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hexdump: Support truncating output with -n

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This commit is contained in:
Eli Youngs 2022-10-21 20:54:15 -07:00 • committed by Sam Atkins
parent ae68def54b
commit 1b4ebcaa0c
1 changed files with 31 additions and 12 deletions
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43
Userland/Utilities/hexdump.cpp
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@ -27,8 +27,11 @@ ErrorOr<int> serenity_main(Main::Arguments args)
Core::ArgsParser args_parser; Core::ArgsParser args_parser;
char const* path = nullptr; char const* path = nullptr;
bool verbose = false; bool verbose = false;
Optional<size_t> max_bytes;
args_parser.add_positional_argument(path, "Input", "input", Core::ArgsParser::Required::No); args_parser.add_positional_argument(path, "Input", "input", Core::ArgsParser::Required::No);
args_parser.add_option(verbose, "Display all input data", "verbose", 'v'); args_parser.add_option(verbose, "Display all input data", "verbose", 'v');
args_parser.add_option(max_bytes, "Truncate to a fixed number of bytes", nullptr, 'n', "bytes");
args_parser.parse(args); args_parser.parse(args);
@ -67,18 +70,34 @@ ErrorOr<int> serenity_main(Main::Arguments args)
Array<u8, BUFSIZ> contents; Array<u8, BUFSIZ> contents;
Span<u8> previous_line; Span<u8> previous_line;
static_assert(LINE_LENGTH_BYTES * 2 <= contents.size(), "Buffer is too small?!"); static_assert(LINE_LENGTH_BYTES * 2 <= contents.size(), "Buffer is too small?!");
size_t contents_size = 0; size_t bytes_in_buffer = 0;
size_t total_bytes_read = 0;
size_t bytes_remaining = 0;
size_t bytes_to_read = 0;
int nread; int nread;
auto state = State::Print; auto state = State::Print;
while (true) { bool is_input_remaining = true;
nread = file->read(&contents[contents_size], BUFSIZ - contents_size); while (is_input_remaining) {
bytes_to_read = BUFSIZ - bytes_in_buffer;
if (max_bytes.has_value()) {
bytes_remaining = max_bytes.value() - total_bytes_read;
if (bytes_remaining < bytes_to_read) {
bytes_to_read = bytes_remaining;
is_input_remaining = false;
}
}
nread = file->read(&contents[bytes_in_buffer], (int)bytes_to_read);
if (nread <= 0) if (nread <= 0)
break; break;
contents_size += nread;
total_bytes_read += nread;
bytes_in_buffer += nread;
size_t offset; size_t offset;
for (offset = 0; offset + LINE_LENGTH_BYTES - 1 < contents_size; offset += LINE_LENGTH_BYTES) { for (offset = 0; offset + LINE_LENGTH_BYTES - 1 < bytes_in_buffer; offset += LINE_LENGTH_BYTES) {
if (verbose) { if (verbose) {
print_line(&contents[offset], LINE_LENGTH_BYTES); print_line(&contents[offset], LINE_LENGTH_BYTES);
continue; continue;
@ -106,17 +125,17 @@ ErrorOr<int> serenity_main(Main::Arguments args)
previous_line = current_line; previous_line = current_line;
} }
contents_size -= offset; bytes_in_buffer -= offset;
VERIFY(contents_size < LINE_LENGTH_BYTES); VERIFY(bytes_in_buffer < LINE_LENGTH_BYTES);
// If we managed to make the buffer exactly full, &contents[BUFSIZ] would blow up. // If we managed to make the buffer exactly full, &contents[BUFSIZ] would blow up.
if (contents_size > 0) { if (bytes_in_buffer > 0) {
// Regions cannot overlap due to above static_assert. // Regions cannot overlap due to above static_assert.
memcpy(&contents[0], &contents[offset], contents_size); memcpy(&contents[0], &contents[offset], bytes_in_buffer);
} }
} }
VERIFY(contents_size <= LINE_LENGTH_BYTES - 1); VERIFY(bytes_in_buffer <= LINE_LENGTH_BYTES - 1);
if (contents_size > 0) if (bytes_in_buffer > 0)
print_line(&contents[0], contents_size); print_line(&contents[0], bytes_in_buffer);
return 0; return 0;
} }