| 1 |
/* |
| 2 |
* A C++ I/O streams interface to the zlib gz* functions |
| 3 |
* |
| 4 |
* by Ludwig Schwardt <schwardt@sun.ac.za> |
| 5 |
* original version by Kevin Ruland <kevin@rodin.wustl.edu> |
| 6 |
* |
| 7 |
* This version is standard-compliant and compatible with gcc 3.x. |
| 8 |
*/ |
| 9 |
|
| 10 |
#include "zfstream.h" |
| 11 |
#include <cstring> // for strcpy, strcat, strlen (mode strings) |
| 12 |
#include <cstdio> // for BUFSIZ |
| 13 |
|
| 14 |
// Internal buffer sizes (default and "unbuffered" versions) |
| 15 |
#define BIGBUFSIZE BUFSIZ |
| 16 |
#define SMALLBUFSIZE 1 |
| 17 |
|
| 18 |
/*****************************************************************************/ |
| 19 |
|
| 20 |
// Default constructor |
| 21 |
gzfilebuf::gzfilebuf() |
| 22 |
: file(NULL), io_mode(std::ios_base::openmode(0)), own_fd(false), |
| 23 |
buffer(NULL), buffer_size(BIGBUFSIZE), own_buffer(true) |
| 24 |
{ |
| 25 |
// No buffers to start with |
| 26 |
this->disable_buffer(); |
| 27 |
} |
| 28 |
|
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// Destructor |
| 30 |
gzfilebuf::~gzfilebuf() |
| 31 |
{ |
| 32 |
// Sync output buffer and close only if responsible for file |
| 33 |
// (i.e. attached streams should be left open at this stage) |
| 34 |
this->sync(); |
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if (own_fd) |
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this->close(); |
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// Make sure internal buffer is deallocated |
| 38 |
this->disable_buffer(); |
| 39 |
} |
| 40 |
|
| 41 |
// Set compression level and strategy |
| 42 |
int |
| 43 |
gzfilebuf::setcompression(int comp_level, |
| 44 |
int comp_strategy) |
| 45 |
{ |
| 46 |
return gzsetparams(file, comp_level, comp_strategy); |
| 47 |
} |
| 48 |
|
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// Open gzipped file |
| 50 |
gzfilebuf* |
| 51 |
gzfilebuf::open(const char *name, |
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std::ios_base::openmode mode) |
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{ |
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// Fail if file already open |
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if (this->is_open()) |
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return NULL; |
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// Don't support simultaneous read/write access (yet) |
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if ((mode & std::ios_base::in) && (mode & std::ios_base::out)) |
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return NULL; |
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|
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// Build mode string for gzopen and check it [27.8.1.3.2] |
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char char_mode[6] = "\0\0\0\0\0"; |
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if (!this->open_mode(mode, char_mode)) |
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return NULL; |
| 65 |
|
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// Attempt to open file |
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if ((file = gzopen(name, char_mode)) == NULL) |
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return NULL; |
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|
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// On success, allocate internal buffer and set flags |
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this->enable_buffer(); |
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io_mode = mode; |
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own_fd = true; |
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return this; |
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} |
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|
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// Attach to gzipped file |
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gzfilebuf* |
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gzfilebuf::attach(int fd, |
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std::ios_base::openmode mode) |
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{ |
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// Fail if file already open |
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if (this->is_open()) |
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return NULL; |
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// Don't support simultaneous read/write access (yet) |
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if ((mode & std::ios_base::in) && (mode & std::ios_base::out)) |
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return NULL; |
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|
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// Build mode string for gzdopen and check it [27.8.1.3.2] |
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char char_mode[6] = "\0\0\0\0\0"; |
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if (!this->open_mode(mode, char_mode)) |
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return NULL; |
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|
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// Attempt to attach to file |
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if ((file = gzdopen(fd, char_mode)) == NULL) |
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return NULL; |
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|
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// On success, allocate internal buffer and set flags |
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this->enable_buffer(); |
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io_mode = mode; |
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own_fd = false; |
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return this; |
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} |
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|
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// Close gzipped file |
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gzfilebuf* |
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gzfilebuf::close() |
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{ |
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// Fail immediately if no file is open |
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if (!this->is_open()) |
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return NULL; |
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// Assume success |
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gzfilebuf* retval = this; |
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// Attempt to sync and close gzipped file |
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if (this->sync() == -1) |
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retval = NULL; |
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if (gzclose(file) < 0) |
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retval = NULL; |
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// File is now gone anyway (postcondition [27.8.1.3.8]) |
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file = NULL; |
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own_fd = false; |
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// Destroy internal buffer if it exists |
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this->disable_buffer(); |
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return retval; |
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} |
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|
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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
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|
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// Convert int open mode to mode string |
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bool |
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gzfilebuf::open_mode(std::ios_base::openmode mode, |
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char* c_mode) const |
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{ |
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bool testb = mode & std::ios_base::binary; |
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bool testi = mode & std::ios_base::in; |
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bool testo = mode & std::ios_base::out; |
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bool testt = mode & std::ios_base::trunc; |
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bool testa = mode & std::ios_base::app; |
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|
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// Check for valid flag combinations - see [27.8.1.3.2] (Table 92) |
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// Original zfstream hardcoded the compression level to maximum here... |
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// Double the time for less than 1% size improvement seems |
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// excessive though - keeping it at the default level |
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// To change back, just append "9" to the next three mode strings |
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if (!testi && testo && !testt && !testa) |
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strcpy(c_mode, "w"); |
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if (!testi && testo && !testt && testa) |
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strcpy(c_mode, "a"); |
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if (!testi && testo && testt && !testa) |
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strcpy(c_mode, "w"); |
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if (testi && !testo && !testt && !testa) |
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strcpy(c_mode, "r"); |
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// No read/write mode yet |
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// if (testi && testo && !testt && !testa) |
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// strcpy(c_mode, "r+"); |
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// if (testi && testo && testt && !testa) |
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// strcpy(c_mode, "w+"); |
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|
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// Mode string should be empty for invalid combination of flags |
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if (strlen(c_mode) == 0) |
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return false; |
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if (testb) |
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strcat(c_mode, "b"); |
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return true; |
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} |
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|
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// Determine number of characters in internal get buffer |
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std::streamsize |
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gzfilebuf::showmanyc() |
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{ |
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// Calls to underflow will fail if file not opened for reading |
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if (!this->is_open() || !(io_mode & std::ios_base::in)) |
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return -1; |
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// Make sure get area is in use |
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if (this->gptr() && (this->gptr() < this->egptr())) |
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return std::streamsize(this->egptr() - this->gptr()); |
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else |
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return 0; |
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} |
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|
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// Fill get area from gzipped file |
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gzfilebuf::int_type |
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gzfilebuf::underflow() |
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{ |
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// If something is left in the get area by chance, return it |
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// (this shouldn't normally happen, as underflow is only supposed |
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// to be called when gptr >= egptr, but it serves as error check) |
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if (this->gptr() && (this->gptr() < this->egptr())) |
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return traits_type::to_int_type(*(this->gptr())); |
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|
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// If the file hasn't been opened for reading, produce error |
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if (!this->is_open() || !(io_mode & std::ios_base::in)) |
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return traits_type::eof(); |
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|
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// Attempt to fill internal buffer from gzipped file |
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// (buffer must be guaranteed to exist...) |
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int bytes_read = gzread(file, buffer, buffer_size); |
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// Indicates error or EOF |
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if (bytes_read <= 0) |
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{ |
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// Reset get area |
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this->setg(buffer, buffer, buffer); |
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return traits_type::eof(); |
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} |
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// Make all bytes read from file available as get area |
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this->setg(buffer, buffer, buffer + bytes_read); |
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|
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// Return next character in get area |
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return traits_type::to_int_type(*(this->gptr())); |
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} |
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|
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// Write put area to gzipped file |
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gzfilebuf::int_type |
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gzfilebuf::overflow(int_type c) |
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{ |
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// Determine whether put area is in use |
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if (this->pbase()) |
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{ |
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// Double-check pointer range |
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if (this->pptr() > this->epptr() || this->pptr() < this->pbase()) |
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return traits_type::eof(); |
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// Add extra character to buffer if not EOF |
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if (!traits_type::eq_int_type(c, traits_type::eof())) |
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{ |
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*(this->pptr()) = traits_type::to_char_type(c); |
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this->pbump(1); |
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} |
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// Number of characters to write to file |
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int bytes_to_write = this->pptr() - this->pbase(); |
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// Overflow doesn't fail if nothing is to be written |
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if (bytes_to_write > 0) |
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{ |
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// If the file hasn't been opened for writing, produce error |
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if (!this->is_open() || !(io_mode & std::ios_base::out)) |
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return traits_type::eof(); |
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// If gzipped file won't accept all bytes written to it, fail |
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if (gzwrite(file, this->pbase(), bytes_to_write) != bytes_to_write) |
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return traits_type::eof(); |
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// Reset next pointer to point to pbase on success |
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this->pbump(-bytes_to_write); |
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} |
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} |
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// Write extra character to file if not EOF |
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else if (!traits_type::eq_int_type(c, traits_type::eof())) |
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{ |
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// If the file hasn't been opened for writing, produce error |
| 247 |
if (!this->is_open() || !(io_mode & std::ios_base::out)) |
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return traits_type::eof(); |
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// Impromptu char buffer (allows "unbuffered" output) |
| 250 |
char_type last_char = traits_type::to_char_type(c); |
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// If gzipped file won't accept this character, fail |
| 252 |
if (gzwrite(file, &last_char, 1) != 1) |
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return traits_type::eof(); |
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} |
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|
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// If you got here, you have succeeded (even if c was EOF) |
| 257 |
// The return value should therefore be non-EOF |
| 258 |
if (traits_type::eq_int_type(c, traits_type::eof())) |
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return traits_type::not_eof(c); |
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else |
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return c; |
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} |
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|
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// Assign new buffer |
| 265 |
std::streambuf* |
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gzfilebuf::setbuf(char_type* p, |
| 267 |
std::streamsize n) |
| 268 |
{ |
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// First make sure stuff is sync'ed, for safety |
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if (this->sync() == -1) |
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return NULL; |
| 272 |
// If buffering is turned off on purpose via setbuf(0,0), still allocate one... |
| 273 |
// "Unbuffered" only really refers to put [27.8.1.4.10], while get needs at |
| 274 |
// least a buffer of size 1 (very inefficient though, therefore make it bigger?) |
| 275 |
// This follows from [27.5.2.4.3]/12 (gptr needs to point at something, it seems) |
| 276 |
if (!p || !n) |
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{ |
| 278 |
// Replace existing buffer (if any) with small internal buffer |
| 279 |
this->disable_buffer(); |
| 280 |
buffer = NULL; |
| 281 |
buffer_size = 0; |
| 282 |
own_buffer = true; |
| 283 |
this->enable_buffer(); |
| 284 |
} |
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else |
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{ |
| 287 |
// Replace existing buffer (if any) with external buffer |
| 288 |
this->disable_buffer(); |
| 289 |
buffer = p; |
| 290 |
buffer_size = n; |
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own_buffer = false; |
| 292 |
this->enable_buffer(); |
| 293 |
} |
| 294 |
return this; |
| 295 |
} |
| 296 |
|
| 297 |
// Write put area to gzipped file (i.e. ensures that put area is empty) |
| 298 |
int |
| 299 |
gzfilebuf::sync() |
| 300 |
{ |
| 301 |
return traits_type::eq_int_type(this->overflow(), traits_type::eof()) ? -1 : 0; |
| 302 |
} |
| 303 |
|
| 304 |
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */ |
| 305 |
|
| 306 |
// Allocate internal buffer |
| 307 |
void |
| 308 |
gzfilebuf::enable_buffer() |
| 309 |
{ |
| 310 |
// If internal buffer required, allocate one |
| 311 |
if (own_buffer && !buffer) |
| 312 |
{ |
| 313 |
// Check for buffered vs. "unbuffered" |
| 314 |
if (buffer_size > 0) |
| 315 |
{ |
| 316 |
// Allocate internal buffer |
| 317 |
buffer = new char_type[buffer_size]; |
| 318 |
// Get area starts empty and will be expanded by underflow as need arises |
| 319 |
this->setg(buffer, buffer, buffer); |
| 320 |
// Setup entire internal buffer as put area. |
| 321 |
// The one-past-end pointer actually points to the last element of the buffer, |
| 322 |
// so that overflow(c) can safely add the extra character c to the sequence. |
| 323 |
// These pointers remain in place for the duration of the buffer |
| 324 |
this->setp(buffer, buffer + buffer_size - 1); |
| 325 |
} |
| 326 |
else |
| 327 |
{ |
| 328 |
// Even in "unbuffered" case, (small?) get buffer is still required |
| 329 |
buffer_size = SMALLBUFSIZE; |
| 330 |
buffer = new char_type[buffer_size]; |
| 331 |
this->setg(buffer, buffer, buffer); |
| 332 |
// "Unbuffered" means no put buffer |
| 333 |
this->setp(0, 0); |
| 334 |
} |
| 335 |
} |
| 336 |
else |
| 337 |
{ |
| 338 |
// If buffer already allocated, reset buffer pointers just to make sure no |
| 339 |
// stale chars are lying around |
| 340 |
this->setg(buffer, buffer, buffer); |
| 341 |
this->setp(buffer, buffer + buffer_size - 1); |
| 342 |
} |
| 343 |
} |
| 344 |
|
| 345 |
// Destroy internal buffer |
| 346 |
void |
| 347 |
gzfilebuf::disable_buffer() |
| 348 |
{ |
| 349 |
// If internal buffer exists, deallocate it |
| 350 |
if (own_buffer && buffer) |
| 351 |
{ |
| 352 |
// Preserve unbuffered status by zeroing size |
| 353 |
if (!this->pbase()) |
| 354 |
buffer_size = 0; |
| 355 |
delete[] buffer; |
| 356 |
buffer = NULL; |
| 357 |
this->setg(0, 0, 0); |
| 358 |
this->setp(0, 0); |
| 359 |
} |
| 360 |
else |
| 361 |
{ |
| 362 |
// Reset buffer pointers to initial state if external buffer exists |
| 363 |
this->setg(buffer, buffer, buffer); |
| 364 |
if (buffer) |
| 365 |
this->setp(buffer, buffer + buffer_size - 1); |
| 366 |
else |
| 367 |
this->setp(0, 0); |
| 368 |
} |
| 369 |
} |
| 370 |
|
| 371 |
/*****************************************************************************/ |
| 372 |
|
| 373 |
// Default constructor initializes stream buffer |
| 374 |
gzifstream::gzifstream() |
| 375 |
: std::istream(NULL), sb() |
| 376 |
{ this->init(&sb); } |
| 377 |
|
| 378 |
// Initialize stream buffer and open file |
| 379 |
gzifstream::gzifstream(const char* name, |
| 380 |
std::ios_base::openmode mode) |
| 381 |
: std::istream(NULL), sb() |
| 382 |
{ |
| 383 |
this->init(&sb); |
| 384 |
this->open(name, mode); |
| 385 |
} |
| 386 |
|
| 387 |
// Initialize stream buffer and attach to file |
| 388 |
gzifstream::gzifstream(int fd, |
| 389 |
std::ios_base::openmode mode) |
| 390 |
: std::istream(NULL), sb() |
| 391 |
{ |
| 392 |
this->init(&sb); |
| 393 |
this->attach(fd, mode); |
| 394 |
} |
| 395 |
|
| 396 |
// Open file and go into fail() state if unsuccessful |
| 397 |
void |
| 398 |
gzifstream::open(const char* name, |
| 399 |
std::ios_base::openmode mode) |
| 400 |
{ |
| 401 |
if (!sb.open(name, mode | std::ios_base::in)) |
| 402 |
this->setstate(std::ios_base::failbit); |
| 403 |
else |
| 404 |
this->clear(); |
| 405 |
} |
| 406 |
|
| 407 |
// Attach to file and go into fail() state if unsuccessful |
| 408 |
void |
| 409 |
gzifstream::attach(int fd, |
| 410 |
std::ios_base::openmode mode) |
| 411 |
{ |
| 412 |
if (!sb.attach(fd, mode | std::ios_base::in)) |
| 413 |
this->setstate(std::ios_base::failbit); |
| 414 |
else |
| 415 |
this->clear(); |
| 416 |
} |
| 417 |
|
| 418 |
// Close file |
| 419 |
void |
| 420 |
gzifstream::close() |
| 421 |
{ |
| 422 |
if (!sb.close()) |
| 423 |
this->setstate(std::ios_base::failbit); |
| 424 |
} |
| 425 |
|
| 426 |
/*****************************************************************************/ |
| 427 |
|
| 428 |
// Default constructor initializes stream buffer |
| 429 |
gzofstream::gzofstream() |
| 430 |
: std::ostream(NULL), sb() |
| 431 |
{ this->init(&sb); } |
| 432 |
|
| 433 |
// Initialize stream buffer and open file |
| 434 |
gzofstream::gzofstream(const char* name, |
| 435 |
std::ios_base::openmode mode) |
| 436 |
: std::ostream(NULL), sb() |
| 437 |
{ |
| 438 |
this->init(&sb); |
| 439 |
this->open(name, mode); |
| 440 |
} |
| 441 |
|
| 442 |
// Initialize stream buffer and attach to file |
| 443 |
gzofstream::gzofstream(int fd, |
| 444 |
std::ios_base::openmode mode) |
| 445 |
: std::ostream(NULL), sb() |
| 446 |
{ |
| 447 |
this->init(&sb); |
| 448 |
this->attach(fd, mode); |
| 449 |
} |
| 450 |
|
| 451 |
// Open file and go into fail() state if unsuccessful |
| 452 |
void |
| 453 |
gzofstream::open(const char* name, |
| 454 |
std::ios_base::openmode mode) |
| 455 |
{ |
| 456 |
if (!sb.open(name, mode | std::ios_base::out)) |
| 457 |
this->setstate(std::ios_base::failbit); |
| 458 |
else |
| 459 |
this->clear(); |
| 460 |
} |
| 461 |
|
| 462 |
// Attach to file and go into fail() state if unsuccessful |
| 463 |
void |
| 464 |
gzofstream::attach(int fd, |
| 465 |
std::ios_base::openmode mode) |
| 466 |
{ |
| 467 |
if (!sb.attach(fd, mode | std::ios_base::out)) |
| 468 |
this->setstate(std::ios_base::failbit); |
| 469 |
else |
| 470 |
this->clear(); |
| 471 |
} |
| 472 |
|
| 473 |
// Close file |
| 474 |
void |
| 475 |
gzofstream::close() |
| 476 |
{ |
| 477 |
if (!sb.close()) |
| 478 |
this->setstate(std::ios_base::failbit); |
| 479 |
} |
