LLAPI_PATH2PARENT(3)

💖 LLAPI_PATH2PARENT 💖

okay bestie, this is llapi_path2parent(3) — a Lustre library functions page, and it's giving "find my file's parent directory and its name" energy. let's get into it 🫶

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✨ NAME ✨

llapi_path2parent, llapi_fd2parent — retrieve <parent FID>/name(s) for an entry in Lustre. yes literally, that's the whole job 💅

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🌸 SYNOPSIS 🌸

#include <lustre/lustreapi.h>

int llapi_path2parent(const char *path, unsigned int linkno,
                      struct lu_fid *parent_fid, char *name,
                      size_t name_size);

int llapi_fd2parent(int fd, unsigned int linkno,
                    struct lu_fid *parent_fid, char *name,
                    size_t name_size);

two functions, same shape, different entry point. iconic behavior fr fr ✨

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🦋 DESCRIPTION 🦋

so <italic>llapi_path2parent()</italic> does the thing: for link number linkno, it drops the FID of the parent directory into parent_fid, and it puts the NUL-terminated name of the entry into the buffer name, which is expected to be of size name_size. 🎀

and here's the part people always mess up 👀 — linkno should be initialized to -1 when you're starting to iterate over all links of a file. note it down, no cap.

<italic>llapi_fd2parent()</italic> is the twin 🧚 it behaves similarly except it operates on an open file descriptor instead of a path. same vibe, different door.

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🔥 RETURN VALUES 🔥

0 is returned on success, or a negative errno value on failure. that's it, that's the tea ☕

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👑 ERRORS 👑

here's where it gets real bestie — the glow-down list 💀

• -ENODATA — linkno has reached the total link count of the file. you've gone too far, wrap it up 🏁
• -ENOTTY — path or fd does not reside on a Lustre filesystem. not our turf, sorry 🙈
• -ENOENT — path does not exist. ghosted 👻
• -EINVAL — an invalid argument was specified. check ur args bb 🌸
• -EOVERFLOW — the given buffer was too small to hold the pathname. name_size said "i cannot", size up 📏
• -EPERM — the file cannot be open by user or CAP_DAC_READ_SEARCH is not granted. permission slip denied 🚫

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🌈 AVAILABILITY 🌈

llapi_path2parent() and llapi_fd2parent() are part of the lustre(7) user application interface library since release 2.4.0 ⭐ so if you're on anything older, that's a you problem (affectionately) 💜

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💅 SEE ALSO 💅

• lfs-path2fid(1)
• llapi_fid2path(3)
• llapi_path2fid(3)
• lustreapi(7)

go read those too, iykyk 📚✨

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aaaand that's the whole page, bestie 🎀 this was the Lustre User API, dated 2024-08-28, and it lives at LLAPI_PATH2PARENT(3). slay, read responsibly, and remember: linkno starts at -1 😌💖