Adding upstream version 15.4.upstream/15.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 358 insertions, 0 deletions

diff --git a/src/common/compression.c b/src/common/compression.c
new file mode 100644
index 0000000..df5b627
--- /dev/null
+++ b/src/common/compression.c
@@ -0,0 +1,358 @@
+/*-------------------------------------------------------------------------
+ *
+ * compression.c
+ *
+ * Shared code for compression methods and specifications.
+ *
+ * A compression specification specifies the parameters that should be used
+ * when performing compression with a specific algorithm. The simplest
+ * possible compression specification is an integer, which sets the
+ * compression level.
+ *
+ * Otherwise, a compression specification is a comma-separated list of items,
+ * each having the form keyword or keyword=value.
+ *
+ * Currently, the only supported keywords are "level" and "workers".
+ *
+ * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		  src/common/compression.c
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#ifdef USE_ZSTD
+#include <zstd.h>
+#endif
+#ifdef HAVE_LIBZ
+#include <zlib.h>
+#endif
+
+#include "common/compression.h"
+
+static int	expect_integer_value(char *keyword, char *value,
+								 pg_compress_specification *result);
+
+/*
+ * Look up a compression algorithm by name. Returns true and sets *algorithm
+ * if the name is recognized. Otherwise returns false.
+ */
+bool
+parse_compress_algorithm(char *name, pg_compress_algorithm *algorithm)
+{
+	if (strcmp(name, "none") == 0)
+		*algorithm = PG_COMPRESSION_NONE;
+	else if (strcmp(name, "gzip") == 0)
+		*algorithm = PG_COMPRESSION_GZIP;
+	else if (strcmp(name, "lz4") == 0)
+		*algorithm = PG_COMPRESSION_LZ4;
+	else if (strcmp(name, "zstd") == 0)
+		*algorithm = PG_COMPRESSION_ZSTD;
+	else
+		return false;
+	return true;
+}
+
+/*
+ * Get the human-readable name corresponding to a particular compression
+ * algorithm.
+ */
+const char *
+get_compress_algorithm_name(pg_compress_algorithm algorithm)
+{
+	switch (algorithm)
+	{
+		case PG_COMPRESSION_NONE:
+			return "none";
+		case PG_COMPRESSION_GZIP:
+			return "gzip";
+		case PG_COMPRESSION_LZ4:
+			return "lz4";
+		case PG_COMPRESSION_ZSTD:
+			return "zstd";
+			/* no default, to provoke compiler warnings if values are added */
+	}
+	Assert(false);
+	return "???";				/* placate compiler */
+}
+
+/*
+ * Parse a compression specification for a specified algorithm.
+ *
+ * See the file header comments for a brief description of what a compression
+ * specification is expected to look like.
+ *
+ * On return, all fields of the result object will be initialized.
+ * In particular, result->parse_error will be NULL if no errors occurred
+ * during parsing, and will otherwise contain an appropriate error message.
+ * The caller may free this error message string using pfree, if desired.
+ * Note, however, even if there's no parse error, the string might not make
+ * sense: e.g. for gzip, level=12 is not sensible, but it does parse OK.
+ *
+ * The compression level is assigned by default if not directly specified
+ * by the specification.
+ *
+ * Use validate_compress_specification() to find out whether a compression
+ * specification is semantically sensible.
+ */
+void
+parse_compress_specification(pg_compress_algorithm algorithm, char *specification,
+							 pg_compress_specification *result)
+{
+	int			bare_level;
+	char	   *bare_level_endp;
+
+	/* Initial setup of result object. */
+	result->algorithm = algorithm;
+	result->options = 0;
+	result->parse_error = NULL;
+
+	/*
+	 * Assign a default level depending on the compression method.  This may
+	 * be enforced later.
+	 */
+	switch (result->algorithm)
+	{
+		case PG_COMPRESSION_NONE:
+			result->level = 0;
+			break;
+		case PG_COMPRESSION_LZ4:
+#ifdef USE_LZ4
+			result->level = 0;	/* fast compression mode */
+#else
+			result->parse_error =
+				psprintf(_("this build does not support compression with %s"),
+						 "LZ4");
+#endif
+			break;
+		case PG_COMPRESSION_ZSTD:
+#ifdef USE_ZSTD
+			result->level = ZSTD_CLEVEL_DEFAULT;
+#else
+			result->parse_error =
+				psprintf(_("this build does not support compression with %s"),
+						 "ZSTD");
+#endif
+			break;
+		case PG_COMPRESSION_GZIP:
+#ifdef HAVE_LIBZ
+			result->level = Z_DEFAULT_COMPRESSION;
+#else
+			result->parse_error =
+				psprintf(_("this build does not support compression with %s"),
+						 "gzip");
+#endif
+			break;
+	}
+
+	/* If there is no specification, we're done already. */
+	if (specification == NULL)
+		return;
+
+	/* As a special case, the specification can be a bare integer. */
+	bare_level = strtol(specification, &bare_level_endp, 10);
+	if (specification != bare_level_endp && *bare_level_endp == '\0')
+	{
+		result->level = bare_level;
+		return;
+	}
+
+	/* Look for comma-separated keyword or keyword=value entries. */
+	while (1)
+	{
+		char	   *kwstart;
+		char	   *kwend;
+		char	   *vstart;
+		char	   *vend;
+		int			kwlen;
+		int			vlen;
+		bool		has_value;
+		char	   *keyword;
+		char	   *value;
+
+		/* Figure start, end, and length of next keyword and any value. */
+		kwstart = kwend = specification;
+		while (*kwend != '\0' && *kwend != ',' && *kwend != '=')
+			++kwend;
+		kwlen = kwend - kwstart;
+		if (*kwend != '=')
+		{
+			vstart = vend = NULL;
+			vlen = 0;
+			has_value = false;
+		}
+		else
+		{
+			vstart = vend = kwend + 1;
+			while (*vend != '\0' && *vend != ',')
+				++vend;
+			vlen = vend - vstart;
+			has_value = true;
+		}
+
+		/* Reject empty keyword. */
+		if (kwlen == 0)
+		{
+			result->parse_error =
+				pstrdup(_("found empty string where a compression option was expected"));
+			break;
+		}
+
+		/* Extract keyword and value as separate C strings. */
+		keyword = palloc(kwlen + 1);
+		memcpy(keyword, kwstart, kwlen);
+		keyword[kwlen] = '\0';
+		if (!has_value)
+			value = NULL;
+		else
+		{
+			value = palloc(vlen + 1);
+			memcpy(value, vstart, vlen);
+			value[vlen] = '\0';
+		}
+
+		/* Handle whatever keyword we found. */
+		if (strcmp(keyword, "level") == 0)
+		{
+			result->level = expect_integer_value(keyword, value, result);
+
+			/*
+			 * No need to set a flag in "options", there is a default level
+			 * set at least thanks to the logic above.
+			 */
+		}
+		else if (strcmp(keyword, "workers") == 0)
+		{
+			result->workers = expect_integer_value(keyword, value, result);
+			result->options |= PG_COMPRESSION_OPTION_WORKERS;
+		}
+		else
+			result->parse_error =
+				psprintf(_("unrecognized compression option: \"%s\""), keyword);
+
+		/* Release memory, just to be tidy. */
+		pfree(keyword);
+		if (value != NULL)
+			pfree(value);
+
+		/*
+		 * If we got an error or have reached the end of the string, stop.
+		 *
+		 * If there is no value, then the end of the keyword might have been
+		 * the end of the string. If there is a value, then the end of the
+		 * keyword cannot have been the end of the string, but the end of the
+		 * value might have been.
+		 */
+		if (result->parse_error != NULL ||
+			(vend == NULL ? *kwend == '\0' : *vend == '\0'))
+			break;
+
+		/* Advance to next entry and loop around. */
+		specification = vend == NULL ? kwend + 1 : vend + 1;
+	}
+}
+
+/*
+ * Parse 'value' as an integer and return the result.
+ *
+ * If parsing fails, set result->parse_error to an appropriate message
+ * and return -1.
+ */
+static int
+expect_integer_value(char *keyword, char *value, pg_compress_specification *result)
+{
+	int			ivalue;
+	char	   *ivalue_endp;
+
+	if (value == NULL)
+	{
+		result->parse_error =
+			psprintf(_("compression option \"%s\" requires a value"),
+					 keyword);
+		return -1;
+	}
+
+	ivalue = strtol(value, &ivalue_endp, 10);
+	if (ivalue_endp == value || *ivalue_endp != '\0')
+	{
+		result->parse_error =
+			psprintf(_("value for compression option \"%s\" must be an integer"),
+					 keyword);
+		return -1;
+	}
+	return ivalue;
+}
+
+/*
+ * Returns NULL if the compression specification string was syntactically
+ * valid and semantically sensible.  Otherwise, returns an error message.
+ *
+ * Does not test whether this build of PostgreSQL supports the requested
+ * compression method.
+ */
+char *
+validate_compress_specification(pg_compress_specification *spec)
+{
+	int			min_level = 1;
+	int			max_level = 1;
+	int			default_level = 0;
+
+	/* If it didn't even parse OK, it's definitely no good. */
+	if (spec->parse_error != NULL)
+		return spec->parse_error;
+
+	/*
+	 * Check that the algorithm expects a compression level and it is within
+	 * the legal range for the algorithm.
+	 */
+	switch (spec->algorithm)
+	{
+		case PG_COMPRESSION_GZIP:
+			max_level = 9;
+#ifdef HAVE_LIBZ
+			default_level = Z_DEFAULT_COMPRESSION;
+#endif
+			break;
+		case PG_COMPRESSION_LZ4:
+			max_level = 12;
+			default_level = 0;	/* fast mode */
+			break;
+		case PG_COMPRESSION_ZSTD:
+#ifdef USE_ZSTD
+			max_level = ZSTD_maxCLevel();
+			min_level = ZSTD_minCLevel();
+			default_level = ZSTD_CLEVEL_DEFAULT;
+#endif
+			break;
+		case PG_COMPRESSION_NONE:
+			if (spec->level != 0)
+				return psprintf(_("compression algorithm \"%s\" does not accept a compression level"),
+								get_compress_algorithm_name(spec->algorithm));
+			break;
+	}
+
+	if ((spec->level < min_level || spec->level > max_level) &&
+		spec->level != default_level)
+		return psprintf(_("compression algorithm \"%s\" expects a compression level between %d and %d (default at %d)"),
+						get_compress_algorithm_name(spec->algorithm),
+						min_level, max_level, default_level);
+
+	/*
+	 * Of the compression algorithms that we currently support, only zstd
+	 * allows parallel workers.
+	 */
+	if ((spec->options & PG_COMPRESSION_OPTION_WORKERS) != 0 &&
+		(spec->algorithm != PG_COMPRESSION_ZSTD))
+	{
+		return psprintf(_("compression algorithm \"%s\" does not accept a worker count"),
+						get_compress_algorithm_name(spec->algorithm));
+	}
+
+	return NULL;
+}