Initial import

libc/sock/sendfile.c

@@ -0,0 +1,101 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ This program is free software; you can redistribute it and/or modify         │
+│ it under the terms of the GNU General Public License as published by         │
+│ the Free Software Foundation; version 2 of the License.                      │
+│                                                                              │
+│ This program is distributed in the hope that it will be useful, but          │
+│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
+│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
+│ General Public License for more details.                                     │
+│                                                                              │
+│ You should have received a copy of the GNU General Public License            │
+│ along with this program; if not, write to the Free Software                  │
+│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
+│ 02110-1301 USA                                                               │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/bits/safemacros.h"
+#include "libc/calls/calls.h"
+#include "libc/calls/internal.h"
+#include "libc/dce.h"
+#include "libc/nt/winsock.h"
+#include "libc/sock/internal.h"
+#include "libc/str/str.h"
+#include "libc/sysv/errfuns.h"
+
+static textwindows ssize_t sendfile$linux2nt(int outfd, int infd,
+                                             int64_t *inout_opt_inoffset,
+                                             size_t uptobytes) {
+  struct NtOverlapped Overlapped;
+  struct NtOverlapped *lpOverlapped;
+  if (!isfdkind(outfd, kFdSocket) || !isfdkind(outfd, kFdFile)) return ebadf();
+  if (inout_opt_inoffset) {
+    memset(&Overlapped, 0, sizeof(Overlapped));
+    Overlapped.Pointer = (void *)(intptr_t)(*inout_opt_inoffset);
+    lpOverlapped = &Overlapped;
+  } else {
+    lpOverlapped = NULL;
+  }
+  /* TODO(jart): Fetch this on a per-socket basis via GUID. */
+  if (TransmitFile(g_fds.p[outfd].handle, g_fds.p[infd].handle, uptobytes, 0,
+                   lpOverlapped, NULL, 0)) {
+    return uptobytes;
+  } else {
+    return winsockerr();
+  }
+}
+
+static ssize_t sendfile$linux2netflix(int outfd, int infd,
+                                      int64_t *inout_opt_inoffset,
+                                      size_t uptobytes) {
+  int sendfile$netflix(int32_t infd, int32_t outfd, int64_t offset,
+                       size_t nbytes, const void *opt_hdtr,
+                       int64_t *out_opt_sbytes,
+                       int32_t flags) asm("sendfile$sysv") hidden;
+  int rc;
+  int64_t offset, sbytes;
+  if (inout_opt_inoffset) {
+    offset = *inout_opt_inoffset;
+  } else if ((offset = lseek$sysv(infd, 0, SEEK_CUR)) == -1) {
+    return -1;
+  }
+  if ((rc = sendfile$netflix(infd, outfd, offset, uptobytes, NULL, &sbytes,
+                             0)) != -1) {
+    if (inout_opt_inoffset) *inout_opt_inoffset += sbytes;
+    return sbytes;
+  } else {
+    return -1;
+  }
+}
+
+/**
+ * Transfers data from file to network.
+ *
+ * @param outfd needs to be a socket
+ * @param infd needs to be a file
+ * @param inout_opt_inoffset may be specified for pread()-like behavior
+ * @param uptobytes is usually the number of bytes remaining in file; it
+ *     can't exceed INT_MAX-1; some platforms block until everything's
+ *     sent, whereas others won't; zero isn't allowed
+ * @return number of bytes transmitted which may be fewer than requested
+ * @see copy_file_range() for file ↔ file
+ * @see splice() for fd ↔ pipe
+ */
+ssize_t sendfile(int outfd, int infd, int64_t *inout_opt_inoffset,
+                 size_t uptobytes) {
+  if (!uptobytes) return einval();
+  if (uptobytes > 0x7ffffffe /* Microsoft's off-by-one */) return eoverflow();
+  if (IsModeDbg() && uptobytes > 1) uptobytes >>= 1;
+  if (IsLinux()) {
+    return sendfile$sysv(outfd, infd, inout_opt_inoffset, uptobytes);
+  } else if (IsFreebsd() || IsXnu()) {
+    return sendfile$linux2netflix(outfd, infd, inout_opt_inoffset, uptobytes);
+  } else if (IsWindows()) {
+    return sendfile$linux2nt(outfd, infd, inout_opt_inoffset, uptobytes);
+  } else {
+    return copyfd(infd, inout_opt_inoffset, outfd, NULL, uptobytes, 0);
+  }
+}