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Add APIs for external precmd/preexec integrations
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* Rename public functions and variables as "bash_preexec_*"
* Remove the compatibility variable name "__bp_install_string"
* Add a note on the "trace" function attribute
* Preserve the previous exit status and argument
* Test the installation of convenience functions
* Test "bash_preexec_uninstall"
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@akinomyoga
akinomyoga committed Jan 13, 2025
1 parent befc702 commit cbd3390
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Showing 2 changed files with 122 additions and 26 deletions.
70 changes: 58 additions & 12 deletions bash-preexec.sh
View file
Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,11 @@ __bp_inside_precmd=0
__bp_inside_preexec=0

# Initial PROMPT_COMMAND string that is removed from PROMPT_COMMAND post __bp_install
__bp_install_string=$'__bp_trap_string="$(trap -p DEBUG)"\ntrap - DEBUG\n__bp_install'
bash_preexec_install_string=$'__bp_trap_string="$(trap -p DEBUG)"\ntrap - DEBUG\n__bp_install'

# The command string that is registered to the DEBUG trap.
# shellcheck disable=SC2016
bash_preexec_trapdebug_string='__bp_preexec_invoke_exec "$_"'

# Fails if any of the given variables are readonly
# Reference https://stackoverflow.com/a/4441178
Expand Down Expand Up @@ -157,7 +161,7 @@ __bp_precmd_invoke_cmd() {
return
fi
local __bp_inside_precmd=1
__bp_invoke_precmd_functions "$__bp_last_ret_value" "$__bp_last_argument_prev_command"
bash_preexec_invoke_precmd_functions "$__bp_last_ret_value" "$__bp_last_argument_prev_command"

__bp_set_ret_value "$__bp_last_ret_value" "$__bp_last_argument_prev_command"
}
Expand All @@ -167,7 +171,7 @@ __bp_precmd_invoke_cmd() {
# $_, respectively, which will be set for each precmd function. This function
# returns the last non-zero exit status of the hook functions. If there is no
# error, this function returns 0.
__bp_invoke_precmd_functions() {
bash_preexec_invoke_precmd_functions() {
local lastexit=$1 lastarg=$2
# Invoke every function defined in our function array.
local precmd_function
Expand Down Expand Up @@ -277,7 +281,7 @@ __bp_preexec_invoke_exec() {
return
fi

__bp_invoke_preexec_functions "${__bp_last_ret_value:-}" "$__bp_last_argument_prev_command" "$this_command"
bash_preexec_invoke_preexec_functions "${__bp_last_ret_value:-}" "$__bp_last_argument_prev_command" "$this_command"
local preexec_ret_value=$?

# Restore the last argument of the last executed command, and set the return
Expand All @@ -296,7 +300,7 @@ __bp_preexec_invoke_exec() {
# (corresponding to BASH_COMMAND in the DEBUG trap). This function returns the
# last non-zero exit status from the preexec functions. If there is no error,
# this function returns `0`.
__bp_invoke_preexec_functions() {
bash_preexec_invoke_preexec_functions() {
local lastexit=$1 lastarg=$2 this_command=$3
local preexec_function
local preexec_function_ret_value
Expand Down Expand Up @@ -324,7 +328,8 @@ __bp_install() {
return 1
fi

trap '__bp_preexec_invoke_exec "$_"' DEBUG
# shellcheck disable=SC2064
trap "$bash_preexec_trapdebug_string" DEBUG

# Preserve any prior DEBUG trap as a preexec function
local prior_trap
Expand Down Expand Up @@ -357,7 +362,7 @@ __bp_install() {
# Remove setting our trap install string and sanitize the existing prompt command string
existing_prompt_command="${PROMPT_COMMAND:-}"
# Edge case of appending to PROMPT_COMMAND
existing_prompt_command="${existing_prompt_command//$__bp_install_string/:}" # no-op
existing_prompt_command="${existing_prompt_command//$bash_preexec_install_string/:}" # no-op
existing_prompt_command="${existing_prompt_command//$'\n':$'\n'/$'\n'}" # remove known-token only
existing_prompt_command="${existing_prompt_command//$'\n':;/$'\n'}" # remove known-token only
__bp_sanitize_string existing_prompt_command "$existing_prompt_command"
Expand All @@ -376,10 +381,13 @@ __bp_install() {
PROMPT_COMMAND+=$'\n__bp_interactive_mode'
fi

# Add two functions to our arrays for convenience
# of definition.
precmd_functions+=(precmd)
preexec_functions+=(preexec)
# Add two functions to our arrays for convenience of definition only when
# the functions have not yet added.
if [[ ! ${__bp_installed_convenience_functions-} ]]; then
__bp_installed_convenience_functions=1
precmd_functions+=(precmd)
preexec_functions+=(preexec)
fi

# Invoke our two functions manually that were added to $PROMPT_COMMAND
__bp_precmd_invoke_cmd
Expand All @@ -401,8 +409,46 @@ __bp_install_after_session_init() {
PROMPT_COMMAND=${sanitized_prompt_command}$'\n'
fi
# shellcheck disable=SC2179 # PROMPT_COMMAND is not an array in bash <= 5.0
PROMPT_COMMAND+=${__bp_install_string}
PROMPT_COMMAND+=${bash_preexec_install_string}
}

# Remove hooks installed in the DEBUG trap and PROMPT_COMMAND.
bash_preexec_uninstall() {
# Remove __bp_install hook from PROMPT_COMMAND
# shellcheck disable=SC2178 # PROMPT_COMMAND is not an array in bash <= 5.0
if [[ ${PROMPT_COMMAND-} == *"$bash_preexec_install_string"* ]]; then
PROMPT_COMMAND="${PROMPT_COMMAND//${bash_preexec_install_string}[;$'\n']}" # Edge case of appending to PROMPT_COMMAND
PROMPT_COMMAND="${PROMPT_COMMAND//$bash_preexec_install_string}"
fi

# Remove precmd hook from PROMPT_COMMAND
local i prompt_command
for i in "${!PROMPT_COMMAND[@]}"; do
prompt_command=${PROMPT_COMMAND[i]}
case $prompt_command in
__bp_precmd_invoke_cmd | __bp_interactive_mode)
prompt_command= ;;
*)
prompt_command=${prompt_command/#$'__bp_precmd_invoke_cmd\n'/$'\n'}
prompt_command=${prompt_command%$'\n__bp_interactive_mode'}
prompt_command=${prompt_command#$'\n'}
esac
PROMPT_COMMAND[i]=$prompt_command
done

# Remove preexec hook in the DEBUG trap
local q="'" Q="'\''"
if [[ $(trap -p DEBUG) == "trap -- '${bash_preexec_trapdebug_string//$q/$Q}' DEBUG" ]]; then
if [[ ${__bp_trap_string-} ]]; then
eval -- "$__bp_trap_string"
else
trap - DEBUG
fi
fi
}
# Note: We need to add "trace" attribute to the function so that "trap - DEBUG"
# inside the function takes an effect.
declare -ft bash_preexec_uninstall

# Run our install so long as we're not delaying it.
if [[ -z "${__bp_delay_install:-}" ]]; then
Expand Down
78 changes: 64 additions & 14 deletions test/bash-preexec.bats
View file
Original file line number Diff line number Diff line change
Expand Up @@ -76,11 +76,11 @@ set_exit_code_and_run_precmd() {

# Assert that before running, the command contains the install string, and
# afterwards it does not
[[ "$PROMPT_COMMAND" == *"$__bp_install_string"* ]] || return 1
[[ "$PROMPT_COMMAND" == *"$bash_preexec_install_string"* ]] || return 1

eval_PROMPT_COMMAND

[[ "$PROMPT_COMMAND" != *"$__bp_install_string"* ]] || return 1
[[ "$PROMPT_COMMAND" != *"$bash_preexec_install_string"* ]] || return 1
}

@test "__bp_install should preserve an existing DEBUG trap" {
Expand All @@ -103,6 +103,56 @@ set_exit_code_and_run_precmd() {
(( trap_count_snapshot < trap_invoked_count ))
}

@test "__bp_install should register convenience functions \"preexec\" and \"precmd\" only once" {
precmd_functions=()
preexec_functions=()
__bp_install
bash_preexec_uninstall
__bp_install

count=0
for hook in "${precmd_functions[@]}"; do
if [[ "$hook" == precmd ]] ; then
count=$((count+1))
fi
done
[ "$count" == 1 ]

count=0
for hook in "${preexec_functions[@]}"; do
if [[ "$hook" == preexec ]] ; then
count=$((count+1))
fi
done
[ "$count" == 1 ]
}

@test "bash_preexec_uninstall should remove the hooks in DEBUG and PROMPT_COMMAND" {
__bp_install

q="'" Q="'\''"
[[ "$(join_PROMPT_COMMAND)" == *"__bp_precmd_invoke_cmd"* ]] || return 1
[[ "$(join_PROMPT_COMMAND)" == *"__bp_interactive_mode"* ]] || return 1
[ "$(trap -p DEBUG)" == "trap -- '${bash_preexec_trapdebug_string//$q/$Q}' DEBUG" ]

bash_preexec_uninstall

q="'" Q="'\''"
[[ "$(join_PROMPT_COMMAND)" != *"__bp_precmd_invoke_cmd"* ]] || return 1
[[ "$(join_PROMPT_COMMAND)" != *"__bp_interactive_mode"* ]] || return 1
[ "$(trap -p DEBUG)" != "trap -- '${bash_preexec_trapdebug_string//$q/$Q}' DEBUG" ]
}

@test "bash_preexec_uninstall should remove the unprocessed __bp_install hook in PROMPT_COMMAND" {
__bp_install_after_session_init

[[ "$PROMPT_COMMAND" == *"$bash_preexec_install_string"* ]]

bash_preexec_uninstall

[[ "$PROMPT_COMMAND" != *"$bash_preexec_install_string"* ]]
}

@test "__bp_sanitize_string should remove semicolons and trim space" {

__bp_sanitize_string output " true1; "$'\n'
Expand Down Expand Up @@ -308,71 +358,71 @@ set_exit_code_and_run_precmd() {
[ $status -eq 1 ]
}

@test "__bp_invoke_precmd_functions should be transparent for \$? and \$_" {
@test "bash_preexec_invoke_precmd_functions should be transparent for \$? and \$_" {
tester1() { test1_lastexit=$? test1_lastarg=$_; }
tester2() { test2_lastexit=$? test2_lastarg=$_; }
precmd_functions=(tester1 tester2)
trap - DEBUG # remove the Bats stack-trace trap so $_ doesn't get overwritten
__bp_invoke_precmd_functions 111 'vxxJlwNx9VPJDA' || true
bash_preexec_invoke_precmd_functions 111 'vxxJlwNx9VPJDA' || true

[ "$test1_lastexit" == 111 ]
[ "$test1_lastarg" == 'vxxJlwNx9VPJDA' ]
[ "$test2_lastexit" == 111 ]
[ "$test2_lastarg" == 'vxxJlwNx9VPJDA' ]
}

@test "__bp_invoke_precmd_functions returns the last non-zero exit status" {
@test "bash_preexec_invoke_precmd_functions returns the last non-zero exit status" {
tester1() { return 91; }
tester2() { return 38; }
tester3() { return 0; }
precmd_functions=(tester1 tester2 tester3)
status=0
__bp_invoke_precmd_functions 1 'lastarg' || status=$?
bash_preexec_invoke_precmd_functions 1 'lastarg' || status=$?

[ "$status" == 38 ]

precmd_functions=(tester3)
status=0
__bp_invoke_precmd_functions 1 'lastarg' || status=$?
bash_preexec_invoke_precmd_functions 1 'lastarg' || status=$?

[ "$status" == 0 ]
}

@test "__bp_invoke_preexec_functions should be transparent for \$? and \$_" {
@test "bash_preexec_invoke_preexec_functions should be transparent for \$? and \$_" {
tester1() { test1_lastexit=$? test1_lastarg=$_; }
tester2() { test2_lastexit=$? test2_lastarg=$_; }
preexec_functions=(tester1 tester2)
trap - DEBUG # remove the Bats stack-trace trap so $_ doesn't get overwritten
__bp_invoke_preexec_functions 87 'ehQrzHTHtE2E7Q' 'command' || true
bash_preexec_invoke_preexec_functions 87 'ehQrzHTHtE2E7Q' 'command' || true

[ "$test1_lastexit" == 87 ]
[ "$test1_lastarg" == 'ehQrzHTHtE2E7Q' ]
[ "$test2_lastexit" == 87 ]
[ "$test2_lastarg" == 'ehQrzHTHtE2E7Q' ]
}

@test "__bp_invoke_preexec_functions returns the last non-zero exit status" {
@test "bash_preexec_invoke_preexec_functions returns the last non-zero exit status" {
tester1() { return 52; }
tester2() { return 112; }
tester3() { return 0; }
preexec_functions=(tester1 tester2 tester3)
status=0
__bp_invoke_preexec_functions 1 'lastarg' 'command' || status=$?
bash_preexec_invoke_preexec_functions 1 'lastarg' 'command' || status=$?

[ "$status" == 112 ]

preexec_functions=(tester3)
status=0
__bp_invoke_preexec_functions 1 'lastarg' 'command' || status=$?
bash_preexec_invoke_preexec_functions 1 'lastarg' 'command' || status=$?

[ "$status" == 0 ]
}

@test "__bp_invoke_preexec_functions should supply a current command in the first argument" {
@test "bash_preexec_invoke_preexec_functions should supply a current command in the first argument" {
tester1() { test1_bash_command=$1; }
tester2() { test2_bash_command=$1; }
preexec_functions=(tester1 tester2)
__bp_invoke_preexec_functions 1 'lastarg' 'UEVkErELArSwjA' || true
bash_preexec_invoke_preexec_functions 1 'lastarg' 'UEVkErELArSwjA' || true

[ "$test1_bash_command" == 'UEVkErELArSwjA' ]
[ "$test2_bash_command" == 'UEVkErELArSwjA' ]
Expand Down

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