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vfs: add 'with_xml_file_content()' and 'with_raw_file_content()'

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Fixes #4372
This commit is contained in:
Christian Prochaska 2022-01-14 10:49:32 +01:00 committed by Christian Helmuth
parent 8fd2847a48
commit 8ced0f184e
2 changed files with 81 additions and 16 deletions
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17
repos/base/include/util/string.h
View File

@ -23,6 +23,7 @@
namespace Genode {
class Number_of_bytes;
class Byte_range_ptr;
class Cstring;
template <Genode::size_t> class String;
}
@ -67,6 +68,22 @@ class Genode::Number_of_bytes
};
/**
* Data structure for describing a byte buffer
*
* The type is intended to be used as 'Byte_range_ptr const &' argument.
* It is deliberately non-copyable.
*/
struct Genode::Byte_range_ptr
{
char * const start;
size_t const num_bytes;
Byte_range_ptr(char *start, size_t num_bytes)
: start(start), num_bytes(num_bytes) { }
};
/***********************
** Utility functions **
***********************/

80
repos/os/include/os/vfs.h
View File

@ -31,6 +31,12 @@ namespace Genode {
class Watcher;
template <typename>
class Watch_handler;
template <typename FN>
void with_raw_file_content(Readonly_file const &,
Byte_range_ptr const &, FN const &);
template <typename FN>
void with_xml_file_content(Readonly_file const &,
Byte_range_ptr const &, FN const &);
}
@ -487,6 +493,60 @@ class Genode::Readonly_file : public File
};
/**
* Call functor 'fn' with the data pointer and size in bytes
*
* If the buffer has a size of zero, 'fn' is not called.
*/
template <typename FN>
void Genode::with_raw_file_content(Readonly_file const &file,
Byte_range_ptr const &range, FN const &fn)
{
if (range.num_bytes == 0)
return;
size_t total_read = 0;
while (total_read < range.num_bytes) {
size_t read_bytes = file.read(Readonly_file::At{total_read},
range.start + total_read,
range.num_bytes - total_read);
if (read_bytes == 0)
break;
total_read += read_bytes;
}
if (total_read != range.num_bytes)
throw File::Truncated_during_read();
fn(range.start, range.num_bytes);
}
/**
* Call functor 'fn' with content as 'Xml_node' argument
*
* If the file does not contain valid XML, 'fn' is called with an
* '<empty/>' node as argument.
*/
template <typename FN>
void Genode::with_xml_file_content(Readonly_file const &file,
Byte_range_ptr const &range, FN const &fn)
{
with_raw_file_content(file, range,
[&] (char const *ptr, size_t num_bytes) {
try {
fn(Xml_node(ptr, num_bytes));
return;
}
catch (Xml_node::Invalid_syntax) { }
fn(Xml_node("<empty/>"));
});
}
class Genode::File_content
{
private:
@ -533,22 +593,10 @@ class Genode::File_content
:
_buffer(alloc, min((size_t)dir.file_size(rel_path), limit.value))
{
Readonly_file file {dir, rel_path};
size_t total_read = 0;
while (total_read < _buffer.size) {
size_t read_bytes = file.read(Readonly_file::At{total_read},
_buffer.ptr + total_read,
_buffer.size - total_read);
if (read_bytes == 0)
break;
total_read += read_bytes;
}
if (total_read != _buffer.size)
throw Truncated_during_read();
/* read the file content into the buffer */
with_raw_file_content(Readonly_file(dir, rel_path),
Byte_range_ptr(_buffer.ptr, _buffer.size),
[] (char const*, size_t) { });
}
/**