On Sun, May 01, 2016 at 01:24:19AM +0300, Vadim Zhukov wrote:
> When matching by PID, we'd better return ESRCH expicitly rather
> than zero entries. This makes, for example, fstat(1) behaviour
> more consistent and makes it easier to replace "if lsof -p ..."
> checks in third-party code with "if fstat -p ...".
>
> For libkvm, I explicitly test for ESRCH to avoid going inside
> kmem without real need.
>
> Tested on amd64.
>
> Comments? Okays?
Your use case makes sense. So I think this should go in.
Can we have the same logic for KERN_FILE_BYPID and KERN_FILE_BYUID?
man kvm_getfiles says (-1 for all processes), but code does arg > 0.
I think it should be arg => 0 like in KERN_FILE_BYUID.
The (arg < -1) EINVAL check is missing in KERN_FILE_BYUID. Does
anyone know why?
errno ESRCH should be documented in kvm_getfiles(3).
exit code 1 should be documented in fstat(1). Should it behave
like grep?
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bluhm
>
> --
> WBR,
> Vadim Zhukov
>
>
> Index: sys/kern/kern_sysctl.c
> ===================================================================
> RCS file: /cvs/src/sys/kern/kern_sysctl.c,v
> retrieving revision 1.300
> diff -u -p -r1.300 kern_sysctl.c
> --- sys/kern/kern_sysctl.c 29 Feb 2016 19:44:07 -0000 1.300
> +++ sys/kern/kern_sysctl.c 30 Apr 2016 22:26:06 -0000
> @@ -1225,7 +1225,7 @@ sysctl_file(int *name, u_int namelen, ch
> struct process *pr;
> size_t buflen, elem_size, elem_count, outsize;
> char *dp = where;
> - int arg, i, error = 0, needed = 0;
> + int arg, i, error = 0, needed = 0, matched;
> u_int op;
> int show_pointers;
>
> @@ -1325,6 +1325,7 @@ sysctl_file(int *name, u_int namelen, ch
> error = EINVAL;
> break;
> }
> + matched = (arg <= 0);
> LIST_FOREACH(pr, &allprocess, ps_list) {
> /*
> * skip system, exiting, embryonic and undead
> @@ -1332,9 +1333,12 @@ sysctl_file(int *name, u_int namelen, ch
> */
> if (pr->ps_flags & (PS_SYSTEM | PS_EMBRYO | PS_EXITING))
> continue;
> - if (arg > 0 && pr->ps_pid != (pid_t)arg) {
> - /* not the pid we are looking for */
> - continue;
> + if (arg > 0) {
> + /* is this the pid we are looking for? */
> + if (pr->ps_pid == (pid_t)arg)
> + matched = 1;
> + else
> + continue;
> }
> fdp = pr->ps_fd;
> if (pr->ps_textvp)
> @@ -1353,6 +1357,8 @@ sysctl_file(int *name, u_int namelen, ch
> FILLIT(fp, fdp, i, NULL, pr);
> }
> }
> + if (!matched)
> + error = ESRCH;
> break;
> case KERN_FILE_BYUID:
> LIST_FOREACH(pr, &allprocess, ps_list) {
> Index: lib/libkvm/kvm_file2.c
> ===================================================================
> RCS file: /cvs/src/lib/libkvm/kvm_file2.c,v
> retrieving revision 1.47
> diff -u -p -r1.47 kvm_file2.c
> --- lib/libkvm/kvm_file2.c 4 Sep 2015 02:58:14 -0000 1.47
> +++ lib/libkvm/kvm_file2.c 30 Apr 2016 22:26:06 -0000
> @@ -149,7 +149,7 @@ kvm_getfiles(kvm_t *kd, int op, int arg,
> /* find size and alloc buffer */
> rv = sysctl(mib, 6, NULL, &size, NULL, 0);
> if (rv == -1) {
> - if (kd->vmfd != -1)
> + if (errno != ESRCH && kd->vmfd != -1)
> goto deadway;
> _kvm_syserr(kd, kd->program, "kvm_getfiles");
> return (NULL);
> @@ -266,7 +266,7 @@ kvm_deadfile_byid(kvm_t *kd, int op, int
> {
> size_t buflen;
> struct nlist nl[4], *np;
> - int n = 0;
> + int n = 0, matched = 0;
> char *where;
> struct kinfo_file kf;
> struct file *fp, file;
> @@ -312,6 +312,9 @@ kvm_deadfile_byid(kvm_t *kd, int op, int
> kd->filebase = (void *)where;
> buflen = (nfiles + 10) * esize;
>
> + if (op != KERN_FILE_BYPID || arg <= 0)
> + matched = 1;
> +
> for (pr = LIST_FIRST(&allprocess);
> pr != NULL;
> pr = LIST_NEXT(&process, ps_list)) {
> @@ -333,10 +336,12 @@ kvm_deadfile_byid(kvm_t *kd, int op, int
> goto cleanup;
> }
>
> - if (op == KERN_FILE_BYPID && arg > 0 &&
> - proc.p_pid != (pid_t)arg) {
> - /* not the pid we are looking for */
> + if (op == KERN_FILE_BYPID) {
> + /* check if this is the pid we are looking for */
> + if (arg > 0 && proc.p_pid != (pid_t)arg)
> continue;
> + else
> + matched = 1;
> }
>
> if (KREAD(kd, (u_long)process.ps_ucred, &ucred)) {
> @@ -457,6 +462,10 @@ kvm_deadfile_byid(kvm_t *kd, int op, int
> buflen -= esize;
> n++;
> }
> + }
> + if (!matched) {
> + errno = ESRCH;
> + goto cleanup;
> }
> done:
> *cnt = n;
