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Physical file stream api with more specific flags, create parent dire…
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…ctories, better error printing
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Dextinfire committed Oct 5, 2024
1 parent cd1482e commit 6124773
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Showing 2 changed files with 133 additions and 29 deletions.
123 changes: 107 additions & 16 deletions src/io/physicalfilestream.cpp
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,25 +3,84 @@

#include <cstring>
#include <algorithm>
#include <system_error>

namespace Impacto {
namespace Io {
std::ios_base::openmode PhysicalFileStream::PrepareFileOpenMode(
CreateFlags flags, std::error_code& ec) {
std::ios_base::openmode mode = std::ios::binary;
bool fileExists = std::filesystem::exists(SourceFileName, ec);
if (ec) {
ImpLog(LL_Error, LC_IO,
"Failed to check whether file exists \"%s\", error: \"%s\"\n",
SourceFileName.generic_string().c_str(), ec.message().c_str());
return {};
}

IoError PhysicalFileStream::Create(std::string const& fileName, Stream** out,
bool exists) {
std::error_code ec;
if (exists && !std::filesystem::exists(fileName, ec)) {
bool writeNoExistNoCreate =
(flags & WRITE) && !fileExists && !(flags & CREATE_IF_NOT_EXISTS);
bool readNoExist = !(flags & WRITE) && (flags & READ) && !fileExists;
if (writeNoExistNoCreate || readNoExist) {
ec = std::make_error_code(std::errc::no_such_file_or_directory);
ImpLog(LL_Error, LC_IO, "Failed to open stream \"%s\", error: \"%s\"\n",
SourceFileName.generic_string().c_str(), ec.message().c_str());
return {};
}

bool writeExistNoOverwrite =
(flags & WRITE) && fileExists && !(flags & TRUNCATE) && !(flags & APPEND);
if (writeExistNoOverwrite) {
// avoid truncating when in write only mode without truncate flag to
// preserve file size
// I think this is more intuitive than making it an error
// or letting the truncate happen
flags |= CreateFlagsMode::READ;
}

// require write for create/overwrite flags
assert((flags & WRITE) || !(flags & CREATE_DIRS));
assert((flags & WRITE) || !(flags & CREATE_IF_NOT_EXISTS));

// truncate is only needed when creating nonexistent if also reading
bool truncFlag = (flags & TRUNCATE) ||
((flags & READ) && !fileExists &&
(flags & CREATE_IF_NOT_EXISTS) && !(flags & APPEND));

// trunc and append are mutually exclusive
assert(!truncFlag || !(flags & APPEND));

if (flags & READ) mode |= std::ios::in;
if (flags & WRITE) mode |= std::ios::out;
if (flags & APPEND) mode |= std::ios::app;
if (truncFlag) mode |= std::ios::trunc;
if (flags & CREATE_DIRS) {
std::filesystem::create_directories(SourceFileName.parent_path(), ec);
if (ec) {
ImpLog(LL_Error, LC_IO, "Error checking file existence: %s\n",
ec.message().c_str());
return IoError_Fail;
ImpLog(LL_Error, LC_IO,
"Failed to create directories for file \"%s\", error: \"%s\"\n",
SourceFileName.generic_string().c_str(), ec.message().c_str());
return {};
}
return IoError_NotFound;
}
PhysicalFileStream* result = new PhysicalFileStream(fileName, !exists);
return mode;
}

IoError PhysicalFileStream::Create(std::string const& fileName, Stream** out,
CreateFlags flags) {
std::error_code ec;
PhysicalFileStream* result = new PhysicalFileStream(fileName, flags);
if (result->ErrorCode) {
ImpLog(LL_Error, LC_IO, "Failed to open file \"%s\", error: \"%s\"\n",
fileName.c_str(), result->ErrorCode.message().c_str());
delete result;
return result->ErrorCode == std::errc::no_such_file_or_directory
? IoError_NotFound
: IoError_Fail;
}
if (!result->FileStream) {
ImpLog(LL_Error, LC_IO, "Failed to open file \"%s\", error: \"%s\"\n",
fileName.c_str(), std::strerror(errno));
fileName.c_str(), std::generic_category().message(errno).c_str());
delete result;
return IoError_Fail;
}
Expand All @@ -37,21 +96,32 @@ IoError PhysicalFileStream::Create(std::string const& fileName, Stream** out,
}

int64_t PhysicalFileStream::Read(void* buffer, int64_t sz) {
if (!(Flags & READ)) {
return IoError_Fail;
}
if (FileStream.eof()) {
FileStream.clear();
return IoError_Eof;
}
FileStream.read((char*)buffer, sz);
if (!FileStream && !FileStream.eof()) {
ImpLog(LL_Error, LC_IO, "Read failed for file \"%s\" with error: \"%s\"\n",
SourceFileName.string().c_str(), std::strerror(errno));
SourceFileName.string().c_str(),
std::generic_category().message(errno).c_str());
FileStream.clear();
return IoError_Fail;
}
int64_t read = FileStream.gcount();
if (read == 0 && sz) return IoError_Eof;
Position += read;
return read;
}

int64_t PhysicalFileStream::Seek(int64_t offset, int origin) {
if (!(Flags & READ) && (Flags & APPEND)) {
// seeking is useless in readless append mode
return IoError_Fail;
}
int64_t absPos;
switch (origin) {
case RW_SEEK_SET:
Expand All @@ -64,11 +134,16 @@ int64_t PhysicalFileStream::Seek(int64_t offset, int origin) {
absPos = Meta.Size + offset;
break;
}
if (absPos < 0 || absPos > Meta.Size) return IoError_Fail;

// seeking past EOF is a legal operation, after write past EOF, the gap
// between prev file size and write pos is zero padded
if (absPos < 0) return IoError_Fail;
FileStream.seekg(absPos, std::ios::beg);
if (!FileStream && !FileStream.eof()) {
ImpLog(LL_Error, LC_IO, "Seek failed for file \"%s\" with error: \"%s\"\n",
SourceFileName.string().c_str(), std::strerror(errno));
SourceFileName.string().c_str(),
std::generic_category().message(errno).c_str());
FileStream.clear();
return IoError_Fail;
}
Position = FileStream.tellg();
Expand All @@ -78,9 +153,19 @@ int64_t PhysicalFileStream::Seek(int64_t offset, int origin) {
IoError PhysicalFileStream::Duplicate(Stream** outStream) {
PhysicalFileStream* result = new PhysicalFileStream(*this);
std::error_code ec;
if (result->ErrorCode) {
ImpLog(LL_Error, LC_IO, "Failed to open file \"%s\", error: \"%s\"\n",
SourceFileName.string().c_str(),
result->ErrorCode.message().c_str());
delete result;
return result->ErrorCode == std::errc::no_such_file_or_directory
? IoError_NotFound
: IoError_Fail;
}
if (!result->FileStream) {
ImpLog(LL_Error, LC_IO, "Failed to open file \"%s\", error: \"%s\"\n",
SourceFileName.string().c_str(), std::strerror(errno));
SourceFileName.string().c_str(),
std::generic_category().message(errno).c_str());
delete result;
return IoError_Fail;
}
Expand All @@ -93,7 +178,8 @@ IoError PhysicalFileStream::Duplicate(Stream** outStream) {
}
if (result->Seek(Position, RW_SEEK_SET) < 0) {
ImpLog(LL_Error, LC_IO, "Seek failed for file \"%s\" with error: \"%s\"\n",
SourceFileName.string().c_str(), std::strerror(errno));
SourceFileName.string().c_str(),
std::generic_category().message(errno).c_str());
delete result;
return IoError_Fail;
}
Expand All @@ -102,10 +188,15 @@ IoError PhysicalFileStream::Duplicate(Stream** outStream) {
}

int64_t PhysicalFileStream::Write(void* buffer, int64_t sz, int cnt) {
if (!(Flags & WRITE)) {
return IoError_Fail;
}
FileStream.write((char*)buffer, sz * cnt);
if (!FileStream) {
ImpLog(LL_Error, LC_IO, "Write failed for file \"%s\" with error: \"%s\"\n",
SourceFileName.string().c_str(), std::strerror(errno));
SourceFileName.string().c_str(),
std::generic_category().message(errno).c_str());
FileStream.clear();
return IoError_Fail;
}
int64_t written = sz * cnt;
Expand Down
39 changes: 26 additions & 13 deletions src/io/physicalfilestream.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,40 +3,53 @@
#include "stream.h"
#include <fstream>
#include <filesystem>
#include <system_error>
#include "buffering.h"

namespace Impacto {
namespace Io {

class PhysicalFileStream : public Stream {
public:
enum CreateFlagsMode {
READ = 1,
WRITE = READ << 1,
CREATE_IF_NOT_EXISTS = WRITE << 1,
TRUNCATE = CREATE_IF_NOT_EXISTS << 1,
APPEND = TRUNCATE << 1,
CREATE_DIRS = CREATE_IF_NOT_EXISTS << 1
};
using CreateFlags = int;
static IoError Create(std::string const& fileName, Stream** out,
bool exists = true);
CreateFlags flags = CreateFlagsMode::READ);
int64_t Read(void* buffer, int64_t sz) override;
int64_t Seek(int64_t offset, int origin) override;
IoError Duplicate(Stream** outStream) override;
int64_t Write(void* buffer, int64_t sz, int cnt = 1) override;

protected:
std::ios_base::openmode GetFileMode(bool truncate) {
// trunc will clear file if it exists, and allows creation of new file
return (truncate) ? std::ios::in | std::ios::out | std::ios::trunc |
std::ios::binary
: std::ios::in | std::ios::out | std::ios::binary;
}
PhysicalFileStream(std::filesystem::path filePath, bool truncate = false)
: Truncate(truncate),
std::ios_base::openmode PrepareFileOpenMode(CreateFlags flags,
std::error_code& ec);

PhysicalFileStream(std::filesystem::path filePath, CreateFlags flags)
: Flags(flags),
SourceFileName(std::move(filePath)),
FileStream(SourceFileName, GetFileMode(truncate)) {
FileStream(SourceFileName, PrepareFileOpenMode(flags, ErrorCode)) {
Meta.FileName = SourceFileName.string();
}

PhysicalFileStream(std::filesystem::path filePath)
: PhysicalFileStream(std::move(filePath), CreateFlagsMode::READ) {}

PhysicalFileStream(PhysicalFileStream const& other)
: SourceFileName(other.SourceFileName),
FileStream(other.SourceFileName, GetFileMode(other.Truncate)) {
: Flags(other.Flags),
SourceFileName(other.SourceFileName),
FileStream(other.SourceFileName,
PrepareFileOpenMode(Flags, ErrorCode)) {
Meta.FileName = SourceFileName.string();
}
bool Truncate;
std::error_code ErrorCode;
CreateFlags Flags;
std::filesystem::path SourceFileName;
std::fstream FileStream;
};
Expand Down

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