Commit 23dce387 authored by Max Reitz's avatar Max Reitz Committed by Jeff Cody
Browse files

block/curl: Drop TFTP "support" 



Because TFTP does not support byte ranges, it was never usable with our
curl block driver. Since apparently nobody has ever complained loudly
enough for someone to take care of the issue until now, it seems
reasonable to assume that nobody has ever actually used it.

Therefore, it should be safe to just drop it from curl's protocol list.

[Jeff Cody: Below is additional summary pulled, with some rewording,
            from followup emails between Max and Markus, to explain what
            worked and what didn't]

TFTP would sometimes work, to a limited extent, for images <= the curl
"readahead" size, so long as reads started at offset zero.  By default,
that readahead size is 256KB.

Reads starting at a non-zero offset would also have returned data from a
zero offset.  It can become more complicated still, with mixed reads at
zero offset and non-zero offsets, due to data buffering.

In short, TFTP could only have worked before in very specific scenarios
with unrealistic expectations and constraints.

Signed-off-by: default avatarMax Reitz <mreitz@redhat.com>
Reviewed-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarJeff Cody <jcody@redhat.com>
Message-id: 20161102175539.4375-4-mreitz@redhat.com
Signed-off-by: default avatarJeff Cody <jcody@redhat.com>
parent 0a4c0c3f

block/curl.c

+1 −19
Original line number Diff line number Diff line
@@ -68,8 +68,7 @@ static CURLMcode __curl_multi_socket_action(CURLM *multi_handle, 
#endif



#define PROTOCOLS (CURLPROTO_HTTP | CURLPROTO_HTTPS | \

                   CURLPROTO_FTP | CURLPROTO_FTPS | \

                   CURLPROTO_TFTP)

                   CURLPROTO_FTP | CURLPROTO_FTPS)



#define CURL_NUM_STATES 8

#define CURL_NUM_ACB    8
@@ -886,29 +885,12 @@ static BlockDriver bdrv_ftps = { 
    .bdrv_attach_aio_context    = curl_attach_aio_context,

};



static BlockDriver bdrv_tftp = {

    .format_name                = "tftp",

    .protocol_name              = "tftp",



    .instance_size              = sizeof(BDRVCURLState),

    .bdrv_parse_filename        = curl_parse_filename,

    .bdrv_file_open             = curl_open,

    .bdrv_close                 = curl_close,

    .bdrv_getlength             = curl_getlength,



    .bdrv_aio_readv             = curl_aio_readv,



    .bdrv_detach_aio_context    = curl_detach_aio_context,

    .bdrv_attach_aio_context    = curl_attach_aio_context,

};



static void curl_block_init(void)

{

    bdrv_register(&bdrv_http);

    bdrv_register(&bdrv_https);

    bdrv_register(&bdrv_ftp);

    bdrv_register(&bdrv_ftps);

    bdrv_register(&bdrv_tftp);

}



block_init(curl_block_init);

docs/qmp-commands.txt

+1 −1
Original line number Diff line number Diff line
@@ -1803,7 +1803,7 @@ Each json-object contain the following: 
                                "file", "file", "ftp", "ftps", "host_cdrom",

                                "host_device", "http", "https",

                                "nbd", "parallels", "qcow", "qcow2", "raw",

                                "tftp", "vdi", "vmdk", "vpc", "vvfat"

                                "vdi", "vmdk", "vpc", "vvfat"

         - "backing_file": backing file name (json-string, optional)

         - "backing_file_depth": number of files in the backing file chain (json-int)

         - "encrypted": true if encrypted, false otherwise (json-bool)

qapi/block-core.json

+3 −4
Original line number Diff line number Diff line
@@ -243,12 +243,12 @@ 
#       0.14.0 this can be: 'blkdebug', 'bochs', 'cloop', 'cow', 'dmg',

#       'file', 'file', 'ftp', 'ftps', 'host_cdrom', 'host_device',

#       'http', 'https', 'luks', 'nbd', 'parallels', 'qcow',

#       'qcow2', 'raw', 'tftp', 'vdi', 'vmdk', 'vpc', 'vvfat'

#       'qcow2', 'raw', 'vdi', 'vmdk', 'vpc', 'vvfat'

#       2.2: 'archipelago' added, 'cow' dropped

#       2.3: 'host_floppy' deprecated

#       2.5: 'host_floppy' dropped

#       2.6: 'luks' added

#       2.8: 'replication' added

#       2.8: 'replication' added, 'tftp' dropped

#

# @backing_file: #optional the name of the backing file (for copy-on-write)

#
@@ -1723,7 +1723,7 @@ 
            'dmg', 'file', 'ftp', 'ftps', 'gluster', 'host_cdrom',

            'host_device', 'http', 'https', 'luks', 'nbd', 'nfs', 'null-aio',

            'null-co', 'parallels', 'qcow', 'qcow2', 'qed', 'quorum', 'raw',

            'replication', 'ssh', 'tftp', 'vdi', 'vhdx', 'vmdk', 'vpc',

            'replication', 'ssh', 'vdi', 'vhdx', 'vmdk', 'vpc',

            'vvfat' ] }



##
@@ -2410,7 +2410,6 @@ 
      'replication':'BlockdevOptionsReplication',

# TODO sheepdog: Wait for structured options

      'ssh':        'BlockdevOptionsSsh',

      'tftp':       'BlockdevOptionsCurl',

      'vdi':        'BlockdevOptionsGenericFormat',

      'vhdx':       'BlockdevOptionsGenericFormat',

      'vmdk':       'BlockdevOptionsGenericCOWFormat',

qemu-options.hx

+3 −3
Original line number Diff line number Diff line
@@ -2606,8 +2606,8 @@ qemu-system-x86_64 --drive file=gluster://192.0.2.1/testvol/a.img 


See also @url{http://www.gluster.org}.



@item HTTP/HTTPS/FTP/FTPS/TFTP

QEMU supports read-only access to files accessed over http(s), ftp(s) and tftp.

@item HTTP/HTTPS/FTP/FTPS

QEMU supports read-only access to files accessed over http(s) and ftp(s).



Syntax using a single filename:

@example
@@ -2617,7 +2617,7 @@ Syntax using a single filename: 
where:

@table @option

@item protocol

'http', 'https', 'ftp', 'ftps', or 'tftp'.

'http', 'https', 'ftp', or 'ftps'.



@item username

Optional username for authentication to the remote server.