diff options
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/libc/stdlib/malloc.3 | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3 index 55237984354..d92ebdb2b4f 100644 --- a/lib/libc/stdlib/malloc.3 +++ b/lib/libc/stdlib/malloc.3 @@ -30,7 +30,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.\" $OpenBSD: malloc.3,v 1.28 2003/06/02 20:18:37 millert Exp $ +.\" $OpenBSD: malloc.3,v 1.29 2003/09/18 22:49:13 tedu Exp $ .\" .Dd August 27, 1996 .Dt MALLOC 3 @@ -143,23 +143,29 @@ When using one must be careful to avoid the following idiom: .Pp .Bd -literal -offset indent -if ((p = realloc(p, nsize)) == NULL) - return NULL; +size += 50; +if ((p = realloc(p, size)) == NULL) + return (NULL); .Ed .Pp -In most cases, this will result in a leak of memory. +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 -if ((p2 = realloc(p, nsize)) == NULL) { +newsize = size + 50; +if ((p2 = realloc(p, newsize)) == NULL) { if (p) free(p); p = NULL; - return NULL; + return (NULL); } p = p2; +size = newsize; .Ed .Pp Malloc will first look for a symbolic link called |