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07a9c2e65d
libproc previously created a new handle for each symbol lookup, which gives rather egregious performance for DTrace's ustack() action. With this change libproc will cache the libelf descriptor upon access, making lookups much faster in the common case.
254 lines
5.9 KiB
C
254 lines
5.9 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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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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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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error = ENOMEM;
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if ((phdl = malloc(sizeof(*phdl))) == NULL)
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goto out;
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memset(phdl, 0, sizeof(*phdl));
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phdl->public.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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goto out;
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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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goto out;
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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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goto out;
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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, proc_getpid(phdl), 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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struct file_info *file;
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size_t i;
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for (i = 0; i < phdl->nmappings; i++) {
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file = phdl->mappings[i].file;
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if (file != NULL && --file->refs == 0) {
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if (file->elf != NULL) {
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(void)elf_end(file->elf);
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(void)close(file->fd);
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}
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free(file);
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}
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}
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if (phdl->maparrsz > 0)
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free(phdl->mappings);
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if (phdl->procstat != NULL)
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procstat_close(phdl->procstat);
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if (phdl->rdap != NULL)
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rd_delete(phdl->rdap);
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free(phdl);
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}
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