Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * local_source.c
       4             :  *    Functions for using a local data directory as the source.
       5             :  *
       6             :  * Portions Copyright (c) 2013-2025, PostgreSQL Global Development Group
       7             :  *
       8             :  *-------------------------------------------------------------------------
       9             :  */
      10             : #include "postgres_fe.h"
      11             : 
      12             : #include <fcntl.h>
      13             : #include <unistd.h>
      14             : 
      15             : #include "common/logging.h"
      16             : #include "file_ops.h"
      17             : #include "rewind_source.h"
      18             : 
      19             : typedef struct
      20             : {
      21             :     rewind_source common;       /* common interface functions */
      22             : 
      23             :     const char *datadir;        /* path to the source data directory */
      24             : } local_source;
      25             : 
      26             : static void local_traverse_files(rewind_source *source,
      27             :                                  process_file_callback_t callback);
      28             : static char *local_fetch_file(rewind_source *source, const char *path,
      29             :                               size_t *filesize);
      30             : static void local_queue_fetch_file(rewind_source *source, const char *path,
      31             :                                    size_t len);
      32             : static void local_queue_fetch_range(rewind_source *source, const char *path,
      33             :                                     off_t off, size_t len);
      34             : static void local_finish_fetch(rewind_source *source);
      35             : static void local_destroy(rewind_source *source);
      36             : 
      37             : rewind_source *
      38          24 : init_local_source(const char *datadir)
      39             : {
      40             :     local_source *src;
      41             : 
      42          24 :     src = pg_malloc0(sizeof(local_source));
      43             : 
      44          24 :     src->common.traverse_files = local_traverse_files;
      45          24 :     src->common.fetch_file = local_fetch_file;
      46          24 :     src->common.queue_fetch_file = local_queue_fetch_file;
      47          24 :     src->common.queue_fetch_range = local_queue_fetch_range;
      48          24 :     src->common.finish_fetch = local_finish_fetch;
      49          24 :     src->common.get_current_wal_insert_lsn = NULL;
      50          24 :     src->common.destroy = local_destroy;
      51             : 
      52          24 :     src->datadir = datadir;
      53             : 
      54          24 :     return &src->common;
      55             : }
      56             : 
      57             : static void
      58          16 : local_traverse_files(rewind_source *source, process_file_callback_t callback)
      59             : {
      60          16 :     traverse_datadir(((local_source *) source)->datadir, callback);
      61          16 : }
      62             : 
      63             : static char *
      64          52 : local_fetch_file(rewind_source *source, const char *path, size_t *filesize)
      65             : {
      66          52 :     return slurpFile(((local_source *) source)->datadir, path, filesize);
      67             : }
      68             : 
      69             : /*
      70             :  * Copy a file from source to target.
      71             :  *
      72             :  * 'len' is the expected length of the file.
      73             :  */
      74             : static void
      75        4954 : local_queue_fetch_file(rewind_source *source, const char *path, size_t len)
      76             : {
      77        4954 :     const char *datadir = ((local_source *) source)->datadir;
      78             :     PGIOAlignedBlock buf;
      79             :     char        srcpath[MAXPGPATH];
      80             :     int         srcfd;
      81             :     size_t      written_len;
      82             : 
      83        4954 :     snprintf(srcpath, sizeof(srcpath), "%s/%s", datadir, path);
      84             : 
      85             :     /* Open source file for reading */
      86        4954 :     srcfd = open(srcpath, O_RDONLY | PG_BINARY, 0);
      87        4954 :     if (srcfd < 0)
      88           0 :         pg_fatal("could not open source file \"%s\": %m",
      89             :                  srcpath);
      90             : 
      91             :     /* Truncate and open the target file for writing */
      92        4954 :     open_target_file(path, true);
      93             : 
      94        4954 :     written_len = 0;
      95             :     for (;;)
      96      112684 :     {
      97             :         ssize_t     read_len;
      98             : 
      99      117638 :         read_len = read(srcfd, buf.data, sizeof(buf));
     100             : 
     101      117638 :         if (read_len < 0)
     102           0 :             pg_fatal("could not read file \"%s\": %m", srcpath);
     103      117638 :         else if (read_len == 0)
     104        4954 :             break;              /* EOF reached */
     105             : 
     106      112684 :         write_target_range(buf.data, written_len, read_len);
     107      112684 :         written_len += read_len;
     108             :     }
     109             : 
     110             :     /*
     111             :      * A local source is not expected to change while we're rewinding, so
     112             :      * check that the size of the file matches our earlier expectation.
     113             :      */
     114        4954 :     if (written_len != len)
     115           2 :         pg_fatal("size of source file \"%s\" changed concurrently: %d bytes expected, %d copied",
     116             :                  srcpath, (int) len, (int) written_len);
     117             : 
     118        4952 :     if (close(srcfd) != 0)
     119           0 :         pg_fatal("could not close file \"%s\": %m", srcpath);
     120        4952 : }
     121             : 
     122             : /*
     123             :  * Copy a file from source to target, starting at 'off', for 'len' bytes.
     124             :  */
     125             : static void
     126        1716 : local_queue_fetch_range(rewind_source *source, const char *path, off_t off,
     127             :                         size_t len)
     128             : {
     129        1716 :     const char *datadir = ((local_source *) source)->datadir;
     130             :     PGIOAlignedBlock buf;
     131             :     char        srcpath[MAXPGPATH];
     132             :     int         srcfd;
     133        1716 :     off_t       begin = off;
     134        1716 :     off_t       end = off + len;
     135             : 
     136        1716 :     snprintf(srcpath, sizeof(srcpath), "%s/%s", datadir, path);
     137             : 
     138        1716 :     srcfd = open(srcpath, O_RDONLY | PG_BINARY, 0);
     139        1716 :     if (srcfd < 0)
     140           0 :         pg_fatal("could not open source file \"%s\": %m",
     141             :                  srcpath);
     142             : 
     143        1716 :     if (lseek(srcfd, begin, SEEK_SET) == -1)
     144           0 :         pg_fatal("could not seek in source file: %m");
     145             : 
     146        1716 :     open_target_file(path, false);
     147             : 
     148        3924 :     while (end - begin > 0)
     149             :     {
     150             :         ssize_t     readlen;
     151             :         size_t      thislen;
     152             : 
     153        2208 :         if (end - begin > sizeof(buf))
     154         492 :             thislen = sizeof(buf);
     155             :         else
     156        1716 :             thislen = end - begin;
     157             : 
     158        2208 :         readlen = read(srcfd, buf.data, thislen);
     159             : 
     160        2208 :         if (readlen < 0)
     161           0 :             pg_fatal("could not read file \"%s\": %m", srcpath);
     162        2208 :         else if (readlen == 0)
     163           0 :             pg_fatal("unexpected EOF while reading file \"%s\"", srcpath);
     164             : 
     165        2208 :         write_target_range(buf.data, begin, readlen);
     166        2208 :         begin += readlen;
     167             :     }
     168             : 
     169        1716 :     if (close(srcfd) != 0)
     170           0 :         pg_fatal("could not close file \"%s\": %m", srcpath);
     171        1716 : }
     172             : 
     173             : static void
     174          14 : local_finish_fetch(rewind_source *source)
     175             : {
     176             :     /*
     177             :      * Nothing to do, local_queue_fetch_range() copies the ranges immediately.
     178             :      */
     179          14 : }
     180             : 
     181             : static void
     182          14 : local_destroy(rewind_source *source)
     183             : {
     184          14 :     pfree(source);
     185          14 : }