[Libguestfs] [PATCH 2/2] New API: write for creating files with fixed content (RHBZ#501889).

Richard W.M. Jones
Tue, 18 May 2010 21:04:03 -0000

virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/
-------------- next part --------------
>From 40a88c206f7759bcd13f8e483b23373d49958056 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones at redhat.com>
Date: Tue, 18 May 2010 21:51:05 +0100
Subject: [PATCH 2/2] New API: write for creating files with fixed content
(RHBZ#501889).

The guestfs_write call can be used to create small files with
arbitrary 8 bit content, including \0 bytes.

This replaces and deprecates write-file, which cannot be modified
to use BufferIn because of an unfortunate choice in the ABI: the
size parameter to write-file, if zero, means that the daemon tries
to calculate the length of the buffer using strlen.  However this
fails if we pass a zero-length buffer using BufferIn because then
the daemon tries to do strlen on a (really) zero length buffer, not
even containing a terminating \0 character, thus segfaulting.
---
 daemon/file.c          |   28 +++++++++++++
 fish/edit.c            |    2 +-
 fish/fish.c            |    2 +-
 fish/guestfish.pod     |    4 +-
 fuse/test-fuse.sh      |    4 +-
 recipes/clone.sh       |    4 +-
 src/MAX_PROC_NR        |    2 +-
 src/generator.ml       |   99 +++++++++++++++++++++++++-----------------------
 src/guestfs.pod        |    4 +-
 tools/make-test-img.sh |   12 +++---
 10 files changed, 96 insertions(+), 65 deletions(-)

diff --git a/daemon/file.c b/daemon/file.c
index 2399828..7d37f56 100644
--- a/daemon/file.c
+++ b/daemon/file.c
@@ -314,6 +314,34 @@ do_write_file (const char *path, const char *content, int
size)
   return 0;
 }

+int
+do_write (const char *path, const char *content, size_t size)
+{
+  int fd;
+
+  CHROOT_IN;
+  fd = open (path, O_WRONLY | O_TRUNC | O_CREAT | O_NOCTTY, 0666);
+  CHROOT_OUT;
+
+  if (fd == -1) {
+    reply_with_perror ("open: %s", path);
+    return -1;
+  }
+
+  if (xwrite (fd, content, size) == -1) {
+    reply_with_perror ("write");
+    close (fd);
+    return -1;
+  }
+
+  if (close (fd) == -1) {
+    reply_with_perror ("close: %s", path);
+    return -1;
+  }
+
+  return 0;
+}
+
 char *
 do_read_file (const char *path, size_t *size_r)
 {
diff --git a/fish/edit.c b/fish/edit.c
index 3fc41fb..a010057 100644
--- a/fish/edit.c
+++ b/fish/edit.c
@@ -156,7 +156,7 @@ do_edit (const char *cmd, int argc, char *argv[])
   }

   /* Write new content. */
-  if (guestfs_write_file (g, argv[0], content_new, size) == -1) {
+  if (guestfs_write (g, argv[0], content_new, size) == -1) {
     free (content);
     free (content_new);
     return -1;
diff --git a/fish/fish.c b/fish/fish.c
index a630cdc..5d89d60 100644
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -1091,7 +1091,7 @@ display_builtin_command (const char *cmd)
               "    This is used to edit a file.\n"
               "\n"
               "    It is the equivalent of (and is implemented by)\n"
-              "    running \"cat\", editing locally, and then
\"write-file\".\n"
+              "    running \"cat\", editing locally, and then
\"write\".\n"
               "\n"
               "    Normally it uses $EDITOR, but if you use the
aliases\n"
               "    \"vi\" or \"emacs\" you will get
those editors.\n"
diff --git a/fish/guestfish.pod b/fish/guestfish.pod
index 7260caf..274f1d4 100644
--- a/fish/guestfish.pod
+++ b/fish/guestfish.pod
@@ -41,7 +41,7 @@ Create a new C</etc/motd> file in a guest:
  add disk.img
  run
  mount /dev/vg_guest/lv_root /
- write_file /etc/motd "Welcome, new users" 0
+ write /etc/motd "Welcome, new users"
  _EOF_

 List the LVM logical volumes in a guest:
@@ -57,7 +57,7 @@ Update C</etc/resolv.conf> in a guest:

  guestfish \
    add disk.img : run : mount /dev/vg_guest/lv_root / : \
-   write-file /etc/resolv.conf "nameserver 1.2.3.4" 0
+   write /etc/resolv.conf "nameserver 1.2.3.4"

 Edit C</boot/grub/grub.conf> interactively:

diff --git a/fuse/test-fuse.sh b/fuse/test-fuse.sh
index 7dc8e4b..e31ea9d 100755
--- a/fuse/test-fuse.sh
+++ b/fuse/test-fuse.sh
@@ -93,8 +93,8 @@ $guestfish <<EOF
   part-disk /dev/sda mbr
   mkfs ext2 /dev/sda1
   mount /dev/sda1 /
-  write-file /hello.txt hello 0
-  write-file /world.txt "hello world" 0
+  write /hello.txt hello
+  write /world.txt "hello world"
   touch /empty
 EOF

diff --git a/recipes/clone.sh b/recipes/clone.sh
index e3fc11c..d2b9d99 100755
--- a/recipes/clone.sh
+++ b/recipes/clone.sh
@@ -9,7 +9,7 @@ hostname="$5"
 dd if="$preimage" of="$newimage"

 guestfish -a "$newimage" -m "$root" <<EOF
-write-file /etc/resolv.conf "nameserver $nameserver" 0
-write-file /etc/HOSTNAME "$hostname" 0
+write /etc/resolv.conf "nameserver $nameserver"
+write /etc/HOSTNAME "$hostname"
 sync
 EOF
diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR
index 2c2b1af..5d165ff 100644
--- a/src/MAX_PROC_NR
+++ b/src/MAX_PROC_NR
@@ -1 +1 @@
-245
+246
diff --git a/src/generator.ml b/src/generator.ml
index 090c280..dfab8dc 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -938,7 +938,7 @@ let daemon_functions = [
       [["part_disk"; "/dev/sda"; "mbr"];
        ["mkfs"; "ext2"; "/dev/sda1"];
        ["mount"; "/dev/sda1"; "/"];
-       ["write_file"; "/new"; "new file
contents"; "0"];
+       ["write"; "/new"; "new file contents"];
        ["cat"; "/new"]], "new file contents")],
    "mount a guest disk at a position in the filesystem",
    "\
@@ -1500,7 +1500,7 @@ on the volume group C<volgroup>, with C<size>
megabytes.");
       [["part_disk"; "/dev/sda"; "mbr"];
        ["mkfs"; "ext2"; "/dev/sda1"];
        ["mount_options"; ""; "/dev/sda1";
"/"];
-       ["write_file"; "/new"; "new file
contents"; "0"];
+       ["write"; "/new"; "new file contents"];
        ["cat"; "/new"]], "new file contents")],
    "make a filesystem",
    "\
@@ -1537,25 +1537,8 @@ the string C<,> (comma).
 See also: C<guestfs_sfdisk_l>, C<guestfs_sfdisk_N>,
 C<guestfs_part_init>");

-  ("write_file", (RErr, [Pathname "path"; String
"content"; Int "size"]), 44, [ProtocolLimitWarning],
-   [InitBasicFS, Always, TestOutput (
-      [["write_file"; "/new"; "new file
contents"; "0"];
-       ["cat"; "/new"]], "new file contents");
-    InitBasicFS, Always, TestOutput (
-      [["write_file"; "/new"; "\nnew file
contents\n"; "0"];
-       ["cat"; "/new"]], "\nnew file
contents\n");
-    InitBasicFS, Always, TestOutput (
-      [["write_file"; "/new"; "\n\n";
"0"];
-       ["cat"; "/new"]], "\n\n");
-    InitBasicFS, Always, TestOutput (
-      [["write_file"; "/new"; ""; "0"];
-       ["cat"; "/new"]], "");
-    InitBasicFS, Always, TestOutput (
-      [["write_file"; "/new"; "\n\n\n";
"0"];
-       ["cat"; "/new"]], "\n\n\n");
-    InitBasicFS, Always, TestOutput (
-      [["write_file"; "/new"; "\n";
"0"];
-       ["cat"; "/new"]], "\n")],
+  ("write_file", (RErr, [Pathname "path"; String
"content"; Int "size"]), 44, [ProtocolLimitWarning;
DeprecatedBy "write"],
+   [],
    "create a file",
    "\
 This call creates a file called C<path>.  The contents of the
@@ -1567,9 +1550,7 @@ then the length is calculated using C<strlen> (so in
this case
 the content cannot contain embedded ASCII NULs).

 I<NB.> Owing to a bug, writing content containing ASCII NUL
-characters does I<not> work, even if the length is specified.
-We hope to resolve this bug in a future version.  In the meantime
-use C<guestfs_upload>.");
+characters does I<not> work, even if the length is specified.");

   ("umount", (RErr, [String "pathordevice"]), 45,
[FishAlias "unmount"],
    [InitEmpty, Always, TestOutputListOfDevices (
@@ -2088,7 +2069,7 @@ To download an uncompressed tarball, use
C<guestfs_tar_out>.");
        ["mount_ro"; "/dev/sda1"; "/"];
        ["touch"; "/new"]]);
     InitBasicFS, Always, TestOutput (
-      [["write_file"; "/new"; "data";
"0"];
+      [["write"; "/new"; "data"];
        ["umount"; "/"];
        ["mount_ro"; "/dev/sda1"; "/"];
        ["cat"; "/new"]], "data")],
@@ -2340,15 +2321,15 @@ C<device>, with the root directory being
C<root>.");

   ("cp", (RErr, [Pathname "src"; Pathname
"dest"]), 87, [],
    [InitBasicFS, Always, TestOutput (
-      [["write_file"; "/old"; "file content";
"0"];
+      [["write"; "/old"; "file content"];
        ["cp"; "/old"; "/new"];
        ["cat"; "/new"]], "file content");
     InitBasicFS, Always, TestOutputTrue (
-      [["write_file"; "/old"; "file content";
"0"];
+      [["write"; "/old"; "file content"];
        ["cp"; "/old"; "/new"];
        ["is_file"; "/old"]]);
     InitBasicFS, Always, TestOutput (
-      [["write_file"; "/old"; "file content";
"0"];
+      [["write"; "/old"; "file content"];
        ["mkdir"; "/dir"];
        ["cp"; "/old"; "/dir/new"];
        ["cat"; "/dir/new"]], "file content")],
@@ -2361,7 +2342,7 @@ either a destination filename or destination
directory.");
    [InitBasicFS, Always, TestOutput (
       [["mkdir"; "/olddir"];
        ["mkdir"; "/newdir"];
-       ["write_file"; "/olddir/file"; "file
content"; "0"];
+       ["write"; "/olddir/file"; "file content"];
        ["cp_a"; "/olddir"; "/newdir"];
        ["cat"; "/newdir/olddir/file"]], "file
content")],
    "copy a file or directory recursively",
@@ -2371,11 +2352,11 @@ recursively using the C<cp -a> command.");

   ("mv", (RErr, [Pathname "src"; Pathname
"dest"]), 89, [],
    [InitBasicFS, Always, TestOutput (
-      [["write_file"; "/old"; "file content";
"0"];
+      [["write"; "/old"; "file content"];
        ["mv"; "/old"; "/new"];
        ["cat"; "/new"]], "file content");
     InitBasicFS, Always, TestOutputFalse (
-      [["write_file"; "/old"; "file content";
"0"];
+      [["write"; "/old"; "file content"];
        ["mv"; "/old"; "/new"];
        ["is_file"; "/old"]])],
    "move a file",
@@ -2424,12 +2405,12 @@ or attached block device(s) in any other way.");

   ("equal", (RBool "equality", [Pathname "file1";
Pathname "file2"]), 93, [],
    [InitBasicFS, Always, TestOutputTrue (
-      [["write_file"; "/file1"; "contents of a
file"; "0"];
+      [["write"; "/file1"; "contents of a file"];
        ["cp"; "/file1"; "/file2"];
        ["equal"; "/file1"; "/file2"]]);
     InitBasicFS, Always, TestOutputFalse (
-      [["write_file"; "/file1"; "contents of a
file"; "0"];
-       ["write_file"; "/file2"; "contents of another
file"; "0"];
+      [["write"; "/file1"; "contents of a file"];
+       ["write"; "/file2"; "contents of another
file"];
        ["equal"; "/file1"; "/file2"]]);
     InitBasicFS, Always, TestLastFail (
       [["equal"; "/file1"; "/file2"]])],
@@ -2456,8 +2437,8 @@ the list of printable strings found.");
   ("strings_e", (RStringList "stringsout", [String
"encoding"; Pathname "path"]), 95, [ProtocolLimitWarning],
    [InitISOFS, Always, TestOutputList (
       [["strings_e"; "b"; "/known-5"]], []);
-    InitBasicFS, Disabled, TestOutputList (
-      [["write_file"; "/new";
"\000h\000e\000l\000l\000o\000\n\000w\000o\000r\000l\000d\000\n";
"24"];
+    InitBasicFS, Always, TestOutputList (
+      [["write"; "/new";
"\000h\000e\000l\000l\000o\000\n\000w\000o\000r\000l\000d\000\n"];
        ["strings_e"; "b"; "/new"]],
["hello"; "world"])],
    "print the printable strings in a file",
    "\
@@ -2521,7 +2502,7 @@ the human-readable, canonical hex dump of the
file.");
       [["part_disk"; "/dev/sda"; "mbr"];
        ["mkfs"; "ext3"; "/dev/sda1"];
        ["mount_options"; ""; "/dev/sda1";
"/"];
-       ["write_file"; "/new"; "test file";
"0"];
+       ["write"; "/new"; "test file"];
        ["umount"; "/dev/sda1"];
        ["zerofree"; "/dev/sda1"];
        ["mount_options"; ""; "/dev/sda1";
"/"];
@@ -2626,7 +2607,7 @@ are activated or deactivated.");
        ["lvcreate"; "LV"; "VG"; "10"];
        ["mkfs"; "ext2"; "/dev/VG/LV"];
        ["mount_options"; ""; "/dev/VG/LV";
"/"];
-       ["write_file"; "/new"; "test content";
"0"];
+       ["write"; "/new"; "test content"];
        ["umount"; "/"];
        ["lvresize"; "/dev/VG/LV"; "20"];
        ["e2fsck_f"; "/dev/VG/LV"];
@@ -2813,7 +2794,7 @@ manual page for more details.");

   ("scrub_file", (RErr, [Pathname "file"]), 115, [Optional
"scrub"],
    [InitBasicFS, Always, TestRun (
-      [["write_file"; "/file"; "content";
"0"];
+      [["write"; "/file"; "content"];
        ["scrub_file"; "/file"]])],
    "scrub (securely wipe) a file",
    "\
@@ -3721,7 +3702,7 @@ and C<guestfs_setcon>");
       [["part_disk"; "/dev/sda"; "mbr"];
        ["mkfs_b"; "ext2"; "4096";
"/dev/sda1"];
        ["mount_options"; ""; "/dev/sda1";
"/"];
-       ["write_file"; "/new"; "new file
contents"; "0"];
+       ["write"; "/new"; "new file contents"];
        ["cat"; "/new"]], "new file contents")],
    "make a filesystem with block size",
    "\
@@ -3736,7 +3717,7 @@ are C<1024>, C<2048> or C<4096>
only.");
        ["mke2journal"; "4096"; "/dev/sda1"];
        ["mke2fs_J"; "ext2"; "4096";
"/dev/sda2"; "/dev/sda1"];
        ["mount_options"; ""; "/dev/sda2";
"/"];
-       ["write_file"; "/new"; "new file
contents"; "0"];
+       ["write"; "/new"; "new file contents"];
        ["cat"; "/new"]], "new file contents")],
    "make ext2/3/4 external journal",
    "\
@@ -3751,7 +3732,7 @@ to the command:
        ["mke2journal_L"; "4096"; "JOURNAL";
"/dev/sda1"];
        ["mke2fs_JL"; "ext2"; "4096";
"/dev/sda2"; "JOURNAL"];
        ["mount_options"; ""; "/dev/sda2";
"/"];
-       ["write_file"; "/new"; "new file
contents"; "0"];
+       ["write"; "/new"; "new file contents"];
        ["cat"; "/new"]], "new file contents")],
    "make ext2/3/4 external journal with label",
    "\
@@ -3764,7 +3745,7 @@ This creates an ext2 external journal on C<device>
with label C .");
         ["mke2journal_U"; "4096"; uuid;
"/dev/sda1"];
         ["mke2fs_JU"; "ext2"; "4096";
"/dev/sda2"; uuid];
         ["mount_options"; ""; "/dev/sda2";
"/"];
-        ["write_file"; "/new"; "new file
contents"; "0"];
+        ["write"; "/new"; "new file contents"];
         ["cat"; "/new"]], "new file contents")]),
    "make ext2/3/4 external journal with UUID",
    "\
@@ -3927,7 +3908,7 @@ if you used the C<guestfs_mount> call).");

   ("truncate", (RErr, [Pathname "path"]), 199, [],
    [InitBasicFS, Always, TestOutputStruct (
-      [["write_file"; "/test"; "some stuff so size is
not zero"; "0"];
+      [["write"; "/test"; "some stuff so size is not
zero"];
        ["truncate"; "/test"];
        ["stat"; "/test"]], [CompareWithInt
("size", 0)])],
    "truncate a file to zero size",
@@ -4345,7 +4326,7 @@ See also C<guestfs_version>.

   ("dd", (RErr, [Dev_or_Path "src"; Dev_or_Path
"dest"]), 217, [],
    [InitBasicFS, Always, TestOutputBuffer (
-      [["write_file"; "/src"; "hello, world";
"0"];
+      [["write"; "/src"; "hello, world"];
        ["dd"; "/src"; "/dest"];
        ["read_file"; "/dest"]], "hello, world")],
    "copy from source to destination using dd",
@@ -4361,7 +4342,7 @@ This command cannot do partial copies (see
C<guestfs_copy_size>).");

   ("filesize", (RInt64 "size", [Pathname
"file"]), 218, [],
    [InitBasicFS, Always, TestOutputInt (
-      [["write_file"; "/file"; "hello, world";
"0"];
+      [["write"; "/file"; "hello, world"];
        ["filesize"; "/file"]], 12)],
    "return the size of the file in bytes",
    "\
@@ -4452,7 +4433,7 @@ See also C<guestfs_vgpvuuids>.");

   ("copy_size", (RErr, [Dev_or_Path "src"; Dev_or_Path
"dest"; Int64 "size"]), 227, [],
    [InitBasicFS, Always, TestOutputBuffer (
-      [["write_file"; "/src"; "hello, world";
"0"];
+      [["write"; "/src"; "hello, world"];
        ["copy_size"; "/src"; "/dest";
"5"];
        ["read_file"; "/dest"]], "hello")],
    "copy size bytes from source to destination using dd",
@@ -4653,6 +4634,30 @@ a new file of length C<len> containing the
repeating pattern
 of bytes in C<pattern>.  The pattern is truncated if necessary
 to ensure the length of the file is exactly C<len> bytes.");

+  ("write", (RErr, [Pathname "path"; BufferIn
"content"]), 246, [ProtocolLimitWarning],
+   [InitBasicFS, Always, TestOutput (
+      [["write"; "/new"; "new file contents"];
+       ["cat"; "/new"]], "new file contents");
+    InitBasicFS, Always, TestOutput (
+      [["write"; "/new"; "\nnew file
contents\n"];
+       ["cat"; "/new"]], "\nnew file
contents\n");
+    InitBasicFS, Always, TestOutput (
+      [["write"; "/new"; "\n\n"];
+       ["cat"; "/new"]], "\n\n");
+    InitBasicFS, Always, TestOutput (
+      [["write"; "/new"; ""];
+       ["cat"; "/new"]], "");
+    InitBasicFS, Always, TestOutput (
+      [["write"; "/new"; "\n\n\n"];
+       ["cat"; "/new"]], "\n\n\n");
+    InitBasicFS, Always, TestOutput (
+      [["write"; "/new"; "\n"];
+       ["cat"; "/new"]], "\n")],
+   "create a new file",
+   "\
+This call creates a file called C<path>.  The content of the
+file is the string C<content> (which can contain any 8 bit data).");
+
 ]

 let all_functions = non_daemon_functions @ daemon_functions
diff --git a/src/guestfs.pod b/src/guestfs.pod
index e1fa4f5..8404e74 100644
--- a/src/guestfs.pod
+++ b/src/guestfs.pod
@@ -258,9 +258,7 @@ L</guestfs_tgz_out>.
 It's often the case that you want to write a file or files to the disk
 image.

-For small, single files, use L</guestfs_write_file>.  This call
-currently contains a bug which limits the call to plain text files
-(not containing ASCII NUL characters).
+For small, single files, use L</guestfs_write>.

 To upload a single file, use L</guestfs_upload>.  This call has no
 limits on file content or size (even files larger than 4 GB).
diff --git a/tools/make-test-img.sh b/tools/make-test-img.sh
index 9752f1d..fddd8a2 100755
--- a/tools/make-test-img.sh
+++ b/tools/make-test-img.sh
@@ -68,12 +68,12 @@ mkdir /boot/grub
 touch /boot/grub/grub.conf

 # Test files.
-write-file /etc/test1 "abcdefg" 0
-write-file /etc/test2 "" 0
-write-file /bin/test1 "abcdefg" 0
-write-file /bin/test2 "zxcvbnm" 0
-write-file /bin/test3 "1234567" 0
-write-file /bin/test4 "" 0
+write /etc/test1 "abcdefg"
+write /etc/test2 ""
+write /bin/test1 "abcdefg"
+write /bin/test2 "zxcvbnm"
+write /bin/test3 "1234567"
+write /bin/test4 ""
 ln-s /bin/test1 /bin/test5
 mkfifo 0777 /bin/test6
 mknod 0777 10 10 /bin/test7
--
1.6.6.1