Clarify sparse behaviour of truncate-size command.

[libguestfs.git] / src / generator.ml

diff --git a/src/generator.ml b/src/generator.ml
index f094749..99d80fb 100755 (executable)
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -3152,7 +3152,7 @@ Unknown file type
 
 =item '?'
 
 
 =item '?'
 

-The L<readdir(3)> returned a C<d_type> field with an
+The L<readdir(3)> call returned a C<d_type> field with an

 unexpected value
 
 =back
 unexpected value
 
 =back


@@ -3475,7 +3475,7 @@ The C<-f> option removes the link (C<linkname>) if it exists already.");
    "\
 This command reads the target of a symbolic link.");
 
    "\
 This command reads the target of a symbolic link.");
 

-  ("fallocate", (RErr, [Pathname "path"; Int "len"]), 169, [],
+  ("fallocate", (RErr, [Pathname "path"; Int "len"]), 169, [DeprecatedBy "fallocate64"],

    [InitBasicFS, Always, TestOutputStruct (
       [["fallocate"; "/a"; "1000000"];
        ["stat"; "/a"]], [CompareWithInt ("size", 1_000_000)])],
    [InitBasicFS, Always, TestOutputStruct (
       [["fallocate"; "/a"; "1000000"];
        ["stat"; "/a"]], [CompareWithInt ("size", 1_000_000)])],


@@ -3797,8 +3797,8 @@ was built (see C<appliance/kmod.whitelist.in> in the source).");
     )],
    "echo arguments back to the client",
    "\
     )],
    "echo arguments back to the client",
    "\

-This command concatenate the list of C<words> passed with single spaces between
-them and returns the resulting string.
+This command concatenates the list of C<words> passed with single spaces
+between them and returns the resulting string.

 
 You can use this command to test the connection through to the daemon.
 
 
 You can use this command to test the connection through to the daemon.
 


@@ -3925,8 +3925,13 @@ file must exist already.");
    "truncate a file to a particular size",
    "\
 This command truncates C<path> to size C<size> bytes.  The file
    "truncate a file to a particular size",
    "\
 This command truncates C<path> to size C<size> bytes.  The file

-must exist already.  If the file is smaller than C<size> then
-the file is extended to the required size with null bytes.");
+must exist already.
+
+If the current file size is less than C<size> then
+the file is extended to the required size with zero bytes.
+This creates a sparse file (ie. disk blocks are not allocated
+for the file until you write to it).  To create a non-sparse
+file of zeroes, use C<guestfs_fallocate64> instead.");

 
   ("utimens", (RErr, [Pathname "path"; Int64 "atsecs"; Int64 "atnsecs"; Int64 "mtsecs"; Int64 "mtnsecs"]), 201, [],
    [InitBasicFS, Always, TestOutputStruct (
 
   ("utimens", (RErr, [Pathname "path"; Int64 "atsecs"; Int64 "atnsecs"; Int64 "mtsecs"; Int64 "mtnsecs"]), 201, [],
    [InitBasicFS, Always, TestOutputStruct (


@@ -4036,7 +4041,7 @@ C<names> is the list of files from this directory.
 
 On return you get a list of strings, with a one-to-one
 correspondence to the C<names> list.  Each string is the
 
 On return you get a list of strings, with a one-to-one
 correspondence to the C<names> list.  Each string is the

-value of the symbol link.
+value of the symbolic link.

 
 If the C<readlink(2)> operation fails on any name, then
 the corresponding result string is the empty string C<\"\">.
 
 If the C<readlink(2)> operation fails on any name, then
 the corresponding result string is the empty string C<\"\">.


@@ -4711,7 +4716,7 @@ This command is the same as C<guestfs_ntfsresize> except that it
 allows you to specify the new size (in bytes) explicitly.");
 
   ("available_all_groups", (RStringList "groups", []), 251, [],
 allows you to specify the new size (in bytes) explicitly.");
 
   ("available_all_groups", (RStringList "groups", []), 251, [],

-   [],
+   [InitNone, Always, TestRun [["available_all_groups"]]],

    "return a list of all optional groups",
    "\
 This command returns a list of all optional groups that this
    "return a list of all optional groups",
    "\
 This command returns a list of all optional groups that this


@@ -4722,6 +4727,28 @@ returned list.
 
 See also C<guestfs_available> and L<guestfs(3)/AVAILABILITY>.");
 
 
 See also C<guestfs_available> and L<guestfs(3)/AVAILABILITY>.");
 

+  ("fallocate64", (RErr, [Pathname "path"; Int64 "len"]), 252, [],
+   [InitBasicFS, Always, TestOutputStruct (
+      [["fallocate64"; "/a"; "1000000"];
+       ["stat"; "/a"]], [CompareWithInt ("size", 1_000_000)])],
+   "preallocate a file in the guest filesystem",
+   "\
+This command preallocates a file (containing zero bytes) named
+C<path> of size C<len> bytes.  If the file exists already, it
+is overwritten.
+
+Note that this call allocates disk blocks for the file.
+To create a sparse file use C<guestfs_truncate_size> instead.
+
+The deprecated call C<guestfs_fallocate> does the same,
+but owing to an oversight it only allowed 30 bit lengths
+to be specified, effectively limiting the maximum size
+of files created through that call to 1GB.
+
+Do not confuse this with the guestfish-specific
+C<alloc> and C<sparse> commands which create
+a file in the host and attach it as a device.");
+

 ]
 
 let all_functions = non_daemon_functions @ daemon_functions
 ]
 
 let all_functions = non_daemon_functions @ daemon_functions