Add reallocf to the library. This function is simliar to realloc, but

when it returns NULL to indicate failure, it will also free the memory
that was passed to it, if that was non-null.

This does not change the semantics of realloc.

A second commit will be done to commit the conversion of those places in
the code that can safely use this to avoid memory leaks when confronted
with low memory situations.

Beaten-to-death-but-finally-approved-in: -current

3 files changed, 42 insertions, 13 deletions

diff --git a/lib/libc/stdlib/Makefile.inc b/lib/libc/stdlib/Makefile.inc
index 0d7ae27..5ba11f9 100644
--- a/lib/libc/stdlib/Makefile.inc
+++ b/lib/libc/stdlib/Makefile.inc
@@ -1,5 +1,5 @@
 #	from @(#)Makefile.inc	8.3 (Berkeley) 2/4/95
-#	$Id: Makefile.inc,v 1.14 1998/02/20 08:41:46 jb Exp $
+#	$Id: Makefile.inc,v 1.15 1998/05/08 05:41:56 jb Exp $
 
 # machine-independent stdlib sources
 .PATH: ${.CURDIR}/../libc/${MACHINE_ARCH}/stdlib ${.CURDIR}/../libc/stdlib
@@ -8,7 +8,7 @@ MISRCS+=abort.c abs.c atexit.c atof.c atoi.c atol.c bsearch.c calloc.c div.c \
 	exit.c getenv.c getopt.c getsubopt.c heapsort.c labs.c ldiv.c \
 	malloc.c merge.c putenv.c qsort.c radixsort.c rand.c random.c \
 	realpath.c setenv.c strhash.c strtol.c strtoq.c strtoul.c \
-	strtouq.c system.c
+	strtouq.c system.c reallocf.c
 
 .if ${MACHINE_ARCH} == "alpha"
 #  XXX Temporary until the assumption that a long is 32-bits is resolved
@@ -35,5 +35,5 @@ MLINKS+=random.3 initstate.3 random.3 setstate.3 random.3 srandom.3 \
 	random.3 srandomdev.3
 MLINKS+=strtol.3 strtoq.3
 MLINKS+=strtoul.3 strtouq.3
-MLINKS+=malloc.3 calloc.3 malloc.3 free.3 malloc.3 realloc.3
+MLINKS+=malloc.3 calloc.3 malloc.3 free.3 malloc.3 realloc.3 malloc.3 reallocf.3
 .endif
diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3
index a7d3240..bb3d08c 100644
--- a/lib/libc/stdlib/malloc.3
+++ b/lib/libc/stdlib/malloc.3
@@ -34,13 +34,13 @@
 .\" SUCH DAMAGE.
 .\"
 .\"     @(#)malloc.3	8.1 (Berkeley) 6/4/93
-.\"     $Id: malloc.3,v 1.14 1997/08/27 06:40:34 phk Exp $
+.\"     $Id: malloc.3,v 1.15 1997/09/18 06:51:22 charnier Exp $
 .\"
 .Dd August 27, 1996
 .Dt MALLOC 3
 .Os FreeBSD 2
 .Sh NAME
-.Nm malloc, calloc, realloc, free
+.Nm malloc, calloc, realloc, free, reallocf
 .Nd general purpose memory allocation functions
 .Sh SYNOPSIS
 .Fd #include <stdlib.h>
@@ -54,6 +54,8 @@
 .Fn free "void *ptr"
 .Ft char *
 .Va malloc_options;
+.Ft void *
+.Fn reallocf "void *ptr" "size_t size"
 .Sh DESCRIPTION
 The
 .Fn malloc
@@ -109,6 +111,14 @@ function behaves identically to
 for the specified size.
 .Pp
 The
+.Fn reallocf
+function call is identical to the realloc function call, except that it
+will free the passed pointer when the requested memory cannot be allocated.
+This is a FreeBSD
+specific API designed to ease the problems with traditional coding styles
+for realloc causing memory leaks in libraries.
+.Pp
+The
 .Fn free
 function causes the allocated memory referenced by
 .Fa ptr
@@ -141,13 +151,15 @@ The process will call
 in these cases.
 .It J
 Each byte of new memory allocated by
-.Fn malloc
-or
+.Fn malloc ,
 .Fn realloc
+or
+.Fn freealloc
 as well as all memory returned by
-.Fn free
-or 
+.Fn free ,
 .Fn realloc
+or
+.Fn reallocf
 will be initialized to 0xd0.
 This options also sets the
 .Dq R
@@ -158,9 +170,11 @@ Pass a hint to the kernel about pages unused by the allocation functions.
 This will help performance if the system is paging excessively.  This
 option is on by default.
 .It R
-Cause the
+Causes the
 .Fn realloc
-function to always reallocate memory even if the initial allocation was
+and
+.Fn reallocf
+functions to always reallocate memory even if the initial allocation was
 sufficiently large.
 This can substantially aid in compacting memory.
 .It U
@@ -247,7 +261,9 @@ a NULL pointer is returned.
 .Pp
 The
 .Fn realloc
-function returns a pointer, possibly identical to
+and
+.Fn reallocf
+functions return a pointer, possibly identical to
 .Fa ptr ,
 to the allocated memory
 if successful; otherwise a NULL pointer is returned, in which case the
@@ -421,4 +437,5 @@ The present allocation implementation started out as a filesystem for a
 drum attached to a 20bit binary challenged computer which was built 
 with discrete germanium transistors.  It has since graduated to 
 handle primary storage rather than secondary.
-It first appeared in its new shape and ability in FreeBSD release 2.2.
+It first appeared in its new shape and ability in
+.Fx 2.2 .
diff --git a/lib/libc/stdlib/reallocf.c b/lib/libc/stdlib/reallocf.c
new file mode 100644
index 0000000..728acc9
--- /dev/null
+++ b/lib/libc/stdlib/reallocf.c
@@ -0,0 +1,12 @@
+#include <stdlib.h>
+
+void *
+reallocf(void *ptr, size_t size)
+{
+    void *nptr;
+
+    nptr = realloc(ptr, size);
+    if (!nptr && ptr)
+        free(ptr);
+    return (nptr);
+}