commit b641f1292c3ebdb92a831d9548b712eb5a00d1c3
parent 897bff6fc9e2b8446e9b6f6b43d9d158f86857b9
Author: phoebos <ben@bvnf.space>
Date: Thu, 23 Sep 2021 01:40:31 +0100
nonfunctional ed
Diffstat:
| M | Makefile | | | 1 | + |
| M | PROGRESS | | | 1 | + |
| A | ed.c | | | 177 | +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
3 files changed, 179 insertions(+), 0 deletions(-)
diff --git a/Makefile b/Makefile
@@ -3,6 +3,7 @@
BINS = \
cat \
echo \
+ ed \
false \
ls \
tee \
diff --git a/PROGRESS b/PROGRESS
@@ -13,6 +13,7 @@
[ ] dirname
[ ] du
[x] echo
+[ ] ed
[x] false
[ ] find
[ ] grep
diff --git a/ed.c b/ed.c
@@ -0,0 +1,177 @@
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+int s_flag;
+char prompt;
+
+/* buf is a pointer to the bit we're working on at the moment,
+ * while buf_start stores the beginning of our data.
+ */
+char *buf, *buf_start;
+int buf_size = BUFSIZ;
+int buf_used = 0;
+
+void
+print_byte_counts(size_t n) {
+ if (!s_flag)
+ printf("%zu\n", n);
+}
+
+int
+read_buf(char *path) {
+ int fd;
+ ssize_t n = 0;
+
+ fd = open(path, O_RDONLY);
+ if (fd == -1) {
+ fprintf(stderr, "ed: %s: %s\n", path, strerror(errno));
+ return -1;
+ }
+ do {
+ if (buf_used >= buf_size) {
+ int size_new = buf_size * 3 / 2;
+ char *b_new = realloc(buf_start, size_new);
+ buf_start = b_new;
+ buf = buf_start + buf_used;
+ buf_size = size_new;
+ }
+ n = read(fd, buf, buf_size - buf_used);
+ buf_used += n;
+ } while (n > 0);
+ if (n == -1) {
+ fprintf(stderr, "ed: %s: %s\n", path, strerror(errno));
+ return -1;
+ }
+ close(fd);
+ print_byte_counts(buf_used);
+ return 0;
+}
+
+int
+write_buf(char *path) {
+ int fd;
+ ssize_t n;
+
+ fd = open(path, O_WRONLY);
+ if (fd == -1) {
+ fprintf(stderr, "ed: %s: %s\n", path, strerror(errno));
+ return -1;
+ }
+ n = write(fd, buf_start, buf_used);
+ if (n == -1) {
+ fprintf(stderr, "ed: %s: %s\n", path, strerror(errno));
+ return -1;
+ }
+ printf("%ld\n", n);
+ close(fd);
+ return 0;
+}
+
+
+/* set buf appropriately so that input() reads into the right bit. */
+void
+input(void) {
+ ssize_t n;
+ char *tmp = malloc(BUFSIZ);
+ size_t len = BUFSIZ;
+ while (1) {
+ n = getline(&tmp, &len, stdin);
+ /* getline returns bytes + 1 for \n delimiter */
+ if (n == 0)
+ return;
+ if (n < 0) {
+ fprintf(stderr, "ed: %s\n", strerror(errno));
+ return;
+ }
+ if (tmp[0] == '.' && tmp[1] == '\n' && tmp[2] == '\0')
+ return;
+ memcpy(buf, tmp, n);
+ buf += n;
+ buf_used += n;
+ }
+}
+
+int
+ed(char *startfile) {
+ if (startfile)
+ if (read_buf(startfile) != 0)
+ return 1;
+ while (1) {
+
+ if (prompt)
+ printf("%c ", prompt);
+ fflush(stdout);
+ int c = fgetc(stdin);
+ switch (c) {
+ case 'i':
+ buf = buf_start;
+ input();
+ break;
+ case 'a':
+ buf += buf_used;
+ input();
+ break;
+ case 'p':
+ printf("%s", buf_start);
+ break;
+ case 'w':
+ if (startfile)
+ write_buf(startfile);
+ else
+ printf("? writing to a new filename not yet implemented\n");
+ break;
+ case 'q':
+ return 0;
+ case '\n':
+ break;
+ default:
+ printf("?\n");
+ break;
+ }
+ }
+ return 0;
+}
+
+void
+usage_quit(char *argv0) {
+ fprintf(stderr, "usage: %s [-p prompt] [-s] [file]\n", argv0);
+ exit(1);
+}
+
+int
+main(int argc, char **argv) {
+ s_flag = 0;
+ prompt = 0;
+ int c;
+
+ buf_start = malloc(buf_size);
+ buf = buf_start;
+ while ((c = getopt(argc, argv, "p:s")) != EOF) {
+ switch (c) {
+ case 's':
+ s_flag = 1;
+ break;
+ case 'p':
+ prompt = optarg[0];
+ break;
+ case '?':
+ usage_quit(*argv);
+ break;
+ }
+ }
+ if (argc - optind > 1)
+ usage_quit(*argv);
+
+ argv += optind;
+
+ char *startfile = NULL;
+ if (*argv)
+ startfile = *argv;
+
+ ed(startfile);
+ return 0;
+}
