WebAssembly · alexcrichton · Apr 22, 2026 · Apr 22, 2026 · Apr 22, 2026 · Apr 22, 2026
diff --git a/expected/wasm32-wasip1-threads/predefined-macros.txt b/expected/wasm32-wasip1-threads/predefined-macros.txt
@@ -619,7 +619,7 @@
 #define IN6_IS_ADDR_MULTICAST(a) (((uint8_t *) (a))[0] == 0xff)
 #define IN6_IS_ADDR_SITELOCAL(a) ((((uint8_t *) (a))[0]) == 0xfe && (((uint8_t *) (a))[1] & 0xc0) == 0xc0)
 #define IN6_IS_ADDR_UNSPECIFIED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint32_t *) (a))[3] == 0)
-#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint8_t *) (a))[15] > 1)
+#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && !IN6_IS_ADDR_UNSPECIFIED(a) && !IN6_IS_ADDR_LOOPBACK(a))
 #define IN6_IS_ADDR_V4MAPPED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint8_t *) (a))[8] == 0 && ((uint8_t *) (a))[9] == 0 && ((uint8_t *) (a))[10] == 0xff && ((uint8_t *) (a))[11] == 0xff)
 #define INADDRSZ NS_INADDRSZ
 #define INADDR_ALLHOSTS_GROUP ((in_addr_t) 0xe0000001)
@@ -657,8 +657,8 @@
 #define INTMAX_MIN INT64_MIN
 #define INTPTR_MAX INT32_MAX
 #define INTPTR_MIN INT32_MIN
-#define INT_FAST16_MAX INT16_MAX
-#define INT_FAST16_MIN INT16_MIN
+#define INT_FAST16_MAX INT32_MAX
+#define INT_FAST16_MIN INT32_MIN
 #define INT_FAST32_MAX INT32_MAX
 #define INT_FAST32_MIN INT32_MIN
 #define INT_FAST64_MAX INT64_MAX
@@ -1521,6 +1521,9 @@
 #define REG_NOTBOL 1
 #define REG_NOTEOL 2
 #define REG_OK 0
+#define RENAME_EXCHANGE (1 << 1)
+#define RENAME_NOREPLACE (1 << 0)
+#define RENAME_WHITEOUT (1 << 2)
 #define RE_DUP_MAX 255
 #define RMSGD 0x0001
 #define RMSGN 0x0002
@@ -2050,7 +2053,7 @@
 #define UINTMAX_C(c) c ## ULL
 #define UINTMAX_MAX UINT64_MAX
 #define UINTPTR_MAX UINT32_MAX
-#define UINT_FAST16_MAX UINT16_MAX
+#define UINT_FAST16_MAX UINT32_MAX
 #define UINT_FAST32_MAX UINT32_MAX
 #define UINT_FAST64_MAX UINT64_MAX
 #define UINT_FAST8_MAX UINT8_MAX
@@ -2271,8 +2274,8 @@
 #define _POSIX_TRACE_USER_EVENT_MAX 32
 #define _POSIX_TTY_NAME_MAX 9
 #define _POSIX_TZNAME_MAX 6
-#define _POSIX_V6_ILP32_OFFBIG (1)
-#define _POSIX_V7_ILP32_OFFBIG (1)
+#define _POSIX_V6_ILP32_OFFBIG 1
+#define _POSIX_V7_ILP32_OFFBIG 1
 #define _POSIX_VDISABLE 0
 #define _POSIX_VERSION 200809L
 #define _PTHREAD_H 
@@ -3105,7 +3108,7 @@
 #define __WINT_MAX__ 2147483647
 #define __WINT_TYPE__ int
 #define __WINT_WIDTH__ 32
-#define __WORDSIZE 64
+#define __WORDSIZE 32
 #define __alignas_is_defined 1
 #define __alignof_is_defined 1
 #define __bitop(x,i,o) ((x)[(i)/8] o (1<<(i)%8))

diff --git a/expected/wasm32-wasip1/predefined-macros.txt b/expected/wasm32-wasip1/predefined-macros.txt
@@ -619,7 +619,7 @@
 #define IN6_IS_ADDR_MULTICAST(a) (((uint8_t *) (a))[0] == 0xff)
 #define IN6_IS_ADDR_SITELOCAL(a) ((((uint8_t *) (a))[0]) == 0xfe && (((uint8_t *) (a))[1] & 0xc0) == 0xc0)
 #define IN6_IS_ADDR_UNSPECIFIED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint32_t *) (a))[3] == 0)
-#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint8_t *) (a))[15] > 1)
+#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && !IN6_IS_ADDR_UNSPECIFIED(a) && !IN6_IS_ADDR_LOOPBACK(a))
 #define IN6_IS_ADDR_V4MAPPED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint8_t *) (a))[8] == 0 && ((uint8_t *) (a))[9] == 0 && ((uint8_t *) (a))[10] == 0xff && ((uint8_t *) (a))[11] == 0xff)
 #define INADDRSZ NS_INADDRSZ
 #define INADDR_ALLHOSTS_GROUP ((in_addr_t) 0xe0000001)
@@ -657,8 +657,8 @@
 #define INTMAX_MIN INT64_MIN
 #define INTPTR_MAX INT32_MAX
 #define INTPTR_MIN INT32_MIN
-#define INT_FAST16_MAX INT16_MAX
-#define INT_FAST16_MIN INT16_MIN
+#define INT_FAST16_MAX INT32_MAX
+#define INT_FAST16_MIN INT32_MIN
 #define INT_FAST32_MAX INT32_MAX
 #define INT_FAST32_MIN INT32_MIN
 #define INT_FAST64_MAX INT64_MAX
@@ -1521,6 +1521,9 @@
 #define REG_NOTBOL 1
 #define REG_NOTEOL 2
 #define REG_OK 0
+#define RENAME_EXCHANGE (1 << 1)
+#define RENAME_NOREPLACE (1 << 0)
+#define RENAME_WHITEOUT (1 << 2)
 #define RE_DUP_MAX 255
 #define RMSGD 0x0001
 #define RMSGN 0x0002
@@ -2048,7 +2051,7 @@
 #define UINTMAX_C(c) c ## ULL
 #define UINTMAX_MAX UINT64_MAX
 #define UINTPTR_MAX UINT32_MAX
-#define UINT_FAST16_MAX UINT16_MAX
+#define UINT_FAST16_MAX UINT32_MAX
 #define UINT_FAST32_MAX UINT32_MAX
 #define UINT_FAST64_MAX UINT64_MAX
 #define UINT_FAST8_MAX UINT8_MAX
@@ -2269,8 +2272,8 @@
 #define _POSIX_TRACE_USER_EVENT_MAX 32
 #define _POSIX_TTY_NAME_MAX 9
 #define _POSIX_TZNAME_MAX 6
-#define _POSIX_V6_ILP32_OFFBIG (1)
-#define _POSIX_V7_ILP32_OFFBIG (1)
+#define _POSIX_V6_ILP32_OFFBIG 1
+#define _POSIX_V7_ILP32_OFFBIG 1
 #define _POSIX_VDISABLE 0
 #define _POSIX_VERSION 200809L
 #define _PTHREAD_H 
@@ -3102,7 +3105,7 @@
 #define __WINT_MAX__ 2147483647
 #define __WINT_TYPE__ int
 #define __WINT_WIDTH__ 32
-#define __WORDSIZE 64
+#define __WORDSIZE 32
 #define __alignas_is_defined 1
 #define __alignof_is_defined 1
 #define __bitop(x,i,o) ((x)[(i)/8] o (1<<(i)%8))

diff --git a/expected/wasm32-wasip2/defined-symbols.txt b/expected/wasm32-wasip2/defined-symbols.txt
@@ -1570,4 +1570,4 @@ y0f
 y1
 y1f
 yn
-ynf
+ynf
diff --git a/expected/wasm32-wasip2/predefined-macros.txt b/expected/wasm32-wasip2/predefined-macros.txt
@@ -710,7 +710,7 @@
 #define IN6_IS_ADDR_MULTICAST(a) (((uint8_t *) (a))[0] == 0xff)
 #define IN6_IS_ADDR_SITELOCAL(a) ((((uint8_t *) (a))[0]) == 0xfe && (((uint8_t *) (a))[1] & 0xc0) == 0xc0)
 #define IN6_IS_ADDR_UNSPECIFIED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint32_t *) (a))[3] == 0)
-#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint8_t *) (a))[15] > 1)
+#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && !IN6_IS_ADDR_UNSPECIFIED(a) && !IN6_IS_ADDR_LOOPBACK(a))
 #define IN6_IS_ADDR_V4MAPPED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint8_t *) (a))[8] == 0 && ((uint8_t *) (a))[9] == 0 && ((uint8_t *) (a))[10] == 0xff && ((uint8_t *) (a))[11] == 0xff)
 #define INADDRSZ NS_INADDRSZ
 #define INADDR_ALLHOSTS_GROUP ((in_addr_t) 0xe0000001)
@@ -748,8 +748,8 @@
 #define INTMAX_MIN INT64_MIN
 #define INTPTR_MAX INT32_MAX
 #define INTPTR_MIN INT32_MIN
-#define INT_FAST16_MAX INT16_MAX
-#define INT_FAST16_MIN INT16_MIN
+#define INT_FAST16_MAX INT32_MAX
+#define INT_FAST16_MIN INT32_MIN
 #define INT_FAST32_MAX INT32_MAX
 #define INT_FAST32_MIN INT32_MIN
 #define INT_FAST64_MAX INT64_MAX
@@ -1652,6 +1652,9 @@
 #define REG_NOTBOL 1
 #define REG_NOTEOL 2
 #define REG_OK 0
+#define RENAME_EXCHANGE (1 << 1)
+#define RENAME_NOREPLACE (1 << 0)
+#define RENAME_WHITEOUT (1 << 2)
 #define RE_DUP_MAX 255
 #define RMSGD 0x0001
 #define RMSGN 0x0002
@@ -2198,7 +2201,7 @@
 #define UINTMAX_C(c) c ## ULL
 #define UINTMAX_MAX UINT64_MAX
 #define UINTPTR_MAX UINT32_MAX
-#define UINT_FAST16_MAX UINT16_MAX
+#define UINT_FAST16_MAX UINT32_MAX
 #define UINT_FAST32_MAX UINT32_MAX
 #define UINT_FAST64_MAX UINT64_MAX
 #define UINT_FAST8_MAX UINT8_MAX
@@ -2420,8 +2423,8 @@
 #define _POSIX_TRACE_USER_EVENT_MAX 32
 #define _POSIX_TTY_NAME_MAX 9
 #define _POSIX_TZNAME_MAX 6
-#define _POSIX_V6_ILP32_OFFBIG (1)
-#define _POSIX_V7_ILP32_OFFBIG (1)
+#define _POSIX_V6_ILP32_OFFBIG 1
+#define _POSIX_V7_ILP32_OFFBIG 1
 #define _POSIX_VDISABLE 0
 #define _POSIX_VERSION 200809L
 #define _PTHREAD_H 
@@ -3100,7 +3103,7 @@
 #define __WINT_MAX__ 2147483647
 #define __WINT_TYPE__ int
 #define __WINT_WIDTH__ 32
-#define __WORDSIZE 64
+#define __WORDSIZE 32
 #define __alignas_is_defined 1
 #define __alignof_is_defined 1
 #define __bitop(x,i,o) ((x)[(i)/8] o (1<<(i)%8))

diff --git a/expected/wasm32-wasip3/defined-symbols.txt b/expected/wasm32-wasip3/defined-symbols.txt
@@ -1603,4 +1603,4 @@ y0f
 y1
 y1f
 yn
-ynf
+ynf
diff --git a/expected/wasm32-wasip3/predefined-macros.txt b/expected/wasm32-wasip3/predefined-macros.txt
@@ -710,7 +710,7 @@
 #define IN6_IS_ADDR_MULTICAST(a) (((uint8_t *) (a))[0] == 0xff)
 #define IN6_IS_ADDR_SITELOCAL(a) ((((uint8_t *) (a))[0]) == 0xfe && (((uint8_t *) (a))[1] & 0xc0) == 0xc0)
 #define IN6_IS_ADDR_UNSPECIFIED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint32_t *) (a))[3] == 0)
-#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && ((uint8_t *) (a))[15] > 1)
+#define IN6_IS_ADDR_V4COMPAT(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint32_t *) (a))[2] == 0 && !IN6_IS_ADDR_UNSPECIFIED(a) && !IN6_IS_ADDR_LOOPBACK(a))
 #define IN6_IS_ADDR_V4MAPPED(a) (((uint32_t *) (a))[0] == 0 && ((uint32_t *) (a))[1] == 0 && ((uint8_t *) (a))[8] == 0 && ((uint8_t *) (a))[9] == 0 && ((uint8_t *) (a))[10] == 0xff && ((uint8_t *) (a))[11] == 0xff)
 #define INADDRSZ NS_INADDRSZ
 #define INADDR_ALLHOSTS_GROUP ((in_addr_t) 0xe0000001)
@@ -748,8 +748,8 @@
 #define INTMAX_MIN INT64_MIN
 #define INTPTR_MAX INT32_MAX
 #define INTPTR_MIN INT32_MIN
-#define INT_FAST16_MAX INT16_MAX
-#define INT_FAST16_MIN INT16_MIN
+#define INT_FAST16_MAX INT32_MAX
+#define INT_FAST16_MIN INT32_MIN
 #define INT_FAST32_MAX INT32_MAX
 #define INT_FAST32_MIN INT32_MIN
 #define INT_FAST64_MAX INT64_MAX
@@ -1631,6 +1631,9 @@
 #define REG_NOTBOL 1
 #define REG_NOTEOL 2
 #define REG_OK 0
+#define RENAME_EXCHANGE (1 << 1)
+#define RENAME_NOREPLACE (1 << 0)
+#define RENAME_WHITEOUT (1 << 2)
 #define RE_DUP_MAX 255
 #define RMSGD 0x0001
 #define RMSGN 0x0002
@@ -2193,7 +2196,7 @@
 #define UINTMAX_C(c) c ## ULL
 #define UINTMAX_MAX UINT64_MAX
 #define UINTPTR_MAX UINT32_MAX
-#define UINT_FAST16_MAX UINT16_MAX
+#define UINT_FAST16_MAX UINT32_MAX
 #define UINT_FAST32_MAX UINT32_MAX
 #define UINT_FAST64_MAX UINT64_MAX
 #define UINT_FAST8_MAX UINT8_MAX
@@ -2426,8 +2429,8 @@
 #define _POSIX_TRACE_USER_EVENT_MAX 32
 #define _POSIX_TTY_NAME_MAX 9
 #define _POSIX_TZNAME_MAX 6
-#define _POSIX_V6_ILP32_OFFBIG (1)
-#define _POSIX_V7_ILP32_OFFBIG (1)
+#define _POSIX_V6_ILP32_OFFBIG 1
+#define _POSIX_V7_ILP32_OFFBIG 1
 #define _POSIX_VDISABLE 0
 #define _POSIX_VERSION 200809L
 #define _PTHREAD_H 
@@ -3106,7 +3109,7 @@
 #define __WINT_MAX__ 2147483647
 #define __WINT_TYPE__ int
 #define __WINT_WIDTH__ 32
-#define __WORDSIZE 64
+#define __WORDSIZE 32
 #define __alignas_is_defined 1
 #define __alignof_is_defined 1
 #define __bitop(x,i,o) ((x)[(i)/8] o (1<<(i)%8))

diff --git a/libc-top-half/CMakeLists.txt b/libc-top-half/CMakeLists.txt
@@ -282,6 +282,7 @@ set(top_half_sources
   musl/src/time/__secs_to_tm.c
   musl/src/time/__tm_to_secs.c
   musl/src/time/__tz.c
+  musl/src/time/__utc.c
   musl/src/time/__year_to_secs.c
   musl/src/time/asctime.c
   musl/src/time/asctime_r.c

diff --git a/libc-top-half/README.md b/libc-top-half/README.md
@@ -23,3 +23,18 @@ Some major known missing areas include:
  - non-builtin locales
  - TIOCGWINSZ (because cloudabi lacks it; affects isatty, line buffering for stdout)
  - O\_CLOEXEC, O\_NOCTTY (because cloudabi lacks them)
+
+## Updating Musl
+
+The `libc-top-half/musl` directory is a `git subtree` for the upstream musl
+repository. Updating it can be done with:
+
+```
+git subtree pull \
+    --prefix libc-top-half/musl \
+    https://git.musl-libc.org/git/musl v1.2.6 \
+    --squash
+```
+
+Resolve all conflicts and such that come about from the merge. Track deleted and
+updated files and update `libc-top-half/CMakeLists.txt` as appropriate.
diff --git a/libc-top-half/musl/COPYRIGHT b/libc-top-half/musl/COPYRIGHT
@@ -74,6 +74,7 @@ Kylie McClain
 Leah Neukirchen
 Luca Barbato
 Luka Perkov
+Lynn Ochs
 M Farkas-Dyck (Strake)
 Mahesh Bodapati
 Markus Wichmann
@@ -103,7 +104,6 @@ Stefan O'Rear
 Szabolcs Nagy
 Timo Teräs
 Trutz Behn
-Valentin Ochs
 Will Dietz
 William Haddon
 William Pitcock
@@ -143,7 +143,7 @@ domain. The code also comes with a fallback permissive license for use
 in jurisdictions that may not recognize the public domain.
 
 The smoothsort implementation (src/stdlib/qsort.c) is Copyright © 2011
-Valentin Ochs and is licensed under an MIT-style license.
+Lynn Ochs and is licensed under an MIT-style license.
 
 The x86_64 port was written by Nicholas J. Kain and is licensed under
 the standard MIT terms.

diff --git a/libc-top-half/musl/Makefile b/libc-top-half/musl/Makefile
@@ -109,7 +109,7 @@ obj/src/internal/version.o obj/src/internal/version.lo: obj/src/internal/version
 
 obj/crt/rcrt1.o obj/ldso/dlstart.lo obj/ldso/dynlink.lo: $(srcdir)/src/internal/dynlink.h $(srcdir)/arch/$(ARCH)/reloc.h
 
-obj/crt/crt1.o obj/crt/scrt1.o obj/crt/rcrt1.o obj/ldso/dlstart.lo: $(srcdir)/arch/$(ARCH)/crt_arch.h
+obj/crt/crt1.o obj/crt/Scrt1.o obj/crt/rcrt1.o obj/ldso/dlstart.lo: $(srcdir)/arch/$(ARCH)/crt_arch.h
 
 obj/crt/rcrt1.o: $(srcdir)/ldso/dlstart.c
 

diff --git a/libc-top-half/musl/VERSION b/libc-top-half/musl/VERSION
@@ -1 +1 @@
-1.2.5
+1.2.6
diff --git a/libc-top-half/musl/WHATSNEW b/libc-top-half/musl/WHATSNEW
@@ -2438,3 +2438,56 @@ arch-specific bugs fixed:
 - riscv64 icache flush operation was non-functional
 - sh sigsetjmp failed to properly restore call-saved register r8 on return
 - sh dlsym RTLD_NEXT did not identify calling module correctly
+
+
+
+1.2.6 release notes
+
+new features:
+- posix_getdents interface (new in POSIX-2024)
+- renameat2 interface (linux extension)
+- iconv support for CP858
+- vdso clock_gettime for riscv{32,64}, powerpc{,64}, and s390x
+- loongarch64 TLSDESC support
+- exposed __getauxval for compiler runtime use detecting cpu features
+
+compatibility:
+- initgroups no longer artificially limits number of supplementary groups
+- getusershell now skips blank lines and comments
+- exit is now explicitly thread-safe (possible future requirement)
+- atexit now fails rather than deadlocking if called from late dtor
+- strerror now has error strings for EUCLEAN and ENAVAIL
+- isatty no longer collapses errors to ENOTTY
+- sched.h namespace pollution with _GNU_SOURCE is reduced
+- hasmntopt now matches only whole options, not arbitrary substrings
+- shadow.h no longer declares an unimplemented sgetspent interface
+- vdso with missing sysv hash table (only gnu hash) is now supported
+
+conformance:
+- pwrite now handles O_APPEND correctly, reports error if it can't
+- mbnrtowcs now conforms to new POSIX-2024 requirement for partial character
+- iconv GBK now properly includes euro symbol
+- strptime now accepts conversion specifiers added in POSIX-2024
+- inet_ntop IPv6 "zero compression" now conforms to RFC 5952
+
+bugs fixed:
+- iconv euc-kr decoder could do oob writes on invalid inputs (CVE-2025-26519)
+- iconv shift_jis decoder could produce wrong outputs for some invalid inputs
+- printf did not honor hex float precision correctly in some cases
+- lost or delayed wakes in sem_post under race condition
+- termios input speed handling was wrong
+- strcasestr failed to match zero-length needle
+- fma handled corner case with negative zero wrongly
+- syslog LOG_MAKEPRI macro was incorrect
+- timer_create is no longer affected by known pthread_barrier bugs
+- sysconf(_SC_MINSIGSTKSZ) computed min size incorrectly
+- statx emulation left some fields uninitialized
+- mntent wrongly included final newline in parsed field output
+- SIGEV_THREAD timers could abort process if SIGTIMER became unblocked
+- bind_textdomain_codeset returned wrong value
+
+arch-specific bugs fixed:
+- early dynamic linker handled page size wrong on dynamic pagesize archs
+- arm and aarch64 crti/n files had wrong alignment
+- m68k POLLWRNORM and POLLWRBAND values were incorrect
+- x32 mq ABI was mismatched
diff --git a/libc-top-half/musl/arch/aarch64/bits/posix.h b/libc-top-half/musl/arch/aarch64/bits/posix.h
diff --git a/libc-top-half/musl/arch/aarch64/bits/reg.h b/libc-top-half/musl/arch/aarch64/bits/reg.h
diff --git a/libc-top-half/musl/arch/aarch64/bits/stat.h b/libc-top-half/musl/arch/aarch64/bits/stat.h
-Original file line number
+Diff line change
@@ Expand Up / @@ -1570,4 +1570,4 @@ y0f @@
     y1
     y1f
     yn
-    ynf
+    ynf