skunkworks-c/subprojects/zlib-1.2.13/contrib/iostream3/zfstream.cc

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2022-12-21 12:09:42 +01:00
/*
* A C++ I/O streams interface to the zlib gz* functions
*
* by Ludwig Schwardt <schwardt@sun.ac.za>
* original version by Kevin Ruland <kevin@rodin.wustl.edu>
*
* This version is standard-compliant and compatible with gcc 3.x.
*/
#include "zfstream.h"
#include <cstring> // for strcpy, strcat, strlen (mode strings)
#include <cstdio> // for BUFSIZ
// Internal buffer sizes (default and "unbuffered" versions)
#define BIGBUFSIZE BUFSIZ
#define SMALLBUFSIZE 1
/*****************************************************************************/
// Default constructor
gzfilebuf::gzfilebuf()
: file(NULL), io_mode(std::ios_base::openmode(0)), own_fd(false),
buffer(NULL), buffer_size(BIGBUFSIZE), own_buffer(true)
{
// No buffers to start with
this->disable_buffer();
}
// Destructor
gzfilebuf::~gzfilebuf()
{
// Sync output buffer and close only if responsible for file
// (i.e. attached streams should be left open at this stage)
this->sync();
if (own_fd)
this->close();
// Make sure internal buffer is deallocated
this->disable_buffer();
}
// Set compression level and strategy
int
gzfilebuf::setcompression(int comp_level,
int comp_strategy)
{
return gzsetparams(file, comp_level, comp_strategy);
}
// Open gzipped file
gzfilebuf*
gzfilebuf::open(const char *name,
std::ios_base::openmode mode)
{
// Fail if file already open
if (this->is_open())
return NULL;
// Don't support simultaneous read/write access (yet)
if ((mode & std::ios_base::in) && (mode & std::ios_base::out))
return NULL;
// Build mode string for gzopen and check it [27.8.1.3.2]
char char_mode[6] = "\0\0\0\0\0";
if (!this->open_mode(mode, char_mode))
return NULL;
// Attempt to open file
if ((file = gzopen(name, char_mode)) == NULL)
return NULL;
// On success, allocate internal buffer and set flags
this->enable_buffer();
io_mode = mode;
own_fd = true;
return this;
}
// Attach to gzipped file
gzfilebuf*
gzfilebuf::attach(int fd,
std::ios_base::openmode mode)
{
// Fail if file already open
if (this->is_open())
return NULL;
// Don't support simultaneous read/write access (yet)
if ((mode & std::ios_base::in) && (mode & std::ios_base::out))
return NULL;
// Build mode string for gzdopen and check it [27.8.1.3.2]
char char_mode[6] = "\0\0\0\0\0";
if (!this->open_mode(mode, char_mode))
return NULL;
// Attempt to attach to file
if ((file = gzdopen(fd, char_mode)) == NULL)
return NULL;
// On success, allocate internal buffer and set flags
this->enable_buffer();
io_mode = mode;
own_fd = false;
return this;
}
// Close gzipped file
gzfilebuf*
gzfilebuf::close()
{
// Fail immediately if no file is open
if (!this->is_open())
return NULL;
// Assume success
gzfilebuf* retval = this;
// Attempt to sync and close gzipped file
if (this->sync() == -1)
retval = NULL;
if (gzclose(file) < 0)
retval = NULL;
// File is now gone anyway (postcondition [27.8.1.3.8])
file = NULL;
own_fd = false;
// Destroy internal buffer if it exists
this->disable_buffer();
return retval;
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
// Convert int open mode to mode string
bool
gzfilebuf::open_mode(std::ios_base::openmode mode,
char* c_mode) const
{
bool testb = mode & std::ios_base::binary;
bool testi = mode & std::ios_base::in;
bool testo = mode & std::ios_base::out;
bool testt = mode & std::ios_base::trunc;
bool testa = mode & std::ios_base::app;
// Check for valid flag combinations - see [27.8.1.3.2] (Table 92)
// Original zfstream hardcoded the compression level to maximum here...
// Double the time for less than 1% size improvement seems
// excessive though - keeping it at the default level
// To change back, just append "9" to the next three mode strings
if (!testi && testo && !testt && !testa)
strcpy(c_mode, "w");
if (!testi && testo && !testt && testa)
strcpy(c_mode, "a");
if (!testi && testo && testt && !testa)
strcpy(c_mode, "w");
if (testi && !testo && !testt && !testa)
strcpy(c_mode, "r");
// No read/write mode yet
// if (testi && testo && !testt && !testa)
// strcpy(c_mode, "r+");
// if (testi && testo && testt && !testa)
// strcpy(c_mode, "w+");
// Mode string should be empty for invalid combination of flags
if (strlen(c_mode) == 0)
return false;
if (testb)
strcat(c_mode, "b");
return true;
}
// Determine number of characters in internal get buffer
std::streamsize
gzfilebuf::showmanyc()
{
// Calls to underflow will fail if file not opened for reading
if (!this->is_open() || !(io_mode & std::ios_base::in))
return -1;
// Make sure get area is in use
if (this->gptr() && (this->gptr() < this->egptr()))
return std::streamsize(this->egptr() - this->gptr());
else
return 0;
}
// Fill get area from gzipped file
gzfilebuf::int_type
gzfilebuf::underflow()
{
// If something is left in the get area by chance, return it
// (this shouldn't normally happen, as underflow is only supposed
// to be called when gptr >= egptr, but it serves as error check)
if (this->gptr() && (this->gptr() < this->egptr()))
return traits_type::to_int_type(*(this->gptr()));
// If the file hasn't been opened for reading, produce error
if (!this->is_open() || !(io_mode & std::ios_base::in))
return traits_type::eof();
// Attempt to fill internal buffer from gzipped file
// (buffer must be guaranteed to exist...)
int bytes_read = gzread(file, buffer, buffer_size);
// Indicates error or EOF
if (bytes_read <= 0)
{
// Reset get area
this->setg(buffer, buffer, buffer);
return traits_type::eof();
}
// Make all bytes read from file available as get area
this->setg(buffer, buffer, buffer + bytes_read);
// Return next character in get area
return traits_type::to_int_type(*(this->gptr()));
}
// Write put area to gzipped file
gzfilebuf::int_type
gzfilebuf::overflow(int_type c)
{
// Determine whether put area is in use
if (this->pbase())
{
// Double-check pointer range
if (this->pptr() > this->epptr() || this->pptr() < this->pbase())
return traits_type::eof();
// Add extra character to buffer if not EOF
if (!traits_type::eq_int_type(c, traits_type::eof()))
{
*(this->pptr()) = traits_type::to_char_type(c);
this->pbump(1);
}
// Number of characters to write to file
int bytes_to_write = this->pptr() - this->pbase();
// Overflow doesn't fail if nothing is to be written
if (bytes_to_write > 0)
{
// If the file hasn't been opened for writing, produce error
if (!this->is_open() || !(io_mode & std::ios_base::out))
return traits_type::eof();
// If gzipped file won't accept all bytes written to it, fail
if (gzwrite(file, this->pbase(), bytes_to_write) != bytes_to_write)
return traits_type::eof();
// Reset next pointer to point to pbase on success
this->pbump(-bytes_to_write);
}
}
// Write extra character to file if not EOF
else if (!traits_type::eq_int_type(c, traits_type::eof()))
{
// If the file hasn't been opened for writing, produce error
if (!this->is_open() || !(io_mode & std::ios_base::out))
return traits_type::eof();
// Impromptu char buffer (allows "unbuffered" output)
char_type last_char = traits_type::to_char_type(c);
// If gzipped file won't accept this character, fail
if (gzwrite(file, &last_char, 1) != 1)
return traits_type::eof();
}
// If you got here, you have succeeded (even if c was EOF)
// The return value should therefore be non-EOF
if (traits_type::eq_int_type(c, traits_type::eof()))
return traits_type::not_eof(c);
else
return c;
}
// Assign new buffer
std::streambuf*
gzfilebuf::setbuf(char_type* p,
std::streamsize n)
{
// First make sure stuff is sync'ed, for safety
if (this->sync() == -1)
return NULL;
// If buffering is turned off on purpose via setbuf(0,0), still allocate one...
// "Unbuffered" only really refers to put [27.8.1.4.10], while get needs at
// least a buffer of size 1 (very inefficient though, therefore make it bigger?)
// This follows from [27.5.2.4.3]/12 (gptr needs to point at something, it seems)
if (!p || !n)
{
// Replace existing buffer (if any) with small internal buffer
this->disable_buffer();
buffer = NULL;
buffer_size = 0;
own_buffer = true;
this->enable_buffer();
}
else
{
// Replace existing buffer (if any) with external buffer
this->disable_buffer();
buffer = p;
buffer_size = n;
own_buffer = false;
this->enable_buffer();
}
return this;
}
// Write put area to gzipped file (i.e. ensures that put area is empty)
int
gzfilebuf::sync()
{
return traits_type::eq_int_type(this->overflow(), traits_type::eof()) ? -1 : 0;
}
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
// Allocate internal buffer
void
gzfilebuf::enable_buffer()
{
// If internal buffer required, allocate one
if (own_buffer && !buffer)
{
// Check for buffered vs. "unbuffered"
if (buffer_size > 0)
{
// Allocate internal buffer
buffer = new char_type[buffer_size];
// Get area starts empty and will be expanded by underflow as need arises
this->setg(buffer, buffer, buffer);
// Setup entire internal buffer as put area.
// The one-past-end pointer actually points to the last element of the buffer,
// so that overflow(c) can safely add the extra character c to the sequence.
// These pointers remain in place for the duration of the buffer
this->setp(buffer, buffer + buffer_size - 1);
}
else
{
// Even in "unbuffered" case, (small?) get buffer is still required
buffer_size = SMALLBUFSIZE;
buffer = new char_type[buffer_size];
this->setg(buffer, buffer, buffer);
// "Unbuffered" means no put buffer
this->setp(0, 0);
}
}
else
{
// If buffer already allocated, reset buffer pointers just to make sure no
// stale chars are lying around
this->setg(buffer, buffer, buffer);
this->setp(buffer, buffer + buffer_size - 1);
}
}
// Destroy internal buffer
void
gzfilebuf::disable_buffer()
{
// If internal buffer exists, deallocate it
if (own_buffer && buffer)
{
// Preserve unbuffered status by zeroing size
if (!this->pbase())
buffer_size = 0;
delete[] buffer;
buffer = NULL;
this->setg(0, 0, 0);
this->setp(0, 0);
}
else
{
// Reset buffer pointers to initial state if external buffer exists
this->setg(buffer, buffer, buffer);
if (buffer)
this->setp(buffer, buffer + buffer_size - 1);
else
this->setp(0, 0);
}
}
/*****************************************************************************/
// Default constructor initializes stream buffer
gzifstream::gzifstream()
: std::istream(NULL), sb()
{ this->init(&sb); }
// Initialize stream buffer and open file
gzifstream::gzifstream(const char* name,
std::ios_base::openmode mode)
: std::istream(NULL), sb()
{
this->init(&sb);
this->open(name, mode);
}
// Initialize stream buffer and attach to file
gzifstream::gzifstream(int fd,
std::ios_base::openmode mode)
: std::istream(NULL), sb()
{
this->init(&sb);
this->attach(fd, mode);
}
// Open file and go into fail() state if unsuccessful
void
gzifstream::open(const char* name,
std::ios_base::openmode mode)
{
if (!sb.open(name, mode | std::ios_base::in))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Attach to file and go into fail() state if unsuccessful
void
gzifstream::attach(int fd,
std::ios_base::openmode mode)
{
if (!sb.attach(fd, mode | std::ios_base::in))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Close file
void
gzifstream::close()
{
if (!sb.close())
this->setstate(std::ios_base::failbit);
}
/*****************************************************************************/
// Default constructor initializes stream buffer
gzofstream::gzofstream()
: std::ostream(NULL), sb()
{ this->init(&sb); }
// Initialize stream buffer and open file
gzofstream::gzofstream(const char* name,
std::ios_base::openmode mode)
: std::ostream(NULL), sb()
{
this->init(&sb);
this->open(name, mode);
}
// Initialize stream buffer and attach to file
gzofstream::gzofstream(int fd,
std::ios_base::openmode mode)
: std::ostream(NULL), sb()
{
this->init(&sb);
this->attach(fd, mode);
}
// Open file and go into fail() state if unsuccessful
void
gzofstream::open(const char* name,
std::ios_base::openmode mode)
{
if (!sb.open(name, mode | std::ios_base::out))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Attach to file and go into fail() state if unsuccessful
void
gzofstream::attach(int fd,
std::ios_base::openmode mode)
{
if (!sb.attach(fd, mode | std::ios_base::out))
this->setstate(std::ios_base::failbit);
else
this->clear();
}
// Close file
void
gzofstream::close()
{
if (!sb.close())
this->setstate(std::ios_base::failbit);
}