138 lines
2.5 KiB
C
138 lines
2.5 KiB
C
/* cat - concatenates files Author: Andy Tanenbaum */
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/* 30 March 1990 - Slightly modified for efficiency by Norbert Schlenker. */
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/* 23 March 2002 - Proper error messages by Kees J. Bot. */
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#include <errno.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <minix/minlib.h>
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#include <stdio.h>
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#define CHUNK_SIZE (2048 * sizeof(char *))
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static int unbuffered;
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static char ibuf[CHUNK_SIZE];
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static char obuf[CHUNK_SIZE];
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static char *op = obuf;
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static void copyout(const char *file, int fd);
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static void output(const char *buf, size_t count);
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static void report(const char *label);
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static void fatal(const char *label);
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static char STDIN[] = "standard input";
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static char STDOUT[] = "standard output";
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static int excode = 0;
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int main(int argc, char *argv[])
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{
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int i, fd;
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i = 1;
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while (i < argc && argv[i][0] == '-') {
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char *opt = argv[i] + 1;
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if (opt[0] == 0) break; /* - */
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i++;
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if (opt[0] == '-' && opt[1] == 0) break; /* -- */
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while (*opt != 0) switch (*opt++) {
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case 'u':
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unbuffered = 1;
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break;
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default:
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std_err("Usage: cat [-u] [file ...]\n");
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exit(1);
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}
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}
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if (i >= argc) {
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copyout(STDIN, STDIN_FILENO);
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} else {
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while (i < argc) {
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char *file = argv[i++];
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if (file[0] == '-' && file[1] == 0) {
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copyout(STDIN, STDIN_FILENO);
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} else {
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fd = open(file, O_RDONLY);
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if (fd < 0) {
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report(file);
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} else {
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copyout(file, fd);
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close(fd);
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}
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}
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}
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}
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output(obuf, (op - obuf));
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return(excode);
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}
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static void copyout(const char *file, int fd)
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{
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int n;
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while (1) {
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n = read(fd, ibuf, CHUNK_SIZE);
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if (n < 0) fatal(file);
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if (n == 0) return;
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if (unbuffered || (op == obuf && n == CHUNK_SIZE)) {
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output(ibuf, n);
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} else {
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int bytes_left;
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bytes_left = &obuf[CHUNK_SIZE] - op;
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if (n <= bytes_left) {
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memcpy(op, ibuf, (size_t)n);
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op += n;
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} else {
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memcpy(op, ibuf, (size_t)bytes_left);
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output(obuf, CHUNK_SIZE);
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n -= bytes_left;
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memcpy(obuf, ibuf + bytes_left, (size_t)n);
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op = obuf + n;
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}
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}
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}
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}
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static void output(const char *buf, size_t count)
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{
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ssize_t n;
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while (count > 0) {
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n = write(STDOUT_FILENO, buf, count);
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if (n <= 0) {
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if (n < 0) fatal(STDOUT);
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std_err("cat: standard output: EOF\n");
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exit(1);
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}
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buf += n;
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count -= n;
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}
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}
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static void report(const char *label)
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{
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int e = errno;
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std_err("cat: ");
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std_err(label);
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std_err(": ");
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std_err(strerror(e));
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std_err("\n");
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excode = 1;
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}
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static void fatal(const char *label)
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{
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report(label);
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exit(1);
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}
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