100 lines
2.5 KiB
C
100 lines
2.5 KiB
C
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/* @(#)procnameat.c 1.2 11/10/22 Copyright 2011 J. Schilling */
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/*
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* Return a path name for a /proc related access to fd/name if possible.
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*
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* We need to test this at runtime in order to avoid incorrect behavior
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* from running a program on a newer OS that it has been compiled for.
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*
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* NOTE: The entries /proc/self/{fd|path}/%d are symlinks and thus do
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* not allow to access paths of unlimited length as possible
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* with a real openat(fd, name, flags) call.
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*
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* Copyright (c) 2011 J. Schilling
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*/
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/*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License, Version 1.0 only
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* (the "License"). You may not use this file except in compliance
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* with the License.
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*
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* See the file CDDL.Schily.txt in this distribution for details.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file CDDL.Schily.txt from this distribution.
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*/
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#include <schily/unistd.h>
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#include <schily/types.h>
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#include <schily/fcntl.h>
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#include <schily/maxpath.h>
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#include <schily/errno.h>
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#include <schily/standard.h>
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#include <schily/schily.h>
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#include "at-defs.h"
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#ifndef ENAMETOOLONG
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#define ENAMETOOLONG EINVAL
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#endif
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#define PROC_SELF_FD_FORMAT "/proc/self/fd/%d/%s" /* Older procfs */
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#define PROC_SELF_PATH_FORMAT "/proc/self/path/%d/%s" /* Newer procfs */
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#define PROC_PID_FD_FORMAT "/proc/%ld/fd/%d/%s" /* AIX has no self */
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char *
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proc_fd2name(buf, fd, name)
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char *buf;
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int fd;
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const char *name;
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{
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static int proc_type;
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if (proc_type == 0) {
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int proc_fd;
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/*
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* First test the newer feature as the older /proc/self/fd/%d
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* feature is still available on newer systems.
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*/
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proc_fd = open("/proc/self/path", O_SEARCH);
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if (proc_fd >= 0) {
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proc_type = 1;
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close(proc_fd);
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} else {
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proc_fd = open("/proc/self/fd", O_SEARCH);
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if (proc_fd >= 0) {
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proc_type = 2;
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close(proc_fd);
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} else {
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js_snprintf(buf, PATH_MAX,
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"/proc/%ld/fd", (long)getpid());
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proc_fd = open(buf, O_SEARCH);
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if (proc_fd >= 0) {
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proc_type = 3;
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close(proc_fd);
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} else {
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proc_type = -1;
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return ((char *)0);
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}
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}
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}
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} else if (proc_type < 0) {
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return ((char *)0);
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}
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if (proc_type == 3) {
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if (js_snprintf(buf, PATH_MAX,
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PROC_PID_FD_FORMAT,
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(long)getpid(), fd, name) >= PATH_MAX) {
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seterrno(ENAMETOOLONG);
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return (NULL);
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}
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} else if (js_snprintf(buf, PATH_MAX,
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proc_type == 1 ?
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PROC_SELF_PATH_FORMAT :
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PROC_SELF_FD_FORMAT,
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fd, name) >= PATH_MAX) {
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seterrno(ENAMETOOLONG);
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return (NULL);
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}
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return (buf);
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}
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