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Merge pull request #2633 from rear/jsmeix-stdout-stderr-non-debug-1
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Show some stdout and stderr messages also in non-debug modes:
In non-debug modes (in particular also in verbose mode)
stdout and stderr are redirected to a temporary file
STDOUT_STDERR_FILE=TMP_DIR/rear.WORKFLOW.stdout_stderr
so in non-debug modes stdout and stderr of all programs is still available
for the Error() function to extract some latest messages that get shown
on the usrer's terminal and those extracted lines are also copied into the log.
Furthermore the log files and the stdout/stderr file can now only be read by root.
Additionally when there is something still mounted within the build area
when rear finishes, the user is informed what is mounted and that he must
manually umount it before he can (also manually) remove the build area.
Finally the Error() and cleanup_build_area_and_end_program() functions
are made fail-safe against not yet existing log files and not yet sourced
other functions in case of early Error() exits in usr/sbin/rear
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@jsmeix
jsmeix committed Jun 24, 2021
2 parents 98a2240 + 5ed5b2e commit e670f50
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Showing 3 changed files with 210 additions and 70 deletions.
102 changes: 73 additions & 29 deletions usr/sbin/rear
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Expand Up @@ -262,8 +262,8 @@ esac
# Set the variables v and verbose to be used in called programs
# that support the '-v' or '--verbose' options like
# "cp $v ..." or "rm $verbose ..." and so on.
# Normally stdout and stderr are redirected to /dev/null (see below).
# In debug modes stdout and stderr are redirected to the log
# Normally stdout and stderr are not redirected to the log file (see below).
# Only in debug modes stdout and stderr are redirected to the log
# so setting that variables only makes sense in debug modes.
# Cf. https://github.com/rear/rear/issues/2416
v=""
Expand Down Expand Up @@ -398,28 +398,79 @@ fi
# and fd6 to get input from the user regardless where to STDIN is redirected:
source $SHARE_DIR/lib/_input-output-functions.sh

# Via source usr/share/rear/lib/_input-output-functions.sh
# those exit tasks are now set to be executed (via bash EXIT trap) in the following order:
# "(( EXIT_FAIL_MESSAGE )) && echo '${MESSAGE_PREFIX}$PROGRAM $WORKFLOW failed, check $RUNTIME_LOGFILE for details' 1>&8"
# "exec 8>&-"
# "exec 7>&-"
# "exec 6<&-"

if test "$WORKFLOW" != "help" ; then
# Prepend temporary working area (BUILD_DIR) removal exit task
# so it gets executed directly before the above listed exit tasks.
# This must be done before the first possible call of the 'Error' function
# otherwise we may error out but leave the build area behind:
QuietAddExitTask cleanup_build_area_and_end_program
# Create temporary working area:
BUILD_DIR="$( mktemp -d -t rear.XXXXXXXXXXXXXXX || Error "Could not create build area '$BUILD_DIR'" )"
ROOTFS_DIR=$BUILD_DIR/rootfs
TMP_DIR=$BUILD_DIR/tmp
mkdir -p $ROOTFS_DIR || Error "Could not create $ROOTFS_DIR"
mkdir -p $TMP_DIR || Error "Could not create $TMP_DIR"
# Since the above BUILD_DIR="$( mktemp ... )" does not always return a path under /tmp
# the build directory must be excluded from the backup to be on the safe side:
BACKUP_PROG_EXCLUDE+=( "$BUILD_DIR" )
fi

# Keep old log file:
test -r "$RUNTIME_LOGFILE" && mv -f "$RUNTIME_LOGFILE" "$RUNTIME_LOGFILE".old 2>/dev/null

# Start logging:
mkdir -p $LOG_DIR || echo "ERROR: Could not create $LOG_DIR" >&2
mkdir -p $LOG_DIR || Error "Could not create $LOG_DIR"
rm -f "$RUNTIME_LOGFILE"
cat /dev/null >"$RUNTIME_LOGFILE"
# Normally stdout and stderr are redirected to /dev/null.
# In debug modes stdout and stderr are redirected to the log.
# Cf. https://github.com/rear/rear/issues/2416
# The log file may contain sensitive information so only root should be able to read it:
chmod u=rw,go=- "$RUNTIME_LOGFILE"
# In debug modes stdout and stderr are redirected to the log
# cf. https://github.com/rear/rear/issues/2416
# In non-debug modes (in particular also in verbose mode)
# stdout and stderr are redirected to a temporary file if possible
# i.e. when TMP_DIR exists - it does not exist for the 'help' workflow
# so use /dev/null as fallback because TMP_DIR does not exists for the 'help' workflow:
STDOUT_STDERR_FILE="/dev/null"
# In non-debug modes the log cannot contain possibly false alarm messages
# cf. https://github.com/rear/rear/issues/2416
# but in non-debug modes stdout and stderr of all programs is still available
# for the Error function to extract some latest messages
# cf. https://github.com/rear/rear/issues/2623
if test "$DEBUG" ; then
# To be on the safe side append to the log file '>>' instead of plain writing to it '>'
# because when a program (bash in this case) is plain writing to the log file it can overwrite
# output of a possibly simultaneously running process that likes to append to the log file
# (e.g. when a background process runs that also uses the ReaR log file for logging).
exec 2>>"$RUNTIME_LOGFILE"
# Make stdout the same what stderr already is.
# This keeps strict ordering of stdout and stderr outputs
# because now both stdout and stderr use one same file descriptor.
# Make stdout the same what stderr already is because
# it is a bad idea to handle stderr and stdout differently
# cf. https://github.com/rear/rear/issues/2416#issuecomment-702159687
# Here we keep strict ordering of stdout and stderr outputs
# because both stdout and stderr use one same file descriptor:
exec 1>&2
else
exec 2>/dev/null
exec 1>/dev/null
if test -d $TMP_DIR ; then
STDOUT_STDERR_FILE="$TMP_DIR/$PROGRAM.$WORKFLOW.stdout_stderr"
# The stdout and stderr file that is used during runtime must not be changed:
readonly STDOUT_STDERR_FILE
rm -f "$STDOUT_STDERR_FILE"
cat /dev/null >"$STDOUT_STDERR_FILE"
# Programs stdout and stderr may show sensitive information so only root should be able to read it:
chmod u=rw,go=- "$STDOUT_STDERR_FILE"
fi
# To be on the safe side append stderr to the file (see above):
exec 2>>"$STDOUT_STDERR_FILE"
# Make stdout the same what stderr already is (see above).
# The stdout redirection is intentionally two times there (both for debug modes and non-debug modes)
# to make it easier to change the stdout redirection if needed different for both kind of modes:
exec 1>&2
fi

# Include functions after RUNTIME_LOGFILE is set and readonly
Expand All @@ -432,8 +483,9 @@ done
if test "$WORKFLOW" != "help" ; then
LogPrint "$PRODUCT $VERSION / $RELEASE_DATE"
LogPrint "Running $PROGRAM $WORKFLOW (PID $MASTER_PID date $START_DATE_TIME_STRING)"
Log "Command line options: $0 ${CMD_OPTS[@]}"
DebugPrint "Command line options: $0 ${CMD_OPTS[@]}"
LogPrint "Using log file: $RUNTIME_LOGFILE"
DebugPrint "Using build area: $BUILD_DIR"
fi

# In DEBUG mode keep by default the build area but that can be overridden in user config files
Expand Down Expand Up @@ -544,21 +596,6 @@ Host $( uname -n ) using Backup $BACKUP and Output $OUTPUT
Build date: $( date -R )
"

if test "$WORKFLOW" != "help" ; then
# Create temporary work area and register removal exit task:
BUILD_DIR="$( mktemp -d -t rear.XXXXXXXXXXXXXXX || Error "Could not create build area '$BUILD_DIR'" )"
# Since 'mktemp' doesn't always return a path under /tmp, the build
# directory has always to be excluded for safety
BACKUP_PROG_EXCLUDE+=( "$BUILD_DIR" )

QuietAddExitTask cleanup_build_area_and_end_program
Log "Using build area '$BUILD_DIR'"
ROOTFS_DIR=$BUILD_DIR/rootfs
TMP_DIR=$BUILD_DIR/tmp
mkdir -p $v $ROOTFS_DIR >&2 || Error "Could not create $ROOTFS_DIR"
mkdir -p $v $TMP_DIR >&2 || Error "Could not create $TMP_DIR"
fi

# Check for and run the requested workflow:
if has_binary WORKFLOW_$WORKFLOW ; then
Log "Running $WORKFLOW workflow"
Expand All @@ -576,8 +613,15 @@ fi
# but later user config files are sourced where LOGFILE can be set different
# so that the user config LOGFILE is used as final logfile name:
if test "$RUNTIME_LOGFILE" != "$LOGFILE" ; then
test "$WORKFLOW" != "help" && LogPrint "Saving $RUNTIME_LOGFILE as $LOGFILE"
cat "$RUNTIME_LOGFILE" > "$LOGFILE"
# Do this only when LOGFILE is a regular file (e.g. do not do this if LOGFILE is /dev/null):
if test -f "$LOGFILE" ; then
rm -f "$LOGFILE"
cat /dev/null >"$LOGFILE"
# The log file may contain sensitive information so only root should be able to read it:
chmod u=rw,go=- "$LOGFILE"
test "$WORKFLOW" != "help" && LogPrint "Saving $RUNTIME_LOGFILE as $LOGFILE"
cat "$RUNTIME_LOGFILE" >"$LOGFILE"
fi
fi

# When this point is reached, the workflow is done without a real error because
Expand Down

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