From b25850f25b4d1a0bb4a1a8709dc019e5fab21b96 Mon Sep 17 00:00:00 2001
From: Willy Tarreau <w@1wt.eu>
Date: Mon, 6 Jan 2025 19:34:41 +0100
Subject: [PATCH] MINOR: tools: add a few functions to simply check for a
 file's existence

At many places we'd like to be able to simply construct a path from a
format string and check if that path corresponds to an existing file,
directory etc. Here we add 3 functions, a generic one to test that a
path corresponds to a given file mode (e.g. S_IFDIR, S_IFREG etc), and
two other ones specifically checking for a file or a dir for easier
use.
---
 include/haproxy/tools.h |  3 ++
 src/tools.c             | 64 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+)

diff --git a/include/haproxy/tools.h b/include/haproxy/tools.h
index ef2f5c4ec..b96436115 100644
--- a/include/haproxy/tools.h
+++ b/include/haproxy/tools.h
@@ -1020,6 +1020,9 @@ int my_unsetenv(const char *name);
  * some expansion is made.
  */
 char *env_expand(char *in);
+int is_path_mode(mode_t mode, const char *path_fmt, ...);
+int is_file_present(const char *path_fmt, ...);
+int is_dir_present(const char *path_fmt, ...);
 uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbargs, uint32_t opts, const char **errptr);
 ssize_t read_line_to_trash(const char *path_fmt, ...);
 size_t sanitize_for_printing(char *line, size_t pos, size_t width);
diff --git a/src/tools.c b/src/tools.c
index 472baf919..5524ae7e0 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -5975,6 +5975,70 @@ void ha_generate_uuid_v7(struct buffer *output)
 }
 
 
+/* See is_path_mode(). This version is for internal use and uses a va_list. */
+static int _is_path_mode(mode_t mode, const char *path_fmt, va_list args)
+{
+	struct stat file_stat;
+	ssize_t ret;
+
+	chunk_reset(&trash);
+
+	ret = vsnprintf(trash.area, trash.size, path_fmt, args);
+	if (ret >= trash.size)
+		return 0;
+
+	if (stat(trash.area, &file_stat) != 0)
+		return 0;
+
+	return (file_stat.st_mode & S_IFMT) == mode;
+}
+
+/* Use <path_fmt> and following arguments as a printf format to build up the
+ * name of a file, which will be checked for existence and for mode matching
+ * <mode> among S_IF*. On success, non-zero is returned. On failure, zero is
+ * returned. The trash is destroyed.
+ */
+int is_path_mode(mode_t mode, const char *path_fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, path_fmt);
+	ret = _is_path_mode(mode, path_fmt, args);
+	va_end(args);
+	return ret;
+}
+
+/* Use <path_fmt> and following arguments as a printf format to build up the
+ * name of a file, which will be checked for existence. On success, non-zero
+ * is returned. On failure, zero is returned. The trash is destroyed.
+ */
+int is_file_present(const char *path_fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, path_fmt);
+	ret = _is_path_mode(S_IFREG, path_fmt, args);
+	va_end(args);
+	return ret;
+}
+
+/* Use <path_fmt> and following arguments as a printf format to build up the
+ * name of a directory, which will be checked for existence. On success, non-zero
+ * is returned. On failure, zero is returned. The trash is destroyed.
+ */
+int is_dir_present(const char *path_fmt, ...)
+{
+	va_list args;
+	int ret;
+
+	va_start(args, path_fmt);
+	ret = _is_path_mode(S_IFDIR, path_fmt, args);
+	va_end(args);
+	return ret;
+}
+
 /* only used by parse_line() below. It supports writing in place provided that
  * <in> is updated to the next location before calling it. In that case, the
  * char at <in> may be overwritten.