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cmp: support reading STDIN #310

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merged 1 commit into from
Nov 4, 2023
Merged

cmp: support reading STDIN #310

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131 changes: 80 additions & 51 deletions bin/cmp
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,8 @@ my $chunk_size = 10_000; # how many bytes in a gulp

my $volume=1; # controlled by -s and -l

my $fh1;
my $fh2;
my $file1;
my $file2;
my $skip1;
Expand Down Expand Up @@ -83,67 +85,93 @@ while (@ARGV) {
usage() unless @ARGV >= 1 and @ARGV <= 3; # exits;

$file2 = shift;
$skip1 = skipnum(shift) if @ARGV;
$skip2 = skipnum(shift) if @ARGV;

my @stat1 = stat $file1;
unless (@stat1) {
warn "$Program: '$file1': $!\n";
exit EX_FAILURE;
if ($file1 eq '-') {
if ($file2 eq '-') {
exit EX_SUCCESS;
}
$fh1 = *STDIN;
}
my @stat2 = stat $file2;
unless (@stat2) {
warn "$Program: '$file2': $!\n";
exit EX_FAILURE;
if ($file2 eq '-') {
$fh2 = *STDIN;
}

if (defined($stat1[ST_INO]) && $stat1[ST_INO] == $stat2[ST_INO]) {
exit EX_SUCCESS; # hopefully, on platforms where
} # inode is meaningless, stat
# returns undef.
if (!$fh1 && !$fh2) {
my @stat1 = stat $file1;
unless (@stat1) {
warn "$Program: '$file1': $!\n";
exit EX_FAILURE;
}
my @stat2 = stat $file2;
unless (@stat2) {
warn "$Program: '$file2': $!\n";
exit EX_FAILURE;
}

if ($stat1[ST_SIZE] == 0 || $stat2[ST_SIZE] == 0) {
# special handling for zero-length files
if ($stat1[ST_SIZE] == 0 && $stat2[ST_SIZE] == 0) {
exit EX_SUCCESS;
} else { # Can't we say 'differ at byte zero'
# and so on here? That might make
# more sense than this behavior.
# Also, this should be made consistent
# with the behavior when skip >=
# filesize.
if ($volume) {
warn "$Program: EOF on $file1\n" unless $stat1[ST_SIZE];
warn "$Program: EOF on $file2\n" unless $stat2[ST_SIZE];
if (defined($stat1[ST_INO]) && $stat1[ST_INO] == $stat2[ST_INO]) {
exit EX_SUCCESS; # hopefully, on platforms where
} # inode is meaningless, stat
# returns undef.

if ($stat1[ST_SIZE] == 0 || $stat2[ST_SIZE] == 0) {
# special handling for zero-length files
if ($stat1[ST_SIZE] == 0 && $stat2[ST_SIZE] == 0) {
exit EX_SUCCESS;
} else { # Can't we say 'differ at byte zero'
# and so on here? That might make
# more sense than this behavior.
# Also, this should be made consistent
# with the behavior when skip >=
# filesize.
if ($volume) {
warn "$Program: EOF on $file1\n" unless $stat1[ST_SIZE];
warn "$Program: EOF on $file2\n" unless $stat2[ST_SIZE];
}
exit EX_DIFFERENT;
}
exit EX_DIFFERENT;
}
}

$skip1 = skipnum(shift) if @ARGV;
$skip2 = skipnum(shift) if @ARGV;

if( -d $file1 ) {
warn( "$Program: $file1 is a directory\n" );
exit EX_USAGE;
unless ($fh1) {
if (-d $file1) {
warn "$Program: '$file1' is a directory\n";
exit EX_FAILURE;
}
unless (open $fh1, '<', $file1) {
warn "$Program: cannot open '$file1'\n";
exit EX_FAILURE;
}
}
if( -d $file2 ) {
warn( "$Program: $file2 is a directory\n" );
exit EX_USAGE;
unless ($fh2) {
if (-d $file2) {
warn "$Program: '$file2' is a directory\n";
exit EX_FAILURE;
}
unless (open $fh2, '<', $file2) {
warn "$Program: cannot open '$file2'\n";
exit EX_FAILURE;
}
}

unless( open FILE1, '<', $file1 ) {
warn "$Program: cannot open '$file1'\n";
exit EX_FAILURE;
}
unless( open FILE2, '<', $file2 ) {
warn "$Program: cannot open '$file2'\n";
exit EX_FAILURE;
}

sysseek FILE1, $skip1, 0 if $skip1;
sysseek FILE2, $skip2, 0 if $skip2;
if ($skip1) {
if (-p $fh1) {
sysread $fh1, $buffer1, $skip1;
} else {
sysseek $fh1, $skip1, 0;
}
}
if ($skip2) {
if (-p $fh2) {
sysread $fh2, $buffer2, $skip2;
} else {
sysseek $fh2, $skip2, 0;
}
}

READ: while (defined ($read_in1 = sysread FILE1, $buffer1, $chunk_size)) {
$read_in2 = sysread FILE2, $buffer2, $chunk_size;
READ: while (defined ($read_in1 = sysread $fh1, $buffer1, $chunk_size)) {
$read_in2 = sysread $fh2, $buffer2, $chunk_size;

my $checklength = $chunk_size;
if ($read_in1 < $chunk_size or $read_in2 < $chunk_size) {
Expand Down Expand Up @@ -186,9 +214,8 @@ READ: while (defined ($read_in1 = sysread FILE1, $buffer1, $chunk_size)) {
}
}

close FILE1;
close FILE2;

close $fh1;
close $fh2;
exit $saw_difference;

sub skipnum {
Expand Down Expand Up @@ -246,6 +273,8 @@ will begin. Offsets may be given in decimal, octal, or hexadecimal
form. Indicate octal notation with a leading '0', and hexadecimal
notation with a leading '0x'.

file1 or file2 may be given as '-', which reads from standard input.

=head2 OPTIONS

=over
Expand Down