bore

commit 0f1826ad5aea5a7e10c94d37f3ae960d615c6adc
parent 660e87bbb6963521534f817f1f2c88c549772489
Author: aabacchus <ben@bvnf.space>
Date:   Sun, 19 Sep 2021 21:22:53 +0100

tee: add

Diffstat:
M
Makefile
 | 
2
+-
A
tee.c
 | 
73
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 74 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
@@ -1,6 +1,6 @@
 .POSIX:
 
-BINS = cat echo
+BINS = cat echo tee
 XCFLAGS = $(CFLAGS) -Wall -Wextra -Wpedantic -g
 
 .PHONY: clean
diff --git a/tee.c b/tee.c
@@ -0,0 +1,73 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#define BUF_SIZE 4096
+
+int
+tee(int *fds, int len) {
+    unsigned char buf[BUF_SIZE];
+    ssize_t n;
+    while ((n = read(0, buf, BUF_SIZE)) > 0) {
+        int i = 0;
+        for (; i < len; i++) {
+            if (write(fds[i], buf, n) == -1) {
+                fprintf(stderr, "tee: write: %s\n", strerror(errno));
+                return 1;
+            }
+        }
+        if (write(1, buf, n) == -1) {
+            fprintf(stderr, "tee: write: %s\n", strerror(errno));
+            return 1;
+        }
+    }
+    if (n == -1){
+        fprintf(stderr, "tee: read: %s\n", strerror(errno));
+        return 1;
+    }
+    return 0;
+}
+
+int
+main(int argc, char **argv) {
+    int err = 0;
+    int flags = O_WRONLY | O_CREAT;
+
+    int c;
+    while ((c = getopt(argc, argv, "ai")) != EOF) {
+        switch (c) {
+            case 'a':
+                flags |= O_APPEND;
+                break;
+            case 'i':
+                signal(SIGINT, SIG_IGN);
+                break;
+        }
+    }
+
+    argv += optind - 1;
+    int fds[argc-optind];
+    int i = 0;
+
+    while (*++argv) {
+        fds[i] = open(*argv, flags, 0644);
+        if (fds[i++] == -1) {
+            fprintf(stderr, "tee: open %s: %s\n", *argv, strerror(errno));
+            err = 1;
+            continue;
+        }
+    }
+    if (tee(fds, i) != 0) {
+        err = 1;
+    }
+    while (--i) {
+        if (close(fds[i]) == -1){
+            fprintf(stderr, "tee: close: %s\n", strerror(errno));
+            err = 1;
+        }
+    }
+    return err;
+}