2 files changed, 32 insertions, 18 deletions

diff --git a/lib/libc/stdlib/malloc.3 b/lib/libc/stdlib/malloc.3
index 03feaa37a01b..e7d53f955d08 100644
--- a/lib/libc/stdlib/malloc.3
+++ b/lib/libc/stdlib/malloc.3
@@ -57,7 +57,9 @@
 .Ft void
 .Fn free "void *ptr"
 .Ft char *
-.Va malloc_options;
+.Va _malloc_options
+.Ft void
+.Va (*_malloc_message)(char *p1, char *p2, char *p3, char *p4)
 .Sh DESCRIPTION
 The
 .Fn malloc
@@ -146,7 +148,7 @@ The ``name'' of the file referenced by the symbolic link named
 the value of the environment variable
 .Ev MALLOC_OPTIONS ,
 and the string pointed to by the global variable
-.Va malloc_options 
+.Va _malloc_options 
 will be interpreted, in that order, character by character as flags.
 .Pp
 Most flags are single letters,
@@ -211,8 +213,7 @@ core (using
 This option should be set at compile time by including the following in
 the source code:
 .Bd -literal -offset indent
-extern char *malloc_options;
-malloc_options = "X";
+_malloc_options = "X";
 .Ed
 .It Z
 This option implicitly sets the
@@ -249,8 +250,7 @@ ln -s 'A<' /etc/malloc.conf
 To specify in the source that a program does no return value checking
 on calls to these functions:
 .Bd -literal -offset indent
-extern char *malloc_options;
-malloc_options = "X";
+_malloc_options = "X";
 .Ed
 .Sh ENVIRONMENT
 The following environment variables affect the execution of the allocation
@@ -364,6 +364,14 @@ If the
 .Dq A
 option is set, all warnings are treated as errors.
 .Pp
+The
+.Va _malloc_message
+variable allows the programmer to override the function which emits
+the text strings forming the errors and warnings if for some reason
+the stderr filedescriptor is not suitable for this.
+Please note that doing anything which tries to allocate memory in
+this function will certain suicide for the process.
+.Pp
 The following is a brief description of possible error messages and
 their meanings:
 .Pp
diff --git a/lib/libc/stdlib/malloc.c b/lib/libc/stdlib/malloc.c
index 3b631e86de79..bb6bb6fb8744 100644
--- a/lib/libc/stdlib/malloc.c
+++ b/lib/libc/stdlib/malloc.c
@@ -251,7 +251,7 @@ static void *malloc_brk;
 static struct pgfree *px;
 
 /* compile-time options */
-char *malloc_options;
+char *_malloc_options;
 
 /* Name of the current public function */
 static char *malloc_func;
@@ -269,30 +269,36 @@ static void *imalloc(size_t size);
 static void ifree(void *ptr);
 static void *irealloc(void *ptr, size_t size);
 
+static void
+wrtmessage(char *p1, char *p2, char *p3, char *p4)
+{
+
+    _write(STDERR_FILENO, p1, strlen(p1));
+    _write(STDERR_FILENO, p2, strlen(p2));
+    _write(STDERR_FILENO, p3, strlen(p3));
+    _write(STDERR_FILENO, p4, strlen(p4));
+}
+
+void (*_malloc_message)(char *p1, char *p2, char *p3, char *p4) = wrtmessage;
+
 extern char *__progname;
 
 static void
 wrterror(char *p)
 {
-    char *q = " error: ";
-    _write(STDERR_FILENO, __progname, strlen(__progname));
-    _write(STDERR_FILENO, malloc_func, strlen(malloc_func));
-    _write(STDERR_FILENO, q, strlen(q));
-    _write(STDERR_FILENO, p, strlen(p));
+
     suicide = 1;
+    _malloc_message(__progname, malloc_func, " error: ", p);
     abort();
 }
 
 static void
 wrtwarning(char *p)
 {
-    char *q = " warning: ";
+
     if (malloc_abort)
 	wrterror(p);
-    _write(STDERR_FILENO, __progname, strlen(__progname));
-    _write(STDERR_FILENO, malloc_func, strlen(malloc_func));
-    _write(STDERR_FILENO, q, strlen(q));
-    _write(STDERR_FILENO, p, strlen(p));
+    _malloc_message(__progname, malloc_func, " warning: ", p);
 }
 
 /*
@@ -403,7 +409,7 @@ malloc_init ()
 	} else if (i == 1) {
 	    p = getenv("MALLOC_OPTIONS");
 	} else {
-	    p = malloc_options;
+	    p = _malloc_options;
 	}
 	for (; p && *p; p++) {
 	    switch (*p) {