cmdtag.c

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/*-------------------------------------------------------------------------
 *
 * cmdtag.c
 *    Data and routines for commandtag names and enumeration.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * IDENTIFICATION
 *    src/backend/tcop/cmdtag.c
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"
 
#include "tcop/cmdtag.h"
#include "utils/builtins.h"
 
 
typedef struct CommandTagBehavior
{
    const char *name;           /* tag name, e.g. "SELECT" */
    const uint8 namelen;        /* set to strlen(name) */
    const bool  event_trigger_ok;
    const bool  table_rewrite_ok;
    const bool  display_rowcount;   /* should the number of rows affected be
                                     * shown in the command completion string */
} CommandTagBehavior;
 
#define PG_CMDTAG(tag, name, evtrgok, rwrok, rowcnt) \
    { name, (uint8) (sizeof(name) - 1), evtrgok, rwrok, rowcnt },
 
static const CommandTagBehavior tag_behavior[] = {
#include "tcop/cmdtaglist.h"
};
 
#undef PG_CMDTAG
 
void
InitializeQueryCompletion(QueryCompletion *qc)
{
    qc->commandTag = CMDTAG_UNKNOWN;
    qc->nprocessed = 0;
}
 
const char *
GetCommandTagName(CommandTag commandTag)
{
    return tag_behavior[commandTag].name;
}
 
const char *
GetCommandTagNameAndLen(CommandTag commandTag, Size *len)
{
    *len = (Size) tag_behavior[commandTag].namelen;
    return tag_behavior[commandTag].name;
}
 
bool
command_tag_display_rowcount(CommandTag commandTag)
{
    return tag_behavior[commandTag].display_rowcount;
}
 
bool
command_tag_event_trigger_ok(CommandTag commandTag)
{
    return tag_behavior[commandTag].event_trigger_ok;
}
 
bool
command_tag_table_rewrite_ok(CommandTag commandTag)
{
    return tag_behavior[commandTag].table_rewrite_ok;
}
 
/*
 * Search CommandTag by name
 *
 * Returns CommandTag, or CMDTAG_UNKNOWN if not recognized
 */
CommandTag
GetCommandTagEnum(const char *commandname)
{
    const CommandTagBehavior *base,
               *last,
               *position;
    int         result;
 
    if (commandname == NULL || *commandname == '\0')
        return CMDTAG_UNKNOWN;
 
    base = tag_behavior;
    last = tag_behavior + lengthof(tag_behavior) - 1;
    while (last >= base)
    {
        position = base + ((last - base) >> 1);
        result = pg_strcasecmp(commandname, position->name);
        if (result == 0)
            return (CommandTag) (position - tag_behavior);
        else if (result < 0)
            last = position - 1;
        else
            base = position + 1;
    }
    return CMDTAG_UNKNOWN;
}
 
/*
 * BuildQueryCompletionString
 *      Build a string containing the command tag name with the
 *      QueryCompletion's nprocessed for command tags with display_rowcount
 *      set.  Returns the strlen of the constructed string.
 *
 * The caller must ensure that buff is at least COMPLETION_TAG_BUFSIZE bytes.
 *
 * If nameonly is true, then the constructed string will contain only the tag
 * name.
 */
Size
BuildQueryCompletionString(char *buff, const QueryCompletion *qc,
                           bool nameonly)
{
    CommandTag  tag = qc->commandTag;
    Size        taglen;
    const char *tagname = GetCommandTagNameAndLen(tag, &taglen);
    char       *bufp;
 
    /*
     * We assume the tagname is plain ASCII and therefore requires no encoding
     * conversion.
     */
    memcpy(buff, tagname, taglen);
    bufp = buff + taglen;
 
    /* ensure that the tagname isn't long enough to overrun the buffer */
    Assert(taglen <= COMPLETION_TAG_BUFSIZE - MAXINT8LEN - 4);
 
    /*
     * In PostgreSQL versions 11 and earlier, it was possible to create a
     * table WITH OIDS.  When inserting into such a table, INSERT used to
     * include the Oid of the inserted record in the completion tag.  To
     * maintain compatibility in the wire protocol, we now write a "0" (for
     * InvalidOid) in the location where we once wrote the new record's Oid.
     */
    if (command_tag_display_rowcount(tag) && !nameonly)
    {
        if (tag == CMDTAG_INSERT)
        {
            *bufp++ = ' ';
            *bufp++ = '0';
        }
        *bufp++ = ' ';
        bufp += pg_ulltoa_n(qc->nprocessed, bufp);
    }
 
    /* and finally, NUL terminate the string */
    *bufp = '\0';
 
    Assert((bufp - buff) == strlen(buff));
 
    return bufp - buff;
}