summaryrefslogtreecommitdiffstats
path: root/src/runtime/print.go
diff options
context:
space:
mode:
Diffstat (limited to 'src/runtime/print.go')
-rw-r--r--src/runtime/print.go312
1 files changed, 312 insertions, 0 deletions
diff --git a/src/runtime/print.go b/src/runtime/print.go
new file mode 100644
index 0000000..64055a3
--- /dev/null
+++ b/src/runtime/print.go
@@ -0,0 +1,312 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import (
+ "runtime/internal/atomic"
+ "runtime/internal/sys"
+ "unsafe"
+)
+
+// The compiler knows that a print of a value of this type
+// should use printhex instead of printuint (decimal).
+type hex uint64
+
+func bytes(s string) (ret []byte) {
+ rp := (*slice)(unsafe.Pointer(&ret))
+ sp := stringStructOf(&s)
+ rp.array = sp.str
+ rp.len = sp.len
+ rp.cap = sp.len
+ return
+}
+
+var (
+ // printBacklog is a circular buffer of messages written with the builtin
+ // print* functions, for use in postmortem analysis of core dumps.
+ printBacklog [512]byte
+ printBacklogIndex int
+)
+
+// recordForPanic maintains a circular buffer of messages written by the
+// runtime leading up to a process crash, allowing the messages to be
+// extracted from a core dump.
+//
+// The text written during a process crash (following "panic" or "fatal
+// error") is not saved, since the goroutine stacks will generally be readable
+// from the runtime datastructures in the core file.
+func recordForPanic(b []byte) {
+ printlock()
+
+ if atomic.Load(&panicking) == 0 {
+ // Not actively crashing: maintain circular buffer of print output.
+ for i := 0; i < len(b); {
+ n := copy(printBacklog[printBacklogIndex:], b[i:])
+ i += n
+ printBacklogIndex += n
+ printBacklogIndex %= len(printBacklog)
+ }
+ }
+
+ printunlock()
+}
+
+var debuglock mutex
+
+// The compiler emits calls to printlock and printunlock around
+// the multiple calls that implement a single Go print or println
+// statement. Some of the print helpers (printslice, for example)
+// call print recursively. There is also the problem of a crash
+// happening during the print routines and needing to acquire
+// the print lock to print information about the crash.
+// For both these reasons, let a thread acquire the printlock 'recursively'.
+
+func printlock() {
+ mp := getg().m
+ mp.locks++ // do not reschedule between printlock++ and lock(&debuglock).
+ mp.printlock++
+ if mp.printlock == 1 {
+ lock(&debuglock)
+ }
+ mp.locks-- // now we know debuglock is held and holding up mp.locks for us.
+}
+
+func printunlock() {
+ mp := getg().m
+ mp.printlock--
+ if mp.printlock == 0 {
+ unlock(&debuglock)
+ }
+}
+
+// write to goroutine-local buffer if diverting output,
+// or else standard error.
+func gwrite(b []byte) {
+ if len(b) == 0 {
+ return
+ }
+ recordForPanic(b)
+ gp := getg()
+ // Don't use the writebuf if gp.m is dying. We want anything
+ // written through gwrite to appear in the terminal rather
+ // than be written to in some buffer, if we're in a panicking state.
+ // Note that we can't just clear writebuf in the gp.m.dying case
+ // because a panic isn't allowed to have any write barriers.
+ if gp == nil || gp.writebuf == nil || gp.m.dying > 0 {
+ writeErr(b)
+ return
+ }
+
+ n := copy(gp.writebuf[len(gp.writebuf):cap(gp.writebuf)], b)
+ gp.writebuf = gp.writebuf[:len(gp.writebuf)+n]
+}
+
+func printsp() {
+ printstring(" ")
+}
+
+func printnl() {
+ printstring("\n")
+}
+
+func printbool(v bool) {
+ if v {
+ printstring("true")
+ } else {
+ printstring("false")
+ }
+}
+
+func printfloat(v float64) {
+ switch {
+ case v != v:
+ printstring("NaN")
+ return
+ case v+v == v && v > 0:
+ printstring("+Inf")
+ return
+ case v+v == v && v < 0:
+ printstring("-Inf")
+ return
+ }
+
+ const n = 7 // digits printed
+ var buf [n + 7]byte
+ buf[0] = '+'
+ e := 0 // exp
+ if v == 0 {
+ if 1/v < 0 {
+ buf[0] = '-'
+ }
+ } else {
+ if v < 0 {
+ v = -v
+ buf[0] = '-'
+ }
+
+ // normalize
+ for v >= 10 {
+ e++
+ v /= 10
+ }
+ for v < 1 {
+ e--
+ v *= 10
+ }
+
+ // round
+ h := 5.0
+ for i := 0; i < n; i++ {
+ h /= 10
+ }
+ v += h
+ if v >= 10 {
+ e++
+ v /= 10
+ }
+ }
+
+ // format +d.dddd+edd
+ for i := 0; i < n; i++ {
+ s := int(v)
+ buf[i+2] = byte(s + '0')
+ v -= float64(s)
+ v *= 10
+ }
+ buf[1] = buf[2]
+ buf[2] = '.'
+
+ buf[n+2] = 'e'
+ buf[n+3] = '+'
+ if e < 0 {
+ e = -e
+ buf[n+3] = '-'
+ }
+
+ buf[n+4] = byte(e/100) + '0'
+ buf[n+5] = byte(e/10)%10 + '0'
+ buf[n+6] = byte(e%10) + '0'
+ gwrite(buf[:])
+}
+
+func printcomplex(c complex128) {
+ print("(", real(c), imag(c), "i)")
+}
+
+func printuint(v uint64) {
+ var buf [100]byte
+ i := len(buf)
+ for i--; i > 0; i-- {
+ buf[i] = byte(v%10 + '0')
+ if v < 10 {
+ break
+ }
+ v /= 10
+ }
+ gwrite(buf[i:])
+}
+
+func printint(v int64) {
+ if v < 0 {
+ printstring("-")
+ v = -v
+ }
+ printuint(uint64(v))
+}
+
+func printhex(v uint64) {
+ const dig = "0123456789abcdef"
+ var buf [100]byte
+ i := len(buf)
+ for i--; i > 0; i-- {
+ buf[i] = dig[v%16]
+ if v < 16 {
+ break
+ }
+ v /= 16
+ }
+ i--
+ buf[i] = 'x'
+ i--
+ buf[i] = '0'
+ gwrite(buf[i:])
+}
+
+func printpointer(p unsafe.Pointer) {
+ printhex(uint64(uintptr(p)))
+}
+func printuintptr(p uintptr) {
+ printhex(uint64(p))
+}
+
+func printstring(s string) {
+ gwrite(bytes(s))
+}
+
+func printslice(s []byte) {
+ sp := (*slice)(unsafe.Pointer(&s))
+ print("[", len(s), "/", cap(s), "]")
+ printpointer(sp.array)
+}
+
+func printeface(e eface) {
+ print("(", e._type, ",", e.data, ")")
+}
+
+func printiface(i iface) {
+ print("(", i.tab, ",", i.data, ")")
+}
+
+// hexdumpWords prints a word-oriented hex dump of [p, end).
+//
+// If mark != nil, it will be called with each printed word's address
+// and should return a character mark to appear just before that
+// word's value. It can return 0 to indicate no mark.
+func hexdumpWords(p, end uintptr, mark func(uintptr) byte) {
+ p1 := func(x uintptr) {
+ var buf [2 * sys.PtrSize]byte
+ for i := len(buf) - 1; i >= 0; i-- {
+ if x&0xF < 10 {
+ buf[i] = byte(x&0xF) + '0'
+ } else {
+ buf[i] = byte(x&0xF) - 10 + 'a'
+ }
+ x >>= 4
+ }
+ gwrite(buf[:])
+ }
+
+ printlock()
+ var markbuf [1]byte
+ markbuf[0] = ' '
+ for i := uintptr(0); p+i < end; i += sys.PtrSize {
+ if i%16 == 0 {
+ if i != 0 {
+ println()
+ }
+ p1(p + i)
+ print(": ")
+ }
+
+ if mark != nil {
+ markbuf[0] = mark(p + i)
+ if markbuf[0] == 0 {
+ markbuf[0] = ' '
+ }
+ }
+ gwrite(markbuf[:])
+ val := *(*uintptr)(unsafe.Pointer(p + i))
+ p1(val)
+ print(" ")
+
+ // Can we symbolize val?
+ fn := findfunc(val)
+ if fn.valid() {
+ print("<", funcname(fn), "+", val-fn.entry, "> ")
+ }
+ }
+ println()
+ printunlock()
+}