Author: markj
Date: Tue Dec 6 04:22:38 2016
New Revision: 309597
URL: https://svnweb.freebsd.org/changeset/base/309597
Log:
libproc: Add support for some proc_attach() flags.
This change adds some handling for the equivalent of Solaris' PGRAB_*
flags. In particular, support for PGRAB_RDONLY is needed to avoid a
nasty deadlock: dtrace(1) may otherwise stop the master process for its
pseudo-terminal and end up blocking while writing to standard output.
Modified:
head/cddl/compat/opensolaris/include/libproc.h
head/cddl/lib/libdtrace/libproc_compat.h
head/lib/libproc/libproc.h
head/lib/libproc/proc_create.c
head/lib/libproc/proc_util.c
Modified: head/cddl/compat/opensolaris/include/libproc.h
==============================================================================
--- head/cddl/compat/opensolaris/include/libproc.h Tue Dec 6 04:21:35
2016 (r309596)
+++ head/cddl/compat/opensolaris/include/libproc.h Tue Dec 6 04:22:38
2016 (r309597)
@@ -38,9 +38,6 @@
#define PR_RLC 0x0001
#define PR_KLC 0x0002
-#define PGRAB_RDONLY O_RDONLY
-#define PGRAB_FORCE 0
-
#include_next <libproc.h>
#endif
Modified: head/cddl/lib/libdtrace/libproc_compat.h
==============================================================================
--- head/cddl/lib/libdtrace/libproc_compat.h Tue Dec 6 04:21:35 2016
(r309596)
+++ head/cddl/lib/libdtrace/libproc_compat.h Tue Dec 6 04:22:38 2016
(r309597)
@@ -34,6 +34,9 @@
* Functions sorted alphabetically.
*/
#define PR_LMID_EVERY 0
+#define PGRAB_RDONLY PATTACH_RDONLY
+#define PGRAB_FORCE PATTACH_FORCE
+
#define Psetrun(p, a1, a2) proc_continue((p))
#define Pxlookup_by_addr(p, a, n, s, sym, i) \
proc_addr2sym(p, a, n, s, sym)
Modified: head/lib/libproc/libproc.h
==============================================================================
--- head/lib/libproc/libproc.h Tue Dec 6 04:21:35 2016 (r309596)
+++ head/lib/libproc/libproc.h Tue Dec 6 04:22:38 2016 (r309597)
@@ -50,6 +50,11 @@ typedef void (*proc_child_func)(void *);
#define PS_DEAD 5
#define PS_LOST 6
+/* Flags for proc_attach(). */
+#define PATTACH_FORCE 0x01
+#define PATTACH_RDONLY 0x02
+#define PATTACH_NOSTOP 0x04
+
/* Reason values for proc_detach(). */
#define PRELEASE_HANG 1
#define PRELEASE_KILL 2
Modified: head/lib/libproc/proc_create.c
==============================================================================
--- head/lib/libproc/proc_create.c Tue Dec 6 04:21:35 2016
(r309596)
+++ head/lib/libproc/proc_create.c Tue Dec 6 04:22:38 2016
(r309597)
@@ -127,7 +127,7 @@ proc_attach(pid_t pid, int flags, struct
struct proc_handle *phdl;
int error, status;
- if (pid == 0 || pid == getpid())
+ if (pid == 0 || (pid == getpid() && (flags & PATTACH_RDONLY) == 0))
return (EINVAL);
if (elf_version(EV_CURRENT) == EV_NONE)
return (ENOENT);
@@ -140,27 +140,32 @@ proc_attach(pid_t pid, int flags, struct
if (error != 0)
goto out;
- if (ptrace(PT_ATTACH, proc_getpid(phdl), 0, 0) != 0) {
- error = errno;
- DPRINTF("ERROR: cannot ptrace child process %d", pid);
- goto out;
- }
+ if ((flags & PATTACH_RDONLY) == 0) {
+ if (ptrace(PT_ATTACH, proc_getpid(phdl), 0, 0) != 0) {
+ error = errno;
+ DPRINTF("ERROR: cannot ptrace child process %d", pid);
+ goto out;
+ }
- /* Wait for the child process to stop. */
- if (waitpid(pid, &status, WUNTRACED) == -1) {
- error = errno;
- DPRINTF("ERROR: child process %d didn't stop as expected", pid);
- goto out;
- }
+ /* Wait for the child process to stop. */
+ if (waitpid(pid, &status, WUNTRACED) == -1) {
+ error = errno;
+ DPRINTF("ERROR: child process %d didn't stop as
expected", pid);
+ goto out;
+ }
- /* Check for an unexpected status. */
- if (!WIFSTOPPED(status))
- DPRINTFX("ERROR: child process %d status 0x%x", pid, status);
- else
- phdl->status = PS_STOP;
+ /* Check for an unexpected status. */
+ if (!WIFSTOPPED(status))
+ DPRINTFX("ERROR: child process %d status 0x%x", pid,
status);
+ else
+ phdl->status = PS_STOP;
+
+ if ((flags & PATTACH_NOSTOP) != 0)
+ proc_continue(phdl);
+ }
out:
- if (error && phdl != NULL) {
+ if (error != 0 && phdl != NULL) {
proc_free(phdl);
phdl = NULL;
}
Modified: head/lib/libproc/proc_util.c
==============================================================================
--- head/lib/libproc/proc_util.c Tue Dec 6 04:21:35 2016
(r309596)
+++ head/lib/libproc/proc_util.c Tue Dec 6 04:22:38 2016
(r309597)
@@ -87,21 +87,25 @@ proc_detach(struct proc_handle *phdl, in
if (phdl == NULL)
return (EINVAL);
+ if (reason == PRELEASE_HANG)
+ return (EINVAL);
if (reason == PRELEASE_KILL) {
kill(proc_getpid(phdl), SIGKILL);
- return (0);
+ goto free;
}
+ if ((phdl->flags & PATTACH_RDONLY) != 0)
+ goto free;
pid = proc_getpid(phdl);
if (ptrace(PT_DETACH, pid, 0, 0) != 0 && errno == ESRCH)
- return (0);
+ goto free;
if (errno == EBUSY) {
kill(pid, SIGSTOP);
waitpid(pid, &status, WUNTRACED);
ptrace(PT_DETACH, pid, 0, 0);
kill(pid, SIGCONT);
- return (0);
}
-
+free:
+ proc_free(phdl);
return (0);
}
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