examples/bashdb/bashdb.fns

   1 # bashdb.fns - Bourne-Again Shell Debugger functions
   2
   3 _BUFSIZ=100
   4
   5 # Here after each statement in script being debugged.
   6 # Handle single-step and breakpoints.
   7 _steptrap() {
   8         let _curline=$1-1               # no. of line that just ran
   9         let "$_curline < 1" && let _curline=1
  10
  11         let "$_curline > $_firstline+$_BUFSIZ" && _readin $_curline
  12
  13         let " $_trace" &&
  14                 _msg "$PS4, line $_curline: ${_lines[$(($_curline-$_firstline+1))]}"
  15
  16
  17         # if in step mode, decrement counter
  18         let " $_steps >= 0" && let _steps="$_steps - 1"
  19
  20         # first check if line num or string brkpt. reached
  21         if _at_linenumbp || _at_stringbp; then
  22                 _msg "Reached breakpoint at line $_curline"
  23                 _cmdloop                # enter debugger
  24
  25         # if not, check whether break condition exists and is true
  26         elif [ -n "$_brcond" ] && eval $_brcond; then
  27                 _msg "Break condition $_brcond true at line $_curline"
  28                 _cmdloop                # enter debugger
  29
  30         # next, check if step mode and no. of steps is up
  31         elif let "$_steps == 0"; then
  32                 _msg "Stopped at line $_curline"
  33                 _cmdloop                # enter debugger
  34         fi
  35 }
  36
  37
  38 # Debugger command loop.
  39 # Here at start of debugger session, when brkpt. reached, or after single-step.
  40 _cmdloop() {
  41         local cmd args
  42
  43 # added support for default command (last one entered)
  44
  45         while read -e -p "bashdb> [$lastcmd $lastargs] " cmd args; do
  46                 if [ -z "$cmd" ]; then
  47                         cmd=$lastcmd
  48                         args=$lastargs
  49                 fi
  50
  51                 lastcmd="$cmd"
  52                 lastargs=$args
  53
  54 # made commands to be debugger commands by default, no need for '*' prefix
  55
  56                 case $cmd in
  57                 bp ) _setbp $args ;;    #set brkpt at line num or string
  58
  59                 bc ) _setbc $args ;;    # set break condition
  60
  61                 cb ) _clearbp ;;        # clear all brkpts.
  62
  63                 g ) return ;;           # start/resume execution
  64
  65                 s ) let _steps=${args:-1}
  66                     return ;;           # single-step N times(default 1)
  67
  68                 x ) _xtrace ;;  # toggle execution trace
  69
  70                 pr ) _print $args ;;    # print lines in file
  71
  72                 \? | h | help ) _menu ;; # print command menu
  73
  74                 hi ) history ;;         # show command history
  75
  76                 q ) _cleanup; exit ;;           # quit
  77
  78                 \! ) eval $args ;;      # run shell command
  79
  80                 * ) _msg "\aInvalid command: $cmd" ; _menu ;;
  81                 esac
  82         done
  83 }
  84
  85
  86 # see if next line no. is a brkpt.
  87 _at_linenumbp() {
  88         if [ -z "${_linebp}" ]; then
  89                 return 1
  90         fi
  91         echo "${_curline}" | egrep "(${_linebp%\|})" >/dev/null 2>&1
  92         return $?
  93 }
  94
  95
  96 # search string brkpts to see if next line in script matches.
  97 _at_stringbp() {
  98         local l;
  99
 100         if [ -z "$_stringbp" ]; then
 101                 return 1;
 102         fi
 103         l=${_lines[$_curline-$_firstline+1]}
 104         echo "${l}" | egrep "*(${_stringbp%\|})*" >/dev/null 2>&1
 105         return $?
 106 }
 107
 108
 109 # print message to stderr
 110 _msg() {
 111         echo -e "$@" >&2
 112 }
 113
 114
 115 # set brkpt(s) at given line numbers and/or strings
 116 # by appending lines to brkpt file
 117 _setbp() {
 118         declare -i n
 119         case "$1" in
 120         "")     _listbp ;;
 121         [0-9]*) #number, set brkpt at that line
 122                 n=$1
 123                 _linebp="${_linebp}$n|"
 124                 _msg "Breakpoint at line " $1
 125                 ;;
 126         *)      #string, set brkpt at next line w/string
 127                 _stringbp="${_stringbp}$@|"
 128                 _msg "Breakpoint at next line containing $@."
 129                 ;;
 130         esac
 131 }
 132
 133
 134 # list brkpts and break condition.
 135 _listbp() {
 136         _msg "Breakpoints at lines:"
 137         _msg "${_linebp//\|/ }"
 138         _msg "Breakpoints at strings:"
 139         _msg "${_stringbp//\|/ }"
 140         _msg "Break on condition:"
 141         _msg "$_brcond"
 142 }
 143
 144
 145 # set or clear break condition
 146 _setbc() {
 147         if [ -n "$@" ] ; then
 148                 _brcond=$args
 149                 _msg "Break when true: $_brcond"
 150         else
 151                 _brcond=
 152                 _msg "Break condition cleared"
 153         fi
 154 }
 155
 156
 157 # clear all brkpts
 158 _clearbp() {
 159         _linebp=
 160         _stringbp=
 161         _msg "All breakpoints cleared"
 162 }
 163
 164
 165 # toggle execution trace feature
 166 _xtrace() {
 167         let _trace="! $_trace"
 168
 169         _msg "Execution trace \c"
 170         let " $_trace" && _msg "on." || _msg "off."
 171 }
 172
 173
 174 # print command menu
 175 _menu() {
 176
 177 # made commands to be debugger commands by default, no need for '*' prefix
 178
 179         _msg 'bashdb commands:
 180         bp N                    set breakpoint at line N
 181         bp string               set breakpoint at next line containing "string"
 182         bp                      list breakpoints and break condition
 183         bc string               set break condition to "string"
 184         bc                      clear break condition
 185         cb                      clear all breakpoints
 186         g                       start/resume execution
 187         s [N]                   execute N statements (default 1)
 188         x                       toggle execution trace on/off (default on)
 189         pr [start|.] [cnt]      print "cnt" lines from line no. "start"
 190         ?, h, help              print this menu
 191         hi                      show command history
 192         q                       quit
 193
 194         ! cmd [args]            execute command "cmd" with "args"
 195
 196         default:                last command (in "[ ]" at the prompt)
 197
 198         Readline command line editing (emacs/vi mode) is available'
 199 }
 200
 201
 202 # erase temp files before exiting
 203 _cleanup() {
 204         rm $_dbgfile 2>/dev/null
 205 }
 206
 207
 208 # read $_BUFSIZ lines from $_guineapig into _lines array, starting from line $1
 209 # save number of first line read in _firstline
 210 _readin() {
 211         declare -i _i=1
 212         let _firstline=$1
 213
 214         SEDCMD="$_firstline,$(($_firstline+$_BUFSIZ))p"
 215
 216         sed -n "$SEDCMD" $_guineapig > /tmp/_script.$$
 217         while read -r _lines[$_i]; do
 218                 _i=_i+1
 219         done  < /tmp/_script.$$
 220         rm -f /tmp/_script.$$ 2>/dev/null
 221 }
 222
 223 _print() {
 224         typeset _start _cnt
 225
 226         if [ -z "$1" ] || [ "$1" = . ]; then
 227                 _start=$_curline
 228         else
 229                 _start=$1
 230         fi
 231
 232         _cnt=${2:-9}
 233
 234         SEDCMD="$_start,$(($_start+$_cnt))p"
 235
 236         pr -tn $_guineapig | sed -n "$SEDCMD"
 237 }