[src/trunk]: src/sys/kern snprintf/vsnprintf can accept NULL/0 buffers and wo...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/8b815d102c59
branches:  trunk
changeset: 771445:8b815d102c59
user:      christos <christos%NetBSD.org@localhost>
date:      Sun Nov 20 23:01:18 2011 +0000

description:
snprintf/vsnprintf can accept NULL/0 buffers and work properly as expected.
Before they used to return incorrect length on short buffers. Remove unused
error path.

diffstat:

 sys/kern/subr_prf.c |  48 ++++++++++++++++++++++--------------------------
 1 files changed, 22 insertions(+), 26 deletions(-)

diffs (116 lines):

diff -r 22aae567e1c3 -r 8b815d102c59 sys/kern/subr_prf.c
--- a/sys/kern/subr_prf.c       Sun Nov 20 22:58:31 2011 +0000
+++ b/sys/kern/subr_prf.c       Sun Nov 20 23:01:18 2011 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: subr_prf.c,v 1.143 2011/09/29 20:52:39 christos Exp $  */
+/*     $NetBSD: subr_prf.c,v 1.144 2011/11/20 23:01:18 christos Exp $  */
 
 /*-
  * Copyright (c) 1986, 1988, 1991, 1993
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_prf.c,v 1.143 2011/09/29 20:52:39 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_prf.c,v 1.144 2011/11/20 23:01:18 christos Exp $");
 
 #include "opt_ddb.h"
 #include "opt_ipkdb.h"
@@ -1024,8 +1024,9 @@
        va_start(ap, fmt);
        retval = kprintf(fmt, TOBUFONLY, NULL, bf, ap);
        va_end(ap);
-       *(bf + retval) = 0;     /* null terminate */
-       return(retval);
+       if (bf)
+               bf[retval] = '\0';      /* nul terminate */
+       return retval;
 }
 
 /*
@@ -1038,8 +1039,9 @@
        int retval;
 
        retval = kprintf(fmt, TOBUFONLY, NULL, bf, ap);
-       *(bf + retval) = 0;     /* null terminate */
-       return (retval);
+       if (bf)
+               bf[retval] = '\0';      /* nul terminate */
+       return retval;
 }
 
 /*
@@ -1052,14 +1054,13 @@
        va_list ap;
        char *p;
 
-       if (size < 1)
-               return (-1);
-       p = bf + size - 1;
+       p = bf + size;
        va_start(ap, fmt);
        retval = kprintf(fmt, TOBUFONLY, &p, bf, ap);
        va_end(ap);
-       *(p) = 0;       /* null terminate */
-       return(retval);
+       if (bf && p < bf + size)
+               *p = '\0';      /* nul terminate */
+       return retval;
 }
 
 /*
@@ -1071,12 +1072,11 @@
        int retval;
        char *p;
 
-       if (size < 1)
-               return (-1);
-       p = bf + size - 1;
+       p = bf + size;
        retval = kprintf(fmt, TOBUFONLY, &p, bf, ap);
-       *(p) = 0;       /* null terminate */
-       return(retval);
+       if (bf && p < bf + size)
+               *p = '\0';      /* nul terminate */
+       return retval;
 }
 
 /*
@@ -1134,13 +1134,10 @@
 
 #define KPRINTF_PUTCHAR(C) {                                           \
        if (oflags == TOBUFONLY) {                                      \
-               if ((vp != NULL) && (sbuf == tailp)) {                  \
-                       ret += 1;               /* indicate error */    \
-                       goto overflow;                                  \
-               }                                                       \
-               *sbuf++ = (C);                                          \
+               if ((vp == NULL) || (sbuf < tailp))                     \
+                       *sbuf++ = (C);                                  \
        } else {                                                        \
-               putchar((C), oflags, (struct tty *)vp);                 \
+               putchar((C), oflags, vp);                               \
        }                                                               \
 }
 
@@ -1181,9 +1178,10 @@
        char bf[KPRINTF_BUFSIZE]; /* space for %c, %[diouxX] */
        char *tailp;            /* tail pointer for snprintf */
 
-       tailp = NULL;   /* XXX: shutup gcc */
        if (oflags == TOBUFONLY && (vp != NULL))
                tailp = *(char **)vp;
+       else
+               tailp = NULL;
 
        cp = NULL;      /* XXX: shutup gcc */
        size = 0;       /* XXX: shutup gcc */
@@ -1526,7 +1524,5 @@
        if ((oflags == TOBUFONLY) && (vp != NULL))
                *(char **)vp = sbuf;
        (*v_flush)();
-overflow:
-       return (ret);
-       /* NOTREACHED */
+       return ret;
 }