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Refactor the pg_dump zlib code from pg_backup_custom.c to a separate file,
to make it easier to reuse that code. There is no user-visible changes. This is in preparation for the patch to add a new archive format, a directory, to perform a custom-like dump but with each table being dumped to a separate file (that in turn is a prerequisite for parallel pg_dump). This also makes it easier to add new compression methods in the future, and makes the pg_backup_custom.c code easier to read, when the compression-related code is factored out. Joachim Wieland, with heavy editorialization by me.
This commit is contained in:
Heikki Linnakangas
403
src/bin/pg_dump/compress_io.c
Normal file
403
src/bin/pg_dump/compress_io.c
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@@ -0,0 +1,403 @@
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/*-------------------------------------------------------------------------
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*
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* compress_io.c
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* Routines for archivers to write an uncompressed or compressed data
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* stream.
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*
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* The interface for writing to an archive consists of three functions:
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* AllocateCompressor, WriteDataToArchive and EndCompressor. First you call
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* AllocateCompressor, then write all the data by calling WriteDataToArchive
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* as many times as needed, and finally EndCompressor. WriteDataToArchive
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* and EndCompressor will call the WriteFunc that was provided to
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* AllocateCompressor for each chunk of compressed data.
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*
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* The interface for reading an archive consists of just one function:
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* ReadDataFromArchive. ReadDataFromArchive reads the whole compressed input
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* stream, by repeatedly calling the given ReadFunc. ReadFunc returns the
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* compressed data chunk at a time, and ReadDataFromArchive decompresses it
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* and passes the decompressed data to ahwrite(), until ReadFunc returns 0
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* to signal EOF.
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*
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* The interface is the same for compressed and uncompressed streams.
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*
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*
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* IDENTIFICATION
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* src/bin/pg_dump/compress_io.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "compress_io.h"
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static const char *modulename = gettext_noop("compress_io");
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static void ParseCompressionOption(int compression, CompressionAlgorithm *alg,
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int *level);
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/* Routines that support zlib compressed data I/O */
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#ifdef HAVE_LIBZ
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static void InitCompressorZlib(CompressorState *cs, int level);
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static void DeflateCompressorZlib(ArchiveHandle *AH, CompressorState *cs,
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bool flush);
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static void ReadDataFromArchiveZlib(ArchiveHandle *AH, ReadFunc readF);
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static size_t WriteDataToArchiveZlib(ArchiveHandle *AH, CompressorState *cs,
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const char *data, size_t dLen);
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static void EndCompressorZlib(ArchiveHandle *AH, CompressorState *cs);
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#endif
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/* Routines that support uncompressed data I/O */
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static void ReadDataFromArchiveNone(ArchiveHandle *AH, ReadFunc readF);
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static size_t WriteDataToArchiveNone(ArchiveHandle *AH, CompressorState *cs,
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const char *data, size_t dLen);
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/*
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* Interprets a numeric 'compression' value. The algorithm implied by the
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* value (zlib or none at the moment), is returned in *alg, and the
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* zlib compression level in *level.
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*/
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static void
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ParseCompressionOption(int compression, CompressionAlgorithm *alg, int *level)
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{
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if (compression == Z_DEFAULT_COMPRESSION ||
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(compression > 0 && compression <= 9))
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*alg = COMPR_ALG_LIBZ;
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else if (compression == 0)
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*alg = COMPR_ALG_NONE;
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else
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die_horribly(NULL, modulename, "Invalid compression code: %d\n",
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compression);
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/* The level is just the passed-in value. */
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if (level)
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*level = compression;
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}
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/* Public interface routines */
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/* Allocate a new compressor */
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CompressorState *
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AllocateCompressor(int compression, WriteFunc writeF)
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{
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CompressorState *cs;
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CompressionAlgorithm alg;
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int level;
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ParseCompressionOption(compression, &alg, &level);
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#ifndef HAVE_LIBZ
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if (alg == COMPR_ALG_LIBZ)
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die_horribly(NULL, modulename, "not built with zlib support\n");
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#endif
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cs = (CompressorState *) calloc(1, sizeof(CompressorState));
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if (cs == NULL)
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die_horribly(NULL, modulename, "out of memory\n");
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cs->writeF = writeF;
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cs->comprAlg = alg;
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/*
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* Perform compression algorithm specific initialization.
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*/
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#ifdef HAVE_LIBZ
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if (alg == COMPR_ALG_LIBZ)
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InitCompressorZlib(cs, level);
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#endif
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return cs;
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}
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/*
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* Read all compressed data from the input stream (via readF) and print it
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* out with ahwrite().
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*/
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void
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ReadDataFromArchive(ArchiveHandle *AH, int compression, ReadFunc readF)
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{
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CompressionAlgorithm alg;
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ParseCompressionOption(compression, &alg, NULL);
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if (alg == COMPR_ALG_NONE)
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ReadDataFromArchiveNone(AH, readF);
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if (alg == COMPR_ALG_LIBZ)
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{
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#ifdef HAVE_LIBZ
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ReadDataFromArchiveZlib(AH, readF);
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#else
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die_horribly(NULL, modulename, "not built with zlib support\n");
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#endif
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}
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}
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/*
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* Compress and write data to the output stream (via writeF).
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*/
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size_t
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WriteDataToArchive(ArchiveHandle *AH, CompressorState *cs,
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const void *data, size_t dLen)
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{
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switch(cs->comprAlg)
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{
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case COMPR_ALG_LIBZ:
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#ifdef HAVE_LIBZ
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return WriteDataToArchiveZlib(AH, cs, data, dLen);
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#else
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die_horribly(NULL, modulename, "not built with zlib support\n");
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#endif
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case COMPR_ALG_NONE:
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return WriteDataToArchiveNone(AH, cs, data, dLen);
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}
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return 0; /* keep compiler quiet */
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}
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/*
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* Terminate compression library context and flush its buffers.
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*/
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void
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EndCompressor(ArchiveHandle *AH, CompressorState *cs)
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{
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#ifdef HAVE_LIBZ
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if (cs->comprAlg == COMPR_ALG_LIBZ)
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EndCompressorZlib(AH, cs);
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#endif
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free(cs);
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}
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/* Private routines, specific to each compression method. */
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#ifdef HAVE_LIBZ
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/*
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* Functions for zlib compressed output.
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*/
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static void
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InitCompressorZlib(CompressorState *cs, int level)
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{
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z_streamp zp;
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zp = cs->zp = (z_streamp) malloc(sizeof(z_stream));
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if (cs->zp == NULL)
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die_horribly(NULL, modulename, "out of memory\n");
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zp->zalloc = Z_NULL;
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zp->zfree = Z_NULL;
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zp->opaque = Z_NULL;
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/*
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* zlibOutSize is the buffer size we tell zlib it can output
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* to. We actually allocate one extra byte because some routines
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* want to append a trailing zero byte to the zlib output.
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*/
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cs->zlibOut = (char *) malloc(ZLIB_OUT_SIZE + 1);
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cs->zlibOutSize = ZLIB_OUT_SIZE;
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if (cs->zlibOut == NULL)
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die_horribly(NULL, modulename, "out of memory\n");
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if (deflateInit(zp, level) != Z_OK)
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die_horribly(NULL, modulename,
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"could not initialize compression library: %s\n",
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zp->msg);
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/* Just be paranoid - maybe End is called after Start, with no Write */
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zp->next_out = (void *) cs->zlibOut;
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zp->avail_out = cs->zlibOutSize;
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}
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static void
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EndCompressorZlib(ArchiveHandle *AH, CompressorState *cs)
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{
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z_streamp zp = cs->zp;
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zp->next_in = NULL;
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zp->avail_in = 0;
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/* Flush any remaining data from zlib buffer */
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DeflateCompressorZlib(AH, cs, true);
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if (deflateEnd(zp) != Z_OK)
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die_horribly(AH, modulename,
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"could not close compression stream: %s\n", zp->msg);
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free(cs->zlibOut);
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free(cs->zp);
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}
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static void
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DeflateCompressorZlib(ArchiveHandle *AH, CompressorState *cs, bool flush)
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{
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z_streamp zp = cs->zp;
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char *out = cs->zlibOut;
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int res = Z_OK;
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while (cs->zp->avail_in != 0 || flush)
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{
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res = deflate(zp, flush ? Z_FINISH : Z_NO_FLUSH);
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if (res == Z_STREAM_ERROR)
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die_horribly(AH, modulename,
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"could not compress data: %s\n", zp->msg);
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if ((flush && (zp->avail_out < cs->zlibOutSize))
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|| (zp->avail_out == 0)
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|| (zp->avail_in != 0)
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)
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{
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/*
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* Extra paranoia: avoid zero-length chunks, since a zero length
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* chunk is the EOF marker in the custom format. This should never
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* happen but...
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*/
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if (zp->avail_out < cs->zlibOutSize)
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{
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/*
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* Any write function shoud do its own error checking but
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* to make sure we do a check here as well...
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*/
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size_t len = cs->zlibOutSize - zp->avail_out;
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if (cs->writeF(AH, out, len) != len)
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die_horribly(AH, modulename,
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"could not write to output file: %s\n",
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strerror(errno));
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}
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zp->next_out = (void *) out;
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zp->avail_out = cs->zlibOutSize;
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}
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if (res == Z_STREAM_END)
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break;
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}
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}
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static size_t
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WriteDataToArchiveZlib(ArchiveHandle *AH, CompressorState *cs,
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const char *data, size_t dLen)
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{
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cs->zp->next_in = (void *) data;
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cs->zp->avail_in = dLen;
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DeflateCompressorZlib(AH, cs, false);
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/* we have either succeeded in writing dLen bytes or we have called
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* die_horribly() */
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return dLen;
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}
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static void
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ReadDataFromArchiveZlib(ArchiveHandle *AH, ReadFunc readF)
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{
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z_streamp zp;
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char *out;
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int res = Z_OK;
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size_t cnt;
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char *buf;
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size_t buflen;
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zp = (z_streamp) malloc(sizeof(z_stream));
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if (zp == NULL)
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die_horribly(NULL, modulename, "out of memory\n");
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zp->zalloc = Z_NULL;
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zp->zfree = Z_NULL;
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zp->opaque = Z_NULL;
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buf = malloc(ZLIB_IN_SIZE);
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if (buf == NULL)
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die_horribly(NULL, modulename, "out of memory\n");
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buflen = ZLIB_IN_SIZE;
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out = malloc(ZLIB_OUT_SIZE + 1);
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if (out == NULL)
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die_horribly(NULL, modulename, "out of memory\n");
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if (inflateInit(zp) != Z_OK)
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die_horribly(NULL, modulename,
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"could not initialize compression library: %s\n",
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zp->msg);
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/* no minimal chunk size for zlib */
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while ((cnt = readF(AH, &buf, &buflen)))
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{
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zp->next_in = (void *) buf;
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zp->avail_in = cnt;
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while (zp->avail_in > 0)
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{
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zp->next_out = (void *) out;
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zp->avail_out = ZLIB_OUT_SIZE;
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res = inflate(zp, 0);
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if (res != Z_OK && res != Z_STREAM_END)
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die_horribly(AH, modulename,
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"could not uncompress data: %s\n", zp->msg);
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out[ZLIB_OUT_SIZE - zp->avail_out] = '\0';
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ahwrite(out, 1, ZLIB_OUT_SIZE - zp->avail_out, AH);
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}
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}
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zp->next_in = NULL;
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zp->avail_in = 0;
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while (res != Z_STREAM_END)
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{
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zp->next_out = (void *) out;
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zp->avail_out = ZLIB_OUT_SIZE;
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res = inflate(zp, 0);
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if (res != Z_OK && res != Z_STREAM_END)
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die_horribly(AH, modulename,
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"could not uncompress data: %s\n", zp->msg);
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out[ZLIB_OUT_SIZE - zp->avail_out] = '\0';
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ahwrite(out, 1, ZLIB_OUT_SIZE - zp->avail_out, AH);
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}
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if (inflateEnd(zp) != Z_OK)
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die_horribly(AH, modulename,
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"could not close compression library: %s\n", zp->msg);
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free(buf);
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free(out);
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free(zp);
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}
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#endif /* HAVE_LIBZ */
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/*
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* Functions for uncompressed output.
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*/
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static void
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ReadDataFromArchiveNone(ArchiveHandle *AH, ReadFunc readF)
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{
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size_t cnt;
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char *buf;
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size_t buflen;
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buf = malloc(ZLIB_OUT_SIZE);
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if (buf == NULL)
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die_horribly(NULL, modulename, "out of memory\n");
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buflen = ZLIB_OUT_SIZE;
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while ((cnt = readF(AH, &buf, &buflen)))
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{
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ahwrite(buf, 1, cnt, AH);
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}
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free(buf);
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}
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static size_t
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WriteDataToArchiveNone(ArchiveHandle *AH, CompressorState *cs,
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const char *data, size_t dLen)
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{
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/*
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* Any write function should do its own error checking but to make
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* sure we do a check here as well...
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*/
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if (cs->writeF(AH, data, dLen) != dLen)
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die_horribly(AH, modulename,
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"could not write to output file: %s\n",
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strerror(errno));
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return dLen;
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}
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Reference in New Issue
Block a user