granicus.if.org Git - postgresql/blob - src/common/controldata_utils.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * controldata_utils.c
   4  *              Common code for control data file output.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  *
  11  * IDENTIFICATION
  12  *        src/common/controldata_utils.c
  13  *
  14  *-------------------------------------------------------------------------
  15  */
  16
  17 #ifndef FRONTEND
  18 #include "postgres.h"
  19 #else
  20 #include "postgres_fe.h"
  21 #endif
  22
  23 #include <unistd.h>
  24 #include <sys/stat.h>
  25 #include <fcntl.h>
  26
  27 #include "catalog/pg_control.h"
  28 #include "common/controldata_utils.h"
  29 #include "port/pg_crc32c.h"
  30
  31 /*
  32  * get_controlfile(char *DataDir, const char *progname)
  33  *
  34  * Get controlfile values. The caller is responsible
  35  * for pfreeing the result.
  36  *
  37  * Returns NULL if the CRC did not match.
  38  */
  39 ControlFileData *
  40 get_controlfile(const char *DataDir, const char *progname)
  41 {
  42         ControlFileData *ControlFile;
  43         int                     fd;
  44         char            ControlFilePath[MAXPGPATH];
  45         pg_crc32c       crc;
  46
  47         ControlFile = palloc(sizeof(ControlFileData));
  48         snprintf(ControlFilePath, MAXPGPATH, "%s/global/pg_control", DataDir);
  49
  50         if ((fd = open(ControlFilePath, O_RDONLY | PG_BINARY, 0)) == -1)
  51 #ifndef FRONTEND
  52                 ereport(ERROR,
  53                                 (errcode_for_file_access(),
  54                                  errmsg("could not open file \"%s\" for reading: %m",
  55                                                 ControlFilePath)));
  56 #else
  57         {
  58                 fprintf(stderr, _("%s: could not open file \"%s\" for reading: %s\n"),
  59                                 progname, ControlFilePath, strerror(errno));
  60                 exit(EXIT_FAILURE);
  61         }
  62 #endif
  63
  64         if (read(fd, ControlFile, sizeof(ControlFileData)) != sizeof(ControlFileData))
  65 #ifndef FRONTEND
  66                 ereport(ERROR,
  67                                 (errcode_for_file_access(),
  68                                  errmsg("could not read file \"%s\": %m", ControlFilePath)));
  69 #else
  70         {
  71                 fprintf(stderr, _("%s: could not read file \"%s\": %s\n"),
  72                                 progname, ControlFilePath, strerror(errno));
  73                 exit(EXIT_FAILURE);
  74         }
  75 #endif
  76
  77         close(fd);
  78
  79         /* Check the CRC. */
  80         INIT_CRC32C(crc);
  81         COMP_CRC32C(crc,
  82                                 (char *) ControlFile,
  83                                 offsetof(ControlFileData, crc));
  84         FIN_CRC32C(crc);
  85
  86         if (!EQ_CRC32C(crc, ControlFile->crc))
  87         {
  88                 pfree(ControlFile);
  89                 return NULL;
  90         }
  91
  92         /* Make sure the control file is valid byte order. */
  93         if (ControlFile->pg_control_version % 65536 == 0 &&
  94                 ControlFile->pg_control_version / 65536 != 0)
  95 #ifndef FRONTEND
  96                 elog(ERROR, _("byte ordering mismatch"));
  97 #else
  98                 printf(_("WARNING: possible byte ordering mismatch\n"
  99                                  "The byte ordering used to store the pg_control file might not match the one\n"
 100                                  "used by this program.  In that case the results below would be incorrect, and\n"
 101                                  "the PostgreSQL installation would be incompatible with this data directory.\n"));
 102 #endif
 103
 104         return ControlFile;
 105 }