/* swcinp( filecnt,fileptr ) is responsible for switching between input files for standard input. filecnt is the number of input filnames specified on the command line and fileptr is points to an array of character pointers. all files on the command line are read before the standard input provided by the shell. after all input is exhausted a -1 is returned to indicate EOF. */ int swcinp( filecnt,fileptr ) int filecnt; char *fileptr[]; { static int curfile = -1, originp = 0; register int fd; if (filecnt == 0) { if (originp == 0) { --originp; fd = 0; } else { fd = -1; } } else { if (originp == -1) return originp; if (originp == 0) originp = dup( 0 ); close( 0 ); fd = -1; if (curfile < filecnt - 1) { do { fd = open( fileptr[++curfile],0 ); if (fd != 0) { register int len = 0; write( 2,"can't open ",11 ); while ( fileptr[curfile][len] != '\0' ) len++; write( 2,fileptr[curfile],len ); write( 2,"\n",1 ); } } while ( fd != 0 && curfile < filecnt - 1 ); } if ( curfile == filecnt - 1 && fd != 0 ) { if (originp > 0) { fd = dup( originp ); close( originp ); originp = -1; } else { fd = -1; } } } return fd; }