dirent.h(0P)

🌸 dirent.h — the tea on directory entries (POSIX Programmer's Manual, section 0P) 🌸

Hey bestie 💖 before we even start: this page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ — so go check the corresponding Linux manual page for the deets on Linux behavior — or, plot twist, the interface might not even be implemented on Linux at all. 😭

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✨ NAME ✨

dirent.h — the format of directory entries. That's it, that's the whole vibe. 🦋

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🎀 SYNOPSIS 🎀

#include <dirent.h>

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💅 DESCRIPTION 💅

Okay so, first thing: the internal format of directories? Unspecified. Nobody's promising you anything about how dirs look on the inside, and honestly, respect. 🙈

The <dirent.h> header shall define the following type:

• DIR — a type representing a directory stream. The DIR type may be an incomplete type. (She's mysterious like that. 👑)

It shall also define the structure dirent, and that struct shall include these members:

ino_t  d_ino       File serial number.
char   d_name[]    Filename string of entry.

The <dirent.h> header shall define the ino_t type as described in <sys/types.h>.

The array d_name is of unspecified size, but it shall contain a filename of at most {NAME_MAX} bytes followed by a terminating null byte. No cap. Well, actually, there's a cap, it's {NAME_MAX} bytes, and then a null byte. Slay. ✨

The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided. 👇

int            alphasort(const struct dirent **, const struct dirent **);
int            closedir(DIR *);
int            dirfd(DIR *);
DIR           *fdopendir(int);
DIR           *opendir(const char *);
struct dirent *readdir(DIR *);
int            readdir_r(DIR *restrict, struct dirent *restrict,
                   struct dirent **restrict);
void           rewinddir(DIR *);
int            scandir(const char *, struct dirent ***,
                   int (*)(const struct dirent *),
                   int (*)(const struct dirent **,
                   const struct dirent **));
void           seekdir(DIR *, long);
long           telldir(DIR *);

The following sections are informative. (So like, cute extra context, not the actual requirements. 🫶)

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🌈 APPLICATION USAGE 🌈

None.

That's it. That's the whole section. Nothing. Nada. Not a single use case. Iconic, honestly. 💀

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🧚 RATIONALE 🧚

So the lore: info similar to what's in the <dirent.h> header lives in a file called <sys/dir.h> in 4.2 BSD and 4.3 BSD. And in those implementations, the equivalent of struct dirent from this volume of POSIX.1‐2017 is called struct direct.

Why the name change? Because <sys/dir.h> was also used in earlier implementations to refer to definitions related to the older access method — which produced name conflicts. Messy. 😭

And why did the structure get renamed? Because this volume of POSIX.1‐2017 does not completely define what's in the structure, so it could be different on some implementations from struct direct. So like, they had to be careful. No cap. 🎀

Also super important, bestie, listen up: the name of an array of char of an unspecified size should not be used as an lvalue. So this:

sizeof(d_name)

is incorrect. Use this instead:

strlen(d_name)

💅 periodt.

The array of char d_name is not a fixed size. Implementations may need to declare struct dirent with an array size for d_name of 1, but the actual number of bytes provided matches (or only slightly exceeds) the length of the filename string.

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🦋 FUTURE DIRECTIONS 🦋

None.

Again. Nothing coming. We're chilling. ⭐

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🔥 SEE ALSO 🔥

• <sys_types.h>
• The System Interfaces volume of POSIX.1‐2017: alphasort(), closedir(), dirfd(), fdopendir(), readdir(), rewinddir(), seekdir(), telldir()

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👑 COPYRIGHT 👑

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group.

In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

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okay bestie that's the whole page, mwah 💖 this one came from IEEE/The Open Group, 2017 — go forth and read some directory entries, you've got this 🫶✨