Port environment variables to use wasip2 methods (WebAssembly#610)

Author: catamorphism

libc-bottom-half/sources/__wasilibc_initialize_environ.c

@@ -1,7 +1,11 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <sysexits.h>
+#ifdef __wasilibc_use_wasip2
+#include <wasi/wasip2.h>
+#else
 #include <wasi/api.h>
+#endif
 #include <wasi/libc.h>
 #include <wasi/libc-environ.h>
 
@@ -26,6 +30,55 @@ static char *empty_environ[1] = { NULL };
 
 // See the comments in libc-environ.h.
 void __wasilibc_initialize_environ(void) {
+#ifdef __wasilibc_use_wasip2
+    // Get the environment
+    wasip2_list_tuple2_string_string_t wasi_environment;
+    environment_get_environment(&wasi_environment);
+
+    size_t environ_count = wasi_environment.len;
+    if (environ_count == 0) {
+        __wasilibc_environ = empty_environ;
+        return;
+    }
+
+    // Add 1 for the NULL pointer to mark the end, and check for overflow.
+    size_t num_ptrs = environ_count + 1;
+    if (num_ptrs == 0) {
+        goto software;
+    }
+
+    // Allocate memory for the array of pointers. This uses `calloc` both to
+    // handle overflow and to initialize the NULL pointer at the end.
+    char **environ_ptrs = calloc(num_ptrs, sizeof(char *));
+
+    // Copy the environment variables
+    for (size_t i = 0; i < environ_count; i++) {
+        wasip2_tuple2_string_string_t pair = wasi_environment.ptr[i];
+        // 1 extra character for the null terminator, 1 for the '=' character
+        environ_ptrs[i] = malloc(pair.f0.len + pair.f1.len + 2);
+        if (!environ_ptrs[i]) {
+            for (size_t j = 0; j < i; j++)
+                free(environ_ptrs[j]);
+            free(environ_ptrs);
+            goto software;
+        }
+        memcpy(environ_ptrs[i], pair.f0.ptr, pair.f0.len);
+        environ_ptrs[i][pair.f0.len] = '=';
+        memcpy(environ_ptrs[i] + pair.f0.len + 1, pair.f1.ptr, pair.f1.len);
+        environ_ptrs[i][pair.f0.len + pair.f1.len + 1] = '\0';
+    }
+
+    // Free the WASI environment list
+    wasip2_list_tuple2_string_string_free(&wasi_environment);
+
+    // Initialize the environment from the created array
+    __wasilibc_environ = environ_ptrs;
+    return;
+software:
+    wasip2_list_tuple2_string_string_free(&wasi_environment);
+    _Exit(EX_SOFTWARE);
+
+#else
     // Get the sizes of the arrays we'll have to create to copy in the environment.
     size_t environ_count;
     size_t environ_buf_size;
@@ -74,6 +127,7 @@ void __wasilibc_initialize_environ(void) {
     _Exit(EX_OSERR);
 software:
     _Exit(EX_SOFTWARE);
+#endif
 }
 
 // See the comments in libc-environ.h.

test/Makefile

@@ -210,8 +210,10 @@ wasm_to_c = $(patsubst $(OBJPAT),$(SRCDIR)/%.c,$1)
 $(RUNDIR)/%/success: $(OBJPAT)
 	@mkdir -p $(@D)
 	@DIR="$(abspath $(@D))" \
+	  ENV="$(shell scripts/add-flags.py ENV $(call wasm_to_c,$<))" \
 	  WASM="$(abspath $<)" \
-	  ENGINE="$(ENGINE) $(shell scripts/add-flags.py RUN $(call wasm_to_c,$<))" \
+	  ENGINE="$(ENGINE)" \
+          RUN="$(shell scripts/add-flags.py RUN $(call wasm_to_c,$<))" \
           ARGS="$(shell scripts/add-flags.py ARGS $(call wasm_to_c,$<))" \
 	    scripts/run-test.sh
 

test/scripts/browser-test/harness.mjs

@@ -26,6 +26,8 @@ const SKIP_TESTS = [
     "libc-test/functional/pthread_tsd",
     // Skip test that uses command-line arguments
     "misc/argv_two_args",
+    // Skip test that uses environment variables
+    "misc/external_env",
     // XFAIL: @bjorn3/browser_wasi_shim doesn't support symlinks for now
     "misc/fts",
 ];

test/scripts/run-test.sh

@@ -6,15 +6,15 @@
 # - a `fs` directory which the test may have used for file IO
 # - an `output.log` file containing the output of the test
 #
-# Usage: DIR=... WASM=... ENGINE=... ARGS="..." ./run-test.sh
+# Usage: ENV="..." DIR=... WASM=... ENGINE=... RUN="..." ARGS="..." ./run-test.sh
 
 ENGINE="${ENGINE:-wasmtime}"
 [ -n "$WASM" ] || (echo "missing WASM variable" && exit 1)
 [ -n "$DIR" ] || (echo "missing DIR variable" && exit 1)
 
 cd $DIR
 mkdir -p fs
-echo "$ENGINE $WASM $ARGS" > cmd.sh
+echo "$ENV $ENGINE $RUN $WASM $ARGS" > cmd.sh
 chmod +x cmd.sh
 ./cmd.sh &> output.log
 [ $? -eq 0 ] || echo "Test failed" >> output.log

test/src/misc/external_env.c

@@ -0,0 +1,20 @@
+//! add-flags.py(CFLAGS): -I.
+//! add-flags.py(RUN): --wasi=inherit-env=y
+//! add-flags.py(ENV): VAR1=foo VAR2=bar
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include "test.h"
+
+#define TEST(c, ...) \
+	( (c) || (t_error(#c " failed: " __VA_ARGS__),0) )
+
+int main(int argc, char **argv)
+{
+        char* s = getenv("VAR1");
+        TEST(strcmp(s, "foo")==0);
+        s = getenv("VAR2");
+        TEST(strcmp(s, "bar")==0);
+
+        return t_status;
+}