vm: fix potential null deref

[minix.git] / common / lib / libprop / prop_array.3

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.Dd October 10, 2009
.Dt PROP_ARRAY 3
.Os
.Sh NAME
.Nm prop_array ,
.Nm prop_array_create ,
.Nm prop_array_create_with_capacity ,
.Nm prop_array_copy ,
.Nm prop_array_copy_mutable ,
.Nm prop_array_capacity ,
.Nm prop_array_count ,
.Nm prop_array_ensure_capacity ,
.Nm prop_array_iterator ,
.Nm prop_array_make_immutable ,
.Nm prop_array_mutable ,
.Nm prop_array_get ,
.Nm prop_array_set ,
.Nm prop_array_add ,
.Nm prop_array_remove ,
.Nm prop_array_externalize ,
.Nm prop_array_internalize ,
.Nm prop_array_externalize_to_file ,
.Nm prop_array_internalize_from_file ,
.Nm prop_array_externalize_to_pref ,
.Nm prop_array_internalize_from_pref ,
.Nm prop_array_equals
.Nd array property collection object
.Sh LIBRARY
.Lb libprop
.Sh SYNOPSIS
.In prop/proplib.h
.\"
.Ft prop_array_t
.Fn prop_array_create "void"
.Ft prop_array_t
.Fn prop_array_create_with_capacity "unsigned int capacity"
.\"
.Ft prop_array_t
.Fn prop_array_copy "prop_array_t array"
.Ft prop_array_t
.Fn prop_array_copy_mutable "prop_array_t array"
.\"
.Ft unsigned int
.Fn prop_array_capacity "prop_array_t array"
.Ft unsigned int
.Fn prop_array_count "prop_array_t array"
.Ft bool
.Fn prop_array_ensure_capacity "prop_array_t array" "unsigned int capacity"
.\"
.Ft prop_object_iterator_t
.Fn prop_array_iterator "prop_array_t array"
.\"
.Ft void
.Fn prop_array_make_immutable "prop_array_t array"
.Ft bool
.Fn prop_array_mutable "prop_array_t array"
.\"
.Ft prop_object_t
.Fn prop_array_get "prop_array_t array" "unsigned int index"
.Ft bool
.Fn prop_array_set "prop_array_t array" "unsigned int index" "prop_object_t obj"
.Ft bool
.Fn prop_array_add "prop_array_t array" "prop_object_t obj"
.Ft void
.Fn prop_array_remove "prop_array_t array" "unsigned int index"
.\"
.Ft char *
.Fn prop_array_externalize "prop_array_t array"
.Ft prop_array_t
.Fn prop_array_internalize "const char *xml"
.\"
.Ft bool
.Fn prop_array_externalize_to_file "prop_array_t array" "const char *path"
.Ft prop_array_t
.Fn prop_array_internalize_from_file "const char *path"
.\"
.Ft bool
.Fn prop_array_externalize_to_pref "prop_array_t array" "struct plistref *pref"
.Ft bool
.Fn prop_array_internalize_from_pref "const struct plistref *pref" \
    "prop_array_t *arrayp"
.\"
.Ft bool
.Fn prop_array_equals "prop_array_t array1" "prop_array_t array2"
.Sh DESCRIPTION
The
.Nm prop_array
family of functions operate on the array property collection object type.
An array is an ordered set; an iterated array will return objects in the
same order with which they were stored.
.Bl -tag -width "xxxxx"
.It Fn prop_array_create "void"
Create an empty array.
The array initially has no capacity.
Returns
.Dv NULL
on failure.
.It Fn prop_array_create_with_capacity "unsigned int capacity"
Create an array with the capacity to store
.Fa capacity
objects.
Returns
.Dv NULL
on failure.
.It Fn prop_array_copy "prop_array_t array"
Copy an array.
The new array has an initial capacity equal to the number of objects stored
in the array being copied.
The new array contains references to the original array's objects, not
copies of those objects
.Pq i.e. a shallow copy is made .
If the original array is immutable, the resulting array is also immutable.
Returns
.Dv NULL
on failure.
.It Fn prop_array_copy_mutable "prop_array_t array"
Like
.Fn prop_array_copy ,
except the resulting array is always mutable.
.It Fn prop_array_capacity "prop_array_t array"
Returns the total capacity of the array, including objects already stored
in the array.
If the supplied object isn't an array, zero is returned.
.It Fn prop_array_count "prop_array_t array"
Returns the number of objects stored in the array.
If the supplied object isn't an array, zero is returned.
.It Fn prop_array_ensure_capacity "prop_array_t array" "unsigned int capacity"
Ensure that the array has a total capacity of
.Fa capacity ,
including objects already stored in the array.
Returns
.Dv true
if the capacity of the array is greater or equal to
.Fa capacity
or if expansion of the array's capacity was successful
and
.Dv false
otherwise.
.It Fn prop_array_iterator "prop_array_t array"
Create an iterator for the array.
The array is retained by the iterator.
An array iterator returns the object references stored in the array.
Storing to or removing from the array invalidates any active iterators for
the array.
Returns
.Dv NULL
on failure.
.It Fn prop_array_make_immutable "prop_array_t array"
Make
.Fa array
immutable.
.It Fn prop_array_mutable "prop_array_t array"
Returns
.Dv true
if the array is mutable.
.It Fn prop_array_get "prop_array_t array" "unsigned int index"
Return the object stored at the array index
.Fa index .
Returns
.Dv NULL
on failure.
.It Fn prop_array_set "prop_array_t array" "unsigned int index" \
       "prop_object_t obj"
Store a reference to the object
.Fa obj
at the array index
.Fa index .
This function is not allowed to create holes in the array;
the caller must either be setting the object just beyond the existing
count or replacing an already existing object reference.
The object will be retained by the array.
If an existing object reference is being replaced, that object will be
released.
Returns
.Dv true
if storing the object was successful and
.Dv false
otherwise.
.It Fn prop_array_add "prop_array_t array" "prop_object_t obj"
Add a reference to the object
.Fa obj
to the array, appending to the end and growing the array's capacity if
necessary.
The object will be retained by the array.
Returns
.Dv true
if storing the object was successful and
.Dv false
otherwise.
.Pp
During expansion, array's capacity is augmented by the
.Dv EXPAND_STEP
constant, as defined in
.Pa libprop/prop_array.c
file, e.g.
.Pp
.Dl #define     EXPAND_STEP             16
.It Fn prop_array_remove "prop_array_t array" "unsigned int index"
Remove the reference to the object stored at array index
.Fa index .
The object will be released and the array compacted following
the removal.
.It Fn prop_array_externalize "prop_array_t array"
Externalizes an array, returning a NUL-terminated buffer containing
the XML representation of the array.
The caller is responsible for freeing the returned buffer.
If converting to the external representation fails for any reason,
.Dv NULL
is returned.
.Pp
In user space, the buffer is allocated using
.Xr malloc 3 .
In the kernel, the buffer is allocated using
.Xr malloc 9
using the malloc type
.Dv M_TEMP .
.It Fn prop_array_internalize "const char *xml"
Parse the XML representation of a property list in the NUL-terminated
buffer
.Fa xml
and return the corresponding array.
Returns
.Dv NULL
if parsing fails for any reason.
.It Fn prop_array_externalize_to_file "prop_array_t array" "const char *path"
Externalizes an array and writes it to the file specified by
.Fa path .
The file is saved with the mode
.Dv 0666
as modified by the process's file creation mask
.Pq see Xr umask 2
and is written atomically.
Returns
.Dv false
if externalizing or writing the array fails for any reason.
.It Fn prop_array_internalize_from_file "const char *path"
Reads the XML property list contained in the file specified by
.Fa path ,
internalizes it, and returns the corresponding array.
Returns
.Dv NULL
on failure.
.It Fn prop_array_externalize_to_pref "prop_array_t array" \
    "struct plistref *pref"
Externalizes an array and packs it into the plistref specified by
.Fa pref .
Returns
.Dv false
if externalizing the array fails for any reason.
.It Fn prop_array_internalize_from_pref "const struct plistref *pref" \
    "prop_array_t *arrayp"
Reads the plistref specified by
.Fa pref ,
internalizes it, and returns the corresponding array.
Returns
.Dv false
if internalizing or writing the array fails for any reason.
.It Fn prop_array_equals "prop_array_t array1" "prop_array_t array2"
Returns
.Dv true
if the two arrays are equivalent.
If at least one of the supplied objects isn't an array,
.Dv false
is returned.
Note: Objects contained in the array are compared by value, not by reference.
.El
.Sh SEE ALSO
.Xr prop_bool 3 ,
.Xr prop_data 3 ,
.Xr prop_dictionary 3 ,
.Xr prop_number 3 ,
.Xr prop_object 3 ,
.Xr prop_string 3 ,
.Xr proplib 3
.Sh HISTORY
The
.Nm proplib
property container object library first appeared in
.Nx 4.0 .