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stat() completion successful and set wrong errno, when a component of the path prefix is not a directory [ext2, dummyfs, jffs2] #682

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mateusz-bloch opened this issue Apr 5, 2023 · 2 comments · May be fixed by phoenix-rtos/libphoenix#346
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stat() completion successful and set wrong errno, when a component of the path prefix is not a directory [ext2, dummyfs, jffs2] #682

mateusz-bloch opened this issue Apr 5, 2023 · 2 comments · May be fixed by phoenix-rtos/libphoenix#346
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@jmaksymowicz
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@mateusz-bloch
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stat() completion successful and set wrong errno, when a component of the path is existing regular file, not a directory

Tested between ia32-generic and host-generic

Code to reproduction:

#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>


int main(void)
{
	struct stat buf;

	FILE *fp = fopen("testfile.txt", "w");
	fclose(fp);

	errno = 0;
	stat("testfile.txt/", &buf);
	printf("Regular File: %d\n",S_ISREG(buf.st_mode));
 	printf("Directory: %d\n",S_ISDIR(buf.st_mode));
	printf("Errno: %d, %s\n", errno, strerror(errno));

	remove("testfile.txt");

	return 0;
}

Outcome from ia32-generic:
image

Outcome from host-generic:
image

Documentation:
image
image
@nalajcie
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nalajcie commented Apr 5, 2023

Please note that:

  • when function exits with error, output parameter might be left unchanged - IMHO You shouldn't test it unless it's explicitly stated it's also set on error paths
  • most of our FS-related functions are implemented inside particular filesystem - it's worth to check also how the function behaves on jffs2 and dummyfs (I believe it's possible to test on zynq-qemu as rootfs is jffs2 there and /dev is dummyfs ; currently it's not possible to test other FSes on ia32 due to filesystems/ext2: ext2 doesn't support mounting other filesystems #114)
  • due to above - please state on which filesystems the bug is present (preferably all fliesystems in single issue)

@mateusz-bloch mateusz-bloch changed the title stat() completion successful and set wrong errno, when a component of the path prefix is not a directory stat() completion successful and set wrong errno, when a component of the path prefix is not a directory [ext2, dummyfs, jffs2] Apr 21, 2023
@jmaksymowicz jmaksymowicz self-assigned this Feb 16, 2024
@jmaksymowicz
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I managed to track down the bug to the resolve_path function in libphoenix. According to Open Group it should set errno to ENOTDIR when:

[...] the file_name argument contains at least one non-<slash> character and ends with one or more trailing <slash> characters and the last pathname component names an existing file that is neither a directory nor a symbolic link to a directory.

Instead, the function simply ignores trailing slashes, so it cannot behave correctly.

@jmaksymowicz jmaksymowicz linked a pull request Feb 16, 2024 that will close this issue
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unistd/dir: fix resolve_path behavior on trailing slashes phoenix-rtos/libphoenix
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@nalajcie @damianloew @mateusz-bloch @jmaksymowicz