[src/trunk]: src/sys/compat/common Make the usage consistant and document it:

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

details:   https://anonhg.NetBSD.org/src/rev/e19fb6a5e366
branches:  trunk
changeset: 472316:e19fb6a5e366
user:      christos <christos%NetBSD.org@localhost>
date:      Tue Apr 27 11:36:47 1999 +0000

description:
Make the usage consistant and document it:
if the path was given in a user buffer, return the new path in
a user buffer.
if the path was given in a kernel buffer, allocate a new kernel buffer
to return the new path; the caller is responsible for freeing the buffer
if we fail always set the new path to NULL.
This usage broke when I adde the /../ shortcut. Noted by cgd.

diffstat:

 sys/compat/common/compat_util.c |  35 +++++++++++++++++++++++++----------
 1 files changed, 25 insertions(+), 10 deletions(-)

diffs (84 lines):

diff -r 93505327f859 -r e19fb6a5e366 sys/compat/common/compat_util.c
--- a/sys/compat/common/compat_util.c   Tue Apr 27 08:07:26 1999 +0000
+++ b/sys/compat/common/compat_util.c   Tue Apr 27 11:36:47 1999 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: compat_util.c,v 1.12 1999/04/24 02:56:06 cgd Exp $     */
+/*     $NetBSD: compat_util.c,v 1.13 1999/04/27 11:36:47 christos Exp $        */
 
 /*-
  * Copyright (c) 1994 The NetBSD Foundation, Inc.
@@ -62,6 +62,13 @@
  * If cflag is set, we check if an attempt can be made to create
  * the named file, i.e. we check if the directory it should
  * be in exists.
+ *
+ * In case of success, emul_find returns 0:
+ *     If sgp is provided, the path is in user space, and pbuf gets
+ *     allocated in user space (in the stackgap). Otherwise the path
+ *     is already in kernel space and a kernel buffer gets allocated
+ *     and returned in pbuf, that must be freed by the user.
+ * In case of error, the error number is returned and *pbuf = NULL.
  */
 int
 emul_find(p, sgp, prefix, path, pbuf, cflag)
@@ -81,7 +88,7 @@
        const char              *pr;
        size_t                   sz, len;
 
-       buf = (char *) malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
+       buf = (char *)malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
        *pbuf = path;
 
        for (ptr = buf, pr = prefix; (*ptr = *pr) != '\0'; ptr++, pr++)
@@ -111,8 +118,10 @@
         * by /../ we kill the alternate search
         */
        if (ptr[1] == '.' && ptr[2] == '.' && ptr[3] == '/') {
-               *pbuf = &path[3];
-               goto bad;
+               len -= 3;
+               (void)memcpy(buf, &ptr[3], len);
+               ptr = buf;
+               goto good;
        }
 
        /*
@@ -167,19 +176,24 @@
                        goto bad3;
                }
        }
+
+       vrele(nd.ni_vp);
+       if (!cflag)
+               vrele(ndroot.ni_vp);
+
+good:
        if (sgp == NULL)
                *pbuf = buf;
        else {
                sz = &ptr[len] - buf;
                *pbuf = stackgap_alloc(sgp, sz + 1);
-               error = copyout(buf, (void *)*pbuf, sz);
+               if ((error = copyout(buf, (void *)*pbuf, sz)) != 0) {
+                       *pbuf = NULL;
+                       return error;
+               }
                free(buf, M_TEMP);
        }
-
-       vrele(nd.ni_vp);
-       if (!cflag)
-               vrele(ndroot.ni_vp);
-       return error;
+       return 0;
 
 bad3:
        vrele(ndroot.ni_vp);
@@ -187,6 +201,7 @@
        vrele(nd.ni_vp);
 bad:
        free(buf, M_TEMP);
+       *pbuf = NULL;
        return error;
 }