backup.c

操作系统源代码

/* backup - backup a directory		Author: Andy Tanenbaum */

/* This program recursively backs up a directory.  It has two typical uses:
 *
 * 1. Backing up a directory to 1 or more diskettes
 * 2. Backing up RAM disk to a shadow directory on hard disk
 *
 * The backup directory or medium may be empty, in which case, the entire
 * source directory is copied, or it may contain an old backup, in which
 * case only those files that are new or out of date are copied.  In this
 * respect, 'backup' resembles 'make', except that no 'makefile' is needed.
 * The backed up copy may optionally be compressed to save space.
 *
 * The following flags exist:
 *
 *	-d  At the top level, only back up directories (not loose files)
 *	-j  Don't copy junk: *.Z, *.bak, *.log, a.out, and core
 *	-m  If ENOSPC encountered, ask for another diskette
 *	-n  No directories, only loose files are backed up
 *	-o  Don't copy *.o files
 *	-r  Restore files (ie. uncompress if necessary)
 *	-s  Don't copy *.s files
 *	-t  Set creation date of target-file equal to cdate of source-file
 *	-v  Verbose (announce what is being done)
 *	-z  Compress on backup/uncompress on restore
 *
 * Patches:
 *	30 Mar 91.	Added restore option.  cwr. 
 *	 9 Sep 91.	Changed user interface.  cwr.
 *	21 Jan 93.	Revised error messages.  cwr.
 *	29 Mar 95.	Added -o, NARROW define.  cwr.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <utime.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>
#include <stdio.h>

#undef NARROW			/* Width of verbose output */
#define COPY_SIZE 4096
#define MAX_ENTRIES 512
#define DIR_ENT_SIZE 16
#define NAME_SIZE 14
#define MAX_PATH 256
#define NONFATAL 0
#define FATAL 1
#define NO_SAVINGS 512		/* compress can return code 2 */
#define OUT_OF_SPACE 2

struct dir_buf {		/* list of the src directory */
  unsigned short ino;
  char name[NAME_SIZE];
} dir_buf[MAX_ENTRIES];

struct sorted {
  int mode;			/* file mode */
  char *namep;			/* pointer to name in dir_buf */
  long acctime;			/* time of last access */
  long modtime;			/* time of last modification */
} sorted[MAX_ENTRIES];

char copybuf[COPY_SIZE];
char *pname;
int dflag, jflag, mflag, nflag, oflag, rflag, sflag, tflag, vflag, zflag;

extern int errno;
extern char **environ;

_PROTOTYPE(int main, (int argc, char **argv));
_PROTOTYPE(void maketarget, (char *dir2));
_PROTOTYPE(int make_dir, (char *dir));
_PROTOTYPE(int stat_all, (char *dir1, int n));
_PROTOTYPE(void sort_dir, (int m));
_PROTOTYPE(void process, (int m, char *dir1, char *dir2));
_PROTOTYPE(void swap, (struct sorted *sp1, struct sorted *sp2));
_PROTOTYPE(int copy, (char *dir1, struct sorted *sp, char *cbuf2));
_PROTOTYPE(int zcopy, (char *src, char *targ));
_PROTOTYPE(void copydir, (char *dir1, char *dir2, char *namep));
_PROTOTYPE(void newdisk, (char *dir));
_PROTOTYPE(void usage, (void));
_PROTOTYPE(void error, (int type, char *s1, char *s2, char *s3));

int main(argc, argv)
int argc;
char *argv[];
{
  int ct, n, m, fd;
  char *dir1, *dir2, *cp, c;
  struct stat s;

  (void) sync();

  /* Get the flags */
  if ((pname = strrchr(argv[0], '/')) == (char *)NULL)
	pname = argv[0];
  else
	pname++;
  if (argc < 3 || argc > 4) usage();
  if (argc == 4) {
	cp = argv[1];
	if (*cp++ != '-') usage();
	while ((c = *cp++) != '\0') {
		switch (c) {
		    case 'd':	dflag++;	break;
		    case 'j':	jflag++;	break;
		    case 'm':	mflag++;	break;
		    case 'n':	nflag++;	break;
		    case 'o':	oflag++;	break;
		    case 's':	sflag++;	break;
		    case 'r':	rflag++;	break;
		    case 't':	tflag++;	break;
		    case 'v':	vflag++;	break;
		    case 'z':	zflag++;	break;
		    default:	usage();
		}
	}
	dir1 = argv[2];
	dir2 = argv[3];
  } else {
	dir1 = argv[1];
	dir2 = argv[2];
  }
  if (!strcmp(pname, "restore") && !rflag) rflag++;

  /* Check for a valid source */
  if (stat(dir1, &s) < 0) error(FATAL, "cannot stat ", dir1, "");
  if ((s.st_mode & S_IFMT) != S_IFDIR) error(FATAL, "non-directory ", dir1, "");

  /* Read in the source directory */
  fd = open(dir1, O_RDONLY);
  if (fd < 0) error(FATAL, "cannot open ", dir1, "");
  ct = read(fd, (char *)&dir_buf[0], MAX_ENTRIES * DIR_ENT_SIZE);
  close(fd);
  if (ct == MAX_ENTRIES * DIR_ENT_SIZE)
	error(FATAL, "directory ", dir1, " is too large");

  /* Create the target directory. */
  maketarget(dir2);

  /* Stat all the entries. */
  n = ct / DIR_ENT_SIZE;
  m = stat_all(dir1, n);

  /* Remove non-entries and sort what's left. */
  sort_dir(m);

  /* Process each of the m entries one at a time. */
  process(m, dir1, dir2);
  return(0);
}


void maketarget(dir2)
char *dir2;
{
/* The target directory is created if it does not already exist. */

  char *p, c, dbuf[MAX_PATH];

  if (access(dir2, 6) == 0)
	return;			/* if target exists, we're done */
  if (make_dir(dir2) == 0) return;	/* we just made it */

  /* We have to try creating all the higher level directories. */
  strcpy(dbuf, dir2);
  p = dbuf + 1;
  while (1) {
	while (*p != '/' && *p != '\0') p++;
	c = *p;			/* either / or \0 */
	*p = 0;
	make_dir(dbuf);
	if (c == '\0') return;
	*p = c;
	p++;
  }
}

int make_dir(dir)
char *dir;
{
/* Create a directory. */
  int pid, status;

  if ((pid = fork()) < 0)
	error(FATAL, "cannot fork off mkdir to create ", dir, "");
  if (pid > 0) {
	/* Parent process waits for child (mkdir). */
	wait(&status);
	return(status);
  } else {
	/* Child process executes mkdir */
	close(2);		/* don't want mkdir's error messages */
	execle("/bin/mkdir", "mkdir", dir, (char *) 0, environ);
	execle("/usr/bin/mkdir", "mkdir", dir, (char *) 0, environ);
	error(FATAL, "cannot execute mkdir", "", "");
  }
  return(0);
}


int stat_all(dir1, n)
char *dir1;
int n;
{
/* Stat all the directory entries.  By doing this all at once, the disk
 * head can stay in the inode area.
 */

  int i, j;
  char cbuf[MAX_PATH];
  struct stat s;

  for (i = 0; i < n; i++) {
	/* Mark "." and ".." as null entries, as well as unstatable ones. */
	if (strcmp(dir_buf[i].name, ".") == 0) dir_buf[i].ino = 0;
	if (strcmp(dir_buf[i].name, "..") == 0) dir_buf[i].ino = 0;
	if (dir_buf[i].ino == 0) continue;

	/* Stat the file. */
	strcpy(cbuf, dir1);
	strncat(cbuf, "/", (size_t)1);
	strncat(cbuf, dir_buf[i].name, (size_t)NAME_SIZE);
	if (stat(cbuf, &s) < 0) {
		error(NONFATAL, "cannot stat ", cbuf, "");
		dir_buf[i].ino = 0;	/* mark as unusable */
		continue;
	}
	sorted[i].mode = s.st_mode;
	sorted[i].acctime = s.st_atime;
	sorted[i].modtime = s.st_mtime;
	sorted[i].namep = dir_buf[i].name;
  }

  /* Squeeze out all the entries whose ino field is 0. */
  j = 0;
  for (i = 0; i < n; i++) {
	if (dir_buf[i].ino != 0) {
		sorted[j] = sorted[i];
		j++;
	}
  }
  return(j);
}


void sort_dir(m)
int m;
{
/* Sort the directory using bubble sort. */

  struct sorted *sp1, *sp2;

  for (sp1 = &sorted[0]; sp1 < &sorted[m - 1]; sp1++) {
	for (sp2 = sp1 + 1; sp2 < &sorted[m]; sp2++) {
		if (strncmp(sp1->namep, sp2->namep, (size_t)NAME_SIZE) > 0)
			swap(sp1, sp2);
	}
  }
}


void process(m, dir1, dir2)
int m;
char *dir1, *dir2;
{
/* Process each entry in sorted[].  If it is a regular file, stat the target
 * file.  The the source is newer, copy it.  If the entry is a directory,
 * recursively call the entire program to process the directory.
 */

  int er, fmode, res, namlen;
  struct sorted *sp;
  struct stat s;
  char cbuf[MAX_PATH];

  for (sp = &sorted[0]; sp < &sorted[m]; sp++) {
	fmode = sp->mode & S_IFMT;
	if (fmode == S_IFREG) {
		/* Regular file.  Construct target name and stat it. */
		strcpy(cbuf, dir2);
		strncat(cbuf, "/", (size_t)1);
		strncat(cbuf, sp->namep, (size_t)NAME_SIZE);
		namlen = strlen(sp->namep);
		if (namlen > NAME_SIZE)
			namlen = NAME_SIZE; /* no terminating null here */
		/* Switch between compressed and uncompressed file names */
		if (zflag && !rflag && strncmp((sp->namep + namlen - 2), ".Z", (size_t)2)
				&& (namlen <= (NAME_SIZE - 2)))
			strncat(cbuf, ".Z", (size_t)2);
		if (zflag && rflag && !strncmp((sp->namep + namlen - 2), ".Z", (size_t)2))