From b3d5ed960aa9a43df2b48894867ec3481cee77fc Mon Sep 17 00:00:00 2001
From: Scott Worley <scottworley@scottworley.com>
Date: Wed, 30 Aug 2023 22:25:58 -0700
Subject: [PATCH] Begin

---
 .gitignore       |  2 ++
 Makefile         | 17 +++++++++++++++++
 tl-append-test.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 tl-append.c      | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 107 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 Makefile
 create mode 100644 tl-append-test.c
 create mode 100644 tl-append.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..dad8cbc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+tl-append
+tl.log
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..8209ef8
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,17 @@
+prefix = /usr/local
+bindir = $(prefix)/bin
+INSTALL = install
+
+tl-append:
+
+%: %.c
+	$(CC) -Wall -Wextra -pedantic -o $@ $^
+
+.PHONY: check
+check: tl-append tl-append-test
+	./tl-append-test
+
+.PHONY: install
+install: tl-append
+	$(INSTALL) -d $(DESTDIR)$(bindir)
+	$(INSTALL) -m 755 $^ $(DESTDIR)$(bindir)
diff --git a/tl-append-test.c b/tl-append-test.c
new file mode 100644
index 0000000..be2adcb
--- /dev/null
+++ b/tl-append-test.c
@@ -0,0 +1,42 @@
+#define _POSIX_C_SOURCE 2
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+static void die(const char *message) {
+  fputs(message, stderr);
+  fputc('\n', stderr);
+  exit(1);
+}
+
+static void die_err(const char *message) {
+  perror(message);
+  exit(1);
+}
+
+static void write_and_read_line() {
+  char buf[10];
+
+  FILE *p = popen("./tl-append", "w");
+  if (p == NULL)
+    die_err("Couldn't run tl-append");
+  if (fputs("foo\n", p) == EOF)
+    die("Couldn't write to pipe");
+  int status = pclose(p);
+  if (status < 0)
+    die_err("Error closing pipe");
+  if (status != 0)
+    die("tl-append exited abnormally");
+
+  FILE *f = fopen("tl.log", "r");
+  if (f == NULL)
+    die_err("Error opening log file");
+  if (fgets(buf, sizeof(buf), f) == NULL)
+    die("Error reading log file");
+  if (strncmp("foo\n", buf, sizeof(buf)) != 0)
+    die("Wrong contents in log file");
+  if (fclose(f) != 0)
+    die_err("Error closing log file");
+}
+
+int main() { write_and_read_line(); }
diff --git a/tl-append.c b/tl-append.c
new file mode 100644
index 0000000..21e23a6
--- /dev/null
+++ b/tl-append.c
@@ -0,0 +1,46 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+const char *FILENAME = "tl.log";
+const size_t BUF_SIZE = 1024;
+
+static void die(const char *message) {
+  fputs(message, stderr);
+  fputc('\n', stderr);
+  exit(1);
+}
+
+static void die_err(const char *message) {
+  perror(message);
+  exit(1);
+}
+
+static void read_line(char *buf) {
+  if (fgets(buf, BUF_SIZE, stdin) == NULL) {
+    if (ferror(stdin))
+      die("I/O error reading line");
+    if (feof(stdin)) {
+      buf[0] = '\0'; /* Unclear if fgets does this already */
+      return;
+    }
+    die("Unexpected error reading line");
+  }
+}
+
+static void write_line(const char *line) {
+  FILE *f = fopen(FILENAME, "a");
+  if (f == NULL)
+    die_err("Error opening output file");
+  if (fputs(line, f) == EOF)
+    die("Error writing to output file");
+  if (fclose(f) != 0)
+    die_err("Error closing output file");
+}
+
+int main() {
+  char buf[BUF_SIZE];
+  for (read_line(buf); buf[0]; read_line(buf)) {
+    write_line(buf);
+  }
+  return 0;
+}
-- 
2.44.1