Simplify expand_tcbtab and alloc_tcb

Get rid of a few intermediate variables, simplifies a few expressions,
and uses error_msg_and_die instead of more verbose
fprintf+cleanup+exit sequence.
In alloc_tcp, I use memset to clear entire new tcp.
This not only saves a few bytes of code, but lowers the chances
of future bugs where some data "leaks out" into new tcb's
from old ones because we forgot to re-initialize it.

* strace.c (expand_tcbtab): Simplify this function. No logic changes.
  (alloc_tcb): Likewise.

Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>

diff --git a/strace.c b/strace.c
index 94559a5ca507ac3b4466a17a004d81e78f41eb9d..3b393719b49f51b16e306815ccea9c5291f5a81c 100644 (file)
--- a/strace.c
+++ b/strace.c
@@ -1252,21 +1252,15 @@ expand_tcbtab(void)
           callers have pointers and it would be a pain.
           So tcbtab is a table of pointers.  Since we never
           free the TCBs, we allocate a single chunk of many.  */
-       struct tcb **newtab = (struct tcb **)
-               realloc(tcbtab, 2 * tcbtabsize * sizeof tcbtab[0]);
-       struct tcb *newtcbs = (struct tcb *) calloc(tcbtabsize,
-                                                   sizeof *newtcbs);
-       int i;
-       if (newtab == NULL || newtcbs == NULL) {
-               fprintf(stderr, "%s: expand_tcbtab: out of memory\n",
-                       progname);
-               cleanup();
-               exit(1);
-       }
-       for (i = tcbtabsize; i < 2 * tcbtabsize; ++i)
-               newtab[i] = &newtcbs[i - tcbtabsize];
+       int i = tcbtabsize;
+       struct tcb *newtcbs = calloc(tcbtabsize, sizeof(newtcbs[0]));
+       struct tcb **newtab = realloc(tcbtab, tcbtabsize * 2 * sizeof(tcbtab[0]));
+       if (newtab == NULL || newtcbs == NULL)
+               error_msg_and_die("expand_tcbtab: out of memory");
        tcbtabsize *= 2;
        tcbtab = newtab;
+       while (i < tcbtabsize)
+               tcbtab[i++] = newtcbs++;
 }
 
 struct tcb *
@@ -1281,16 +1275,10 @@ alloc_tcb(int pid, int command_options_parsed)
        for (i = 0; i < tcbtabsize; i++) {
                tcp = tcbtab[i];
                if ((tcp->flags & TCB_INUSE) == 0) {
+                       memset(tcp, 0, sizeof(*tcp));
                        tcp->pid = pid;
-                       tcp->parent = NULL;
-#ifdef TCB_CLONE_THREAD
-                       tcp->nclone_threads = 0;
-#endif
                        tcp->flags = TCB_INUSE | TCB_STARTUP;
                        tcp->outf = outf; /* Initialise to current out file */
-                       tcp->curcol = 0;
-                       tcp->stime.tv_sec = 0;
-                       tcp->stime.tv_usec = 0;
                        tcp->pfd = -1;
                        nprocs++;
                        if (command_options_parsed)
@@ -1298,9 +1286,7 @@ alloc_tcb(int pid, int command_options_parsed)
                        return tcp;
                }
        }
-       fprintf(stderr, "%s: bug in alloc_tcb\n", progname);
-       cleanup();
-       exit(1);
+       error_msg_and_die("bug in alloc_tcb");
 }
 
 #ifdef USE_PROCFS