Quelle  astreamer_inject.c

/*-------------------------------------------------------------------------
 *
 * astreamer_inject.c
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/bin/pg_basebackup/astreamer_inject.c
 *-------------------------------------------------------------------------
 */

#include "postgres_fe.h"

#include "astreamer_inject.h"
#include "common/file_perm.h"
#include "common/logging.h"

typedef struct astreamer_recovery_injector
{
 astreamer base;
 bool  skip_file;
 bool  is_recovery_guc_supported;
 bool  is_postgresql_auto_conf;
 bool  found_postgresql_auto_conf;
 PQExpBuffer recoveryconfcontents;
 astreamer_member member;
} astreamer_recovery_injector;

static void astreamer_recovery_injector_content(astreamer *streamer,
            astreamer_member *member,
            const char *data, int len,
            astreamer_archive_context context);
static void astreamer_recovery_injector_finalize(astreamer *streamer);
static void astreamer_recovery_injector_free(astreamer *streamer);

static const astreamer_ops astreamer_recovery_injector_ops = {
 .content = astreamer_recovery_injector_content,
 .finalize = astreamer_recovery_injector_finalize,
 .free = astreamer_recovery_injector_free
};

/*
 * Create a astreamer that can edit recoverydata into an archive stream.
 *
 * The input should be a series of typed chunks (not ASTREAMER_UNKNOWN) as
 * per the conventions described in astreamer.h; the chunks forwarded to
 * the next astreamer will be similarly typed, but the
 * ASTREAMER_MEMBER_HEADER chunks may be zero-length in cases where we've
 * edited the archive stream.
 *
 * Our goal is to do one of the following three things with the content passed
 * via recoveryconfcontents: (1) if is_recovery_guc_supported is false, then
 * put the content into recovery.conf, replacing any existing archive member
 * by that name; (2) if is_recovery_guc_supported is true and
 * postgresql.auto.conf exists in the archive, then append the content
 * provided to the existing file; and (3) if is_recovery_guc_supported is
 * true but postgresql.auto.conf does not exist in the archive, then create
 * it with the specified content.
 *
 * In addition, if is_recovery_guc_supported is true, then we create a
 * zero-length standby.signal file, dropping any file with that name from
 * the archive.
 */
astreamer *
astreamer_recovery_injector_new(astreamer *next,
        bool is_recovery_guc_supported,
        PQExpBuffer recoveryconfcontents)
{
 astreamer_recovery_injector *streamer;

 streamer = palloc0(sizeof(astreamer_recovery_injector));
 *((const astreamer_ops **) &streamer->base.bbs_ops) =
  &astreamer_recovery_injector_ops;
 streamer->base.bbs_next = next;
 streamer->is_recovery_guc_supported = is_recovery_guc_supported;
 streamer->recoveryconfcontents = recoveryconfcontents;

 return &streamer->base;
}

/*
 * Handle each chunk of tar content while injecting recovery configuration.
 */
static void
astreamer_recovery_injector_content(astreamer *streamer,
         astreamer_member *member,
         const char *data, int len,
         astreamer_archive_context context)
{
 astreamer_recovery_injector *mystreamer;

 mystreamer = (astreamer_recovery_injector *) streamer;
 Assert(member != NULL || context == ASTREAMER_ARCHIVE_TRAILER);

 switch (context)
 {
  case ASTREAMER_MEMBER_HEADER:
   /* Must copy provided data so we have the option to modify it. */
   memcpy(&mystreamer->member, member, sizeof(astreamer_member));

   /*
    * On v12+, skip standby.signal and edit postgresql.auto.conf; on
    * older versions, skip recovery.conf.
 */
   if (mystreamer->is_recovery_guc_supported)
   {
    mystreamer->skip_file =
     (strcmp(member->pathname, "standby.signal") == 0);
    mystreamer->is_postgresql_auto_conf =
     (strcmp(member->pathname, "postgresql.auto.conf") == 0);
    if (mystreamer->is_postgresql_auto_conf)
    {
     /* Remember we saw it so we don't add it again. */
     mystreamer->found_postgresql_auto_conf = true;

     /* Increment length by data to be injected. */
     mystreamer->member.size +=
      mystreamer->recoveryconfcontents->len;

     /*
      * Zap data and len because the archive header is no
      * longer valid; some subsequent astreamer must regenerate
      * it if it's necessary.
 */
     data = NULL;
     len = 0;
    }
   }
   else
    mystreamer->skip_file =
     (strcmp(member->pathname, "recovery.conf") == 0);

   /* Do not forward if the file is to be skipped. */
   if (mystreamer->skip_file)
    return;
   break;

  case ASTREAMER_MEMBER_CONTENTS:
   /* Do not forward if the file is to be skipped. */
   if (mystreamer->skip_file)
    return;
   break;

  case ASTREAMER_MEMBER_TRAILER:
   /* Do not forward it the file is to be skipped. */
   if (mystreamer->skip_file)
    return;

   /* Append provided content to whatever we already sent. */
   if (mystreamer->is_postgresql_auto_conf)
    astreamer_content(mystreamer->base.bbs_next, member,
          mystreamer->recoveryconfcontents->data,
          mystreamer->recoveryconfcontents->len,
          ASTREAMER_MEMBER_CONTENTS);
   break;

  case ASTREAMER_ARCHIVE_TRAILER:
   if (mystreamer->is_recovery_guc_supported)
   {
    /*
     * If we didn't already find (and thus modify)
     * postgresql.auto.conf, inject it as an additional archive
     * member now.
 */
    if (!mystreamer->found_postgresql_auto_conf)
     astreamer_inject_file(mystreamer->base.bbs_next,
            "postgresql.auto.conf",
            mystreamer->recoveryconfcontents->data,
            mystreamer->recoveryconfcontents->len);

    /* Inject empty standby.signal file. */
    astreamer_inject_file(mystreamer->base.bbs_next,
           "standby.signal", "", 0);
   }
   else
   {
    /* Inject recovery.conf file with specified contents. */
    astreamer_inject_file(mystreamer->base.bbs_next,
           "recovery.conf",
           mystreamer->recoveryconfcontents->data,
           mystreamer->recoveryconfcontents->len);
   }

   /* Nothing to do here. */
   break;

  default:
   /* Shouldn't happen. */
   pg_fatal("unexpected state while injecting recovery settings");
 }

 astreamer_content(mystreamer->base.bbs_next, &mystreamer->member,
       data, len, context);
}

/*
 * End-of-stream processing for this astreamer.
 */
static void
astreamer_recovery_injector_finalize(astreamer *streamer)
{
 astreamer_finalize(streamer->bbs_next);
}

/*
 * Free memory associated with this astreamer.
 */
static void
astreamer_recovery_injector_free(astreamer *streamer)
{
 astreamer_free(streamer->bbs_next);
 pfree(streamer);
}

/*
 * Inject a member into the archive with specified contents.
 */
void
astreamer_inject_file(astreamer *streamer, char *pathname, char *data,
       int len)
{
 astreamer_member member;

 strlcpy(member.pathname, pathname, MAXPGPATH);
 member.size = len;
 member.mode = pg_file_create_mode;
 member.is_regular = true;
 member.is_directory = false;
 member.is_symlink = false;
 member.linktarget[0] = '\0';

 /*
  * There seems to be no principled argument for these values, but they are
  * what PostgreSQL has historically used.
 */
 member.uid = 04000;
 member.gid = 02000;

 /*
  * We don't know here how to generate valid member headers and trailers
  * for the archiving format in use, so if those are needed, some successor
  * astreamer will have to generate them using the data from 'member'.
 */
 astreamer_content(streamer, &member, NULL, 0,
       ASTREAMER_MEMBER_HEADER);
 astreamer_content(streamer, &member, data, len,
       ASTREAMER_MEMBER_CONTENTS);
 astreamer_content(streamer, &member, NULL, 0,
       ASTREAMER_MEMBER_TRAILER);
}