Readd com(1)

progs/base/bin/com.c

@@ -0,0 +1,129 @@
+#include <sys/select.h>
+#include <termios.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+
+#define OPT_HEX     (1 << 0)
+
+static void usage(char **argv) {
+    fprintf(stderr, "usage: %s [-x] DEVICE\n", argv[0]);
+}
+
+int main(int argc, char **argv) {
+    struct termios tc0r, tc1r, tc0l, tc1l;
+    int flags = 0;
+    int fd, res;
+    ssize_t bread;
+    struct timeval tv;
+    char buf[1024];
+    fd_set fds;
+    static const char *opts = "x";
+    char c;
+
+    while ((c = getopt(argc, argv, opts)) != -1) {
+        switch (c) {
+        case 'x':
+            flags |= OPT_HEX;
+            break;
+        case '?':
+            usage(argv);
+            return -1;
+        }
+    }
+
+    if (optind != argc - 1) {
+        usage(argv);
+        return -1;
+    }
+
+    // Setup local terminal
+    if (tcgetattr(STDIN_FILENO, &tc0l) != 0) {
+        perror("get local termios");
+        return -1;
+    }
+    tc1l = tc0l;
+    tc1l.c_lflag &= ~ICANON;
+    if (tcsetattr(STDIN_FILENO, TCSANOW, &tc1l) != 0) {
+        perror("set local termios");
+        return -1;
+    }
+
+    if ((fd = open(argv[optind], O_RDWR, 0)) < 0) {
+        perror(argv[optind]);
+        goto cleanup_local;
+    }
+
+    // Setup remote terminal
+    if (tcgetattr(fd, &tc0r) != 0) {
+        perror("get remote termios");
+        goto cleanup_local;
+    }
+    tc1r = tc0r;
+    tc1r.c_lflag &= ~ICANON;
+    if (tcsetattr(fd, TCSANOW, &tc1r) != 0) {
+        perror("set remote termios");
+        goto cleanup_local;
+    }
+
+    while (1) {
+        FD_ZERO(&fds);
+        FD_SET(STDIN_FILENO, &fds);
+        FD_SET(fd, &fds);
+        tv.tv_sec = 1;
+        tv.tv_usec = 0;
+
+        res = select(fd + 1, &fds, NULL, NULL, &tv);
+
+        if (res < 0) {
+            perror("select()");
+            goto cleanup_remote;
+        }
+        if (res == 0) {
+            continue;
+        }
+
+        if (FD_ISSET(fd, &fds)) {
+            bread = read(fd, buf, sizeof(buf));
+            if (bread <= 0) {
+                break;
+            }
+            if (!(flags & OPT_HEX)) {
+                write(STDOUT_FILENO, buf, bread);
+            } else {
+                for (ssize_t i = 0; i < bread; ++i) {
+                    printf("%02hhx", buf[i]);
+                }
+                fflush(stdout);
+            }
+        }
+
+        if (FD_ISSET(STDIN_FILENO, &fds)) {
+            bread = read(STDIN_FILENO, buf, sizeof(buf));
+            int brk = 0;
+            if (bread <= 0) {
+                break;
+            }
+            size_t count = 0;
+            for (ssize_t i = 0; i < bread; ++i) {
+                if (buf[i] == 0x04) {
+                    // EOF
+                    brk = 1;
+                    break;
+                }
+                ++count;
+            }
+            write(fd, buf, count);
+            if (brk) {
+                break;
+            }
+        }
+    }
+
+cleanup_remote:
+    tcsetattr(STDIN_FILENO, TCSANOW, &tc0r);
+cleanup_local:
+    tcsetattr(STDIN_FILENO, TCSANOW, &tc0l);
+
+    return 0;
+}