[RFC i-g-t 2/5] lib/igt_dir_explorer: Add function to recursively read all files in a directory

[Zbigniew Kempczyński]

On Wed, May 14, 2025 at 07:51:34PM +0200, Peter Senna Tschudin wrote:
> Introduces igt_dir_explorer_read_and_discard_all(), a function that
> performs a recursive scan of all files within a directory. Each file is
> read, and its content is discarded.
> 
> This functionality is utilized in the following tests:
> - core_debugfs
> - core_debugfs_display_on_off
> - core_sysfs
> 
> This addition enhances the ability to efficiently handle directory
> traversal and file processing in tests.
> 
> Cc: marcin.bernatowicz at intel.com
> Cc: himanshu.girotra at intel.com
> Cc: aditya.chauhan at intel.com
> Cc: pravalika.gurram at intel.com
> Cc: sai.gowtham.ch at intel.com
> Cc: ramadevi.gandi at intel.com
> Cc: lucas.demarchi at intel.com
> Cc: rodrigo.vivi at intel.com
> Cc: kamil.konieczny at linux.intel.com
> Cc: katarzyna.piecielska at intel.com
> Signed-off-by: Peter Senna Tschudin <peter.senna at linux.intel.com>
> ---
>  lib/igt_dir_explorer.c | 72 ++++++++++++++++++++++++++++++++++++++++++
>  lib/igt_dir_explorer.h | 10 ++++++
>  lib/meson.build        |  1 +
>  3 files changed, 83 insertions(+)
>  create mode 100644 lib/igt_dir_explorer.c
>  create mode 100644 lib/igt_dir_explorer.h
> 
> diff --git a/lib/igt_dir_explorer.c b/lib/igt_dir_explorer.c
> new file mode 100644
> index 000000000..d47e08535
> --- /dev/null
> +++ b/lib/igt_dir_explorer.c
> @@ -0,0 +1,72 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2025 Intel Corporation
> + */
> +
> +#include <dirent.h>
> +#include <fcntl.h>
> +
> +#include "igt.h"
> +#include "igt_dir_explorer.h"
> +
> +void igt_dir_explorer_read_and_discard_all(int path_fd, int indent)

Just loose thought - if you're doing recursive directory traversal,
wouldn't be better to pass function (kind of callback) which would be
called for each file/dir entry? I mean single traversal code, and
multiple callbacks for different use cases.

--
Zbigniew

> +{
> +	struct dirent *dirent;
> +	DIR *dir;
> +	char tabs[8];
> +	int i;
> +
> +	igt_assert(indent < sizeof(tabs) - 1);
> +
> +	for (i = 0; i < indent; i++)
> +		tabs[i] = '\t';
> +	tabs[i] = '\0';
> +
> +	dir = fdopendir(path_fd);
> +	if (!dir)
> +		return;
> +
> +	while ((dirent = readdir(dir))) {
> +		if (!strcmp(dirent->d_name, ".") ||
> +		    !strcmp(dirent->d_name, ".."))
> +			continue;
> +
> +		if (dirent->d_type == DT_DIR) {
> +			int sub_fd;
> +
> +			sub_fd = openat(path_fd, dirent->d_name,
> +					O_RDONLY | O_DIRECTORY);
> +			if (sub_fd < 0)
> +				continue;
> +
> +			igt_debug("%sEntering subdir %s\n", tabs, dirent->d_name);
> +			igt_dir_explorer_read_and_discard_all(sub_fd, indent + 1);
> +			close(sub_fd);
> +		} else if (dirent->d_type == DT_REG) {
> +			char buf[512];
> +			int sub_fd;
> +			ssize_t ret;
> +
> +			igt_kmsg(KMSG_DEBUG "Reading file \"%s\"\n", dirent->d_name);
> +			igt_debug("%sReading file \"%s\"\n", tabs, dirent->d_name);
> +
> +			sub_fd = openat(path_fd, dirent->d_name, O_RDONLY | O_NONBLOCK);
> +			if (sub_fd == -1) {
> +				igt_debug("%sCould not open file \"%s\" with error: %m\n",
> +					  tabs, dirent->d_name);
> +				continue;
> +			}
> +
> +			do {
> +				ret = read(sub_fd, buf, sizeof(buf));
> +			} while (ret == sizeof(buf));
> +
> +			if (ret == -1)
> +				igt_debug("%sCould not read file \"%s\" with error: %m\n",
> +					  tabs, dirent->d_name);
> +
> +			close(sub_fd);
> +		}
> +	}
> +	closedir(dir);
> +}
> diff --git a/lib/igt_dir_explorer.h b/lib/igt_dir_explorer.h
> new file mode 100644
> index 000000000..b767928a5
> --- /dev/null
> +++ b/lib/igt_dir_explorer.h
> @@ -0,0 +1,10 @@
> +/* SPDX-License-Identifier: MIT
> + * Copyright © 2024 Intel Corporation
> + */
> +
> +#ifndef IGT_DIR_EXPLORER_H
> +#define IGT_DIR_EXPLORER_H
> +
> +void igt_dir_explorer_read_and_discard_all(int path_fd, int indent);
> +
> +#endif /* IGT_DIR_EXPLORER_H */
> diff --git a/lib/meson.build b/lib/meson.build
> index b58976a43..f98265100 100644
> --- a/lib/meson.build
> +++ b/lib/meson.build
> @@ -90,6 +90,7 @@ lib_sources = [
>  	'igt_kms.c',
>  	'igt_fb.c',
>  	'igt_core.c',
> +	'igt_dir_explorer.c',
>  	'igt_draw.c',
>  	'igt_list.c',
>  	'igt_map.c',
> -- 
> 2.43.0
>