From: Nahim El Atmani <[email protected]>

* strace.c: alloctcb() when no tcbs are available (first call and subsequent
calls when tcbtab is full) call expand_tcbtab(). Now, expand_tcbtab() allocate
the minimum required amount of memory to create the tcbtab if needed and expend
otherwise instead of relying on the preallocation of a large amount of tcbs
and expand if needed.

Signed-off-by: Nahim El Atmani <[email protected]>
Reviewed-By: Gabriel Laskar <[email protected]>
Reported-by: haris iqbal <[email protected]>

---
 strace.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/strace.c b/strace.c
index 785cc60..e97fe9e 100644
--- a/strace.c
+++ b/strace.c
@@ -691,16 +691,26 @@ newoutf(struct tcb *tcp)
 static void
 expand_tcbtab(void)
 {
-       /* Allocate some more TCBs and expand the table.
+       /* Allocate some (more) TCBs (and expand the table).
           We don't want to relocate the TCBs because our
           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.  */
-       unsigned int i = tcbtabsize;
-       struct tcb *newtcbs = xcalloc(tcbtabsize, sizeof(newtcbs[0]));
-       struct tcb **newtab = xreallocarray(tcbtab, tcbtabsize * 2,
-                                           sizeof(tcbtab[0]));
-       tcbtabsize *= 2;
+       unsigned int i, new_tcbtabsize, alloc_tcbtabsize;
+       struct tcb *newtcbs;
+       struct tcb **newtab;
+
+       if (tcbtabsize) {
+               alloc_tcbtabsize = tcbtabsize;
+               new_tcbtabsize = tcbtabsize * 2;
+       } else {
+               new_tcbtabsize = alloc_tcbtabsize = 1;
+       }
+
+       i = tcbtabsize;
+       newtcbs = xcalloc(alloc_tcbtabsize, sizeof(newtcbs[0]));
+       newtab = xreallocarray(tcbtab, new_tcbtabsize, sizeof(tcbtab[0]));
+       tcbtabsize = new_tcbtabsize;
        tcbtab = newtab;
        while (i < tcbtabsize)
                tcbtab[i++] = newtcbs++;
@@ -1484,10 +1494,8 @@ get_os_release(void)
 static void ATTRIBUTE_NOINLINE
 init(int argc, char *argv[])
 {
-       struct tcb *tcp;
        int c, i;
        int optF = 0;
-       unsigned int tcbi;
        struct sigaction sa;

        progname = argv[0] ? argv[0] : "strace";
@@ -1503,13 +1511,6 @@ init(int argc, char *argv[])

        os_release = get_os_release();

-       /* Allocate the initial tcbtab.  */
-       tcbtabsize = argc;      /* Surely enough for all -p args.  */
-       tcbtab = xcalloc(tcbtabsize, sizeof(tcbtab[0]));
-       tcp = xcalloc(tcbtabsize, sizeof(*tcp));
-       for (tcbi = 0; tcbi < tcbtabsize; tcbi++)
-               tcbtab[tcbi] = tcp++;
-
        shared_log = stderr;
        set_sortby(DEFAULT_SORTBY);
        set_personality(DEFAULT_PERSONALITY);
-- 
Nahim El Atmani <[email protected]>
http://naam.me/


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