bin/92395: truss(1) does not work properly, procfs looks like it's limited to 128 elements

[Steve Sears]

The following reply was made to PR bin/92395; it has been noted by GNATS.

From: Steve Sears <sjs at netapp.com>
To: <bug-followup at FreeBSD.org>, <patrick.proniewski at univ-lyon2.fr>
Cc:  
Subject: Re: bin/92395: truss(1) does not work properly, procfs looks like
 it's limited to 128 elements
Date: Mon, 30 Jan 2006 15:18:19 -0500

 I fixed a problem in truss that seems related to some of what you are seeing
 in this PR. The problem I fixed has to do with the number of arguments truss
 reads for a syscall from the kernel. There are a number of conditions that
 will cause the arguments returned from the ioctl to be wrong - it is often a
 signal number and not the number of arguments at all.
 
 Fortunately, truss has a table with all of the commands and the number of
 arguments they take. Obtain the argument count from the table instead of
 relying on the ioctl and things work much better.
 
 My fixes:
 
 ==== ./usr/src/usr.bin/truss/i386-fbsd.c#2 (text) ====
 
 175,182c175,178
 <   if (nargs == 0)
 <     return;
 < 
 <   fsc.args = malloc((1+nargs) * sizeof(unsigned long));
 <   lseek(Procfd, parm_offset, SEEK_SET);
 <   if (read(Procfd, fsc.args, nargs * sizeof(unsigned long)) == -1)
 <     return;
 < 
 ---
 >   /* The passed in nargs is not always reliable, it can be affected by
 >    * signals and other things going on in the kernel. Only use it in
 >    * the last resort.
 >    */
 185a182
 >     nargs = sc->nargs;
 193a191,199
 >   if (nargs == 0)
 >     return;
 > 
 >   fsc.args = malloc((1+nargs) * sizeof(unsigned long));
 >   lseek(Procfd, parm_offset, SEEK_SET);
 >   if (read(Procfd, fsc.args, nargs * sizeof(unsigned long)) == -1)
 >     return;
 > 
 > 
 207d212
 < 
 
 ==== ./usr/src/usr.bin/truss/syscalls.c#3 (text) ====
 
 231c231
 <     buf = malloc( size = (max ? max : 64 ) );
 ---
 >     buf = malloc( size = (max ? max + 1 : 64 ) );
 238d237
 <                 buf[len] = 0;
 251a251
 >         buf[len] = 0;
 416c416
 <       if ((pfd = malloc(bytes)) == NULL)
 ---
 >       if ((pfd = malloc(bytes)) == NULL) {
 417a418
 >       }