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.\"	Id: mandoc_malloc.3,v 1.2 2016/07/07 19:19:01 schwarze Exp
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.\" Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
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.Dd July 7, 2016
.Dt MANDOC_MALLOC 3
.Os
.Sh NAME
.Nm mandoc_malloc ,
.Nm mandoc_realloc ,
.Nm mandoc_reallocarray ,
.Nm mandoc_calloc ,
.Nm mandoc_strdup ,
.Nm mandoc_strndup ,
.Nm mandoc_asprintf
.Nd memory allocation function wrappers used in the mandoc library
.Sh SYNOPSIS
.In sys/types.h
.In mandoc_aux.h
.Ft "void *"
.Fo mandoc_malloc
.Fa "size_t size"
.Fc
.Ft "void *"
.Fo mandoc_realloc
.Fa "void *ptr"
.Fa "size_t size"
.Fc
.Ft "void *"
.Fo mandoc_reallocarray
.Fa "void *ptr"
.Fa "size_t nmemb"
.Fa "size_t size"
.Fc
.Ft "void *"
.Fo mandoc_calloc
.Fa "size_t nmemb"
.Fa "size_t size"
.Fc
.Ft "char *"
.Fo mandoc_strdup
.Fa "const char *s"
.Fc
.Ft "char *"
.Fo mandoc_strndup
.Fa "const char *s"
.Fa "size_t maxlen"
.Fc
.Ft int
.Fo mandoc_asprintf
.Fa "char **ret"
.Fa "const char *format"
.Fa "..."
.Fc
.Sh DESCRIPTION
These functions call the libc functions of the same names, passing
through their return values when successful.
In case of failure, they do not return, but instead call
.Xr err 3 .
They can be used both internally by any code in the mandoc libraries
and externally by programs using that library, for example
.Xr mandoc 1 ,
.Xr man 1 ,
.Xr apropos 1 ,
.Xr makewhatis 8 ,
and
.Xr man.cgi 8 .
.Pp
The function
.Fn mandoc_malloc
allocates one new object, leaving the memory uninitialized.
The functions
.Fn mandoc_realloc
and
.Fn mandoc_reallocarray
change the size of an existing object or array, possibly moving it.
When shrinking the size, existing data is truncated; when growing,
the additional memory is not initialized.
The function
.Fn mandoc_calloc
allocates a new array, initializing it to zero.
.Pp
The argument
.Fa size
is the size of each object.
The argument
.Fa nmemb
is the new number of objects in the array.
The argument
.Fa ptr
is a pointer to the existing object or array to be resized; if it is
.Dv NULL ,
a new object or array is allocated.
.Pp
The functions
.Fn mandoc_strdup
and
.Fn mandoc_strndup
copy a string into newly allocated memory.
For
.Fn mandoc_strdup ,
the string pointed to by
.Fa s
needs to be NUL-terminated.
For
.Fn mandoc_strndup ,
at most
.Fa maxlen
bytes are copied.
The function
.Fn mandoc_asprintf
writes output formatted according to
.Fa format
into newly allocated memory and returns a pointer to the result in
.Fa ret .
For all three string functions, the result is always NUL-terminated.
.Pp
When the objects and strings are no longer needed,
the pointers returned by these functions can be passed to
.Xr free 3 .
.Sh RETURN VALUES
The function
.Fn mandoc_asprintf
always returns the number of characters written, excluding the
final NUL byte.
It never returns -1.
.Pp
The other functions always return a valid pointer; they never return
.Dv NULL .
.Sh FILES
These functions are implemented in
.Pa mandoc_aux.c .
.Sh SEE ALSO
.Xr asprintf 3 ,
.Xr err 3 ,
.Xr malloc 3 ,
.Xr strdup 3
.Sh STANDARDS
The functions
.Fn malloc ,
.Fn realloc ,
and
.Fn calloc
are required by
.St -ansiC .
The functions
.Fn strdup
and
.Fn strndup
are required by
.St -p1003.1-2008 .
The function
.Fn asprintf
is a widespread extension that first appeared in the GNU C library.
.Pp
The function
.Fn reallocarray
is an extension that first appeared in
.Ox 5.6 .
If it is not provided by the operating system, the mandoc build system
uses a bundled portable implementation.
.Sh HISTORY
The functions
.Fn mandoc_malloc ,
.Fn mandoc_realloc ,
.Fn mandoc_calloc ,
and
.Fn mandoc_strdup
have been available since mandoc 1.9.12,
.Fn mandoc_strndup
since 1.11.5,
and
.Fn mandoc_asprintf
and
.Fn mandoc_reallocarray
since 1.12.4 and 1.13.0.
.Sh AUTHORS
.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv
.An Ingo Schwarze Aq Mt schwarze@openbsd.org