wrapper.c

samba-3.0.22.tar.gz 编译smb服务器的源码

/* 
   Unix SMB/Netbios implementation.
   Version 2.0
   SMB wrapper functions
   Copyright (C) Andrew Tridgell 1998
   Copyright (C) Derrell Lipman 2002-2005
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/*
 * This is a rewrite of the original wrapped.c file, using libdl to obtain
 * pointers into the C library rather than attempting to find undocumented
 * functions in the C library to call for native file access.  The problem
 * with the original implementation's paradigm is that samba manipulates
 * defines such that it gets the sizes of structures that it wants
 * (e.g. mapping 32-bit functions to 64-bit functions with their associated
 * 64-bit structure fields), but programs run under smbsh or using
 * smbwrapper.so were not necessarily compiled with the same flags.  As an
 * example of the problem, a program calling stat() passes a pointer to a
 * "struct stat" but the fields in that structure are different in samba than
 * they are in the calling program if the calling program was not compiled to
 * force stat() to be mapped to stat64().
 *
 * In this version, we provide an interface to each of the native functions,
 * not just the ones that samba is compiled to map to.  We obtain the function
 * pointers from the C library using dlsym(), and for native file operations,
 * directly call the same function that the calling application was
 * requesting.  Since the size of the calling application's structures vary
 * depending on what function was called, we use our own internal structures
 * for passing information to/from the SMB equivalent functions, and map them
 * back to the native structures before returning the result to the caller.
 *
 * This implementation was completed 25 December 2002.
 * Derrell Lipman
 */

/* We do not want auto munging of 32->64 bit names in this file (only) */
#undef _FILE_OFFSET_BITS
#undef _GNU_SOURCE

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <utime.h>
#include <stdio.h>
#include <dirent.h>
#include <signal.h>
#include <stdarg.h>
#ifdef __USE_GNU
# define SMBW_USE_GNU
#endif
#define __USE_GNU             /* need this to have RTLD_NEXT defined */
#include <dlfcn.h>
#ifndef SMBW_USE_GNU
# undef __USE_GNU
#endif
#include <errno.h>
#include "libsmbclient.h"
#include "bsd-strlfunc.h"
#include "wrapper.h"

/*
 * Debug bits:
 * 0x0 = none
 * 0x1 = display symbol definitions not found in C library
 * 0x2 = show wrapper functions being called
 * 0x4 = log to file SMBW_DEBUG_FILE instead of stderr
 */
#define SMBW_DEBUG      0x0
#define SMBW_DEBUG_FILE "/tmp/smbw.log"

int      smbw_debug = 0;

#if SMBW_DEBUG & 0x2
static int      debugFd = 2;
#endif

#ifndef ENOTSUP
#define ENOTSUP EOPNOTSUPP
#endif

/*
 * None of the methods of having the initialization function called
 * automatically upon shared library startup are effective in all situations.
 * We provide the "-init" parameter to the linker which is effective most of
 * the time, but fails for applications that provide their own shared
 * libraries with _init() functions (e.g. ps).  We can't use "-z initfirst"
 * because the environment isn't yet set up at that point, so we can't find
 * our shared memory identifier (see shared.c).  We therefore must resort to
 * this tried-and-true method of keeping an "initialized" flag.  We check it
 * prior to calling the initialize() function to save a function call (a slow
 * operation on x86).
 */
#if SMBW_DEBUG & 0x2
#  define check_init(buf)                                               \
        do {                                                            \
                int saved_errno = errno;                                \
                if (! initialized) initialize();                        \
                (* smbw_libc.write)(debugFd, "["buf"]", sizeof(buf)+1); \
                errno = saved_errno;                                    \
        } while (0)
#else
#  define check_init(buf)                               \
        do {                                            \
                if (! initialized) smbw_initialize();   \
        } while (0)
#endif

static void initialize(void);

static int initialized = 0;

SMBW_libc_pointers smbw_libc;

/*
 * A public entry point used by the "-init" option to the linker.
 */
void smbw_initialize(void)
{
        initialize();
}

static void initialize(void)
{
        int saved_errno;
#if SMBW_DEBUG & 0x1
        char *error;
#endif
        
        saved_errno = errno;
        
        if (initialized) {
                return;
        }
        initialized = 1;
        
#if SMBW_DEBUG & 0x1
# define GETSYM(symname, symstring)                                      \
        if ((smbw_libc.symname = dlsym(RTLD_NEXT, symstring)) == NULL) { \
                if (smbw_libc.write != NULL &&                           \
                    (error = dlerror()) != NULL) {                       \
                        (* smbw_libc.write)(1, error, strlen(error));    \
                        (* smbw_libc.write)(1, "\n", 1);                 \
                }                                                        \
        }
#else
# define GETSYM(symname, symstring)                     \
        smbw_libc.symname = dlsym(RTLD_NEXT, symstring);
#endif
        
        /*
         * Get pointers to each of the symbols we'll need, from the C library
         *
         * Some of these symbols may not be found in the C library.  That's
         * fine.  We declare all of them here, and if the C library supports
         * them, they may be called so we have the wrappers for them.  If the
         * C library doesn't support them, then the wrapper function will
         * never be called, and the null pointer will never be dereferenced.
         */
        GETSYM(write, "write"); /* first, to allow debugging */
        GETSYM(open, "open");
        GETSYM(_open, "_open");
        GETSYM(__open, "__open");
        GETSYM(open64, "open64");
        GETSYM(_open64, "_open64");
        GETSYM(__open64, "__open64");
        GETSYM(pread, "pread");
        GETSYM(pread64, "pread64");
        GETSYM(pwrite, "pwrite");
        GETSYM(pwrite64, "pwrite64");
        GETSYM(close, "close");
        GETSYM(__close, "__close");
        GETSYM(_close, "_close");
        GETSYM(fcntl, "fcntl");
        GETSYM(__fcntl, "__fcntl");
        GETSYM(_fcntl, "_fcntl");
        GETSYM(getdents, "getdents");
        GETSYM(__getdents, "__getdents");
        GETSYM(_getdents, "_getdents");
        GETSYM(getdents64, "getdents64");
        GETSYM(lseek, "lseek");
        GETSYM(__lseek, "__lseek");
        GETSYM(_lseek, "_lseek");
        GETSYM(lseek64, "lseek64");
        GETSYM(__lseek64, "__lseek64");
        GETSYM(_lseek64, "_lseek64");
        GETSYM(read, "read");
        GETSYM(__read, "__read");
        GETSYM(_read, "_read");
        GETSYM(__write, "__write");
        GETSYM(_write, "_write");
        GETSYM(access, "access");
        GETSYM(chmod, "chmod");
        GETSYM(fchmod, "fchmod");
        GETSYM(chown, "chown");
        GETSYM(fchown, "fchown");
        GETSYM(__xstat, "__xstat");
        GETSYM(getcwd, "getcwd");
        GETSYM(mkdir, "mkdir");
        GETSYM(__fxstat, "__fxstat");
        GETSYM(__lxstat, "__lxstat");
        GETSYM(stat, "stat");
        GETSYM(lstat, "lstat");
        GETSYM(fstat, "fstat");
        GETSYM(unlink, "unlink");
        GETSYM(utime, "utime");
        GETSYM(utimes, "utimes");
        GETSYM(readlink, "readlink");
        GETSYM(rename, "rename");
        GETSYM(rmdir, "rmdir");
        GETSYM(symlink, "symlink");
        GETSYM(dup, "dup");
        GETSYM(dup2, "dup2");
        GETSYM(opendir, "opendir");
        GETSYM(readdir, "readdir");
        GETSYM(closedir, "closedir");
        GETSYM(telldir, "telldir");
        GETSYM(seekdir, "seekdir");
        GETSYM(creat, "creat");
        GETSYM(creat64, "creat64");
        GETSYM(__xstat64, "__xstat64");
        GETSYM(stat64, "stat64");
        GETSYM(__fxstat64, "__fxstat64");
        GETSYM(fstat64, "fstat64");
        GETSYM(__lxstat64, "__lxstat64");
        GETSYM(lstat64, "lstat64");
        GETSYM(_llseek, "_llseek");
        GETSYM(readdir64, "readdir64");
        GETSYM(readdir_r, "readdir_r");
        GETSYM(readdir64_r, "readdir64_r");
        GETSYM(setxattr, "setxattr");
        GETSYM(lsetxattr, "lsetxattr");
        GETSYM(fsetxattr, "fsetxattr");
        GETSYM(getxattr, "getxattr");
        GETSYM(lgetxattr, "lgetxattr");
        GETSYM(fgetxattr, "fgetxattr");
        GETSYM(removexattr, "removexattr");
        GETSYM(lremovexattr, "lremovexattr");
        GETSYM(fremovexattr, "fremovexattr");
        GETSYM(listxattr, "listxattr");
        GETSYM(llistxattr, "llistxattr");
        GETSYM(flistxattr, "flistxattr");
        GETSYM(chdir, "chdir");
        GETSYM(fchdir, "fchdir");
        GETSYM(fork, "fork");
        GETSYM(select, "select");
        GETSYM(_select, "_select");
        GETSYM(__select, "__select");
        
#if SMBW_DEBUG & 4
        {
                if ((debugFd =
                     open(SMBW_DEBUG_FILE, O_WRONLY | O_CREAT | O_APPEND)) < 0)
                {
#               define SMBW_MESSAGE    "Could not create " SMBW_DEBUG_FILE "\n" 
                        (* smbw_libc.write)(1, SMBW_MESSAGE, sizeof(SMBW_MESSAGE));
#               undef SMBW_MESSAGE
                        exit(1);
                }
        }
#endif
        
        errno = saved_errno;
}

/**
 ** Static Functions
 **/

static void stat_convert(struct SMBW_stat *src, struct stat *dest)
{
        memset(dest, '\0', sizeof(*dest));
	dest->st_size = src->s_size;
	dest->st_mode = src->s_mode;
	dest->st_ino = src->s_ino;
	dest->st_dev = src->s_dev;
	dest->st_rdev = src->s_rdev;
	dest->st_nlink = src->s_nlink;
	dest->st_uid = src->s_uid;
	dest->st_gid = src->s_gid;
	dest->st_atime = src->s_atime;
	dest->st_mtime = src->s_mtime;
	dest->st_ctime = src->s_ctime;
	dest->st_blksize = src->s_blksize;
	dest->st_blocks = src->s_blocks;
}

static void stat64_convert(struct SMBW_stat *src, struct stat64 *dest)
{
        memset(dest, '\0', sizeof(*dest));
	dest->st_size = src->s_size;
	dest->st_mode = src->s_mode;
	dest->st_ino = src->s_ino;
	dest->st_dev = src->s_dev;
	dest->st_rdev = src->s_rdev;
	dest->st_nlink = src->s_nlink;
	dest->st_uid = src->s_uid;
	dest->st_gid = src->s_gid;
	dest->st_atime = src->s_atime;
	dest->st_mtime = src->s_mtime;
	dest->st_ctime = src->s_ctime;
	dest->st_blksize = src->s_blksize;
	dest->st_blocks = src->s_blocks;
}

static void dirent_convert(struct SMBW_dirent *src, struct dirent *dest)
{
        char *p;
        
        memset(dest, '\0', sizeof(*dest));
	dest->d_ino = src->d_ino;
	dest->d_off = src->d_off;
        
        switch(src->d_type)
        {
        case SMBC_WORKGROUP:
        case SMBC_SERVER:
        case SMBC_FILE_SHARE:
        case SMBC_DIR:
                dest->d_type = DT_DIR;
                break;
                
        case SMBC_FILE:
                dest->d_type = DT_REG;
                break;
                
        case SMBC_PRINTER_SHARE:
                dest->d_type = DT_CHR;
                break;
                
        case SMBC_COMMS_SHARE:
                dest->d_type = DT_SOCK;
                break;
                
        case SMBC_IPC_SHARE:
                dest->d_type = DT_FIFO;
                break;
                
        case SMBC_LINK:
                dest->d_type = DT_LNK;
                break;
        }
        
	dest->d_reclen = src->d_reclen;
	smbw_strlcpy(dest->d_name, src->d_name, sizeof(dest->d_name));
        p = dest->d_name + strlen(dest->d_name) + 1;
        smbw_strlcpy(p,
                     src->d_comment,
                     sizeof(dest->d_name) - (p - dest->d_name));
}

static void dirent64_convert(struct SMBW_dirent *src, struct dirent64 *dest)
{
        char *p;
        
        memset(dest, '\0', sizeof(*dest));
	dest->d_ino = src->d_ino;
	dest->d_off = src->d_off;
        
        switch(src->d_type)
        {
        case SMBC_WORKGROUP:
        case SMBC_SERVER:
        case SMBC_FILE_SHARE:
        case SMBC_DIR:
                dest->d_type = DT_DIR;
                break;
                
        case SMBC_FILE:
                dest->d_type = DT_REG;
                break;
                
        case SMBC_PRINTER_SHARE:
                dest->d_type = DT_CHR;
                break;
                
        case SMBC_COMMS_SHARE:
                dest->d_type = DT_SOCK;
                break;
                
        case SMBC_IPC_SHARE:
                dest->d_type = DT_FIFO;
                break;
                
        case SMBC_LINK:
                dest->d_type = DT_LNK;
                break;
        }
        
	dest->d_reclen = src->d_reclen;
	smbw_strlcpy(dest->d_name, src->d_name, sizeof(dest->d_name));
        p = dest->d_name + strlen(dest->d_name) + 1;
        smbw_strlcpy(p,
                     src->d_comment,
                     sizeof(dest->d_name) - (p - dest->d_name));
}

static int openx(char *name, int flags, mode_t mode, int (* f)(char *, int, mode_t))
{
	if (smbw_path(name)) {
		return smbw_open(name, flags, mode);
	}
        
        return (* f)(name, flags, mode);
}

static int closex(int fd, int (* f)(int fd))
{
	if (smbw_fd(fd)) {
		return smbw_close(fd);
	}
        
        return (* f)(fd);
}

static int fcntlx(int fd, int cmd, long arg, int (* f)(int, int, long))
{
	if (smbw_fd(fd)) {
		return smbw_fcntl(fd, cmd, arg);
	}
        
        return (* f)(fd, cmd, arg);
}

static int getdentsx(int fd, struct dirent *external, unsigned int count, int (* f)(int, struct dirent *, unsigned int))
{
	if (smbw_fd(fd)) {
                int i;
                int internal_count;
                struct SMBW_dirent *internal;
                int ret;
                int n;
                
                /*
                 * LIMITATION: If they pass a count which is not a multiple of
                 * the size of struct dirent, they will not get a partial
                 * structure; we ignore the excess count.
                 */
                n = (count / sizeof(struct dirent));
                
                internal_count = sizeof(struct SMBW_dirent) * n;
                internal = malloc(internal_count);
                if (internal == NULL) {
                        errno = ENOMEM;
                        return -1;
                }
		ret = smbw_getdents(fd, internal, internal_count);
                if (ret <= 0)
                        return ret;
                
                ret = sizeof(struct dirent) * n;
                
                for (i = 0; i < n; i++)
                        dirent_convert(&internal[i], &external[i]);
                
                return ret;
	}
        
        return (* f)(fd, external, count);
}

static off_t lseekx(int fd,
                    off_t offset,
                    int whence,
                    off_t (* f)(int, off_t, int))
{
        off_t           ret;
        
        /*
         * We have left the definitions of the smbw_ functions undefined,
         * because types such as off_t can differ in meaning betweent his
         * function and smbw.c et al.  Functions that return other than an
         * integer value, however, MUST have their return value defined.
         */
        off64_t         smbw_lseek();
        
        if (smbw_fd(fd)) {
		return (off_t) smbw_lseek(fd, offset, whence);
	}
        
        ret = (* f)(fd, offset, whence);
        if (smbw_debug)
        {
                printf("lseekx(%d, 0x%llx) returned 0x%llx\n",
                       fd,
                       (unsigned long long) offset,
                       (unsigned long long) ret);
        }
        return ret;
}

static off64_t lseek64x(int fd,
                        off64_t offset,
                        int whence,
                        off64_t (* f)(int, off64_t, int))
{
        off64_t         ret;
        
        /*
         * We have left the definitions of the smbw_ functions undefined,
         * because types such as off_t can differ in meaning betweent his
         * function and smbw.c et al.  Functions that return other than an
         * integer value, however, MUST have their return value defined.
         */
        off64_t         smbw_lseek();
        
	if (smbw_fd(fd))
		ret = smbw_lseek(fd, offset, whence);
        else
                ret = (* f)(fd, offset, whence);
        if (smbw_debug)
        {
                printf("lseek64x(%d, 0x%llx) returned 0x%llx\n",
                       fd,
                       (unsigned long long) offset,
                       (unsigned long long) ret);
        }
        return ret;
}

static ssize_t readx(int fd, void *buf, size_t count, ssize_t (* f)(int, void *, size_t))
{
	if (smbw_fd(fd)) {
		return smbw_read(fd, buf, count);
	}
        
        return (* f)(fd, buf, count);
}

static ssize_t writex(int fd, void *buf, size_t count, ssize_t (* f)(int, void *, size_t))
{
	if (smbw_fd(fd)) {
		return smbw_write(fd, buf, count);
	}
        
        return (* f)(fd, buf, count);
}


/**
 ** Wrapper Functions
 **/

int open(__const char *name, int flags, ...)
{
        va_list ap;
        mode_t mode;
        
        va_start(ap, flags);
        mode = va_arg(ap, mode_t);
        va_end(ap);
        
        check_init("open");
        
        return openx((char *) name, flags, mode, smbw_libc.open);
}

int _open(char *name, int flags, mode_t mode)
{
        check_init("open");