Emulate clock, times, and getrusage using the monotonic clock.

Makefile

@@ -54,6 +54,8 @@ LIBC_BOTTOM_HALF_ALL_SOURCES := $(LIBC_BOTTOM_HALF_ALL_SOURCES) $(LIBC_BOTTOM_HA
 
 LIBWASI_EMULATED_MMAN_SOURCES = \
     $(shell find $(LIBC_BOTTOM_HALF_DIR)/mman -name \*.c)
+LIBWASI_EMULATED_PROCESS_CLOCKS_SOURCES = \
+    $(shell find $(LIBC_BOTTOM_HALF_DIR)/clocks -name \*.c)
 LIBWASI_EMULATED_SIGNAL_SOURCES = \
     $(shell find $(LIBC_BOTTOM_HALF_DIR)/signal -name \*.c)
 LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES = \
@@ -229,6 +231,7 @@ MUSL_PRINTSCAN_OBJS = $(call objs,$(MUSL_PRINTSCAN_SOURCES))
 MUSL_PRINTSCAN_LONG_DOUBLE_OBJS = $(patsubst %.o,%.long-double.o,$(MUSL_PRINTSCAN_OBJS))
 MUSL_PRINTSCAN_NO_FLOATING_POINT_OBJS = $(patsubst %.o,%.no-floating-point.o,$(MUSL_PRINTSCAN_OBJS))
 LIBWASI_EMULATED_MMAN_OBJS = $(call objs,$(LIBWASI_EMULATED_MMAN_SOURCES))
+LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS = $(call objs,$(LIBWASI_EMULATED_PROCESS_CLOCKS_SOURCES))
 LIBWASI_EMULATED_SIGNAL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_SOURCES))
 LIBWASI_EMULATED_SIGNAL_MUSL_OBJS = $(call objs,$(LIBWASI_EMULATED_SIGNAL_MUSL_SOURCES))
 
@@ -332,6 +335,8 @@ $(SYSROOT_LIB)/libc-printscan-no-floating-point.a: $(MUSL_PRINTSCAN_NO_FLOATING_
 
 $(SYSROOT_LIB)/libwasi-emulated-mman.a: $(LIBWASI_EMULATED_MMAN_OBJS)
 
+$(SYSROOT_LIB)/libwasi-emulated-process-clocks.a: $(LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS)
+
 $(SYSROOT_LIB)/libwasi-emulated-signal.a: $(LIBWASI_EMULATED_SIGNAL_OBJS) $(LIBWASI_EMULATED_SIGNAL_MUSL_OBJS)
 
 %.a:
@@ -392,6 +397,9 @@ $(LIBC_TOP_HALF_ALL_OBJS) $(MUSL_PRINTSCAN_LONG_DOUBLE_OBJS) $(MUSL_PRINTSCAN_NO
     -Wno-dangling-else \
     -Wno-unknown-pragmas
 
+$(LIBWASI_EMULATED_PROCESS_CLOCKS_OBJS): CFLAGS += \
+    -I$(LIBC_BOTTOM_HALF_CLOUDLIBC_SRC)
+
 include_dirs:
 	$(RM) -r "$(SYSROOT)"
 
@@ -432,6 +440,7 @@ libc: include_dirs \
     $(SYSROOT_LIB)/libc-printscan-long-double.a \
     $(SYSROOT_LIB)/libc-printscan-no-floating-point.a \
     $(SYSROOT_LIB)/libwasi-emulated-mman.a \
+    $(SYSROOT_LIB)/libwasi-emulated-process-clocks.a \
     $(SYSROOT_LIB)/libwasi-emulated-signal.a
 
 finish: startup_files libc
@@ -454,7 +463,7 @@ finish: startup_files libc
 	@# LLVM PR40497, which is fixed in 9.0, but not in 8.0.
 	@# Ignore certain llvm builtin symbols such as those starting with __mul
 	@# since these dependencies can vary between llvm versions.
-	"$(WASM_NM)" --defined-only "$(SYSROOT_LIB)"/libc.a "$(SYSROOT_LIB)"/*.o \
+	"$(WASM_NM)" --defined-only "$(SYSROOT_LIB)"/libc.a "$(SYSROOT_LIB)"/libwasi-emulated-*.a "$(SYSROOT_LIB)"/*.o \
 	    |grep ' [[:upper:]] ' |sed 's/.* [[:upper:]] //' |LC_ALL=C sort > "$(SYSROOT_SHARE)/defined-symbols.txt"
 	for undef_sym in $$("$(WASM_NM)" --undefined-only "$(SYSROOT_LIB)"/libc.a "$(SYSROOT_LIB)"/libc-*.a "$(SYSROOT_LIB)"/*.o \
 	    |grep ' U ' |sed 's/.* U //' |LC_ALL=C sort |uniq); do \
@@ -467,7 +476,7 @@ finish: startup_files libc
 	# Generate a test file that includes all public header files.
 	#
 	cd "$(SYSROOT)" && \
-	  for header in $$(find include -type f -not -name mman.h -not -name signal.h |grep -v /bits/); do \
+	  for header in $$(find include -type f -not -name mman.h -not -name signal.h -not -name times.h -not -name resource.h |grep -v /bits/); do \
 	      echo '#include <'$$header'>' | sed 's/include\///' ; \
 	done |LC_ALL=C sort >share/$(MULTIARCH_TRIPLE)/include-all.c ; \
 	cd - >/dev/null

expected/wasm32-wasi/defined-symbols.txt

@@ -11,11 +11,14 @@ _IO_putc
 _IO_putc_unlocked
 __EINVAL
 __ENOMEM
+__SIG_ERR
+__SIG_IGN
 __asctime_r
 __assert_fail
 __c_dot_utf8
 __c_dot_utf8_locale
 __c_locale
+__clock
 __clock_gettime
 __cos
 __cosdf
@@ -227,6 +230,7 @@ __strtoull_internal
 __strtoumax_internal
 __strxfrm_l
 __sysinfo
+__sysv_signal
 __tan
 __tandf
 __tanl
@@ -387,6 +391,7 @@ atoll
 basename
 bcmp
 bcopy
+bsd_signal
 bsearch
 btowc
 bzero
@@ -838,10 +843,12 @@ memset
 mkdir
 mkdirat
 mktime
+mmap
 modf
 modff
 modfl
 mrand48
+munmap
 nan
 nanf
 nanl
@@ -893,6 +900,7 @@ printf
 program_invocation_name
 program_invocation_short_name
 pselect
+psignal
 putc
 putc_unlocked
 putchar
@@ -908,6 +916,7 @@ pwrite
 pwritev
 qsort
 quick_exit
+raise
 rand
 rand_r
 random
@@ -969,6 +978,7 @@ setlocale
 setstate
 setvbuf
 shutdown
+signal
 signgam
 significand
 significandf
@@ -1030,6 +1040,7 @@ strpbrk
 strptime
 strrchr
 strsep
+strsignal
 strspn
 strstr
 strtod

expected/wasm32-wasi/include-all.c

@@ -137,7 +137,6 @@
 #include <sys/poll.h>
 #include <sys/random.h>
 #include <sys/reg.h>
-#include <sys/resource.h>
 #include <sys/select.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
@@ -146,7 +145,6 @@
 #include <sys/sysinfo.h>
 #include <sys/time.h>
 #include <sys/timeb.h>
-#include <sys/times.h>
 #include <sys/timex.h>
 #include <sys/ttydefaults.h>
 #include <sys/types.h>

expected/wasm32-wasi/predefined-macros.txt

@@ -2306,14 +2306,12 @@
 #define _SYS_PARAM_H 
 #define _SYS_RANDOM_H 
 #define _SYS_REG_H 
-#define _SYS_RESOURCE_H 
 #define _SYS_SELECT_H 
 #define _SYS_SOCKET_H 
 #define _SYS_STAT_H 
 #define _SYS_SYSCALL_H 
 #define _SYS_SYSINFO_H 
 #define _SYS_TIMEB_H 
-#define _SYS_TIMES_H 
 #define _SYS_TIMEX_H 
 #define _SYS_TIME_H 
 #define _SYS_TTYDEFAULTS_H 

libc-bottom-half/clocks/clock.c

@@ -0,0 +1,35 @@
+#define _WASI_EMULATED_PROCESS_CLOCKS
+#include <time.h>
+#include <wasi/api.h>
+#include <common/time.h>
+
+_Static_assert(
+    CLOCKS_PER_SEC == NSEC_PER_SEC,
+    "This implementation assumes that `clock` is in nanoseconds"
+);
+
+// Snapshot of the monotonic clock at the start of the program.
+static __wasi_timestamp_t start;
+
+// Use a priority of 10 to run fairly early in the implementation-reserved
+// constructor priority range.
+__attribute__((constructor(10)))
+static void init(void) {
+    (void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &start);
+}
+
+// Define the libc symbol as `__clock` so that we can reliably call it
+// from elsewhere in libc.
+clock_t __clock(void) {
+    // Use `MONOTONIC` instead of `PROCESS_CPUTIME_ID` since WASI doesn't have
+    // an inherent concept of a process. Note that this means we'll incorrectly
+    // include time from other processes, so this function is only declared by
+    // the headers if `_WASI_EMULATED_PROCESS_CLOCKS` is defined.
+    __wasi_timestamp_t now = 0;
+    (void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &now);
+    return now - start;
+}
+
+// Define a user-visible alias as a weak symbol.
+__attribute__((__weak__, __alias__("__clock")))
+clock_t clock(void);

libc-bottom-half/clocks/getrusage.c

@@ -0,0 +1,28 @@
+#define _WASI_EMULATED_PROCESS_CLOCKS
+#include <sys/resource.h>
+#include <errno.h>
+#include <time.h>
+#include <wasi/api.h>
+#include <common/time.h>
+
+// `clock` is a weak symbol so that application code can override it.
+// We want to use the function in libc, so use the libc-internal name.
+clock_t __clock(void);
+
+int getrusage(int who, struct rusage *r_usage) {
+    switch (who) {
+    case RUSAGE_SELF: {
+        __wasi_timestamp_t usertime = __clock();
+        *r_usage = (struct rusage) {
+            .ru_utime = timestamp_to_timeval(usertime)
+	};
+        return 0;
+    }
+    case RUSAGE_CHILDREN:
+        *r_usage = (struct rusage) {};
+        return 0;
+    default:
+        errno = EINVAL;
+        return -1;
+    }
+}

libc-bottom-half/clocks/times.c

@@ -0,0 +1,26 @@
+#define _WASI_EMULATED_PROCESS_CLOCKS
+#include <time.h>
+#include <sys/times.h>
+#include <wasi/api.h>
+#include <common/time.h>
+
+_Static_assert(
+    CLOCKS_PER_SEC == NSEC_PER_SEC,
+    "This implementation assumes that `clock` is in nanoseconds"
+);
+
+// `clock` is a weak symbol so that application code can override it.
+// We want to use the function in libc, so use the libc-internal name.
+clock_t __clock(void);
+
+clock_t times(struct tms *buffer) {
+    __wasi_timestamp_t user = __clock();
+    *buffer = (struct tms){
+        .tms_utime = user,
+        .tms_cutime = user
+    };
+
+    __wasi_timestamp_t realtime = 0;
+    (void)__wasi_clock_time_get(__WASI_CLOCKID_MONOTONIC, 0, &realtime);
+    return realtime;
+}

libc-top-half/musl/include/sys/param.h

@@ -28,7 +28,9 @@
 #define roundup(n,d) (howmany(n,d)*(d))
 #define powerof2(n) !(((n)-1) & (n))
 
+#if defined(__wasilibc_unmodified_upstream) || defined(_WASI_EMULATED_PROCESS_CLOCKS)
 #include <sys/resource.h>
+#endif
 #include <endian.h>
 #include <limits.h>
 

libc-top-half/musl/include/sys/resource.h

@@ -1,3 +1,8 @@
+#ifndef _WASI_EMULATED_PROCESS_CLOCKS
+#error WASI lacks process-associated clocks; to enable emulation of the `getrusage` function using \
+the wall clock, which isn't sensitive to whether the program is running or suspended, \
+compile with -D_WASI_EMULATED_PROCESS_CLOCKS and link with -lwasi-emulated-process-clocks
+#else
 #ifndef	_SYS_RESOURCE_H
 #define	_SYS_RESOURCE_H
 
@@ -118,3 +123,4 @@ __REDIR(getrusage, __getrusage_time64);
 #endif
 
 #endif
+#endif

libc-top-half/musl/include/sys/times.h

@@ -1,3 +1,8 @@
+#ifndef _WASI_EMULATED_PROCESS_CLOCKS
+#error WASI lacks process-associated clocks; to enable emulation of the `times` function using \
+the wall clock, which isn't sensitive to whether the program is running or suspended, \
+compile with -D_WASI_EMULATED_PROCESS_CLOCKS and link with -lwasi-emulated-process-clocks
+#else
 #ifndef	_SYS_TIMES_H
 #define	_SYS_TIMES_H
 
@@ -26,4 +31,4 @@ clock_t times (struct tms *);
 #endif
 
 #endif
-
+#endif

libc-top-half/musl/include/time.h

@@ -58,7 +58,16 @@ struct tm {
 #include <__header_time.h>
 #endif
 
+#if defined(__wasilibc_unmodified_upstream) || defined(_WASI_EMULATED_PROCESS_CLOCKS)
 clock_t clock (void);
+#else
+__attribute__((__deprecated__(
+"WASI lacks process-associated clocks; to enable emulation of the `clock` function using "
+"the wall clock, which isn't sensitive to whether the program is running or suspended, "
+"compile with -D_WASI_EMULATED_PROCESS_CLOCKS and link with -lwasi-emulated-process-clocks"
+)))
+clock_t clock (void);
+#endif
 time_t time (time_t *);
 double difftime (time_t, time_t);
 time_t mktime (struct tm *);