval)
                goto cleanup;
 
        io->manager = unix_io_manager;
-       retval = ext2fs_get_mem(strlen(name)+1, (void **) &io->name);
+       retval = ext2fs_get_mem(strlen(name)+1, &io->name);
        if (retval)
                goto cleanup;
 
@@ -399,21 +445,39 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
 
        memset(data, 0, sizeof(struct unix_private_data));
        data->magic = EXT2_ET_MAGIC_UNIX_IO_CHANNEL;
+       data->io_stats.num_fields = 2;
 
        if ((retval = alloc_cache(io, data)))
                goto cleanup;
-       
+
        open_flags = (flags & IO_FLAG_RW) ? O_RDWR : O_RDONLY;
+       if (flags & IO_FLAG_EXCLUSIVE)
+               open_flags |= O_EXCL;
 #ifdef HAVE_OPEN64
-       data->dev = open64(name, open_flags);
+       data->dev = open64(io->name, open_flags);
 #else
-       data->dev = open(name, open_flags);
+       data->dev = open(io->name, open_flags);
 #endif
        if (data->dev < 0) {
                retval = errno;
                goto cleanup;
        }
 
+#ifdef BLKROGET
+       if (flags & IO_FLAG_RW) {
+               int error;
+               int readonly = 0;
+
+               /* Is the block device actually writable? */
+               error = ioctl(data->dev, BLKROGET, &readonly);
+               if (!error && readonly) {
+                       close(data->dev);
+                       retval = EPERM;
+                       goto cleanup;
+               }
+       }
+#endif
+
 #ifdef __linux__
 #undef RLIM_INFINITY
 #if (defined(__alpha__) || ((defined(__sparc__) || defined(__mips__)) && (SIZEOF_LONG == 4)))
@@ -426,7 +490,7 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
         * block devices are wrongly getting hit by the filesize
         * limit.  This workaround isn't perfect, since it won't work
         * if glibc wasn't built against 2.2 header files.  (Sigh.)
-        * 
+        *
         */
        if ((flags & IO_FLAG_RW) &&
            (uname(&ut) == 0) &&
@@ -437,7 +501,7 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
            (fstat(data->dev, &st) == 0) &&
            (S_ISBLK(st.st_mode))) {
                struct rlimit   rlim;
-               
+
                rlim.rlim_cur = rlim.rlim_max = (unsigned long) RLIM_INFINITY;
                setrlimit(RLIMIT_FSIZE, &rlim);
                getrlimit(RLIMIT_FSIZE, &rlim);
@@ -453,11 +517,11 @@ static errcode_t unix_open(const char *name, int flags, io_channel *channel)
 
 cleanup:
        if (data) {
-               free_cache(io, data);
-               ext2fs_free_mem((void **) &data);
+               free_cache(data);
+               ext2fs_free_mem(&data);
        }
        if (io)
-               ext2fs_free_mem((void **) &io);
+               ext2fs_free_mem(&io);
        return retval;
 }
 
@@ -479,12 +543,12 @@ static errcode_t unix_close(io_channel channel)
 
        if (close(data->dev) < 0)
                retval = errno;
-       free_cache(channel, data);
+       free_cache(data);
 
-       ext2fs_free_mem((void **) &channel->private_data);
+       ext2fs_free_mem(&channel->private_data);
        if (channel->name)
-               ext2fs_free_mem((void **) &channel->name);
-       ext2fs_free_mem((void **) &channel);
+               ext2fs_free_mem(&channel->name);
+       ext2fs_free_mem(&channel);
        return retval;
 }
 
@@ -502,9 +566,9 @@ static errcode_t unix_set_blksize(io_channel channel, int blksize)
                if ((retval = flush_cached_blocks(channel, data, 0)))
                        return retval;
 #endif
-               
+
                channel->block_size = blksize;
-               free_cache(channel, data);
+               free_cache(data);
                if ((retval = alloc_cache(channel, data)))
                        return retval;
        }
@@ -512,7 +576,7 @@ static errcode_t unix_set_blksize(io_channel channel, int blksize)
 }
 
 
-static errcode_t unix_read_blk(io_channel channel, unsigned long block,
+static errcode_t unix_read_blk64(io_channel channel, unsigned long long block,
                               int count, void *buf)
 {
        struct unix_private_data *data;
@@ -541,10 +605,9 @@ static errcode_t unix_read_blk(io_channel channel, unsigned long block,
        cp = buf;
        while (count > 0) {
                /* If it's in the cache, use it! */
-               if ((cache = find_cached_block(channel, data, block,
-                                              &reuse[0]))) {
+               if ((cache = find_cached_block(data, block, &reuse[0]))) {
 #ifdef DEBUG
-                       printf("Using cached block %d\n", block);
+                       printf("Using cached block %lu\n", block);
 #endif
                        memcpy(cp, cache->buf, channel->block_size);
                        count--;
@@ -557,15 +620,14 @@ static errcode_t unix_read_blk(io_channel channel, unsigned long block,
                 * single read request
                 */
                for (i=1; i < count; i++)
-                       if (find_cached_block(channel, data, block+i,
-                                             &reuse[i]))
+                       if (find_cached_block(data, block+i, &reuse[i]))
                                break;
 #ifdef DEBUG
-               printf("Reading %d blocks starting at %d\n", i, block);
+               printf("Reading %d blocks starting at %lu\n", i, block);
 #endif
                if ((retval = raw_read_blk(channel, data, block, i, cp)))
                        return retval;
-               
+
                /* Save the results in the cache */
                for (j=0; j < i; j++) {
                        count--;
@@ -579,7 +641,13 @@ static errcode_t unix_read_blk(io_channel channel, unsigned long block,
 #endif /* NO_IO_CACHE */
 }
 
-static errcode_t unix_write_blk(io_channel channel, unsigned long block,
+static errcode_t unix_read_blk(io_channel channel, unsigned long block,
+                              int count, void *buf)
+{
+       return unix_read_blk64(channel, block, count, buf);
+}
+
+static errcode_t unix_write_blk64(io_channel channel, unsigned long long block,
                                int count, const void *buf)
 {
        struct unix_private_data *data;
@@ -594,7 +662,7 @@ static errcode_t unix_write_blk(io_channel channel, unsigned long block,
 
 #ifdef NO_IO_CACHE
        return raw_write_blk(channel, data, block, count, buf);
-#else  
+#else
        /*
         * If we're doing an odd-sized write or a very large write,
         * flush out the cache completely and then do a direct write.
@@ -613,10 +681,10 @@ static errcode_t unix_write_blk(io_channel channel, unsigned long block,
        writethrough = channel->flags & CHANNEL_FLAGS_WRITETHROUGH;
        if (writethrough)
                retval = raw_write_blk(channel, data, block, count, buf);
-       
+
        cp = buf;
        while (count > 0) {
-               cache = find_cached_block(channel, data, block, &reuse);
+               cache = find_cached_block(data, block, &reuse);
                if (!cache) {
                        cache = reuse;
                        reuse_cache(channel, data, cache, block);
@@ -631,12 +699,18 @@ static errcode_t unix_write_blk(io_channel channel, unsigned long block,
 #endif /* NO_IO_CACHE */
 }
 
+static errcode_t unix_write_blk(io_channel channel, unsigned long block,
+                               int count, const void *buf)
+{
+       return unix_write_blk64(channel, block, count, buf);
+}
+
 static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
                                 int size, const void *buf)
 {
        struct unix_private_data *data;
        errcode_t       retval = 0;
-       size_t          actual;
+       ssize_t         actual;
 
        EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
        data = (struct unix_private_data *) channel->private_data;
@@ -650,9 +724,9 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
                return retval;
 #endif
 
-       if (lseek(data->dev, offset, SEEK_SET) < 0)
+       if (lseek(data->dev, offset + data->offset, SEEK_SET) < 0)
                return errno;
-       
+
        actual = write(data->dev, buf, size);
        if (actual != size)
                return EXT2_ET_SHORT_WRITE;
@@ -661,13 +735,13 @@ static errcode_t unix_write_byte(io_channel channel, unsigned long offset,
 }
 
 /*
- * Flush data buffers to disk.  
+ * Flush data buffers to disk.
  */
 static errcode_t unix_flush(io_channel channel)
 {
        struct unix_private_data *data;
        errcode_t retval = 0;
-       
+
        EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
        data = (struct unix_private_data *) channel->private_data;
        EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
@@ -679,3 +753,28 @@ static errcode_t unix_flush(io_channel channel)
        return retval;
 }
 
+static errcode_t unix_set_option(io_channel channel, const char *option,
+                                const char *arg)
+{
+       struct unix_private_data *data;
+       unsigned long long tmp;
+       char *end;
+
+       EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
+       data = (struct unix_private_data *) channel->private_data;
+       EXT2_CHECK_MAGIC(data, EXT2_ET_MAGIC_UNIX_IO_CHANNEL);
+
+       if (!strcmp(option, "offset")) {
+               if (!arg)
+                       return EXT2_ET_INVALID_ARGUMENT;
+
+               tmp = strtoull(arg, &end, 0);
+               if (*end)
+                       return EXT2_ET_INVALID_ARGUMENT;
+               data->offset = tmp;
+               if (data->offset < 0)
+                       return EXT2_ET_INVALID_ARGUMENT;
+               return 0;
+       }
+       return EXT2_ET_INVALID_ARGUMENT;
+}