[Libguestfs] [PATCH] New APIs: hopen-device hopen-file hread hwrite hseek hclose hclose-all

These APIs provide handle-based read/write streaming and random access to files and block devices. --- daemon/.gitignore | 1 + daemon/Makefile.am | 1 + daemon/hfile.c | 224 +++++++++++++++++++++++++++++++++++++++++++++ daemon/m4/gnulib-cache.m4 | 3 +- po/POTFILES.in | 2 + regressions/Makefile.am | 1 + regressions/test-hfile.pl | 194 +++++++++++++++++++++++++++++++++++++++ src/MAX_PROC_NR | 2 +- src/generator.ml | 113 +++++++++++++++++++++++ 9 files changed, 539 insertions(+), 2 deletions(-) create mode 100644 daemon/hfile.c create mode 100755 regressions/test-hfile.pl diff --git a/daemon/.gitignore b/daemon/.gitignore index e06c684..c9837be 100644 --- a/daemon/.gitignore +++ b/daemon/.gitignore @@ -50,6 +50,7 @@ m4/gettime.m4 m4/gettimeofday.m4 m4/getpagesize.m4 m4/getugroups.m4 +m4/gl_list.m4 m4/glibc21.m4 m4/glob.m4 m4/gnulib-common.m4 diff --git a/daemon/Makefile.am b/daemon/Makefile.am index 0c8be08..c243bb6 100644 --- a/daemon/Makefile.am +++ b/daemon/Makefile.am @@ -94,6 +94,7 @@ guestfsd_SOURCES = \ guestfsd.c \ headtail.c \ hexdump.c \ + hfile.c \ htonl.c \ initrd.c \ inotify.c \ diff --git a/daemon/hfile.c b/daemon/hfile.c new file mode 100644 index 0000000..7dc43fa --- /dev/null +++ b/daemon/hfile.c @@ -0,0 +1,224 @@ +/* libguestfs - the guestfsd daemon + * Copyright (C) 2010 Red Hat Inc. + * + * 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. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <config.h> + +#include <errno.h> +#include <fcntl.h> +#include <unistd.h> + +#include "gl_array_list.h" + +#include "daemon.h" +#include "actions.h" + +gl_list_t handles; + +static void init_handle_list (void) __attribute__((constructor)); +void +init_handle_list (void) +{ + handles = gl_list_nx_create_empty(GL_ARRAY_LIST, NULL, NULL, NULL, false); +} + +static gl_list_node_t +get_handle (int handle) +{ + gl_list_node_t node = gl_list_search(handles, (void *)(long)handle); + if (NULL == node) { + reply_with_error("%i does not refer to an open handle", handle); + return NULL; + } + + return node; +} + +static int +hopen_check(int fd, const char *path) +{ + if (fd == -1) { + reply_with_perror("open %s failed", path); + return -1; + } + + gl_list_node_t node = gl_list_nx_add_last(handles, (void *)(long)fd); + if (NULL == node) { + close(fd); + + reply_with_error("gl_list_nx_add_last"); + return -1; + } + + return fd; +} + +int /* RInt */ +do_hopen_file (const char *path, int flags) +{ + int fd; + + CHROOT_IN; + if (flags && O_CREAT) { + fd = open(path, flags, 0777); + } else { + fd = open(path, flags); + } + CHROOT_OUT; + + return hopen_check(fd, path); +} + +int /* RInt */ +do_hopen_device (const char *device, int flags) +{ + int fd; + + fd = open(device, flags); + + return hopen_check(fd, device); +} + +int /* RErr */ +do_hclose (int handle) +{ + gl_list_node_t node = get_handle(handle); + if (NULL == node) { + return -1; + } + + gl_list_remove_node(handles, node); + + if (close(handle) < 0) { + reply_with_perror("close handle %i failed", handle); + return -1; + } + + return 0; +} + +int /* RErr */ +do_hclose_all (void) +{ + const void *eltp; + gl_list_node_t node; + gl_list_iterator_t i = gl_list_iterator(handles); + + char errors[GUESTFS_ERROR_LEN]; + char *error_p = errors; + size_t error_n = sizeof(errors); + + bool failed = false; + while (gl_list_iterator_next(&i, &eltp, &node)) { + gl_list_remove_node(handles, node); + + int fd = (long)eltp; + if (close(fd) < 0) { + failed = true; + + if (error_n != 0) { + size_t len = snprintf(error_p, error_n, + "close handle %i failed: %m ", fd); + if (len < error_n) { + error_p += len; + error_n -= len; + } else { + error_n = 0; + error_p = &errors[GUESTFS_ERROR_LEN]; + } + } + } + } + + if (failed) { + /* Overwrite the trailing space with a NULL terminator */ + *(error_p - 1) = '\0'; + reply_with_error("%s", errors); + return -1; + } + + return 0; +} + +char * /* RBufferOut */ +do_hread (int handle, int64_t size, size_t *size_r) +{ + if (get_handle(handle) == NULL) { + return NULL; + } + +#define HREAD_MESSAGE_MAX (GUESTFS_MESSAGE_MAX - \ + sizeof(guestfs_message_header) - \ + sizeof(guestfs_hread_args)) + if (size > (int64_t) HREAD_MESSAGE_MAX) { + size = HREAD_MESSAGE_MAX; + } +#undef HREAD_MESSAGE_MAX + + char *buf = malloc(size); + if (NULL == buf) { + reply_with_perror("malloc"); + return NULL; + } + + ssize_t in = read(handle, buf, size); + if (in < 0) { + reply_with_perror("error reading from handle %i", handle); + free(buf); + return NULL; + } + + *size_r = in; + return buf; +} + +int /* RErr */ +do_hwrite (int handle, const char *content, size_t content_size) +{ + if (get_handle(handle) == NULL) { + return -1; + } + + size_t pos = 0; + while (pos < content_size) { + ssize_t out = write(handle, content + pos, content_size - pos); + + if (out < 0) { + reply_with_perror("error writing to handle %i", handle); + return -1; + } + pos += out; + } + + return 0; +} + +int64_t /* RInt64 */ +do_hseek (int handle, int64_t offset, int whence) +{ + if (get_handle(handle) == NULL) { + return -1; + } + + int64_t ret = lseek(handle, offset, whence); + if (ret < 0) { + reply_with_perror("error seeking in handle %i", handle); + return -1; + } + + return ret; +} diff --git a/daemon/m4/gnulib-cache.m4 b/daemon/m4/gnulib-cache.m4 index f026cb3..25ffd27 100644 --- a/daemon/m4/gnulib-cache.m4 +++ b/daemon/m4/gnulib-cache.m4 @@ -15,11 +15,12 @@ # Specification in the form of a command-line invocation: -# gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --with-tests --no-libtool --macro-prefix=gl byteswap c-ctype connect error fsusage futimens getaddrinfo getline glob hash ignore-value manywarnings mkdtemp netdb openat perror pread read-file readlink select sleep socket strchrnul strndup symlinkat sys_select sys_wait vasprintf warnings +# gnulib-tool --import --dir=. --lib=libgnu --source-base=lib --m4-base=m4 --doc-base=doc --tests-base=tests --aux-dir=build-aux --with-tests --no-libtool --macro-prefix=gl array-list byteswap c-ctype connect error fsusage futimens getaddrinfo getline glob hash ignore-value manywarnings mkdtemp netdb openat perror pread read-file readlink select sleep socket strchrnul strndup symlinkat sys_select sys_wait vasprintf warnings # Specification in the form of a few gnulib-tool.m4 macro invocations: gl_LOCAL_DIR([]) gl_MODULES([ + array-list byteswap c-ctype connect diff --git a/po/POTFILES.in b/po/POTFILES.in index e5fb857..c846e05 100644 --- a/po/POTFILES.in +++ b/po/POTFILES.in @@ -29,6 +29,7 @@ daemon/grub.c daemon/guestfsd.c daemon/headtail.c daemon/hexdump.c +daemon/hfile.c daemon/htonl.c daemon/initrd.c daemon/inotify.c @@ -99,6 +100,7 @@ perl/lib/Sys/Guestfs.pm perl/lib/Sys/Guestfs/Lib.pm python/guestfs-py.c regressions/rhbz501893.c +regressions/test-hfile.pl regressions/test-lvm-mapping.pl regressions/test-noexec-stack.pl ruby/ext/guestfs/_guestfs.c diff --git a/regressions/Makefile.am b/regressions/Makefile.am index ca4292a..f7d9992 100644 --- a/regressions/Makefile.am +++ b/regressions/Makefile.am @@ -35,6 +35,7 @@ TESTS = \ test-cancellation-download-librarycancels.sh \ test-cancellation-upload-daemoncancels.sh \ test-find0.sh \ + test-hfile.pl \ test-luks.sh \ test-lvm-filtering.sh \ test-lvm-mapping.pl \ diff --git a/regressions/test-hfile.pl b/regressions/test-hfile.pl new file mode 100755 index 0000000..502f303 --- /dev/null +++ b/regressions/test-hfile.pl @@ -0,0 +1,194 @@ +#!/usr/bin/perl + +use strict; +use warnings; + +use File::Temp qw(tempfile); +use Sys::Guestfs; + +# Defined in src/generator.ml +use constant GUESTFS_MESSAGE_MAX => 4 * 1024 * 1024; + +# Create a new guestfs handle +my $g = Sys::Guestfs->new(); + +# Initialise the guestfs handle with a 10M image file +{ + my $testimg = "test.img"; + unlink($testimg); + + my $fh; + open($fh, '>', $testimg) or die("Open $testimg: $!"); + truncate($fh, 1024*1024*10) or die("truncate $testimg: $!"); + close($fh) or die("close $testimg: $!"); + + $g->add_drive($testimg); + $g->launch(); + + # As qemu is now running we can unlink the image + unlink($testimg) or die("unlink $testimg failed: $!"); +} + +my $string = "abcd"; + +# Check we can't read or write handles we haven't opened +{ + # Read from guestfsd's STDIN + eval { my $in = $g->hread(0, 4); }; + die("read guestfsd's STDIN") unless ($@); + + # Write to guestfsd's STDOUT + eval { $g->hwrite(1, "test"); }; + die("write guestfsd's STDOUT") unless ($@); +} + +{ + # Test read and writing directly to a block device + my $h = $g->hopen_device("/dev/vda", 2); + + $g->hwrite($h, $string); + $g->hseek($h, 0, 0); + my $in = $g->hread($h, length($string)); + die("device: hread returned $in") unless ($in eq $string); + + # Check we can't seek past the end of the file + eval { $g->hseek($h, 1024*1024*11, 0); }; + die("device: seek past EOD") unless ($@); + + # Check we can't write past the end of the file + $g->hseek($h, 0, 2); + eval { $g->hwrite($h, "test"); }; + die("device: write past EOD") unless ($@); + + $g->hclose($h); + + # Check $h is no longer valid + eval { + $g->hseek($h, 0, 0); + }; + die("device: handle wasn't closed") unless($@); +} + +# Make an ext2 filesystem and mount it +$g->mkfs("ext2", "/dev/vda"); +$g->mount("/dev/vda", "/"); + +# Open should fail read-only +eval { + my $h = $g->hopen_file("/test", 0); +}; +die("file: read-only open non-existant file") unless($@); + +# Open should fail write-only without O_CREAT +eval { + my $h = $g->hopen_file("/test", 1); +}; +die("file: write-only open non-existant file") unless($@); + +# Open should fail read-write without O_CREAT +eval { + my $h = $g->hopen_file("/test", 2); +}; +die("file: read-write open non-existant file") unless($@); + +{ + # Open the file write only, and create it + my $h = $g->hopen_file("/test", 1 | 64); + my $in; + + # Write data to it + $g->hwrite($h, $string); + + # Verify we can't read from it + $g->hseek($h, 0, 0); + eval { + $in = $g->hread($h, length($string)); + }; + die("file: read of write-only file") unless($@); + + # close and check the contents with cat + $g->hclose($h); + $in = $g->cat("/test"); + die("file: hwrite data test") unless($in eq $string); +} + +{ + # Open the file read-only + my $h = $g->hopen_file("/test", 0); + + # Read the file in 1 byte chunks until the end + my $in = ""; + my $chunk; + do { + $chunk = $g->hread($h, 1); + $in .= $chunk; + } until(length($chunk) == 0); + die("file: hread in chunks") unless($in eq $string); + + # Read past EOF returns a short read + $g->hseek($h, 0, 0); + $in = $g->hread($h, length($string) + 1); + die("file: read past EOF") unless($in eq $string); + + # Test close-all + $g->hclose_all(); + eval { + $g->hseek($h, 0, 0); + }; + die("file: close-all") unless($@); +} + +{ + # Open the file read-write + my $h = $g->hopen_file("/test", 2); + + # Create a list of the first 2M ints + my @ints; + for (my $i = 0; $i < 1024 * 1024 * 2; $i++) { + push(@ints, $i); + } + + # Write 2M of data (512k ints) + $g->hwrite($h, pack("L".512 * 1024, @ints)); + + # Check the file size + my $size = $g->filesize("/test"); + die("file: 2M write wrote $size") unless($size == 1024 * 1024 * 2); + + # Write another 3M of data (768k ints) for the next test + $g->hwrite($h, pack("L".768 * 1024, @ints[512*1024..(512+768)*1024])); + + # Check the file size is now 5M for good measure + $size = $g->filesize("/test"); + die("file: 2M + 3M append wrote $size") unless($size == 1024 * 1024 * 5); + + my $bytes; + my @data; + + # Check that read 2M works + $g->hseek($h, 0, 0); + $bytes = $g->hread($h, 1024*1024*2); + @data = unpack("L*", $bytes); + die("file: read 2M") unless(scalar(@data) == 1024 * 512 && + $data[$#data] == $#data); + + # Check that read 4M-1 works + $g->hseek($h, 0, 0); + $bytes = $g->hread($h, 1024*1024*4-1); + @data = unpack("L*", $bytes); + die("file: read 4M-1") unless($data[$#data] == $#data); + + # Check that read 4M works + $g->hseek($h, 0, 0); + $bytes = $g->hread($h, 1024*1024*4); + @data = unpack("L*", $bytes); + die("file: read 4M") unless($data[$#data] == $#data); + + # Check that we can read 5M in 2 3M max chunks + $g->hseek($h, 0, 0); + $bytes = $g->hread($h, 1024*1024*3-1); # Misalign the data for kicks + $bytes .= $g->hread($h, 1024*1024*3-1); + @data = unpack("L*", $bytes); + die("file: chunked read") unless($#data == (512+768)*1024-1 && + $data[$#data] == $#data); +} diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR index c1d1ffb..305aa98 100644 --- a/src/MAX_PROC_NR +++ b/src/MAX_PROC_NR @@ -1 +1 @@ -266 +273 diff --git a/src/generator.ml b/src/generator.ml index c25c871..dc072ef 100755 --- a/src/generator.ml +++ b/src/generator.ml @@ -5355,6 +5355,119 @@ filesystem can be found. To find the label of a filesystem, use C<guestfs_vfs_label>."); + ("hopen_file", (RInt "handle", [Pathname "path"; Int "flags"]), 267, [], + [], + "open a file", + "\ +This command opens C<path> in the guest and returns a handle +to it. The returned handle is an opaque int which can be passed +to C<guestfs_h*> calls. + +C<flags> determines how the file is opened. It is a bitwise or of: + +=over 4 + +=item 0 + +(O_RDONLY) Open the file read only. + +=item 1 + +(O_WRONLY) Open the file write only. + +=item 2 + +(O_RDWR) Open the file read-write. + +=item 64 + +(O_CREAT) Create the file if it does not already exist. The file +will be created with a mode of 0777, modified by the daemon's +umask. See L<UMASK>. + +=item 512 + +(O_TRUNC) Truncate a file opened for write to zero length when +opening. + +=item 1024 + +(O_APPEND) Always write to the end of the file. + +=item 262144 + +(O_NOATIME) Don't update the access time when reading from a file. + +=back 4"); + + ("hopen_device", (RInt "handle", [Device "device"; Int "flags"]), 268, [], + [], + "open a block device", + "\ +This command opens a block device and returns a handle to it. +The returned handle is an opaque int which can be passed to +C<guestfs_h*> calls. + +See C<guestfs_hopen_file> for a description of C<flags>."); + + ("hclose", (RErr, [Int "handle"]), 269, [], + [], + "close a file handle", + "\ +This command closes C<handle> and releases all resources associated +with it."); + + ("hclose_all", (RErr, []), 270, [], + [], + "close all open file handles", + "\ +This command closes all file handles which have been opened with +C<guestfs_hopen_*>."); + + ("hread", (RBufferOut "content", [Int "handle"; Int64 "length"]), 271, + [ProtocolLimitWarning], [], + "read data from an open handle", + "\ +This command reads up to C<length> bytes from C<handle> and returns +the data in C<content>. It will attempt to read exactly C<length> +bytes, but may return less. Returned C<content> with size 0 +indicates EOF."); + + ("hwrite", (RErr, [Int "handle"; BufferIn "content"]), 272, + [ProtocolLimitWarning], [], + "write data to an open handle", + "\ +This command writes all the data in C<content> to C<handle>."); + + ("hseek", (RInt64 "newoffset", [Int "handle"; Int64 "offset"; + Int "whence"]), 273, [], + [], + "seek on an open handle", + "\ +This command updates the current position in C<handle>. This +affects the C<guestfs_hread> and C<guestfs_hwrite> calls. + +C<whence> determines the point of reference for C<offset>. It +must be one of: + +=over 4 + +=item 0 + +C<offset> is relative to the beginning of the file. + +=item 1 + +C<offset> is relative to the current position. + +=item 2 + +C<offset> is relative to the end of the file. + +=back 4 + +hseek returns the new offset from the beginning of the file."); + ] let all_functions = non_daemon_functions @ daemon_functions -- 1.7.2.2