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	read.c - 9base - revived minimalist port of Plan 9 userland to Unix
	git clone git://git.suckless.org/9base
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	read.c (1771B)
	---
	1 #include <u.h>
	2 #include <libc.h>
	3
	4 int multi;
	5 int nlines;
	6 vlong nchars;
	7 char *status = nil;
	8
	9 int
	10 line(int fd, char *file)
	11 {
	12 char c;
	13 int m, n, nalloc;
	14 char *buf;
	15
	16 nalloc = 0;
	17 buf = nil;
	18 for(m=0; ; ){
	19 n = read(fd, &c, 1);
	20 if(n < 0){
	21 fprint(2, "read: error reading %s: %r\n", file);
	22 exits("read error");
	23 }
	24 if(n == 0){
	25 if(m == 0)
	26 status = "eof";
	27 break;
	28 }
	29 if(m == nalloc){
	30 nalloc += 1024;
	31 buf = realloc(buf, nalloc);
	32 if(buf == nil){
	33 fprint(2, "read: malloc error: %r\n");
	34 exits("malloc");
	35 }
	36 }
	37 buf[m++] = c;
	38 if(c == '\n')
	39 break;
	40 }
	41 if(m > 0)
	42 write(1, buf, m);
	43 free(buf);
	44 return m;
	45 }
	46
	47 void
	48 lines(int fd, char *file)
	49 {
	50 do{
	51 if(line(fd, file) == 0)
	52 break;
	53 }while(multi \|\| --nlines>0);
	54 }
	55
	56 void
	57 chars(int fd, char *file)
	58 {
	59 char buf[8*1024];
	60 vlong m;
	61 int n;
	62
	63 for(m = 0; m < nchars; m += n){
	64 n = sizeof(buf);
	65 if(n > (nchars - m))
	66 n = nchars - m;
	67 if((n = read(fd, buf, n)) < 0){
	68 fprint(2, "read: error reading %s: %r\n", file);
	69 exits("read error");
	70 }
	71 if(n == 0){
	72 if(m == 0)
	73 status = "eof";
	74 break;
	75 }
	76 write(1, buf, n);
	77 }
	78 }
	79
	80 void
	81 usage(void)
	82 {
	83 fprint(2, "usage: read [-m] [-n nlines] [-c nbytes] [files...]\n…
	84 exits("usage");
	85 }
	86
	87 void
	88 main(int argc, char *argv[])
	89 {
	90 void (proc)(int, char);
	91 int i, fd;
	92
	93 proc = lines;
	94 ARGBEGIN{
	95 case 'c':
	96 nchars = atoll(EARGF(usage()));
	97 proc = chars;
	98 break;
	99 case 'n':
	100 nlines = atoi(EARGF(usage()));
	101 break;
	102 case 'm':
	103 multi = 1;
	104 break;
	105 default:
	106 usage();
	107 }ARGEND
	108
	109 if(argc == 0)
	110 (*proc)(0, "<stdin>");
	111 else
	112 for(i=0; i<argc; i++){
	113 fd = open(argv[i], OREAD);
	114 if(fd < 0){
	115 fprint(2, "read: can't open %s: %r\n", a…
	116 exits("open");
	117 }
	118 (*proc)(fd, argv[i]);
	119 close(fd);
	120 }
	121
	122 exits(status);
	123 }