[src/trunk]: src/sys/kern A few tweaks to magic symlinks:

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

details:   https://anonhg.NetBSD.org/src/rev/2d113212da30
branches:  trunk
changeset: 582803:2d113212da30
user:      thorpej <thorpej%NetBSD.org@localhost>
date:      Wed Jul 06 18:53:00 2005 +0000

description:
A few tweaks to magic symlinks:
- Add a @{var} syntax in addition to @var.  This allows for patterns like
  @{ostype}-@{osrelease}-@{machine_arch}.
- Add a @emul variable that expands to the process's emulation name
  (e.g. "netbsd", "netbsd32", "linux", etc.)

diffstat:

 sys/kern/vfs_lookup.c |  116 +++++++++++++++++++++++++++++++------------------
 1 files changed, 73 insertions(+), 43 deletions(-)

diffs (163 lines):

diff -r e295a74c99a6 -r 2d113212da30 sys/kern/vfs_lookup.c
--- a/sys/kern/vfs_lookup.c     Wed Jul 06 18:35:39 2005 +0000
+++ b/sys/kern/vfs_lookup.c     Wed Jul 06 18:53:00 2005 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: vfs_lookup.c,v 1.62 2005/06/23 17:00:30 thorpej Exp $  */
+/*     $NetBSD: vfs_lookup.c,v 1.63 2005/07/06 18:53:00 thorpej Exp $  */
 
 /*
  * Copyright (c) 1982, 1986, 1989, 1993
@@ -37,7 +37,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.62 2005/06/23 17:00:30 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_lookup.c,v 1.63 2005/07/06 18:53:00 thorpej Exp $");
 
 #include "opt_ktrace.h"
 #include "opt_systrace.h"
@@ -82,58 +82,82 @@
  * replacement strings (and replacement string lengths) made
  * that impractical.
  */
+#define        VNL(x)                                                  \
+       (sizeof(x) - 1)
+
+#define        VO      '{'
+#define        VC      '}'
+
 #define        MATCH(str)                                              \
-               ((i + (sizeof(str) - 1) == *len) ||             \
-                   ((i + (sizeof(str) - 1) < *len) &&          \
-                     (cp[i + sizeof(str) - 1] == '/'))) &&     \
-               !strncmp((str), &cp[i], sizeof(str) - 1)
+       ((termchar == '/' && i + VNL(str) == *len) ||           \
+        (i + VNL(str) < *len &&                                \
+         cp[i + VNL(str)] == termchar)) &&                     \
+       !strncmp((str), &cp[i], VNL(str))
 
 #define        SUBSTITUTE(m, s, sl)                                    \
-               if ((newlen + (sl)) > MAXPATHLEN)               \
-                       return (1);                             \
-               i += sizeof(m) - 1;                             \
-               memcpy(&tmp[newlen], (s), (sl));                \
-               newlen += (sl);                                 \
-               change = 1;
+       if ((newlen + (sl)) > MAXPATHLEN)                       \
+               return (1);                                     \
+       i += VNL(m);                                            \
+       if (termchar != '/')                                    \
+               i++;                                            \
+       memcpy(&tmp[newlen], (s), (sl));                        \
+       newlen += (sl);                                         \
+       change = 1;                                             \
+       termchar = '/';
 
 static int
-symlink_magic(char *cp, int *len)
+symlink_magic(struct proc *p, char *cp, int *len)
 {
        char tmp[MAXPATHLEN];
        int change, i, newlen;
+       int termchar = '/';
 
        for (change = i = newlen = 0; i < *len; ) {
-               if (cp[i] != '@')
+               if (cp[i] != '@') {
                        tmp[newlen++] = cp[i++];
-               else {
+                       continue;
+               }
+
+               i++;
+
+               /* Check for @{var} syntax. */
+               if (cp[i] == VO) {
+                       termchar = VC;
                        i++;
-                       /*
-                        * The following checks should be ordered according
-                        * to frequency of use.
-                        */
-                       if (MATCH("machine_arch")) {
-                               SUBSTITUTE("machine_arch", MACHINE_ARCH,
-                                   sizeof(MACHINE_ARCH) - 1);
-                       } else if (MATCH("machine")) {
-                               SUBSTITUTE("machine", MACHINE,
-                                   sizeof(MACHINE) - 1);
-                       } else if (MATCH("hostname")) {
-                               SUBSTITUTE("hostname", hostname,
-                                   hostnamelen);
-                       } else if (MATCH("osrelease")) {
-                               SUBSTITUTE("osrelease", osrelease,
-                                   strlen(osrelease));
-                       } else if (MATCH("kernel_ident")) {
-                               SUBSTITUTE("kernel_ident", kernel_ident,
-                                   strlen(kernel_ident));
-                       } else if (MATCH("domainname")) {
-                               SUBSTITUTE("domainname", domainname,
-                                   domainnamelen);
-                       } else if (MATCH("ostype")) {
-                               SUBSTITUTE("ostype", ostype,
-                                   strlen(ostype));
-                       } else
-                               tmp[newlen++] = '@';
+               }
+
+               /*
+                * The following checks should be ordered according
+                * to frequency of use.
+                */
+               if (MATCH("machine_arch")) {
+                       SUBSTITUTE("machine_arch", MACHINE_ARCH,
+                           sizeof(MACHINE_ARCH) - 1);
+               } else if (MATCH("machine")) {
+                       SUBSTITUTE("machine", MACHINE,
+                           sizeof(MACHINE) - 1);
+               } else if (MATCH("hostname")) {
+                       SUBSTITUTE("hostname", hostname,
+                           hostnamelen);
+               } else if (MATCH("osrelease")) {
+                       SUBSTITUTE("osrelease", osrelease,
+                           strlen(osrelease));
+               } else if (MATCH("emul")) {
+                       SUBSTITUTE("emul", p->p_emul->e_name,
+                           strlen(p->p_emul->e_name));
+               } else if (MATCH("kernel_ident")) {
+                       SUBSTITUTE("kernel_ident", kernel_ident,
+                           strlen(kernel_ident));
+               } else if (MATCH("domainname")) {
+                       SUBSTITUTE("domainname", domainname,
+                           domainnamelen);
+               } else if (MATCH("ostype")) {
+                       SUBSTITUTE("ostype", ostype,
+                           strlen(ostype));
+               } else {
+                       tmp[newlen++] = '@';
+                       if (termchar == VC)
+                               tmp[newlen++] = VO;
                }
        }
 
@@ -146,6 +170,12 @@
        return (0);
 }
 
+#undef VNL
+#undef VO
+#undef VC
+#undef MATCH
+#undef SUBSTITUTE
+
 /*
  * Convert a pathname into a pointer to a locked inode.
  *
@@ -302,7 +332,7 @@
                 * check length for potential overflow.
                 */
                if (((ndp->ni_vp->v_mount->mnt_flag & MNT_MAGICLINKS) &&
-                    symlink_magic(cp, &linklen)) ||
+                    symlink_magic(cnp->cn_proc, cp, &linklen)) ||
                    (linklen + ndp->ni_pathlen >= MAXPATHLEN)) {
                        error = ENAMETOOLONG;
                        goto badlink;