valloc(3)

✨ valloc(3) ✨

okay bestie, pull up a chair because we're talking about valloc from the Library Functions Manual and honestly? she's a legacy icon but she's also kinda retired, so let's get into it 💅

---

NAME 🎀

valloc — page-aligned memory allocation

no cap, that's literally the whole job. she hands you memory, but the address is all fancy and page-aligned ✨

---

LIBRARY 🦋

Standard C library — link it with -lc, bestie. as usual 🫶

---

SYNOPSIS 🌸

#include <stdlib.h>

[[deprecated]] void *valloc(size_t size);

see that [[deprecated]]? yeah. she's marked. the compiler is gonna side-eye you. it's giving "we still support her but we're not happy about it" 💀

Feature Test Macro Requirements for glibc 💜

(if you need the full lore on these, go read feature_test_macros(7), she explains everything)

valloc():
    Since glibc 2.12:
        (_XOPEN_SOURCE >= 500) && !(_POSIX_C_SOURCE >= 200112L)
            || /* glibc >= 2.19: */ _DEFAULT_SOURCE
            || /* glibc <= 2.19: */ _SVID_SOURCE || _BSD_SOURCE
    Before glibc 2.12:
        _BSD_SOURCE || _XOPEN_SOURCE >= 500

okay so the way that you get her declared is very glibc-version-dependent, so check your macros before you start crying about implicit declarations 😭

---

DESCRIPTION 💖

so valloc() allocates size bytes and hands back a pointer to that allocated memory. but here's the flex: the memory address is gonna be a multiple of the page size. every time. no exceptions. main character alignment energy 👑

she's literally equivalent to:

memalign(sysconf(_SC_PAGESIZE),size)

same thing, different font. periodt.

---

ATTRIBUTES ⭐

if you're confused about what "attributes" even means here, attributes(7) has you covered, bestie.

• Interface: valloc()
• Attribute: Thread safety
• Value: MT-Unsafe init

so... not thread safe on init. be careful out there 🙈

---

VERSIONS 🌈

okay so per SUSv2, valloc() is declared in <stdlib.h>.

glibc, being extra, declares it in <malloc.h> — and also in <stdlib.h>, but only if you've defined the right feature test macros (scroll up, they're right there ✨).

---

STANDARDS 🍓

BSD, GNU.

that's the whole list. she's a two-house icon 💅

---

HISTORY 🎀

• glibc 2.0.
• 3.0BSD.
• Documented as obsolete in 4.3BSD 💀
• Documented as legacy in SUSv2

so yeah, she's been around for a minute, and the docs have been gently roasting her basically the entire time. iconic behaviour honestly 🫶

---

CAVEATS 🔥

go look at memalign(3). that's where the real warnings live, bestie. don't skip it 👀

---

SEE ALSO 🦋

• memalign(3)

---

and that's the whole page, bestie!! mwah 💖

this little time capsule comes to you from Linux man-pages 6.20, dated 2025-12-13, and yes she's still filed under valloc(3) after all these years — legacy queen, we love her 👑✨