src/fe_utils/recovery_gen.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * recovery_gen.c
   4  *              Generator for recovery configuration
   5  *
   6  * Portions Copyright (c) 2011-2023, PostgreSQL Global Development Group
   7  *
   8  *-------------------------------------------------------------------------
   9  */
  10 #include "postgres_fe.h"
  11
  12 #include "common/logging.h"
  13 #include "fe_utils/recovery_gen.h"
  14 #include "fe_utils/string_utils.h"
  15
  16 static char *escape_quotes(const char *src);
  17
  18 /*
  19  * Write recovery configuration contents into a fresh PQExpBuffer, and
  20  * return it.
  21  */
  22 PQExpBuffer
  23 GenerateRecoveryConfig(PGconn *pgconn, char *replication_slot)
  24 {
  25         PQconninfoOption *connOptions;
  26         PQExpBufferData conninfo_buf;
  27         char       *escaped;
  28         PQExpBuffer contents;
  29
  30         Assert(pgconn != NULL);
  31
  32         contents = createPQExpBuffer();
  33         if (!contents)
  34                 pg_fatal("out of memory");
  35
  36         /*
  37          * In PostgreSQL 12 and newer versions, standby_mode is gone, replaced by
  38          * standby.signal to trigger a standby state at recovery.
  39          */
  40         if (PQserverVersion(pgconn) < MINIMUM_VERSION_FOR_RECOVERY_GUC)
  41                 appendPQExpBufferStr(contents, "standby_mode = 'on'\n");
  42
  43         connOptions = PQconninfo(pgconn);
  44         if (connOptions == NULL)
  45                 pg_fatal("out of memory");
  46
  47         initPQExpBuffer(&conninfo_buf);
  48         for (PQconninfoOption *opt = connOptions; opt && opt->keyword; opt++)
  49         {
  50                 /* Omit empty settings and those libpqwalreceiver overrides. */
  51                 if (strcmp(opt->keyword, "replication") == 0 ||
  52                         strcmp(opt->keyword, "dbname") == 0 ||
  53                         strcmp(opt->keyword, "fallback_application_name") == 0 ||
  54                         (opt->val == NULL) ||
  55                         (opt->val != NULL && opt->val[0] == '\0'))
  56                         continue;
  57
  58                 /* Separate key-value pairs with spaces */
  59                 if (conninfo_buf.len != 0)
  60                         appendPQExpBufferChar(&conninfo_buf, ' ');
  61
  62                 /*
  63                  * Write "keyword=value" pieces, the value string is escaped and/or
  64                  * quoted if necessary.
  65                  */
  66                 appendPQExpBuffer(&conninfo_buf, "%s=", opt->keyword);
  67                 appendConnStrVal(&conninfo_buf, opt->val);
  68         }
  69         if (PQExpBufferDataBroken(conninfo_buf))
  70                 pg_fatal("out of memory");
  71
  72         /*
  73          * Escape the connection string, so that it can be put in the config file.
  74          * Note that this is different from the escaping of individual connection
  75          * options above!
  76          */
  77         escaped = escape_quotes(conninfo_buf.data);
  78         termPQExpBuffer(&conninfo_buf);
  79         appendPQExpBuffer(contents, "primary_conninfo = '%s'\n", escaped);
  80         free(escaped);
  81
  82         if (replication_slot)
  83         {
  84                 /* unescaped: ReplicationSlotValidateName allows [a-z0-9_] only */
  85                 appendPQExpBuffer(contents, "primary_slot_name = '%s'\n",
  86                                                   replication_slot);
  87         }
  88
  89         if (PQExpBufferBroken(contents))
  90                 pg_fatal("out of memory");
  91
  92         PQconninfoFree(connOptions);
  93
  94         return contents;
  95 }
  96
  97 /*
  98  * Write the configuration file in the directory specified in target_dir,
  99  * with the contents already collected in memory appended.  Then write
 100  * the signal file into the target_dir.  If the server does not support
 101  * recovery parameters as GUCs, the signal file is not necessary, and
 102  * configuration is written to recovery.conf.
 103  */
 104 void
 105 WriteRecoveryConfig(PGconn *pgconn, char *target_dir, PQExpBuffer contents)
 106 {
 107         char            filename[MAXPGPATH];
 108         FILE       *cf;
 109         bool            use_recovery_conf;
 110
 111         Assert(pgconn != NULL);
 112
 113         use_recovery_conf =
 114                 PQserverVersion(pgconn) < MINIMUM_VERSION_FOR_RECOVERY_GUC;
 115
 116         snprintf(filename, MAXPGPATH, "%s/%s", target_dir,
 117                          use_recovery_conf ? "recovery.conf" : "postgresql.auto.conf");
 118
 119         cf = fopen(filename, use_recovery_conf ? "w" : "a");
 120         if (cf == NULL)
 121                 pg_fatal("could not open file \"%s\": %m", filename);
 122
 123         if (fwrite(contents->data, contents->len, 1, cf) != 1)
 124                 pg_fatal("could not write to file \"%s\": %m", filename);
 125
 126         fclose(cf);
 127
 128         if (!use_recovery_conf)
 129         {
 130                 snprintf(filename, MAXPGPATH, "%s/%s", target_dir, "standby.signal");
 131                 cf = fopen(filename, "w");
 132                 if (cf == NULL)
 133                         pg_fatal("could not create file \"%s\": %m", filename);
 134
 135                 fclose(cf);
 136         }
 137 }
 138
 139 /*
 140  * Escape a string so that it can be used as a value in a key-value pair
 141  * a configuration file.
 142  */
 143 static char *
 144 escape_quotes(const char *src)
 145 {
 146         char       *result = escape_single_quotes_ascii(src);
 147
 148         if (!result)
 149                 pg_fatal("out of memory");
 150         return result;
 151 }