[Libguestfs] [nbdkit PATCH 2/4] file: Add .list_exports support

Add a new mode to the file plugin, using directory=DIR instead of [file=]FILE, to allow it to serve all regular/block files in a given directory, as well as advertising the names of those files it will be serving. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- plugins/file/nbdkit-file-plugin.pod | 28 +++++- tests/Makefile.am | 4 +- plugins/file/file.c | 119 +++++++++++++++++++---- tests/test-file-dir.sh | 143 ++++++++++++++++++++++++++++ 4 files changed, 271 insertions(+), 23 deletions(-) create mode 100755 tests/test-file-dir.sh diff --git a/plugins/file/nbdkit-file-plugin.pod b/plugins/file/nbdkit-file-plugin.pod index dac673ae..f9ae6e97 100644 --- a/plugins/file/nbdkit-file-plugin.pod +++ b/plugins/file/nbdkit-file-plugin.pod @@ -6,27 +6,47 @@ nbdkit-file-plugin - nbdkit file plugin nbdkit file [file=]FILENAME + nbdkit file directory=DIRNAME + =head1 DESCRIPTION C<nbdkit-file-plugin> is a file serving plugin for L<nbdkit(1)>. It serves the named C<FILENAME> over NBD. Local block devices -(eg. F</dev/sda>) may also be served. +(eg. F</dev/sda>) may also be served. It may also be used to serve +any file within a given C<DIRECTORY>, according to which export name +the guest requests. =head1 PARAMETERS +One of B<file> or B<directory> must be given to determine which mode +the server will use. + =over 4 =item [B<file=>]FILENAME Serve the file named C<FILENAME>. A local block device name can also -be used here. - -This parameter is required. +be used here. When this mode is used, the export name requested by +the client is ignored. C<file=> is a magic config key and may be omitted in most cases. See L<nbdkit(1)/Magic parameters>. +=item B<directory=>DIRNAME + +(nbdkt E<ge> 1.22) + +Serve all regular files and block devices located directly within the +directory named C<DIRNAME>, including those found by following +symbolic links. Other special files in the directory (such as +subdirectories, fifos, or Unix sockets) are ignored. When this mode +is used, the file to be served is chosen by the export name passed by +the client; a client that requests the default export (C<"">) will be +served whichever file appears first in the L<readdir(3)> listing. For +security, when using directory mode, this plugin will not accept +export names containing slash (C</>). + =back =head1 NOTES diff --git a/tests/Makefile.am b/tests/Makefile.am index b5ef96a7..d9074ba9 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -636,8 +636,8 @@ test_file_block_SOURCES = test-file-block.c test.h test_file_block_CFLAGS = $(WARNINGS_CFLAGS) $(LIBGUESTFS_CFLAGS) test_file_block_LDADD = libtest.la $(LIBGUESTFS_LIBS) -TESTS += test-file-extents.sh -EXTRA_DIST += test-file-extents.sh +TESTS += test-file-extents.sh test-file-dir.sh +EXTRA_DIST += test-file-extents.sh test-file-dir.sh # floppy plugin test. TESTS += test-floppy.sh diff --git a/plugins/file/file.c b/plugins/file/file.c index e049864a..4afcad11 100644 --- a/plugins/file/file.c +++ b/plugins/file/file.c @@ -43,6 +43,7 @@ #include <sys/stat.h> #include <sys/ioctl.h> #include <errno.h> +#include <dirent.h> #include <pthread.h> @@ -66,9 +67,11 @@ #endif static char *filename = NULL; +static char *directory = NULL; +DIR *dir = NULL; -/* Any callbacks using lseek must be protected by this lock. */ -static pthread_mutex_t lseek_lock = PTHREAD_MUTEX_INITIALIZER; +/* Any callbacks using readdir or lseek must be protected by this lock. */ +static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER; /* to enable: -D file.zero=1 */ int file_debug_zero; @@ -83,10 +86,14 @@ static void file_unload (void) { free (filename); + free (directory); + if (dir) + closedir (dir); } /* Called for each key=value passed on the command line. This plugin - * only accepts file=<filename>, which is required. + * only accepts file=<filename> and directory=<dirname>, where exactly + * one is required. */ static int file_config (const char *key, const char *value) @@ -98,6 +105,12 @@ file_config (const char *key, const char *value) if (!filename) return -1; } + else if (strcmp (key, "directory") == 0) { + free (directory); + directory = nbdkit_realpath (value); + if (!directory) + return -1; + } else if (strcmp (key, "rdelay") == 0 || strcmp (key, "wdelay") == 0) { nbdkit_error ("add --filter=delay on the command line"); @@ -111,13 +124,19 @@ file_config (const char *key, const char *value) return 0; } -/* Check the user did pass a file=<FILENAME> parameter. */ +/* Check the user did pass exactly one parameter. */ static int file_config_complete (void) { - if (filename == NULL) { - nbdkit_error ("you must supply the file=<FILENAME> parameter " - "after the plugin name on the command line"); + if (!filename == !directory) { + nbdkit_error ("you must supply exactly one file=<FILENAME> or " + "directory=<DIRNAME> parameter after the plugin name " + "on the command line"); + return -1; + } + + if (directory && (dir = opendir (directory)) == NULL) { + nbdkit_error ("opendir: %m"); return -1; } @@ -125,7 +144,8 @@ file_config_complete (void) } #define file_config_help \ - "file=<FILENAME> (required) The filename to serve." \ + "file=<FILENAME> The filename to serve." \ + "directory=<DIRNAME> A directory containing files to serve." \ /* Print some extra information about how the plugin was compiled. */ static void @@ -145,8 +165,47 @@ file_dump_plugin (void) #endif } +static int file_list_exports (int readonly, int default_only, + struct nbdkit_exports *exports) +{ + struct dirent *entry; + struct stat sb; + int fd; + + if (!directory) + return nbdkit_add_export (exports, "", NULL); + + ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lock); + rewinddir (dir); + fd = dirfd (dir); + if (fd == -1) { + nbdkit_error ("dirfd: %m"); + return -1; + } + errno = 0; + while ((entry = readdir (dir)) != NULL) { + /* TODO: Optimize with d_type and/or statx when present? */ + if (fstatat (fd, entry->d_name, &sb, 0) == 0 && + (S_ISREG (sb.st_mode) || S_ISBLK (sb.st_mode))) { + if (nbdkit_add_export (exports, entry->d_name, NULL) == -1) { + close (fd); + return -1; + } + } + errno = 0; + } + if (errno) { + nbdkit_error ("readdir: %m"); + close (fd); + return -1; + } + close (fd); + return 0; +} + /* The per-connection handle. */ struct handle { + char *file; int fd; bool is_block_device; int sector_size; @@ -170,21 +229,44 @@ file_open (int readonly) return NULL; } + if (directory) { + const char *exportname = nbdkit_export_name (); + + if (strchr (exportname, '/')) { + nbdkit_error ("exportname cannot contain /"); + errno = EINVAL; + free (h); + return NULL; + } + if (asprintf (&h->file, "%s/%s", directory, exportname) == -1) { + nbdkit_error ("asprintf: %m"); + free (h); + return NULL; + } + } + else + h->file = strdup (filename); + if (h->file == NULL) { + nbdkit_error ("malloc: %m"); + free (h); + return NULL; + } + flags = O_CLOEXEC|O_NOCTTY; if (readonly) flags |= O_RDONLY; else flags |= O_RDWR; - h->fd = open (filename, flags); + h->fd = open (h->file, flags); if (h->fd == -1) { - nbdkit_error ("open: %s: %m", filename); + nbdkit_error ("open: %s: %m", h->file); free (h); return NULL; } if (fstat (h->fd, &statbuf) == -1) { - nbdkit_error ("fstat: %s: %m", filename); + nbdkit_error ("fstat: %s: %m", h->file); free (h); return NULL; } @@ -194,7 +276,8 @@ file_open (int readonly) else if (S_ISREG (statbuf.st_mode)) h->is_block_device = false; else { - nbdkit_error ("file is not regular or block device: %s", filename); + nbdkit_error ("file is not regular or block device: %s", h->file); + free (h->file); close (h->fd); free (h); return NULL; @@ -204,7 +287,7 @@ file_open (int readonly) #ifdef BLKSSZGET if (h->is_block_device) { if (ioctl (h->fd, BLKSSZGET, &h->sector_size)) - nbdkit_debug ("cannot get sector size: %s: %m", filename); + nbdkit_debug ("cannot get sector size: %s: %m", h->file); } #endif @@ -232,6 +315,7 @@ file_close (void *handle) { struct handle *h = handle; + free (h->file); close (h->fd); free (h); } @@ -239,7 +323,7 @@ file_close (void *handle) #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL /* For block devices, stat->st_size is not the true size. The caller - * grabs the lseek_lock. + * grabs the lock. */ static int64_t block_device_size (int fd) @@ -262,7 +346,7 @@ file_get_size (void *handle) struct handle *h = handle; if (h->is_block_device) { - ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lseek_lock); + ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lock); return block_device_size (h->fd); } else { /* Regular file. */ @@ -554,7 +638,7 @@ file_can_extents (void *handle) /* A simple test to see whether SEEK_HOLE etc is likely to work on * the current filesystem. */ - ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lseek_lock); + ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lock); r = lseek (h->fd, 0, SEEK_HOLE); if (r == -1) { nbdkit_debug ("extents disabled: lseek: SEEK_HOLE: %m"); @@ -628,7 +712,7 @@ static int file_extents (void *handle, uint32_t count, uint64_t offset, uint32_t flags, struct nbdkit_extents *extents) { - ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lseek_lock); + ACQUIRE_LOCK_FOR_CURRENT_SCOPE (&lock); return do_extents (handle, count, offset, flags, extents); } #endif /* SEEK_HOLE */ @@ -662,6 +746,7 @@ static struct nbdkit_plugin plugin = { .config_help = file_config_help, .magic_config_key = "file", .dump_plugin = file_dump_plugin, + .list_exports = file_list_exports, .open = file_open, .close = file_close, .get_size = file_get_size, diff --git a/tests/test-file-dir.sh b/tests/test-file-dir.sh new file mode 100755 index 00000000..efe3b6cd --- /dev/null +++ b/tests/test-file-dir.sh @@ -0,0 +1,143 @@ +#!/usr/bin/env bash +# nbdkit +# Copyright (C) 2018-2020 Red Hat Inc. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are +# met: +# +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# +# * Neither the name of Red Hat nor the names of its contributors may be +# used to endorse or promote products derived from this software without +# specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY RED HAT AND CONTRIBUTORS ''AS IS'' AND +# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, +# THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A +# PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL RED HAT OR +# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF +# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND +# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +# OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT +# OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +# SUCH DAMAGE. + +# Test the use of the directory mode of the file plugin. + +source ./functions.sh +set -e +set -x + +# Hack: This rejects libnbd 1.3.9, but we really need libnbd >= 1.3.11, +# which does not have its own decent witness... +requires nbdsh -c 'print (h.get_list_export_description)' + +requires nbdinfo --version +requires jq --version + +files="file-dir file-dir.out file-dir.witness" +rm -rf $files +cleanup_fn rm -rf $files +fail=0 + +# do_nbdkit_list [--no-sort] EXPOUT +# Check that the advertised list of exports matches EXPOUT +do_nbdkit_list () +{ + sort=' | sort' + if [ "$1" = --no-sort ]; then + sort= + shift + fi + nbdkit -U - -v file directory=file-dir \ + --run 'nbdinfo --list --json "$uri"' >file-dir.out + cat file-dir.out + diff -u <(jq -c '[.exports[]."export-name"]'"$sort" file-dir.out) \ + <(printf %s\\n "$1") || fail=1 +} + +# do_nbdkit_fail NAME +# Check that attempting to connect to export NAME fails +do_nbdkit_fail () +{ + # The --run script occurs only if nbdkit gets past .config_complete; + # testing for witness proves that our failure was during .open and + # not at some earlier point + rm -f file-dir.witness + nbdkit -U - -v -e "$1" file directory=file-dir \ + --run 'touch file-dir.witness; nbdsh -u "$uri" -c "quit()"' && fail=1 + test -f file-dir.witness || fail=1 +} + +# do_nbdkit_pass NAME DATA +# Check that export NAME serves DATA as its first byte +do_nbdkit_pass () +{ + out=$(nbdkit -U - -v -e "$1" file directory=file-dir \ + --run 'nbdsh -u "$uri" -c "print (h.pread (1, 0).decode (\"utf-8\"))"') + test "$out" = "$2" || fail=1 +} + +# Not possible to serve a missing directory +nbdkit -vf file directory=nosuchdir && fail=1 + +# Serving an empty directory +mkdir file-dir +do_nbdkit_list '[]' +do_nbdkit_fail '' +do_nbdkit_fail 'a' +do_nbdkit_fail '..' +do_nbdkit_fail '/' + +# Serving a directory with one file +echo 1 > file-dir/a +do_nbdkit_list '["a"]' +do_nbdkit_pass '' 1 +do_nbdkit_pass a 1 +do_nbdkit_fail b + +# Serving a directory with multiple files. +# Use 'find' to match readdir's raw order (a is not always first!) +echo 2 > file-dir/b +raw=$(find file-dir -type f | xargs echo) +exp=$(echo $raw | sed 's,file-dir/\(.\),"\1",g; s/ /,/') +do_nbdkit_list --no-sort "[$exp]" +do_nbdkit_list '["a","b"]' +case $raw in + file-dir/a*) byte=1 ;; + file-dir/b*) byte=2 ;; + *) fail=1 ;; +esac +do_nbdkit_pass '' $byte +do_nbdkit_pass 'a' 1 +do_nbdkit_pass 'b' 2 +do_nbdkit_fail 'c' + +# Serving a directory with non-regular files +ln -s b file-dir/c +mkfifo file-dir/d +mkdir file-dir/e +ln -s /dev/null file-dir/f +ln -s . file-dir/g +ln -s dangling file-dir/h +do_nbdkit_list '["a","b","c"]' +do_nbdkit_pass 'a' 1 +do_nbdkit_pass 'b' 2 +do_nbdkit_pass 'c' 2 +do_nbdkit_fail 'd' +do_nbdkit_fail 'e' +do_nbdkit_fail 'f' +do_nbdkit_fail 'g' +do_nbdkit_fail 'h' +do_nbdkit_fail './a' +do_nbdkit_fail '../file-dir/a' + +exit $fail -- 2.28.0