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Previously, text between backquotes in a psql metacommand's arguments was always passed to the shell literally. That considerably hobbles the usefulness of the feature for scripting, so we'd foreseen for a long time that we'd someday want to allow substitution of psql variables into the shell command. IMO the addition of \if metacommands has brought us to that point, since \if can greatly benefit from some sort of client-side expression evaluation capability, and psql itself is not going to grow any such thing in time for v10. Hence, this patch. It allows :VARIABLE to be replaced by the exact contents of the named variable, while :'VARIABLE' is replaced by the variable's contents suitably quoted to become a single shell-command argument. (The quoting rules for that are different from those for SQL literals, so this is a bit of an abuse of the :'VARIABLE' notation, but I doubt anyone will be confused.) As with other situations in psql, no substitution occurs if the word following a colon is not a known variable name. That limits the risk of compatibility problems for existing psql scripts; but the risk isn't zero, so this needs to be called out in the v10 release notes. Discussion: https://postgr.es/m/9561.1490895211@sss.pgh.pa.us
60 lines
2.2 KiB
C
60 lines
2.2 KiB
C
/*-------------------------------------------------------------------------
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*
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* String-processing utility routines for frontend code
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*
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* Utility functions that interpret backend output or quote strings for
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* assorted contexts.
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*
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*
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* Portions Copyright (c) 1996-2017, 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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* src/include/fe_utils/string_utils.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef STRING_UTILS_H
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#define STRING_UTILS_H
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#include "libpq-fe.h"
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#include "pqexpbuffer.h"
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/* Global variables controlling behavior of fmtId() and fmtQualifiedId() */
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extern int quote_all_identifiers;
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extern PQExpBuffer (*getLocalPQExpBuffer) (void);
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/* Functions */
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extern const char *fmtId(const char *identifier);
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extern const char *fmtQualifiedId(int remoteVersion,
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const char *schema, const char *id);
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extern char *formatPGVersionNumber(int version_number, bool include_minor,
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char *buf, size_t buflen);
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extern void appendStringLiteral(PQExpBuffer buf, const char *str,
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int encoding, bool std_strings);
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extern void appendStringLiteralConn(PQExpBuffer buf, const char *str,
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PGconn *conn);
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extern void appendStringLiteralDQ(PQExpBuffer buf, const char *str,
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const char *dqprefix);
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extern void appendByteaLiteral(PQExpBuffer buf,
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const unsigned char *str, size_t length,
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bool std_strings);
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extern void appendShellString(PQExpBuffer buf, const char *str);
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extern bool appendShellStringNoError(PQExpBuffer buf, const char *str);
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extern void appendConnStrVal(PQExpBuffer buf, const char *str);
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extern void appendPsqlMetaConnect(PQExpBuffer buf, const char *dbname);
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extern bool parsePGArray(const char *atext, char ***itemarray, int *nitems);
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extern bool appendReloptionsArray(PQExpBuffer buffer, const char *reloptions,
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const char *prefix, int encoding, bool std_strings);
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extern bool processSQLNamePattern(PGconn *conn, PQExpBuffer buf,
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const char *pattern,
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bool have_where, bool force_escape,
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const char *schemavar, const char *namevar,
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const char *altnamevar, const char *visibilityrule);
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#endif /* STRING_UTILS_H */
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