PMEM2_SOURCE_SIZE(3)

✨ PMEM2_SOURCE_SIZE(3) ✨

okay bestie, welcome to the PMDK Programmer's Manual 💖 you're about to learn how to ask a data source how big it is. it's giving "how many bytes are you, babe" and honestly? iconic.

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🌸 NAME 🌸

pmem2_source_size() — returns the size of the data source

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🎀 SYNOPSIS 🎀

#include <libpmem2.h>

struct pmem2_source;
int pmem2_source_size(const struct pmem2_source *source, size_t *size);

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🦋 DESCRIPTION 🦋

So basically, pmem2_source_size() goes and gets the size of the file — in bytes — the one pointed at by the file descriptor that's chillin' inside source. and then it just... drops it into *size. like a little gift. 🎁

The way this function is lowkey a hero: it hides all the quirkiness of Device DAX size detection. you don't gotta deal with that mess. it does. periodt. 💅

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👑 RETURN VALUE 👑

pmem2_source_size() returns 0 on success. slay. ✨

but if it fails? the *size variable is left unmodified (like, untouched, no notes) and a negative error code is returned. sad girl hours. 😭

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💀 ERRORS 💀

pmem2_source_size() can fail with the following errors, bestie, so listen up:

• PMEM2_E_INVALID_FILE_HANDLE — source contains an invalid file handle. not it. 🙈
• PMEM2_E_INVALID_FILE_TYPE — the file descriptor points to a directory, block device, pipe, or socket. wrong vibe entirely.
• PMEM2_E_INVALID_FILE_TYPE — the file descriptor points to a character device that is not a Device DAX. close but no. 💀
• PMEM2_E_INVALID_SIZE_FORMAT — the kernel query for the Device DAX size came back with data in an invalid format. the kernel was not serving. 😭
• -errno set by failing fstat(2), while trying to validate the file descriptor.
• -errno set by failing realpath(3), while trying to determine whether fd points to a Device DAX.
• -errno set by failing open(2), while trying to determine Device DAX's size.
• -errno set by failing read(2), while trying to determine Device DAX's size.
• -errno set by failing strtoull(3), while trying to determine Device DAX's size.

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🌈 SEE ALSO 🌈

errno(3), fstat(2), realpath(3), open(2), read(2), strtoull(3), pmem2_config_new(3), libpmem2(7) and https://pmem.io

go read those too, iykyk 🫶

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that's the whole page, bestie. this one's from the PMDK crew, dated 2025-07-24 — yeah she's a 2025 girlie and she ate. mwah 💋 🧚