proto.go

// Copyright 2016 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 rprof

import (
	"bytes"
	"strconv"
	"strings"
)

var space = []byte(" ")
var newline = []byte("\n")

func parseProcSelfMaps(data []byte, addMapping func(lo, hi, offset uint64, file, buildID string)) {
	// $ cat /proc/self/maps
	// 00400000-0040b000 r-xp 00000000 fc:01 787766                             /bin/cat
	// 0060a000-0060b000 r--p 0000a000 fc:01 787766                             /bin/cat
	// 0060b000-0060c000 rw-p 0000b000 fc:01 787766                             /bin/cat
	// 014ab000-014cc000 rw-p 00000000 00:00 0                                  [heap]
	// 7f7d76af8000-7f7d7797c000 r--p 00000000 fc:01 1318064                    /usr/lib/locale/locale-archive
	// 7f7d7797c000-7f7d77b36000 r-xp 00000000 fc:01 1180226                    /lib/x86_64-linux-gnu/libc-2.19.so
	// 7f7d77b36000-7f7d77d36000 ---p 001ba000 fc:01 1180226                    /lib/x86_64-linux-gnu/libc-2.19.so
	// 7f7d77d36000-7f7d77d3a000 r--p 001ba000 fc:01 1180226                    /lib/x86_64-linux-gnu/libc-2.19.so
	// 7f7d77d3a000-7f7d77d3c000 rw-p 001be000 fc:01 1180226                    /lib/x86_64-linux-gnu/libc-2.19.so
	// 7f7d77d3c000-7f7d77d41000 rw-p 00000000 00:00 0
	// 7f7d77d41000-7f7d77d64000 r-xp 00000000 fc:01 1180217                    /lib/x86_64-linux-gnu/ld-2.19.so
	// 7f7d77f3f000-7f7d77f42000 rw-p 00000000 00:00 0
	// 7f7d77f61000-7f7d77f63000 rw-p 00000000 00:00 0
	// 7f7d77f63000-7f7d77f64000 r--p 00022000 fc:01 1180217                    /lib/x86_64-linux-gnu/ld-2.19.so
	// 7f7d77f64000-7f7d77f65000 rw-p 00023000 fc:01 1180217                    /lib/x86_64-linux-gnu/ld-2.19.so
	// 7f7d77f65000-7f7d77f66000 rw-p 00000000 00:00 0
	// 7ffc342a2000-7ffc342c3000 rw-p 00000000 00:00 0                          [stack]
	// 7ffc34343000-7ffc34345000 r-xp 00000000 00:00 0                          [vdso]
	// ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0                  [vsyscall]

	var line []byte
	// next removes and returns the next field in the line.
	// It also removes from line any spaces following the field.
	next := func() []byte {
		var f []byte
		f, line, _ = bytes.Cut(line, space)
		line = bytes.TrimLeft(line, " ")
		return f
	}

	for len(data) > 0 {
		line, data, _ = bytes.Cut(data, newline)
		addr := next()
		loStr, hiStr, ok := strings.Cut(string(addr), "-")
		if !ok {
			continue
		}
		lo, err := strconv.ParseUint(loStr, 16, 64)
		if err != nil {
			continue
		}
		hi, err := strconv.ParseUint(hiStr, 16, 64)
		if err != nil {
			continue
		}
		perm := next()
		if len(perm) < 4 || perm[2] != 'x' {
			// Only interested in executable mappings.
			continue
		}
		offset, err := strconv.ParseUint(string(next()), 16, 64)
		if err != nil {
			continue
		}
		next()          // dev
		inode := next() // inode
		if line == nil {
			continue
		}
		file := string(line)

		// Trim deleted file marker.
		deletedStr := " (deleted)"
		deletedLen := len(deletedStr)
		if len(file) >= deletedLen && file[len(file)-deletedLen:] == deletedStr {
			file = file[:len(file)-deletedLen]
		}

		if len(inode) == 1 && inode[0] == '0' && file == "" {
			// Huge-page text mappings list the initial fragment of
			// mapped but unpopulated memory as being inode 0.
			// Don't report that part.
			// But [vdso] and [vsyscall] are inode 0, so let non-empty file names through.
			continue
		}

		// TODO: pprof's remapMappingIDs makes one adjustment:
		// 1. If there is an /anon_hugepage mapping first and it is
		// consecutive to a next mapping, drop the /anon_hugepage.
		// There's no indication why this is needed.
		// Let's try not doing this and see what breaks.
		// If we do need it, it would go here, before we
		// enter the mappings into b.mem in the first place.

		buildID, _ := elfBuildID(file)
		addMapping(lo, hi, offset, file, buildID)
	}
}