Modify strtofflags so that it returns a malloced string instead of a

pointer to a static buffer.

lib/libc/gen/strtofflags.3

@@ -38,7 +38,7 @@
 .Sh NAME
 .Nm fflagstostr ,
 .Nm strtofflags
-.Nd modify file flag bits
+.Nd convert between file flag bits and their string names
 .Sh LIBRARY
 .Lb libc
 .Sh SYNOPSIS
@@ -54,6 +54,19 @@ function returns a comma separated string of the file flags represented by
 .Fa flags .
 If no flags are set a zero length string is returned.
 .Pp
+If memory cannot be allocated for the return value,
+.Fn fflagstostr
+returns
+.Dv NULL . 
+.Pp
+The value returned from 
+.Fn fflagstostr
+is obtained from 
+.Fn malloc 
+and should be returned to the system with
+.Fn free 
+when the program is done with it.
+.Pp
 The
 .Fn strtofflags
 function takes a string of file flags, as described in
@@ -66,13 +79,21 @@ On success
 returns 0, otherwise it returns non-zero and
 .Fa stringp
 is left pointing to the offending token.
+.Sh ERRORS
+The
+.Fn fflagstostr
+function
+may fail and set errno for any of the errors specified for the library
+routine
+.Xr malloc 3 .
 .Sh SEE ALSO
 .Xr chflags 1 ,
 .Xr chflags 2 ,
+.Xr malloc 3
 .Sh HISTORY
 The
-.Fn strtofflags
-and
 .Fn fflagstostr
+and
+.Fn strtofflags
 functions first appeared in
 .Fx 4.0 .

lib/libc/gen/strtofflags.c

@@ -44,6 +44,7 @@ static const char rcsid[] =
 #include <sys/stat.h>
 
 #include <stddef.h>
+#include <stdlib.h>
 #include <string.h>
 
 static struct {
@@ -71,6 +72,7 @@ static struct {
 	{ "nouunlnk",		UF_NOUNLINK,	0 },
 	{ "nouunlink",		UF_NOUNLINK,	0 }
 };
+#define longestflaglen	12
 #define nmappings	(sizeof(mapping) / sizeof(mapping[0]))
 
 /*
@@ -82,11 +84,14 @@ char *
 fflagstostr(flags)
 	u_long flags;
 {
-	static char string[128];
+	char *string;
 	char *sp, *dp;
 	u_long setflags;
 	int i;
 
+	if ((string = (char *)malloc(nmappings * (longestflaglen + 1))) == NULL)
+		return (NULL);
+
 	setflags = flags;
 	dp = string;
 	for (i = 0; i < nmappings; i++) {