github.com/u-root/u-root@v7.0.1-0.20200915234505-ad7babab0a8e+incompatible/pkg/strace/print.go (about)

     1  // Copyright 2018 Google LLC.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  //
    15  // Changes are Copyright 2018 the u-root Authors.
    16  
    17  package strace
    18  
    19  import (
    20  	"bytes"
    21  	"fmt"
    22  	"strings"
    23  
    24  	"golang.org/x/sys/unix"
    25  )
    26  
    27  // DefaultLogMaximumSize is the default LogMaximumSize.
    28  const DefaultLogMaximumSize = 1024
    29  
    30  // LogMaximumSize determines the maximum display size for data blobs (read,
    31  // write, etc.).
    32  var LogMaximumSize uint = DefaultLogMaximumSize
    33  
    34  // EventMaximumSize determines the maximum size for data blobs (read, write,
    35  // etc.) sent over the event channel. Default is 0 because most clients cannot
    36  // do anything useful with binary text dump of byte array arguments.
    37  var EventMaximumSize uint
    38  
    39  func dump(t Task, addr Addr, size uint, maximumBlobSize uint) string {
    40  	origSize := size
    41  	if size > maximumBlobSize {
    42  		size = maximumBlobSize
    43  	}
    44  	if size == 0 {
    45  		return ""
    46  	}
    47  
    48  	b := make([]byte, size)
    49  	amt, err := t.Read(addr, b)
    50  	if err != nil {
    51  		return fmt.Sprintf("%#x (error decoding string: %s)", addr, err)
    52  	}
    53  
    54  	dot := ""
    55  	if uint(amt) < origSize {
    56  		// ... if we truncated the dump.
    57  		dot = "..."
    58  	}
    59  
    60  	return fmt.Sprintf("%#x %q%s", addr, b[:amt], dot)
    61  }
    62  
    63  func iovecs(t Task, addr Addr, iovcnt int, printContent bool, maxBytes uint64) string {
    64  	if iovcnt < 0 || iovcnt > 0x10 /*unix.MSG_MAXIOVLEN*/ {
    65  		return fmt.Sprintf("%#x (error decoding iovecs: invalid iovcnt)", addr)
    66  	}
    67  	v := make([]iovec, iovcnt)
    68  	_, err := t.Read(addr, v)
    69  	if err != nil {
    70  		return fmt.Sprintf("%#x (error decoding iovecs: %v)", addr, err)
    71  	}
    72  
    73  	var totalBytes uint64
    74  	var truncated bool
    75  	iovs := make([]string, iovcnt)
    76  	for i, vv := range v {
    77  		if vv.S == 0 || !printContent {
    78  			iovs[i] = fmt.Sprintf("{base=%#x, len=%d}", vv.P, vv.S)
    79  			continue
    80  		}
    81  
    82  		size := uint64(vv.S)
    83  		if truncated || totalBytes+size > maxBytes {
    84  			truncated = true
    85  			size = maxBytes - totalBytes
    86  		} else {
    87  			totalBytes += uint64(vv.S)
    88  		}
    89  
    90  		b := make([]byte, size)
    91  		amt, err := t.Read(vv.P, b)
    92  		if err != nil {
    93  			iovs[i] = fmt.Sprintf("{base=%#x, len=%d, %q..., error decoding string: %v}", vv.P, vv.S, b[:amt], err)
    94  			continue
    95  		}
    96  
    97  		dot := ""
    98  		if truncated {
    99  			// Indicate truncation.
   100  			dot = "..."
   101  		}
   102  		iovs[i] = fmt.Sprintf("{base=%#x, len=%d, %q%s}", vv.P, vv.S, b[:amt], dot)
   103  	}
   104  
   105  	return fmt.Sprintf("%#x %s", addr, strings.Join(iovs, ", "))
   106  }
   107  
   108  func fdpair(t Task, addr Addr) string {
   109  	var fds [2]int32
   110  	_, err := t.Read(addr, &fds)
   111  	if err != nil {
   112  		return fmt.Sprintf("%#x (error decoding fds: %s)", addr, err)
   113  	}
   114  
   115  	return fmt.Sprintf("%#x [%d %d]", addr, fds[0], fds[1])
   116  }
   117  
   118  type SaneUtsname struct {
   119  	Sysname    string
   120  	Nodename   string
   121  	Release    string
   122  	Version    string
   123  	Machine    string
   124  	Domainname string
   125  }
   126  
   127  func SaneUname(u unix.Utsname) SaneUtsname {
   128  	return SaneUtsname{
   129  		Sysname:    convertUname(u.Sysname),
   130  		Nodename:   convertUname(u.Nodename),
   131  		Release:    convertUname(u.Release),
   132  		Version:    convertUname(u.Version),
   133  		Machine:    convertUname(u.Machine),
   134  		Domainname: convertUname(u.Domainname),
   135  	}
   136  }
   137  
   138  func convertUname(s [65]uint8) string {
   139  	return string(bytes.TrimRight(s[:], "\x00"))
   140  }
   141  
   142  func uname(t Task, addr Addr) string {
   143  	var u unix.Utsname
   144  	if _, err := t.Read(addr, &u); err != nil {
   145  		return fmt.Sprintf("%#x (error decoding utsname: %s)", addr, err)
   146  	}
   147  
   148  	return fmt.Sprintf("%#x %#v", addr, SaneUname(u))
   149  }
   150  
   151  // alignUp rounds a length up to an alignment. align must be a power of 2.
   152  func alignUp(length int, align uint) int {
   153  	return (length + int(align) - 1) & ^(int(align) - 1)
   154  }
   155  
   156  // alignDown rounds a down to an alignment. align must be a power of 2.
   157  func alignDown(length int, align uint) int {
   158  	return length & ^(int(align) - 1)
   159  }