Module Name: src
Committed By: jruoho
Date: Mon May 3 05:11:34 UTC 2010
Modified Files:
src/lib/libc/stdlib: malloc.3
Log Message:
Move the examples to where they belong, in EXAMPLES.
To generate a diff of this commit:
cvs rdiff -u -r1.35 -r1.36 src/lib/libc/stdlib/malloc.3
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libc/stdlib/malloc.3
diff -u src/lib/libc/stdlib/malloc.3:1.35 src/lib/libc/stdlib/malloc.3:1.36
--- src/lib/libc/stdlib/malloc.3:1.35 Mon May 3 05:01:53 2010
+++ src/lib/libc/stdlib/malloc.3 Mon May 3 05:11:34 2010
@@ -1,4 +1,4 @@
-.\" $NetBSD: malloc.3,v 1.35 2010/05/03 05:01:53 jruoho Exp $
+.\" $NetBSD: malloc.3,v 1.36 2010/05/03 05:11:34 jruoho Exp $
.\"
.\" Copyright (c) 1980, 1991, 1993
.\" The Regents of the University of California. All rights reserved.
@@ -78,29 +78,6 @@
with the exception that the allocated memory is explicitly initialized
to zero bytes.
.Pp
-When using
-.Fn malloc
-be careful to avoid the following idiom:
-.Bd -literal -offset indent
-if ((p = malloc(number * size)) == NULL)
- err(EXIT_FAILURE, "malloc");
-.Ed
-.Pp
-The multiplication may lead to an integer overflow.
-To avoid this,
-.Fn calloc
-is recommended.
-.Pp
-If
-.Fn malloc
-must be used, be sure to test for overflow:
-.Bd -literal -offset indent
-if (size && number > SIZE_MAX / size) {
- errno = EOVERFLOW;
- err(EXIT_FAILURE, "overflow");
-}
-.Ed
-.Pp
The
.Fn realloc
function changes the size of the previously allocated memory referenced by
@@ -129,39 +106,6 @@
.Fn malloc
for the specified size.
.Pp
-When using
-.Fn realloc
-one must be careful to avoid the following idiom:
-.Pp
-.Bd -literal -offset indent
-nsize += 50;
-
-if ((p = realloc(p, nsize)) == NULL)
- return (NULL);
-.Ed
-.Pp
-Do not adjust the variable describing how much memory has been allocated
-until one knows the allocation has been successful.
-This can cause aberrant program behavior if the incorrect size value is used.
-In most cases, the above sample will also result in a leak of memory.
-As stated earlier, a return value of
-.Dv NULL
-indicates that the old object still remains allocated.
-Better code looks like this:
-.Bd -literal -offset indent
-newsize = size + 50;
-
-if ((p2 = realloc(p, newsize)) == NULL) {
- if (p)
- free(p);
- p = NULL;
- return (NULL);
-}
-
-p = p2;
-size = newsize;
-.Ed
-.Pp
The
.Fn free
function causes the allocated memory referenced by
@@ -205,6 +149,64 @@
The
.Fn free
function returns no value.
+.Sh EXAMPLES
+When using
+.Fn malloc ,
+be careful to avoid the following idiom:
+.Bd -literal -offset indent
+if ((p = malloc(number * size)) == NULL)
+ err(EXIT_FAILURE, "malloc");
+.Ed
+.Pp
+The multiplication may lead to an integer overflow.
+To avoid this,
+.Fn calloc
+is recommended.
+.Pp
+If
+.Fn malloc
+must be used, be sure to test for overflow:
+.Bd -literal -offset indent
+if (size && number > SIZE_MAX / size) {
+ errno = EOVERFLOW;
+ err(EXIT_FAILURE, "allocation");
+}
+.Ed
+.Pp
+When using
+.Fn realloc ,
+one must be careful to avoid the following idiom:
+.Pp
+.Bd -literal -offset indent
+nsize += 50;
+
+if ((p = realloc(p, nsize)) == NULL)
+ return NULL;
+.Ed
+.Pp
+Do not adjust the variable describing how much memory has been allocated
+until it is known that the allocation has been successful.
+This can cause aberrant program behavior if the incorrect size value is used.
+In most cases, the above example will also leak memory.
+As stated earlier, a return value of
+.Dv NULL
+indicates that the old object still remains allocated.
+Better code looks like this:
+.Bd -literal -offset indent
+newsize = size + 50;
+
+if ((p2 = realloc(p, newsize)) == NULL) {
+
+ if (p != NULL)
+ free(p);
+
+ p = NULL;
+ return NULL;
+}
+
+p = p2;
+size = newsize;
+.Ed
.Sh SEE ALSO
.\" .Xr limits 1 ,
.Xr madvise 2 ,
