PERFORCE change 125099 for review

[Marko Zec]

http://perforce.freebsd.org/chv.cgi?CH=125099

Change 125099 by zec at zec_tpx32 on 2007/08/13 07:01:54

	A hack to resolve character "@" to vimage name when following
	symbolic links.  This is controlled on per-vimage basis via the
	new vfs.morphing_symlinks sysctl and is off by default.  The
	primary use of this will be in IMUNES network topology emulator
	to allow running of multiple instances of unmodified applications
	with some hard coded filesystem paths, most notably quagga.
	
	While here, slightly change the format of warning messages
	displayed if / when vnet "stacking" occurs.

Affected files ...

.. //depot/projects/vimage/src/sys/kern/vfs_lookup.c#6 edit
.. //depot/projects/vimage/src/sys/sys/vimage.h#33 edit

Differences ...

==== //depot/projects/vimage/src/sys/kern/vfs_lookup.c#6 (text+ko) ====

@@ -40,6 +40,7 @@
 #include "opt_ktrace.h"
 #include "opt_mac.h"
 #include "opt_vfs.h"
+#include "opt_vimage.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -53,6 +54,7 @@
 #include <sys/proc.h>
 #include <sys/syscallsubr.h>
 #include <sys/sysctl.h>
+#include <sys/vimage.h>
 #ifdef KTRACE
 #include <sys/ktrace.h>
 #endif
@@ -65,6 +67,15 @@
 #define	NAMEI_DIAGNOSTIC 1
 #undef NAMEI_DIAGNOSTIC
 
+#ifdef VIMAGE
+#define IMUNES_SYMLINK_HACK
+#endif
+
+#ifdef IMUNES_SYMLINK_HACK
+SYSCTL_V_INT(V_PROCG, vprocg, _vfs, OID_AUTO, morphing_symlinks, CTLFLAG_RW,
+    morphing_symlinks, 0, "Resolve @ to vimage name in symlinks");
+#endif
+
 /*
  * Allocation zone for namei
  */
@@ -129,6 +140,9 @@
 	struct thread *td = cnp->cn_thread;
 	struct proc *p = td->td_proc;
 	int vfslocked;
+#ifdef IMUNES_SYMLINK_HACK
+	INIT_VPROCG(td->td_ucred->cr_vimage->v_procg);
+#endif
 
 	KASSERT((cnp->cn_flags & MPSAFE) != 0 || mtx_owned(&Giant) != 0,
 	    ("NOT MPSAFE and Giant not held"));
@@ -284,6 +298,26 @@
 			error = ENOENT;
 			break;
 		}
+#ifdef IMUNES_SYMLINK_HACK
+		if (V_morphing_symlinks) {
+			char *sp = strchr(cp, '@');
+			int vnamelen = strlen(td->td_ucred->cr_vimage->vi_name);
+
+			if (sp) {
+				if (vnamelen >= auio.uio_resid) {
+					if (ndp->ni_pathlen > 1)
+						uma_zfree(namei_zone, cp);
+					error = ENAMETOOLONG;
+					break;
+				}
+				bcopy(sp + 1, sp + vnamelen,
+				    vnamelen - (sp - cp));
+				bcopy(td->td_ucred->cr_vimage->vi_name, sp,
+				    vnamelen);
+				linklen += (vnamelen - 1);
+			}
+		}
+#endif /* IMUNES_SYMLINK_HACK */
 		if (linklen + ndp->ni_pathlen >= MAXPATHLEN) {
 			if (ndp->ni_pathlen > 1)
 				uma_zfree(namei_zone, cp);

==== //depot/projects/vimage/src/sys/sys/vimage.h#33 (text+ko) ====

@@ -197,9 +197,9 @@
 #define CURVNET_SET_VERBOSE(arg)					\
 	CURVNET_SET_QUIET(arg)						\
 	if (saved_vnet)							\
-		printf("curvnet_set(%p) in %s() on cpu %d, prev %s(%p)\n", \
+		printf("curvnet_set(%p) in %s() on cpu %d, prev %p in %s()\n", \
 		       curvnet, curthread->td_vnet_lpush, curcpu,	\
-		       saved_vnet_lpush, saved_vnet);
+		       saved_vnet, saved_vnet_lpush);
 
 #define CURVNET_SET(arg)	CURVNET_SET_VERBOSE(arg)
  
@@ -291,6 +291,7 @@
 #define V_cp_time		VPROCG(cp_time)
 #define V_hostname		VPROCG(hostname)
 #define V_domainname		VPROCG(domainname)
+#define V_morphing_symlinks	VPROCG(morphing_symlinks)
 
 #ifdef VIMAGE
 void vnet_mod_register(const struct vnet_modinfo *);
@@ -355,6 +356,8 @@
 	char	_hostname[MAXHOSTNAMELEN];
 	char	_domainname[MAXHOSTNAMELEN];
 
+	int	_morphing_symlinks;
+
 #if 0
 	struct	loadavg averunnable;	/* from kern/kern_synch.c */
 	int	nrun;
@@ -374,9 +377,6 @@
 	struct	timeval boottime;
 	long	boottdelta_sec;
 
-	int	hostnamelen;
-	int	domainnamelen;
-
 	char	chroot[MAXPATHLEN];	/* assigned/inherited from parent */
 
 	int	big_brother;		/* manage procs in all child vprocgs */