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```{index} single: addfile; Digest::SHA function
```
```{index} single: Digest::SHA::addfile; Perl function
```

# addfile

Feed a filehandle or a file by name into a `Digest::SHA` object.

The public file-ingestion entry point. Accepts either an open
filehandle or a filename string, plus an optional mode character that
controls how bytes are read:

- `"b"` (default): raw binary read. Use this for anything that is not
  human-readable text, or when you need bit-exact file digests.
- `"U"` or `"p"`: read through the PerlIO text layer. On platforms that
  perform CR/LF translation this yields platform-independent digests of
  text files; on Linux it reads identically to `"b"`.
- `"0"`: BITS mode. Interpret every `'0'` and `'1'` character in the
  file as a single bit and feed those bits into the hash. Anything else
  in the file is ignored.

## Synopsis

```perl
$sha->addfile("data.bin");                 # filename, binary
$sha->addfile($fh);                        # handle, binary
$sha->addfile($fh, "U");                   # universal newlines
$sha->addfile("bits.txt", "0");            # ASCII bit stream
```

## What you get back

The receiver, for chaining.

## Examples

```perl
my $sha = Digest::SHA->new(256);
$sha->addfile("archive.tar.gz");
print $sha->hexdigest;
```

```perl

## Cross-platform digest of a source file

my $sha = Digest::SHA->new(256);
$sha->addfile("src/main.c", "U");
```

```perl

## BITS mode: hash the bit pattern "01011010" repeated

open my $fh, "<", "bitstream.txt" or die $!;
my $sha = Digest::SHA->new(1);
$sha->addfile($fh, "0");
```

```perl
my $sha = Digest::SHA->new(256);
open my $fh, "<:raw", "photo.jpg" or die $!;
$sha->addfile($fh);
```

## Edge cases

- Missing or unreadable filename, or a closed filehandle, croaks with
  `Bad filehandle: ...`.
- Unknown mode characters fall back to binary.
- Empty files leave the hash state untouched.
- Called on a non-`Digest::SHA` object, returns `undef`.

## Differences from upstream

Fully compatible with upstream `Digest::SHA` {{ upstream.Digest_SHA }}.

## See also

- `add` — use when the data is already in a Perl scalar.
- `add_bits` — for bit-aligned input strings.
- `digest` — finalise and return the digest after the file has been consumed.