That was by inspection on my system which seems to truncate a lot earlier.
It would be nice to find where in the Linux kernel it is output but I
failed to grep the relevant function last night.
On Fri, 10 Apr 2020, 12:11 Philippe Mathieu-Daudé, <phi...@redhat.com>
wrote:
> Cc'ing Ludovic in case he can test with Guix-HPC.
>
> On 4/9/20 11:15 PM, Alex Bennée wrote:
> > In the original bug report long files names in Guix caused
> > /proc/self/stat be truncated without the trailing ") " as specified in
> > proc manpage which says:
> > (2) comm %s
> > The filename of the executable, in parentheses. This
> > is visible whether or not the executable is swapped
> > out.
> >
> > Additionally it should only be reporting the executable name rather
> > than the full path. Fix both these failings while cleaning up the code
> > to use GString to build up the reported values. As the whole function
> > is cleaned up also adjust the white space to the current coding style.
> >
> > Message-ID: <fb4c55fa-d539-67ee-c6c9-de8fb63c8...@inria.fr>
> > Reported-by: Brice Goglin <brice.gog...@inria.fr>
> > Cc: Philippe_Mathieu-Daudé <phi...@redhat.com>
> > Signed-off-by: Alex Bennée <alex.ben...@linaro.org>
> > ---
> > linux-user/syscall.c | 43 +++++++++++++++++++------------------------
> > 1 file changed, 19 insertions(+), 24 deletions(-)
> >
> > diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> > index 6495ddc4cda..674f70e70a5 100644
> > --- a/linux-user/syscall.c
> > +++ b/linux-user/syscall.c
> > @@ -7295,34 +7295,29 @@ static int open_self_stat(void *cpu_env, int fd)
> > {
> > CPUState *cpu = env_cpu((CPUArchState *)cpu_env);
> > TaskState *ts = cpu->opaque;
> > - abi_ulong start_stack = ts->info->start_stack;
> > + g_autoptr(GString) buf = g_string_new(NULL);
> > int i;
> >
> > for (i = 0; i < 44; i++) {
> > - char buf[128];
> > - int len;
> > - uint64_t val = 0;
> > -
> > - if (i == 0) {
> > - /* pid */
> > - val = getpid();
> > - snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
> > - } else if (i == 1) {
> > - /* app name */
> > - snprintf(buf, sizeof(buf), "(%s) ", ts->bprm->argv[0]);
> > - } else if (i == 27) {
> > - /* stack bottom */
> > - val = start_stack;
> > - snprintf(buf, sizeof(buf), "%"PRId64 " ", val);
> > - } else {
> > - /* for the rest, there is MasterCard */
> > - snprintf(buf, sizeof(buf), "0%c", i == 43 ? '\n' : ' ');
> > - }
> > + if (i == 0) {
> > + /* pid */
> > + g_string_printf(buf, FMT_pid " ", getpid());
> > + } else if (i == 1) {
> > + /* app name */
> > + gchar *bin = g_strrstr(ts->bprm->argv[0], "/");
> > + bin = bin ? bin + 1 : ts->bprm->argv[0];
> > + g_string_printf(buf, "(%.15s) ", bin);
>
> 15 or 125? 15 seems short. From your previous test I understood it was
> 124, for
>
> sizeof("cat_with9_12345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890___40").
>
> > + } else if (i == 27) {
> > + /* stack bottom */
> > + g_string_printf(buf, TARGET_ABI_FMT_ld " ",
> ts->info->start_stack);
> > + } else {
> > + /* for the rest, there is MasterCard */
> > + g_string_printf(buf, "0%c", i == 43 ? '\n' : ' ');
> > + }
> >
> > - len = strlen(buf);
> > - if (write(fd, buf, len) != len) {
> > - return -1;
> > - }
> > + if (write(fd, buf->str, buf->len) != buf->len) {
> > + return -1;
> > + }
> > }
> >
> > return 0;
> >
>
>
