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4808a67805
This is used by libdtrace to determine the data model of target processes. This allows for the creation of pid provider probes in 32-bit processes on amd64. MFC after: 1 month
237 lines
5.5 KiB
C
237 lines
5.5 KiB
C
/*-
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* Copyright (c) 2008 John Birrell (jb@freebsd.org)
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include <sys/types.h>
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#include <sys/sysctl.h>
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#include <sys/user.h>
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#include <sys/wait.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <libelf.h>
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#include <libprocstat.h>
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#include "_libproc.h"
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static int getelfclass(int);
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static int proc_init(pid_t, int, int, struct proc_handle **);
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static int
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getelfclass(int fd)
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{
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GElf_Ehdr ehdr;
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Elf *e;
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int class;
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class = ELFCLASSNONE;
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if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL)
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goto out;
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if (gelf_getehdr(e, &ehdr) == NULL)
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goto out;
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class = ehdr.e_ident[EI_CLASS];
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out:
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(void)elf_end(e);
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return (class);
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}
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static int
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proc_init(pid_t pid, int flags, int status, struct proc_handle **pphdl)
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{
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struct kinfo_proc *kp;
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struct proc_handle *phdl;
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int error, class, count, fd;
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*pphdl = NULL;
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if ((phdl = malloc(sizeof(*phdl))) == NULL)
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return (ENOMEM);
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memset(phdl, 0, sizeof(*phdl));
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phdl->pid = pid;
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phdl->flags = flags;
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phdl->status = status;
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phdl->procstat = procstat_open_sysctl();
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if (phdl->procstat == NULL)
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return (ENOMEM);
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/* Obtain a path to the executable. */
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if ((kp = procstat_getprocs(phdl->procstat, KERN_PROC_PID, pid,
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&count)) == NULL)
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return (ENOMEM);
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error = procstat_getpathname(phdl->procstat, kp, phdl->execpath,
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sizeof(phdl->execpath));
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procstat_freeprocs(phdl->procstat, kp);
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if (error != 0)
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return (error);
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/* Use it to determine the data model for the process. */
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if ((fd = open(phdl->execpath, O_RDONLY)) < 0) {
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error = errno;
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goto out;
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}
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class = getelfclass(fd);
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switch (class) {
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case ELFCLASS64:
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phdl->model = PR_MODEL_LP64;
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break;
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case ELFCLASS32:
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phdl->model = PR_MODEL_ILP32;
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break;
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case ELFCLASSNONE:
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default:
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error = EINVAL;
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break;
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}
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(void)close(fd);
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out:
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*pphdl = phdl;
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return (error);
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}
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int
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proc_attach(pid_t pid, int flags, struct proc_handle **pphdl)
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{
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struct proc_handle *phdl;
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int error, status;
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if (pid == 0 || pid == getpid())
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return (EINVAL);
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if (elf_version(EV_CURRENT) == EV_NONE)
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return (ENOENT);
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/*
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* Allocate memory for the process handle, a structure containing
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* all things related to the process.
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*/
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error = proc_init(pid, flags, PS_RUN, &phdl);
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if (error != 0)
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goto out;
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if (ptrace(PT_ATTACH, phdl->pid, 0, 0) != 0) {
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error = errno;
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DPRINTF("ERROR: cannot ptrace child process %d", pid);
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goto out;
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}
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/* Wait for the child process to stop. */
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if (waitpid(pid, &status, WUNTRACED) == -1) {
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error = errno;
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DPRINTF("ERROR: child process %d didn't stop as expected", pid);
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goto out;
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}
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/* Check for an unexpected status. */
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if (!WIFSTOPPED(status))
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DPRINTFX("ERROR: child process %d status 0x%x", pid, status);
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else
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phdl->status = PS_STOP;
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out:
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if (error && phdl != NULL) {
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proc_free(phdl);
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phdl = NULL;
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}
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*pphdl = phdl;
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return (error);
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}
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int
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proc_create(const char *file, char * const *argv, proc_child_func *pcf,
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void *child_arg, struct proc_handle **pphdl)
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{
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struct proc_handle *phdl;
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int error = 0;
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int status;
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pid_t pid;
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if (elf_version(EV_CURRENT) == EV_NONE)
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return (ENOENT);
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/* Fork a new process. */
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if ((pid = vfork()) == -1)
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error = errno;
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else if (pid == 0) {
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/* The child expects to be traced. */
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if (ptrace(PT_TRACE_ME, 0, 0, 0) != 0)
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_exit(1);
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if (pcf != NULL)
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(*pcf)(child_arg);
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/* Execute the specified file: */
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execvp(file, argv);
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/* Couldn't execute the file. */
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_exit(2);
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/* NOTREACHED */
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} else {
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/* The parent owns the process handle. */
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error = proc_init(pid, 0, PS_IDLE, &phdl);
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if (error != 0)
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goto bad;
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/* Wait for the child process to stop. */
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if (waitpid(pid, &status, WUNTRACED) == -1) {
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error = errno;
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DPRINTF("ERROR: child process %d didn't stop as expected", pid);
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goto bad;
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}
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/* Check for an unexpected status. */
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if (!WIFSTOPPED(status)) {
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error = errno;
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DPRINTFX("ERROR: child process %d status 0x%x", pid, status);
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goto bad;
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} else
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phdl->status = PS_STOP;
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}
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bad:
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if (error && phdl != NULL) {
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proc_free(phdl);
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phdl = NULL;
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}
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*pphdl = phdl;
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return (error);
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}
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void
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proc_free(struct proc_handle *phdl)
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{
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if (phdl->procstat != NULL)
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procstat_close(phdl->procstat);
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free(phdl);
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}
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