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library: standardize handling of cgroup, supgid

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Some inconsistencies have emerged during development
of support for these relatively new proc_t fields.

For example, a PROC_FILLCGROUP flag (via file2strvec)
could return NULL in cgroup whereas PROC_EDITCGRPCVT
(via fill_cgroup_cvt) *almost* guaranteed a return
address (as is true for PROC_EDITCMDLCVT and cmdline).
But even PROC_EDITCGRPCVT could return NULL if the
kernel version was less than 2.6.24.  Then with NULL
ps would display a "-" while top would show "n/a".

And while unlikely, with the PROC_FILLSTATUS flag (via
status2proc) a NULL supgid address was theoretically
possible and both ps and top would then show "n/a".

This commit standardizes the following usage:
  . PROC_FILLSTATUS         (via status2proc)
      guarantees a valid supgid address
      representing either a true comma
      delimited list or "-"
  . PROC_FILLCGROUP  plus
    PROC_EDITCGRPCVT        (via fill_cgroup_cvt)
      guarantees a cgroup single vector
      representing either a true control
      group hierarchy or "-"

And as was true before, the following remains true:
    PROC_FILLCOM     or
    PROC_FILLARG            (via file2strvec)
      may return a NULL cmdline pointer
  . PROC_FILLCGROUP         (via file2strvec)
      may return a NULL cgroup pointer
  . PROC_FILLCOM     or
    PROC_FILLARG     plus
    PROC_EDITCMDLCVT        (via fill_cmdline_cvt)
      guarantees a cmdline single vector
      representing either a true command
      line or a bracketed program name
  . PROC_FILLSTATUS  plus
    PROC_FILLSUPGRP         (via supgrps_from_supgids)
      guarantees a valid supgrp address
      representing either a true comma
      delimited list or "-"

Signed-off-by: Jim Warner <james.warner@comcast.net>
This commit is contained in:
Jim Warner 2012-06-28 00:00:01 -05:00 committed by Craig Small
parent f4b6de1136
commit 8b64b36bbf
1 changed files with 6 additions and 6 deletions
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12
proc/readproc.c
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@ -362,8 +362,7 @@ ENTER(0x220);
for ( ; j; j--)
if (' ' == P->supgid[j])
P->supgid[j] = ',';
} else
P->supgid = xstrdup("-");
}
continue;
}
case_CapBnd:
@ -412,6 +411,9 @@ ENTER(0x220);
P->tid = Pid;
}
if (!P->supgid)
P->supgid = xstrdup("-");
LEAVE(0x220);
}
@ -793,8 +795,7 @@ static proc_t* simple_readproc(PROCTAB *restrict const PT, proc_t *restrict cons
} else
p->cmdline = NULL;
if ((flags & PROC_FILLCGROUP) // read /proc/#/cgroup
&& linux_version_code >= LINUX_VERSION(2,6,24)) {
if ((flags & PROC_FILLCGROUP)) { // read /proc/#/cgroup
if (flags & PROC_EDITCGRPCVT)
fill_cgroup_cvt(path, p);
else
@ -903,8 +904,7 @@ static proc_t* simple_readtask(PROCTAB *restrict const PT, const proc_t *restric
} else
t->cmdline = NULL;
if ((flags & PROC_FILLCGROUP) // read /proc/#/task/#/cgroup
&& linux_version_code >= LINUX_VERSION(2,6,24)) {
if ((flags & PROC_FILLCGROUP)) { // read /proc/#/task/#/cgroup
if (flags & PROC_EDITCGRPCVT)
fill_cgroup_cvt(path, t);
else