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/*-------------------------------------------------------------------------
*
* bbstreamer_gzip.c
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/bin/pg_basebackup/bbstreamer_gzip.c
*-------------------------------------------------------------------------
*/
#include "postgres_fe.h"
#include <unistd.h>
#ifdef HAVE_LIBZ
#include <zlib.h>
#endif
#include "bbstreamer.h"
#include "common/logging.h"
#include "common/file_perm.h"
#include "common/string.h"
#ifdef HAVE_LIBZ
typedef struct bbstreamer_gzip_writer
{
bbstreamer base;
char *pathname;
gzFile gzfile;
} bbstreamer_gzip_writer;
typedef struct bbstreamer_gzip_decompressor
{
bbstreamer base;
z_stream zstream;
size_t bytes_written;
} bbstreamer_gzip_decompressor;
static void bbstreamer_gzip_writer_content(bbstreamer *streamer,
bbstreamer_member *member,
const char *data, int len,
bbstreamer_archive_context context);
static void bbstreamer_gzip_writer_finalize(bbstreamer *streamer);
static void bbstreamer_gzip_writer_free(bbstreamer *streamer);
static const char *get_gz_error(gzFile gzf);
const bbstreamer_ops bbstreamer_gzip_writer_ops = {
.content = bbstreamer_gzip_writer_content,
.finalize = bbstreamer_gzip_writer_finalize,
.free = bbstreamer_gzip_writer_free
};
static void bbstreamer_gzip_decompressor_content(bbstreamer *streamer,
bbstreamer_member *member,
const char *data, int len,
bbstreamer_archive_context context);
static void bbstreamer_gzip_decompressor_finalize(bbstreamer *streamer);
static void bbstreamer_gzip_decompressor_free(bbstreamer *streamer);
static void *gzip_palloc(void *opaque, unsigned items, unsigned size);
static void gzip_pfree(void *opaque, void *address);
const bbstreamer_ops bbstreamer_gzip_decompressor_ops = {
.content = bbstreamer_gzip_decompressor_content,
.finalize = bbstreamer_gzip_decompressor_finalize,
.free = bbstreamer_gzip_decompressor_free
};
#endif
/*
* Create a bbstreamer that just compresses data using gzip, and then writes
* it to a file.
*
* As in the case of bbstreamer_plain_writer_new, pathname is always used
* for error reporting purposes; if file is NULL, it is also the opened and
* closed so that the data may be written there.
*/
bbstreamer *
bbstreamer_gzip_writer_new(char *pathname, FILE *file,
pg_compress_specification *compress)
{
#ifdef HAVE_LIBZ
bbstreamer_gzip_writer *streamer;
streamer = palloc0(sizeof(bbstreamer_gzip_writer));
*((const bbstreamer_ops **) &streamer->base.bbs_ops) =
&bbstreamer_gzip_writer_ops;
streamer->pathname = pstrdup(pathname);
if (file == NULL)
{
streamer->gzfile = gzopen(pathname, "wb");
if (streamer->gzfile == NULL)
pg_fatal("could not create compressed file \"%s\": %m",
pathname);
}
else
{
int fd = dup(fileno(file));
if (fd < 0)
pg_fatal("could not duplicate stdout: %m");
streamer->gzfile = gzdopen(fd, "wb");
if (streamer->gzfile == NULL)
pg_fatal("could not open output file: %m");
}
if (gzsetparams(streamer->gzfile, compress->level, Z_DEFAULT_STRATEGY) != Z_OK)
pg_fatal("could not set compression level %d: %s",
compress->level, get_gz_error(streamer->gzfile));
return &streamer->base;
#else
pg_fatal("this build does not support gzip compression");
return NULL; /* keep compiler quiet */
#endif
}
#ifdef HAVE_LIBZ
/*
* Write archive content to gzip file.
*/
static void
bbstreamer_gzip_writer_content(bbstreamer *streamer,
bbstreamer_member *member, const char *data,
int len, bbstreamer_archive_context context)
{
bbstreamer_gzip_writer *mystreamer;
mystreamer = (bbstreamer_gzip_writer *) streamer;
if (len == 0)
return;
errno = 0;
if (gzwrite(mystreamer->gzfile, data, len) != len)
{
/* if write didn't set errno, assume problem is no disk space */
if (errno == 0)
errno = ENOSPC;
pg_fatal("could not write to compressed file \"%s\": %s",
mystreamer->pathname, get_gz_error(mystreamer->gzfile));
}
}
/*
* End-of-archive processing when writing to a gzip file consists of just
* calling gzclose.
*
* It makes no difference whether we opened the file or the caller did it,
* because libz provides no way of avoiding a close on the underling file
* handle. Notice, however, that bbstreamer_gzip_writer_new() uses dup() to
* work around this issue, so that the behavior from the caller's viewpoint
* is the same as for bbstreamer_plain_writer.
*/
static void
bbstreamer_gzip_writer_finalize(bbstreamer *streamer)
{
bbstreamer_gzip_writer *mystreamer;
mystreamer = (bbstreamer_gzip_writer *) streamer;
errno = 0; /* in case gzclose() doesn't set it */
if (gzclose(mystreamer->gzfile) != 0)
pg_fatal("could not close compressed file \"%s\": %m",
mystreamer->pathname);
mystreamer->gzfile = NULL;
}
/*
* Free memory associated with this bbstreamer.
*/
static void
bbstreamer_gzip_writer_free(bbstreamer *streamer)
{
bbstreamer_gzip_writer *mystreamer;
mystreamer = (bbstreamer_gzip_writer *) streamer;
Assert(mystreamer->base.bbs_next == NULL);
Assert(mystreamer->gzfile == NULL);
pfree(mystreamer->pathname);
pfree(mystreamer);
}
/*
* Helper function for libz error reporting.
*/
static const char *
get_gz_error(gzFile gzf)
{
int errnum;
const char *errmsg;
errmsg = gzerror(gzf, &errnum);
if (errnum == Z_ERRNO)
return strerror(errno);
else
return errmsg;
}
#endif
/*
* Create a new base backup streamer that performs decompression of gzip
* compressed blocks.
*/
bbstreamer *
bbstreamer_gzip_decompressor_new(bbstreamer *next)
{
#ifdef HAVE_LIBZ
bbstreamer_gzip_decompressor *streamer;
z_stream *zs;
Assert(next != NULL);
streamer = palloc0(sizeof(bbstreamer_gzip_decompressor));
*((const bbstreamer_ops **) &streamer->base.bbs_ops) =
&bbstreamer_gzip_decompressor_ops;
streamer->base.bbs_next = next;
initStringInfo(&streamer->base.bbs_buffer);
/* Initialize internal stream state for decompression */
zs = &streamer->zstream;
zs->zalloc = gzip_palloc;
zs->zfree = gzip_pfree;
zs->next_out = (uint8 *) streamer->base.bbs_buffer.data;
zs->avail_out = streamer->base.bbs_buffer.maxlen;
/*
* Data compression was initialized using deflateInit2 to request a gzip
* header. Similarly, we are using inflateInit2 to initialize data
* decompression.
*
* Per the documentation for inflateInit2, the second argument is
* "windowBits" and its value must be greater than or equal to the value
* provided while compressing the data, so we are using the maximum
* possible value for safety.
*/
if (inflateInit2(zs, 15 + 16) != Z_OK)
pg_fatal("could not initialize compression library");
return &streamer->base;
#else
pg_fatal("this build does not support gzip compression");
return NULL; /* keep compiler quiet */
#endif
}
#ifdef HAVE_LIBZ
/*
* Decompress the input data to output buffer until we run out of input
* data. Each time the output buffer is full, pass on the decompressed data
* to the next streamer.
*/
static void
bbstreamer_gzip_decompressor_content(bbstreamer *streamer,
bbstreamer_member *member,
const char *data, int len,
bbstreamer_archive_context context)
{
bbstreamer_gzip_decompressor *mystreamer;
z_stream *zs;
mystreamer = (bbstreamer_gzip_decompressor *) streamer;
zs = &mystreamer->zstream;
zs->next_in = (uint8 *) data;
zs->avail_in = len;
/* Process the current chunk */
while (zs->avail_in > 0)
{
int res;
Assert(mystreamer->bytes_written < mystreamer->base.bbs_buffer.maxlen);
zs->next_out = (uint8 *)
mystreamer->base.bbs_buffer.data + mystreamer->bytes_written;
zs->avail_out =
mystreamer->base.bbs_buffer.maxlen - mystreamer->bytes_written;
/*
* This call decompresses data starting at zs->next_in and updates
* zs->next_in * and zs->avail_in. It generates output data starting
* at zs->next_out and updates zs->next_out and zs->avail_out
* accordingly.
*/
res = inflate(zs, Z_NO_FLUSH);
if (res == Z_STREAM_ERROR)
pg_log_error("could not decompress data: %s", zs->msg);
mystreamer->bytes_written =
mystreamer->base.bbs_buffer.maxlen - zs->avail_out;
/* If output buffer is full then pass data to next streamer */
if (mystreamer->bytes_written >= mystreamer->base.bbs_buffer.maxlen)
{
bbstreamer_content(mystreamer->base.bbs_next, member,
mystreamer->base.bbs_buffer.data,
mystreamer->base.bbs_buffer.maxlen, context);
mystreamer->bytes_written = 0;
}
}
}
/*
* End-of-stream processing.
*/
static void
bbstreamer_gzip_decompressor_finalize(bbstreamer *streamer)
{
bbstreamer_gzip_decompressor *mystreamer;
mystreamer = (bbstreamer_gzip_decompressor *) streamer;
/*
* End of the stream, if there is some pending data in output buffers then
* we must forward it to next streamer.
*/
bbstreamer_content(mystreamer->base.bbs_next, NULL,
mystreamer->base.bbs_buffer.data,
mystreamer->base.bbs_buffer.maxlen,
BBSTREAMER_UNKNOWN);
bbstreamer_finalize(mystreamer->base.bbs_next);
}
/*
* Free memory.
*/
static void
bbstreamer_gzip_decompressor_free(bbstreamer *streamer)
{
bbstreamer_free(streamer->bbs_next);
pfree(streamer->bbs_buffer.data);
pfree(streamer);
}
/*
* Wrapper function to adjust the signature of palloc to match what libz
* expects.
*/
static void *
gzip_palloc(void *opaque, unsigned items, unsigned size)
{
return palloc(items * size);
}
/*
* Wrapper function to adjust the signature of pfree to match what libz
* expects.
*/
static void
gzip_pfree(void *opaque, void *address)
{
pfree(address);
}
#endif
|