Add tee builtin

[owen499]

Summary

• POSIX-subset tee builtin: tee [-a] [file...] — fan stdin out to stdout and any number of files (default 256 cap)
• Wired into check_builtin() dispatch so it runs in-process without forking an external binary
• Added srcs/builtin/tee.c to the Makefile

Behavior

• Reads stdin in 4096-byte chunks until EOF, mirroring each chunk to stdout and to every successfully opened file
• -a switches O_TRUNC → O_APPEND; default mode is 0644
• Per-file open errors print minishell: tee: <path>: <strerror> to stderr and set g_status = 1, but do not abort the remaining writers

42 Norm compliance

• 5 functions, each ≤25 lines and ≤5 locals
• No new globals, reuses existing libft helpers (ft_strequ, ft_putstr_fd, ft_putendl_fd) and g_status

Test plan

• make builds clean on Linux (macOS clang has unrelated -Wunused-but-set-variable noise in pre-existing files)
• echo hi | ./minishell -c 'tee out.txt' writes hi to both stdout and out.txt
• printf 'a\nb\n' | ./minishell -c 'tee -a log.txt' appends without truncating prior content
• echo x | ./minishell -c 'tee /root/no' prints permission-denied error and continues; exit status reflects failure

---

Summary by cubic

Adds a POSIX-style tee builtin to fan stdin to stdout and files, with append support. Runs in-process to avoid spawning an external tee, improving pipeline performance.

• New Features
  • Command: tee [-a] [file...]; reads in 4096-byte chunks; writes to stdout and up to 256 files (0644 default mode).
  • -a appends instead of truncating; per-file open errors print to stderr, continue, and set g_status=1.
  • Integrated into check_builtin() to run in-process and avoid forking.

^{Written for commit 5c1a554. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

1 issue found across 4 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="srcs/builtin/tee.c">

<violation number="1" location="srcs/builtin/tee.c:63">
P2: Return values of `write()` are ignored, which can silently lose data on partial writes or I/O errors. At minimum, a failed `write(1, …)` (broken stdout pipe) should stop the loop, and failed file writes should set `g_status = 1` — consistent with the error reporting you already do for `open()` failures.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review, or fix all with cubic.}

[cubic-dev-ai]

P2: Return values of write() are ignored, which can silently lose data on partial writes or I/O errors. At minimum, a failed write(1, …) (broken stdout pipe) should stop the loop, and failed file writes should set g_status = 1 — consistent with the error reporting you already do for open() failures.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At srcs/builtin/tee.c, line 63:

<comment>Return values of `write()` are ignored, which can silently lose data on partial writes or I/O errors. At minimum, a failed `write(1, …)` (broken stdout pipe) should stop the loop, and failed file writes should set `g_status = 1` — consistent with the error reporting you already do for `open()` failures.</comment>

<file context>
@@ -0,0 +1,101 @@
+	r = read(0, buf, sizeof(buf));
+	while (r > 0)
+	{
+		write(1, buf, r);
+		i = -1;
+		while (++i < n)
</file context>

[owen499]

@cubic-dev-ai plz review this PR

[cubic-dev-ai]

@cubic-dev-ai plz review this PR

@owen499 I have started the AI code review. It will take a few minutes to complete.

[cubic-dev-ai]

No issues found across 4 files