diff options
| author | Nick Khyl <nickk@tailscale.com> | 2024-12-05 13:16:48 -0600 |
|---|---|---|
| committer | Nick Khyl <nickk@tailscale.com> | 2024-12-05 13:16:48 -0600 |
| commit | 0267fe83b200f1702a2fa0a395442c02a053fadb (patch) | |
| tree | 63654c55225eeb834de59a5a0bc8d19033c6145b /util/cstruct/cstruct_example_test.go | |
| parent | 87546a5edf6b6503a87eeb2d666baba57398a066 (diff) | |
| download | tailscale-1.78.0.tar.xz tailscale-1.78.0.zip | |
VERSION.txt: this is v1.78.0v1.78.0
Signed-off-by: Nick Khyl <nickk@tailscale.com>
Diffstat (limited to 'util/cstruct/cstruct_example_test.go')
| -rw-r--r-- | util/cstruct/cstruct_example_test.go | 146 |
1 files changed, 73 insertions, 73 deletions
diff --git a/util/cstruct/cstruct_example_test.go b/util/cstruct/cstruct_example_test.go index 17032267b..a36cbf9f0 100644 --- a/util/cstruct/cstruct_example_test.go +++ b/util/cstruct/cstruct_example_test.go @@ -1,73 +1,73 @@ -// Copyright (c) Tailscale Inc & AUTHORS -// SPDX-License-Identifier: BSD-3-Clause - -// Only built on 64-bit platforms to avoid complexity - -//go:build amd64 || arm64 || mips64le || ppc64le || riscv64 - -package cstruct - -import "fmt" - -// This test provides a semi-realistic example of how you can -// use this package to decode a C structure. -func ExampleDecoder() { - // Our example C structure: - // struct mystruct { - // char *p; - // char c; - // /* implicit: char _pad[3]; */ - // int x; - // }; - // - // The Go structure definition: - type myStruct struct { - Ptr uintptr - Ch byte - Intval uint32 - } - - // Our "in-memory" version of the above structure - buf := []byte{ - 1, 2, 3, 4, 0, 0, 0, 0, // ptr - 5, // ch - 99, 99, 99, // padding - 78, 6, 0, 0, // x - } - d := NewDecoder(buf) - - // Decode the structure; if one of these function returns an error, - // then subsequent decoder functions will return the zero value. - var x myStruct - x.Ptr = d.Uintptr() - x.Ch = d.Byte() - x.Intval = d.Uint32() - - // Note that per the Go language spec: - // [...] when evaluating the operands of an expression, assignment, - // or return statement, all function calls, method calls, and - // (channel) communication operations are evaluated in lexical - // left-to-right order - // - // Since each field is assigned via a function call, one could use the - // following snippet to decode the struct. - // x := myStruct{ - // Ptr: d.Uintptr(), - // Ch: d.Byte(), - // Intval: d.Uint32(), - // } - // - // However, this means that reordering the fields in the initialization - // statement–normally a semantically identical operation–would change - // the way the structure is parsed. Thus we do it as above with - // explicit ordering. - - // After finishing with the decoder, check errors - if err := d.Err(); err != nil { - panic(err) - } - - // Print the decoder offset and structure - fmt.Printf("off=%d struct=%#v\n", d.Offset(), x) - // Output: off=16 struct=cstruct.myStruct{Ptr:0x4030201, Ch:0x5, Intval:0x64e} -} +// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Only built on 64-bit platforms to avoid complexity
+
+//go:build amd64 || arm64 || mips64le || ppc64le || riscv64
+
+package cstruct
+
+import "fmt"
+
+// This test provides a semi-realistic example of how you can
+// use this package to decode a C structure.
+func ExampleDecoder() {
+ // Our example C structure:
+ // struct mystruct {
+ // char *p;
+ // char c;
+ // /* implicit: char _pad[3]; */
+ // int x;
+ // };
+ //
+ // The Go structure definition:
+ type myStruct struct {
+ Ptr uintptr
+ Ch byte
+ Intval uint32
+ }
+
+ // Our "in-memory" version of the above structure
+ buf := []byte{
+ 1, 2, 3, 4, 0, 0, 0, 0, // ptr
+ 5, // ch
+ 99, 99, 99, // padding
+ 78, 6, 0, 0, // x
+ }
+ d := NewDecoder(buf)
+
+ // Decode the structure; if one of these function returns an error,
+ // then subsequent decoder functions will return the zero value.
+ var x myStruct
+ x.Ptr = d.Uintptr()
+ x.Ch = d.Byte()
+ x.Intval = d.Uint32()
+
+ // Note that per the Go language spec:
+ // [...] when evaluating the operands of an expression, assignment,
+ // or return statement, all function calls, method calls, and
+ // (channel) communication operations are evaluated in lexical
+ // left-to-right order
+ //
+ // Since each field is assigned via a function call, one could use the
+ // following snippet to decode the struct.
+ // x := myStruct{
+ // Ptr: d.Uintptr(),
+ // Ch: d.Byte(),
+ // Intval: d.Uint32(),
+ // }
+ //
+ // However, this means that reordering the fields in the initialization
+ // statement–normally a semantically identical operation–would change
+ // the way the structure is parsed. Thus we do it as above with
+ // explicit ordering.
+
+ // After finishing with the decoder, check errors
+ if err := d.Err(); err != nil {
+ panic(err)
+ }
+
+ // Print the decoder offset and structure
+ fmt.Printf("off=%d struct=%#v\n", d.Offset(), x)
+ // Output: off=16 struct=cstruct.myStruct{Ptr:0x4030201, Ch:0x5, Intval:0x64e}
+}
|