internal/runtime/syscall: add basic file system calls

Change-Id: I6a6a636c5e119165dc1018d1fc0354f5b6929656
Reviewed-on: https://go-review.googlesource.com/c/go/+/670496
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

12 files changed, 112 insertions, 0 deletions

diff --git a/src/internal/runtime/syscall/defs_linux.go b/src/internal/runtime/syscall/defs_linux.go
index 70a1388a9e..4c131e23cf 100644
--- a/src/internal/runtime/syscall/defs_linux.go
+++ b/src/internal/runtime/syscall/defs_linux.go
@@ -5,6 +5,10 @@
 package syscall
 
 const (
+	AT_FDCWD = -0x64
+
+	ENOENT = 0x2
+
 	EPOLLIN       = 0x1
 	EPOLLOUT      = 0x4
 	EPOLLERR      = 0x8
@@ -17,6 +21,9 @@ const (
 	EPOLL_CTL_MOD = 0x3
 	EFD_CLOEXEC   = 0x80000
 
+	O_RDONLY  = 0x0
+	O_CLOEXEC = 0x80000
+
 	PR_SET_VMA           = 0x53564d41
 	PR_SET_VMA_ANON_NAME = 0
 )
diff --git a/src/internal/runtime/syscall/defs_linux_386.go b/src/internal/runtime/syscall/defs_linux_386.go
index 2cfedab7c6..6f05fd7306 100644
--- a/src/internal/runtime/syscall/defs_linux_386.go
+++ b/src/internal/runtime/syscall/defs_linux_386.go
@@ -5,6 +5,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 6
 	SYS_FCNTL         = 55
 	SYS_MPROTECT      = 125
 	SYS_PRCTL         = 172
@@ -13,8 +14,13 @@ const (
 	SYS_EPOLL_CREATE1 = 329
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 328
+	SYS_OPENAT        = 295
+	SYS_PREAD64       = 180
+	SYS_READ          = 3
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x8000
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_amd64.go b/src/internal/runtime/syscall/defs_linux_amd64.go
index f664a59ad7..6c62818100 100644
--- a/src/internal/runtime/syscall/defs_linux_amd64.go
+++ b/src/internal/runtime/syscall/defs_linux_amd64.go
@@ -5,6 +5,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 3
 	SYS_MPROTECT      = 10
 	SYS_FCNTL         = 72
 	SYS_PRCTL         = 157
@@ -13,8 +14,13 @@ const (
 	SYS_EPOLL_CREATE1 = 291
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 290
+	SYS_OPENAT        = 257
+	SYS_PREAD64       = 17
+	SYS_READ          = 0
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x0
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_arm.go b/src/internal/runtime/syscall/defs_linux_arm.go
index 2850199a65..2b6005a3da 100644
--- a/src/internal/runtime/syscall/defs_linux_arm.go
+++ b/src/internal/runtime/syscall/defs_linux_arm.go
@@ -5,6 +5,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 6
 	SYS_FCNTL         = 55
 	SYS_MPROTECT      = 125
 	SYS_PRCTL         = 172
@@ -13,8 +14,13 @@ const (
 	SYS_EPOLL_CREATE1 = 357
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 356
+	SYS_OPENAT        = 322
+	SYS_PREAD64       = 180
+	SYS_READ          = 3
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x20000
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_arm64.go b/src/internal/runtime/syscall/defs_linux_arm64.go
index 1c951c1e7d..05922fbf7a 100644
--- a/src/internal/runtime/syscall/defs_linux_arm64.go
+++ b/src/internal/runtime/syscall/defs_linux_arm64.go
@@ -5,6 +5,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 57
 	SYS_EPOLL_CREATE1 = 20
 	SYS_EPOLL_CTL     = 21
 	SYS_EPOLL_PWAIT   = 22
@@ -13,8 +14,13 @@ const (
 	SYS_MPROTECT      = 226
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 19
+	SYS_OPENAT        = 56
+	SYS_PREAD64       = 67
+	SYS_READ          = 63
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x0
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_loong64.go b/src/internal/runtime/syscall/defs_linux_loong64.go
index dfeee05737..2501434ceb 100644
--- a/src/internal/runtime/syscall/defs_linux_loong64.go
+++ b/src/internal/runtime/syscall/defs_linux_loong64.go
@@ -5,6 +5,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 57
 	SYS_EPOLL_CREATE1 = 20
 	SYS_EPOLL_CTL     = 21
 	SYS_EPOLL_PWAIT   = 22
@@ -13,8 +14,13 @@ const (
 	SYS_MPROTECT      = 226
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 19
+	SYS_OPENAT        = 56
+	SYS_PREAD64       = 67
+	SYS_READ          = 63
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x0
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_mips64x.go b/src/internal/runtime/syscall/defs_linux_mips64x.go
index b9b8818d30..92ba3f7398 100644
--- a/src/internal/runtime/syscall/defs_linux_mips64x.go
+++ b/src/internal/runtime/syscall/defs_linux_mips64x.go
@@ -7,6 +7,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 5003
 	SYS_MPROTECT      = 5010
 	SYS_FCNTL         = 5070
 	SYS_PRCTL         = 5153
@@ -15,8 +16,13 @@ const (
 	SYS_EPOLL_CREATE1 = 5285
 	SYS_EPOLL_PWAIT2  = 5441
 	SYS_EVENTFD2      = 5284
+	SYS_OPENAT        = 5247
+	SYS_PREAD64       = 5016
+	SYS_READ          = 5000
 
 	EFD_NONBLOCK = 0x80
+
+	O_LARGEFILE = 0x0
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_mipsx.go b/src/internal/runtime/syscall/defs_linux_mipsx.go
index f147865f44..7b4dee08af 100644
--- a/src/internal/runtime/syscall/defs_linux_mipsx.go
+++ b/src/internal/runtime/syscall/defs_linux_mipsx.go
@@ -7,6 +7,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 4006
 	SYS_FCNTL         = 4055
 	SYS_MPROTECT      = 4125
 	SYS_PRCTL         = 4192
@@ -15,8 +16,13 @@ const (
 	SYS_EPOLL_CREATE1 = 4326
 	SYS_EPOLL_PWAIT2  = 4441
 	SYS_EVENTFD2      = 4325
+	SYS_OPENAT        = 4288
+	SYS_PREAD64       = 4200
+	SYS_READ          = 4003
 
 	EFD_NONBLOCK = 0x80
+
+	O_LARGEFILE = 0x2000
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_ppc64x.go b/src/internal/runtime/syscall/defs_linux_ppc64x.go
index 81421089db..4656517628 100644
--- a/src/internal/runtime/syscall/defs_linux_ppc64x.go
+++ b/src/internal/runtime/syscall/defs_linux_ppc64x.go
@@ -7,6 +7,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 6
 	SYS_FCNTL         = 55
 	SYS_MPROTECT      = 125
 	SYS_PRCTL         = 171
@@ -15,8 +16,13 @@ const (
 	SYS_EPOLL_CREATE1 = 315
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 314
+	SYS_OPENAT        = 286
+	SYS_PREAD64       = 179
+	SYS_READ          = 3
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x0
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_riscv64.go b/src/internal/runtime/syscall/defs_linux_riscv64.go
index dfeee05737..2501434ceb 100644
--- a/src/internal/runtime/syscall/defs_linux_riscv64.go
+++ b/src/internal/runtime/syscall/defs_linux_riscv64.go
@@ -5,6 +5,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 57
 	SYS_EPOLL_CREATE1 = 20
 	SYS_EPOLL_CTL     = 21
 	SYS_EPOLL_PWAIT   = 22
@@ -13,8 +14,13 @@ const (
 	SYS_MPROTECT      = 226
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 19
+	SYS_OPENAT        = 56
+	SYS_PREAD64       = 67
+	SYS_READ          = 63
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x0
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/defs_linux_s390x.go b/src/internal/runtime/syscall/defs_linux_s390x.go
index 1d9d5b2219..8005890e45 100644
--- a/src/internal/runtime/syscall/defs_linux_s390x.go
+++ b/src/internal/runtime/syscall/defs_linux_s390x.go
@@ -5,6 +5,7 @@
 package syscall
 
 const (
+	SYS_CLOSE         = 6
 	SYS_FCNTL         = 55
 	SYS_MPROTECT      = 125
 	SYS_PRCTL         = 172
@@ -13,8 +14,13 @@ const (
 	SYS_EPOLL_CREATE1 = 327
 	SYS_EPOLL_PWAIT2  = 441
 	SYS_EVENTFD2      = 323
+	SYS_OPENAT        = 288
+	SYS_PREAD64       = 180
+	SYS_READ          = 3
 
 	EFD_NONBLOCK = 0x800
+
+	O_LARGEFILE = 0x0
 )
 
 type EpollEvent struct {
diff --git a/src/internal/runtime/syscall/syscall_linux.go b/src/internal/runtime/syscall/syscall_linux.go
index 83df825169..49e5f8de2c 100644
--- a/src/internal/runtime/syscall/syscall_linux.go
+++ b/src/internal/runtime/syscall/syscall_linux.go
@@ -6,6 +6,7 @@
 package syscall
 
 import (
+	"internal/goarch"
 	"unsafe"
 )
 
@@ -42,3 +43,47 @@ func Eventfd(initval, flags int32) (fd int32, errno uintptr) {
 	r1, _, e := Syscall6(SYS_EVENTFD2, uintptr(initval), uintptr(flags), 0, 0, 0, 0)
 	return int32(r1), e
 }
+
+func Open(path *byte, mode int, perm uint32) (fd int, errno uintptr) {
+	// Use SYS_OPENAT to match the syscall package.
+	dfd := AT_FDCWD
+	r1, _, e := Syscall6(SYS_OPENAT, uintptr(dfd), uintptr(unsafe.Pointer(path)), uintptr(mode|O_LARGEFILE), uintptr(perm), 0, 0)
+	return int(r1), e
+}
+
+func Close(fd int) (errno uintptr) {
+	_, _, e := Syscall6(SYS_CLOSE, uintptr(fd), 0, 0, 0, 0, 0)
+	return e
+}
+
+func Read(fd int, p []byte) (n int, errno uintptr) {
+	var p0 unsafe.Pointer
+	if len(p) > 0 {
+		p0 = unsafe.Pointer(&p[0])
+	} else {
+		p0 = unsafe.Pointer(&_zero)
+	}
+	r1, _, e := Syscall6(SYS_READ, uintptr(fd), uintptr(p0), uintptr(len(p)), 0, 0, 0)
+	return int(r1), e
+}
+
+func Pread(fd int, p []byte, offset int64) (n int, errno uintptr) {
+	var p0 unsafe.Pointer
+	if len(p) > 0 {
+		p0 = unsafe.Pointer(&p[0])
+	} else {
+		p0 = unsafe.Pointer(&_zero)
+	}
+	var r1, e uintptr
+	switch goarch.GOARCH {
+	case "386":
+		r1, _, e = Syscall6(SYS_PREAD64, uintptr(fd), uintptr(p0), uintptr(len(p)), uintptr(offset), uintptr(offset>>32), 0)
+	case "arm", "mipsle":
+		r1, _, e = Syscall6(SYS_PREAD64, uintptr(fd), uintptr(p0), uintptr(len(p)), 0, uintptr(offset), uintptr(offset>>32))
+	case "mips":
+		r1, _, e = Syscall6(SYS_PREAD64, uintptr(fd), uintptr(p0), uintptr(len(p)), 0, uintptr(offset>>32), uintptr(offset))
+	default:
+		r1, _, e = Syscall6(SYS_PREAD64, uintptr(fd), uintptr(p0), uintptr(len(p)), uintptr(offset), 0, 0)
+	}
+	return int(r1), e
+}