Extend standalone support

system/lib/libc/musl/src/stdio/freopen.c

@@ -1,6 +1,17 @@
+#ifdef __wasilibc_unmodified_upstream // WASI has no syscall, dup
 #include "stdio_impl.h"
+#else
+#include <wasi/api.h>
+#endif
 #include <fcntl.h>
 #include <unistd.h>
+#ifdef __wasilibc_unmodified_upstream // WASI has no syscall, dup
+#else
+// Move this below fcntl.h and unistd.h so that the __syscall macro doesn't
+// cause trouble.
+#include "stdio_impl.h"
+#include <errno.h>
+#endif
 
 /* The basic idea of this implementation is to open a new FILE,
  * hack the necessary parts of the new FILE into the old one, then
@@ -10,46 +21,70 @@
  * lock, via flockfile or otherwise, when freopen is called, and in that
  * case, freopen cannot act until the lock is released. */
 
+int __wasilibc_fd_renumber(int fd, int newfd) {
+  __wasi_errno_t error = __wasi_fd_renumber(fd, newfd);
+  if (error != 0) {
+    errno = error;
+    return -1;
+  }
+  return 0;
+}
+
 FILE *freopen(const char *restrict filename, const char *restrict mode, FILE *restrict f)
 {
-	int fl = __fmodeflags(mode);
-	FILE *f2;
+  int fl = __fmodeflags(mode);
+  FILE *f2;
 
-	FLOCK(f);
+  FLOCK(f);
 
-	fflush(f);
+  fflush(f);
 
-	if (!filename) {
-#ifndef __EMSCRIPTEN__ // CLOEXEC makes no sense for a single process
-		if (fl&O_CLOEXEC)
-			__syscall(SYS_fcntl, f->fd, F_SETFD, FD_CLOEXEC);
+  if (!filename) {
+    if (fl&O_CLOEXEC)
+#ifdef __wasilibc_unmodified_upstream // WASI has no syscall
+      __syscall(SYS_fcntl, f->fd, F_SETFD, FD_CLOEXEC);
+#else
+      fcntl(f->fd, F_SETFD, FD_CLOEXEC);
+#endif
+    fl &= ~(O_CREAT|O_EXCL|O_CLOEXEC);
+#ifdef __wasilibc_unmodified_upstream // WASI has no syscall
+    if (syscall(SYS_fcntl, f->fd, F_SETFL, fl) < 0)
+#else
+    if (fcntl(f->fd, F_SETFL, fl) < 0)
 #endif
-		fl &= ~(O_CREAT|O_EXCL|O_CLOEXEC);
-		if (syscall(SYS_fcntl, f->fd, F_SETFL, fl) < 0)
-			goto fail;
-	} else {
-		f2 = fopen(filename, mode);
-		if (!f2) goto fail;
-		if (f2->fd == f->fd) f2->fd = -1; /* avoid closing in fclose */
-		else if (__dup3(f2->fd, f->fd, fl&O_CLOEXEC)<0) goto fail2;
-
-		f->flags = (f->flags & F_PERM) | f2->flags;
-		f->read = f2->read;
-		f->write = f2->write;
-		f->seek = f2->seek;
-		f->close = f2->close;
-
-		fclose(f2);
-	}
-
-	f->mode = 0;
-	f->locale = 0;
-	FUNLOCK(f);
-	return f;
-
-fail2:
-	fclose(f2);
-fail:
-	fclose(f);
-	return NULL;
+      goto fail;
+  } else {
+    f2 = fopen(filename, mode);
+    if (!f2) goto fail;
+    if (f2->fd == f->fd) f2->fd = -1; /* avoid closing in fclose */
+#ifdef __wasilibc_unmodified_upstream // WASI has no dup
+      else if (__dup3(f2->fd, f->fd, fl&O_CLOEXEC)<0) goto fail2;
+#else
+      // WASI doesn't have dup3, but does have a way to renumber
+      // an existing file descriptor.
+    else {
+      if (__wasilibc_fd_renumber(f2->fd, f->fd)<0) goto fail2;
+      f2->fd = -1; /* avoid closing in fclose */
+    }
+#endif
+
+    f->flags = (f->flags & F_PERM) | f2->flags;
+    f->read = f2->read;
+    f->write = f2->write;
+    f->seek = f2->seek;
+    f->close = f2->close;
+
+    fclose(f2);
+  }
+
+  FUNLOCK(f);
+  return f;
+
+  fail2:
+  fclose(f2);
+  fail:
+  fclose(f);
+  return NULL;
 }
+
+weak_alias(freopen, freopen64);