[reland][libc] add epoll_wait functions (#79635)

The epoll_wait functions are syscall wrappers that were requested by
upstream users. This patch adds them, as well as their header and types.

The tests are currently incomplete since they require epoll_create to
properly test epoll_wait. That will be added in a followup patch since
this one is already very large.

Author: michaelrj-google

libc/config/linux/aarch64/entrypoints.txt

@@ -179,6 +179,12 @@ set(TARGET_LIBC_ENTRYPOINTS
     # sys/auxv.h entrypoints
     libc.src.sys.auxv.getauxval
 
+    # sys/epoll.h entrypoints
+    # Disabled due to epoll_wait syscalls not being available on this platform.
+    # libc.src.sys.epoll.epoll_wait
+    # libc.src.sys.epoll.epoll_pwait
+    # libc.src.sys.epoll.epoll_pwait2
+
     # termios.h entrypoints
     libc.src.termios.cfgetispeed
     libc.src.termios.cfgetospeed

libc/config/linux/aarch64/headers.txt

@@ -25,4 +25,6 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.unistd
 
     libc.include.sys_ioctl
+    # Disabled due to epoll_wait syscalls not being available on this platform.
+    # libc.include.sys_epoll
 )

libc/config/linux/api.td

@@ -1,11 +1,11 @@
 include "config/public_api.td"
 
-include "spec/bsd_ext.td"
-include "spec/gnu_ext.td"
+include "spec/stdc.td"
+include "spec/posix.td"
 include "spec/linux.td"
+include "spec/gnu_ext.td"
+include "spec/bsd_ext.td"
 include "spec/llvm_libc_ext.td"
-include "spec/posix.td"
-include "spec/stdc.td"
 
 def AssertMacro : MacroDef<"assert"> {
   let Defn = [{
@@ -242,6 +242,10 @@ def SysUtsNameAPI : PublicAPI<"sys/utsname.h"> {
   let Types = ["struct utsname"];
 }
 
+def SysEpollAPI : PublicAPI<"sys/epoll.h"> {
+  let Types = ["struct epoll_event", "struct epoll_data", "sigset_t", "struct timespec"];
+}
+
 def SpawnAPI : PublicAPI<"spawn.h"> {
   let Types = ["mode_t", "pid_t", "posix_spawnattr_t", "posix_spawn_file_actions_t"];
 }

libc/config/linux/arm/entrypoints.txt

@@ -102,6 +102,13 @@ set(TARGET_LIBC_ENTRYPOINTS
 
     # sys/prctl.h entrypoints
     libc.src.sys.prctl.prctl
+
+    # sys/epoll.h entrypoints
+    # Disabled due to epoll_wait syscalls not being available on this platform.
+    # libc.src.sys.epoll.epoll_wait
+    # libc.src.sys.epoll.epoll_pwait
+    # libc.src.sys.epoll.epoll_pwait2
+
 )
 
 set(TARGET_LIBM_ENTRYPOINTS

libc/config/linux/arm/headers.txt

@@ -10,4 +10,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.string
     libc.include.strings
     libc.include.search
+
+    # Disabled due to epoll_wait syscalls not being available on this platform.
+    # libc.include.sys_epoll
 )

libc/config/linux/riscv/entrypoints.txt

@@ -185,6 +185,12 @@ set(TARGET_LIBC_ENTRYPOINTS
     # sys/auxv.h entrypoints
     libc.src.sys.auxv.getauxval
 
+    # sys/epoll.h entrypoints
+    # Disabled due to epoll_wait syscalls not being available on this platform.
+    # libc.src.sys.epoll.epoll_wait
+    # libc.src.sys.epoll.epoll_pwait
+    # libc.src.sys.epoll.epoll_pwait2
+
     # termios.h entrypoints
     libc.src.termios.cfgetispeed
     libc.src.termios.cfgetospeed

libc/config/linux/riscv/headers.txt

@@ -30,6 +30,8 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.arpa_inet
 
     libc.include.sys_auxv
+    # Disabled due to epoll_wait syscalls not being available on this platform.
+    # libc.include.sys_epoll
     libc.include.sys_ioctl
     libc.include.sys_mman
     libc.include.sys_prctl

libc/config/linux/syscall_numbers.h.inc

@@ -258,6 +258,10 @@
 #define SYS_epoll_pwait __NR_epoll_pwait
 #endif
 
+#ifdef __NR_epoll_pwait2
+#define SYS_epoll_pwait2 __NR_epoll_pwait2
+#endif
+
 #ifdef __NR_epoll_wait
 #define SYS_epoll_wait __NR_epoll_wait
 #endif

libc/config/linux/x86_64/entrypoints.txt

@@ -143,6 +143,11 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdio.scanf
     libc.src.stdio.fscanf
 
+    # sys/epoll.h entrypoints
+    libc.src.sys.epoll.epoll_wait
+    libc.src.sys.epoll.epoll_pwait
+    libc.src.sys.epoll.epoll_pwait2
+
     # sys/mman.h entrypoints
     libc.src.sys.mman.madvise
     libc.src.sys.mman.mmap

libc/config/linux/x86_64/headers.txt

@@ -30,6 +30,7 @@ set(TARGET_PUBLIC_HEADERS
     libc.include.arpa_inet
 
     libc.include.sys_auxv
+    libc.include.sys_epoll
     libc.include.sys_ioctl
     libc.include.sys_mman
     libc.include.sys_prctl