ar.c

一个表达式解析器

/* 
**   AR -- File Archiver
**
**   usage: ar -{dptux} arcfile [file...]
**
**   Ar collects text files into a single archive file.
**   Files can be extracted, new ones added,
**   old ones replaced or deleted, and
**   a list of the archive contents produced.
**
**   The first argument is a switch from the following set.
**   The second argument is the name of the archive file.
**   The third and subsequent arguments are file names. 
**
**   -d  delete named files from the library.
**   -p  print named, or all, files on stdout.
**   -t  table of contents of named, or all, files to stdout.
**   -u  update the archive by adding/replacing files
**       (used to create a new library).
**       If no file names are specified in the command line,
**       they are obtained from stdin.
**   -x  extract named, or all, files.
**
**   Control-S to pause execution and control-C to abort.
**
**   This program was given as a class assignment in the
**   Computer Science Department at the University of Arizona.
**   It was contributed by Ernext Payne.  Orignially it was
**   written to work with tape archives, but this version has
**   been modified for higher speed operation with diskette
**   archives under CP/M.
*/

#include <stdio.h>

#define NAMESIZE 30
#define MAXLINE  500
#define MAXFILES 20
#define HDR      ">>>"
#define AUXSIZE  4096

char tname[]="  ar.$$$";
int fnptr[MAXFILES];
int fstat[MAXFILES];
int nfiles;
int errchk;

main(argc, argv) int argc, argv[]; {
  char cmd[3], aname[NAMESIZE];
  if(getarg(1,  cmd,       3,argc,argv) == EOF) usage();
  if(getarg(2,aname,NAMESIZE,argc,argv) == EOF) usage();
  if(aname[1] == ':') {
    tname[0] = aname[0];
    tname[1] = aname[1];
    }
  else left(tname);
  getfns(argc,argv);
  switch(toupper(cmd[1])) {
    case 'D': drop(aname);
              break;
    case 'T': table(aname);
              break;
    case 'U': update(aname);
              break;
    case 'X':
    case 'P': extract(aname, toupper(cmd[1]));
              break;
     default: usage();
    }
  }

/* acopy - copy size characters from fpi to fpo */
acopy(fpi,fpo,size) int fpi, fpo; int size; {
  int c;
  while(size-- > 0) {
    poll(YES);
    if((c = getc(fpi)) == EOF)
      break;
    putc(c,fpo);
    }
  }

/* addfile - add file "name" to archive */
addfile(name,fp) char *name; int fp; {
  int nfp;
  if((nfp = fopen(name,"r")) == NULL) {
    fprintf(stderr,"%s: can't open\n",name);
    errchk = 1;
    }
  if (errchk == 0) {
    if(name[1] == ':') name += 2;
    fprintf(fp,"%s %s %d\n",HDR,name,fsize(nfp));
    fcopy(nfp,fp);
    fclose(nfp);
    fprintf(stderr, " copied new %s\n", name);
    }
  }

/* amove - move file1 to file2 */
amove(file1,file2) char *file1, *file2; {
  if(errchk) {
    printf("fatal errors - archive not altered\n");
    unlink(file1);
    exit(7);
    }
  unlink(file2);
  if(file2[1] == ':') file2 += 2;
  if(rename(file1, file2)) {
    printf("can't rename %s to %s\n", file1, file2);
    exit(7);
    }
  }

/* cant - print file name and die */
cant(name) char *name; {
  fprintf(stderr,"%s: can't open\n",name);
  exit(7);
  }

/* drop - delete files from archive */
drop(aname) char *aname; {
  int afp, tfp;
  if(nfiles <= 0) /* protect innocents  */
    error("delete by name only");
  afp = mustopen(aname,"r");
  tfp = mustopen(tname,"w");
  auxbuf(tfp, AUXSIZE);
  replace(afp,tfp,'d');
  notfound();
  fclose(afp);
  fclose(tfp);
  amove(tname,aname);
  }

/* error - print message and die */
error(msg) char *msg; {
  fprintf(stderr,"%s\n",msg);
  exit(7);
  }

/* extract - extract files from archive */
extract(aname,cmd) char *aname, cmd; {
  int afp, efp;
  char ename[NAMESIZE], in[MAXLINE];
  int size;
  afp = mustopen(aname,"r");
  auxbuf(afp, AUXSIZE);
  if(cmd == 'P') efp = stdout;
  else           efp = NULL;
  while((size = gethdr(afp,in,ename)) >= 0)
    if(!fmatch(ename, YES)) fskip(afp,size);
    else {
      if(efp != stdout) efp = fopen(ename,"w");
      if(efp == NULL) {
        fprintf(stderr,"%s: can't create\n",ename);
        errchk = 1;
        fskip(afp,size);
        }
      else {
        if(cmd == 'P') {
          fprintf(efp, "\n哪哪哪哪哪哪哪哪哪哪哪哪哪哪哪哪哪