webber@athos.rutgers.edu (Bob Webber) (01/09/89)
/* This program writes contents of file descriptor fdin onto the contents of file descriptor fdout and then adjusts the size of fdout to be the size of fdin. If it is passed two parameters, the first is the file name for fdin and the second is the file name for fdout. If it is passed one parameter, then fdin is standard input and the one parameter is the file name for fdout. Note: code uses BSD/SunOS functions ftruncate. This is crucial to its usefulness. If someone knows a POSIX/V7 equiv, I would be interested in hearing of it. [Am posting question to comp.unix.wizards, so any discussion would be best there.] */ #include <stdio.h> #include <errno.h> #include <fcntl.h> #include <sys/types.h> #include <sys/file.h> #include <sys/param.h> extern long lseek(); main(argc,argv) int argc; char *argv[]; { int fdin, fdout; int ReadExit; int ReadSize; char chs[MAXBSIZE]; if (argc == 3) { if ((fdin = open(argv[1],O_RDONLY)) == -1) { perror("Error 1 : ((fdin = open(argv[1],O_RDONLY)) == -1):"); exit(1); } if (lseek(fdin,(long) 0,L_SET) != 0) { perror("Error 2 :(lseek(fdin,(long) 0,L_SET) != 0): "); exit(2); } if ((fdout = open(argv[2],O_WRONLY)) == -1) { perror("Error 3 : ((fdout = open(argv[2],O_WRONLY)) == -1):"); exit(3); } if (lseek(fdout,(long) 0,L_SET) != 0) { perror("Error 4 : (lseek(fdout,(long) 0,L_SET) != 0) :"); exit(4); } } else if (argc == 2) { fdin = 0; if ((fdout = open(argv[1],O_WRONLY)) == -1) { perror("Error 5 :((fdout = open(argv[1],O_WRONLY)) == -1) :"); exit(5); } if (lseek(fdout,(long) 0,L_SET) != 0) { perror("Error 6 : (lseek(fdout,(long) 0,L_SET) != 0) :"); exit(6); } } else { (void)fprintf(stderr,"Error 7 [%d]: Read the source before using\n",argc); exit(7); } ReadSize = 0; while ((ReadExit = read(fdin,chs,MAXBSIZE)) >0) { ReadSize += ReadExit; if (write(fdout,chs,ReadExit) != ReadExit) { perror("Error 8 :(write(fdout,chs,ReadExit) != ReadExit) :"); exit(8); } } if (ReadExit == 0) { /* reached end of input file */ if (ftruncate(fdout,ReadSize) != 0) { perror("Error 9 :(ftruncate(fdout,ReadSize) != 0) :"); exit(9); } } else { perror("Error 10 : read(fdin,chs,MAXBSIZE) <0 :"); exit(10); } exit(0); }