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|
# ==== Purpose ====
#
# Copy a segment from one file to another file.
#
# ==== Usage ====
#
# --let $in_filename = FILENAME1
# --let $out_filename = FILENAME2
# --let $file_start_pos = NUMBER1
# --let $file_stop_pos = NUMBER2
# --source include/copy_file_segment.inc
#
# Parameters:
# $in_filename
# Name of file to copy from.
#
# $out_filename
# Name of file to create.
#
# $file_start_pos
# Start offset in $in_filename. 0 means beginning of file.
#
# $file_stop_pos
# End offset in $in_filename. This is exclusive.
# Example: if $file_stop_pos=$file_start_pos+1, one byte is copied.
if (!$in_filename) {
--die Please assign a file name to $in_filename!!
}
if (!$out_filename) {
--die Please assign a file name to $out_filename!!
}
if ($file_start_pos == '') {
--die Please assign position of segment start offset to $file_start_pos!!
}
if ($file_stop_pos == '') {
--die Please assign position of segment stop offset to $file_stop_pos!!
}
--let IN_FILENAME_ENV = $in_filename
--let OUT_FILENAME_ENV = $out_filename
--let FILE_START_POS_ENV = $file_start_pos
--let FILE_STOP_POS_ENV = $file_stop_pos
--perl
my $in_filename = $ENV{'IN_FILENAME_ENV'};
my $out_filename = $ENV{'OUT_FILENAME_ENV'};
my $file_start_pos = $ENV{'FILE_START_POS_ENV'};
my $file_stop_pos = $ENV{'FILE_STOP_POS_ENV'};
open(IN, '<:raw', $in_filename) || die("Could not open <$in_filename: $!");
open(OUT, '>>:raw', $out_filename) || die("Could not open >>$out_filename: $!");
my ($len_in, $len_out, $data);
# skip $file_start_pos bytes
sysseek(IN, $file_start_pos, SEEK_SET);
# length to be read
my $length = $file_stop_pos - $file_start_pos;
# copy binary segment
while ($length > 0) {
$len_in = sysread(IN, my $data, $length);
if (!defined($len_in)) {
die("Could not sysread data: $!");
}
if ($len_in == 0) {
die("Read zero bytes");
}
$length = $length - $len_in;
my $offset = 0;
while ($len_in > 0) {
$len_out = syswrite(OUT, $data, $len_in, $offset);
if (!defined($len_out)) {
die("Could not syswrite data: $!");
}
$offset += $len_out;
$len_in -= $len_out;
}
}
EOF
|
