LCOV - code coverage report
Current view: top level - src/bin/pg_combinebackup - write_manifest.c (source / functions) Hit Total Coverage
Test: PostgreSQL 17devel Lines: 89 123 72.4 %
Date: 2024-04-22 22:11:44 Functions: 6 6 100.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * Write a new backup manifest.
       4             :  *
       5             :  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
       6             :  * Portions Copyright (c) 1994, Regents of the University of California
       7             :  *
       8             :  * src/bin/pg_combinebackup/write_manifest.c
       9             :  *
      10             :  *-------------------------------------------------------------------------
      11             :  */
      12             : 
      13             : #include "postgres_fe.h"
      14             : 
      15             : #include <fcntl.h>
      16             : #include <time.h>
      17             : #include <unistd.h>
      18             : 
      19             : #include "common/checksum_helper.h"
      20             : #include "common/file_perm.h"
      21             : #include "common/logging.h"
      22             : #include "lib/stringinfo.h"
      23             : #include "load_manifest.h"
      24             : #include "mb/pg_wchar.h"
      25             : #include "write_manifest.h"
      26             : 
      27             : struct manifest_writer
      28             : {
      29             :     char        pathname[MAXPGPATH];
      30             :     int         fd;
      31             :     StringInfoData buf;
      32             :     bool        first_file;
      33             :     bool        still_checksumming;
      34             :     pg_checksum_context manifest_ctx;
      35             : };
      36             : 
      37             : static void escape_json(StringInfo buf, const char *str);
      38             : static void flush_manifest(manifest_writer *mwriter);
      39             : static size_t hex_encode(const uint8 *src, size_t len, char *dst);
      40             : 
      41             : /*
      42             :  * Create a new backup manifest writer.
      43             :  *
      44             :  * The backup manifest will be written into a file named backup_manifest
      45             :  * in the specified directory.
      46             :  */
      47             : manifest_writer *
      48          18 : create_manifest_writer(char *directory, uint64 system_identifier)
      49             : {
      50          18 :     manifest_writer *mwriter = pg_malloc(sizeof(manifest_writer));
      51             : 
      52          18 :     snprintf(mwriter->pathname, MAXPGPATH, "%s/backup_manifest", directory);
      53          18 :     mwriter->fd = -1;
      54          18 :     initStringInfo(&mwriter->buf);
      55          18 :     mwriter->first_file = true;
      56          18 :     mwriter->still_checksumming = true;
      57          18 :     pg_checksum_init(&mwriter->manifest_ctx, CHECKSUM_TYPE_SHA256);
      58             : 
      59          18 :     appendStringInfo(&mwriter->buf,
      60             :                      "{ \"PostgreSQL-Backup-Manifest-Version\": 2,\n"
      61             :                      "\"System-Identifier\": " UINT64_FORMAT ",\n"
      62             :                      "\"Files\": [",
      63             :                      system_identifier);
      64             : 
      65          18 :     return mwriter;
      66             : }
      67             : 
      68             : /*
      69             :  * Add an entry for a file to a backup manifest.
      70             :  *
      71             :  * This is very similar to the backend's AddFileToBackupManifest, but
      72             :  * various adjustments are required due to frontend/backend differences
      73             :  * and other details.
      74             :  */
      75             : void
      76       18662 : add_file_to_manifest(manifest_writer *mwriter, const char *manifest_path,
      77             :                      size_t size, time_t mtime,
      78             :                      pg_checksum_type checksum_type,
      79             :                      int checksum_length,
      80             :                      uint8 *checksum_payload)
      81             : {
      82       18662 :     int         pathlen = strlen(manifest_path);
      83             : 
      84       18662 :     if (mwriter->first_file)
      85             :     {
      86          18 :         appendStringInfoChar(&mwriter->buf, '\n');
      87          18 :         mwriter->first_file = false;
      88             :     }
      89             :     else
      90       18644 :         appendStringInfoString(&mwriter->buf, ",\n");
      91             : 
      92       18662 :     if (pg_encoding_verifymbstr(PG_UTF8, manifest_path, pathlen) == pathlen)
      93             :     {
      94       18662 :         appendStringInfoString(&mwriter->buf, "{ \"Path\": ");
      95       18662 :         escape_json(&mwriter->buf, manifest_path);
      96       18662 :         appendStringInfoString(&mwriter->buf, ", ");
      97             :     }
      98             :     else
      99             :     {
     100           0 :         appendStringInfoString(&mwriter->buf, "{ \"Encoded-Path\": \"");
     101           0 :         enlargeStringInfo(&mwriter->buf, 2 * pathlen);
     102           0 :         mwriter->buf.len += hex_encode((const uint8 *) manifest_path, pathlen,
     103           0 :                                        &mwriter->buf.data[mwriter->buf.len]);
     104           0 :         appendStringInfoString(&mwriter->buf, "\", ");
     105             :     }
     106             : 
     107       18662 :     appendStringInfo(&mwriter->buf, "\"Size\": %zu, ", size);
     108             : 
     109       18662 :     appendStringInfoString(&mwriter->buf, "\"Last-Modified\": \"");
     110       18662 :     enlargeStringInfo(&mwriter->buf, 128);
     111       18662 :     mwriter->buf.len += strftime(&mwriter->buf.data[mwriter->buf.len], 128,
     112             :                                  "%Y-%m-%d %H:%M:%S %Z",
     113       18662 :                                  gmtime(&mtime));
     114       18662 :     appendStringInfoChar(&mwriter->buf, '"');
     115             : 
     116       18662 :     if (mwriter->buf.len > 128 * 1024)
     117          16 :         flush_manifest(mwriter);
     118             : 
     119       18662 :     if (checksum_length > 0)
     120             :     {
     121       16710 :         appendStringInfo(&mwriter->buf,
     122             :                          ", \"Checksum-Algorithm\": \"%s\", \"Checksum\": \"",
     123             :                          pg_checksum_type_name(checksum_type));
     124             : 
     125       16710 :         enlargeStringInfo(&mwriter->buf, 2 * checksum_length);
     126       33420 :         mwriter->buf.len += hex_encode(checksum_payload, checksum_length,
     127       16710 :                                        &mwriter->buf.data[mwriter->buf.len]);
     128             : 
     129       16710 :         appendStringInfoChar(&mwriter->buf, '"');
     130             :     }
     131             : 
     132       18662 :     appendStringInfoString(&mwriter->buf, " }");
     133             : 
     134       18662 :     if (mwriter->buf.len > 128 * 1024)
     135           0 :         flush_manifest(mwriter);
     136       18662 : }
     137             : 
     138             : /*
     139             :  * Finalize the backup_manifest.
     140             :  */
     141             : void
     142          18 : finalize_manifest(manifest_writer *mwriter,
     143             :                   manifest_wal_range *first_wal_range)
     144             : {
     145             :     uint8       checksumbuf[PG_SHA256_DIGEST_LENGTH];
     146             :     int         len;
     147             :     manifest_wal_range *wal_range;
     148             : 
     149             :     /* Terminate the list of files. */
     150          18 :     appendStringInfoString(&mwriter->buf, "\n],\n");
     151             : 
     152             :     /* Start a list of LSN ranges. */
     153          18 :     appendStringInfoString(&mwriter->buf, "\"WAL-Ranges\": [\n");
     154             : 
     155          36 :     for (wal_range = first_wal_range; wal_range != NULL;
     156          18 :          wal_range = wal_range->next)
     157          18 :         appendStringInfo(&mwriter->buf,
     158             :                          "%s{ \"Timeline\": %u, \"Start-LSN\": \"%X/%X\", \"End-LSN\": \"%X/%X\" }",
     159             :                          wal_range == first_wal_range ? "" : ",\n",
     160             :                          wal_range->tli,
     161          18 :                          LSN_FORMAT_ARGS(wal_range->start_lsn),
     162          18 :                          LSN_FORMAT_ARGS(wal_range->end_lsn));
     163             : 
     164             :     /* Terminate the list of WAL ranges. */
     165          18 :     appendStringInfoString(&mwriter->buf, "\n],\n");
     166             : 
     167             :     /* Flush accumulated data and update checksum calculation. */
     168          18 :     flush_manifest(mwriter);
     169             : 
     170             :     /* Checksum only includes data up to this point. */
     171          18 :     mwriter->still_checksumming = false;
     172             : 
     173             :     /* Compute and insert manifest checksum. */
     174          18 :     appendStringInfoString(&mwriter->buf, "\"Manifest-Checksum\": \"");
     175          18 :     enlargeStringInfo(&mwriter->buf, 2 * PG_SHA256_DIGEST_STRING_LENGTH);
     176          18 :     len = pg_checksum_final(&mwriter->manifest_ctx, checksumbuf);
     177             :     Assert(len == PG_SHA256_DIGEST_LENGTH);
     178          18 :     mwriter->buf.len +=
     179          18 :         hex_encode(checksumbuf, len, &mwriter->buf.data[mwriter->buf.len]);
     180          18 :     appendStringInfoString(&mwriter->buf, "\"}\n");
     181             : 
     182             :     /* Flush the last manifest checksum itself. */
     183          18 :     flush_manifest(mwriter);
     184             : 
     185             :     /* Close the file. */
     186          18 :     if (close(mwriter->fd) != 0)
     187           0 :         pg_fatal("could not close \"%s\": %m", mwriter->pathname);
     188          18 :     mwriter->fd = -1;
     189          18 : }
     190             : 
     191             : /*
     192             :  * Produce a JSON string literal, properly escaping characters in the text.
     193             :  */
     194             : static void
     195       18662 : escape_json(StringInfo buf, const char *str)
     196             : {
     197             :     const char *p;
     198             : 
     199       18662 :     appendStringInfoCharMacro(buf, '"');
     200      248628 :     for (p = str; *p; p++)
     201             :     {
     202      229966 :         switch (*p)
     203             :         {
     204           0 :             case '\b':
     205           0 :                 appendStringInfoString(buf, "\\b");
     206           0 :                 break;
     207           0 :             case '\f':
     208           0 :                 appendStringInfoString(buf, "\\f");
     209           0 :                 break;
     210           0 :             case '\n':
     211           0 :                 appendStringInfoString(buf, "\\n");
     212           0 :                 break;
     213           0 :             case '\r':
     214           0 :                 appendStringInfoString(buf, "\\r");
     215           0 :                 break;
     216           0 :             case '\t':
     217           0 :                 appendStringInfoString(buf, "\\t");
     218           0 :                 break;
     219           0 :             case '"':
     220           0 :                 appendStringInfoString(buf, "\\\"");
     221           0 :                 break;
     222           0 :             case '\\':
     223           0 :                 appendStringInfoString(buf, "\\\\");
     224           0 :                 break;
     225      229966 :             default:
     226      229966 :                 if ((unsigned char) *p < ' ')
     227           0 :                     appendStringInfo(buf, "\\u%04x", (int) *p);
     228             :                 else
     229      229966 :                     appendStringInfoCharMacro(buf, *p);
     230      229966 :                 break;
     231             :         }
     232             :     }
     233       18662 :     appendStringInfoCharMacro(buf, '"');
     234       18662 : }
     235             : 
     236             : /*
     237             :  * Flush whatever portion of the backup manifest we have generated and
     238             :  * buffered in memory out to a file on disk.
     239             :  *
     240             :  * The first call to this function will create the file. After that, we
     241             :  * keep it open and just append more data.
     242             :  */
     243             : static void
     244          52 : flush_manifest(manifest_writer *mwriter)
     245             : {
     246          52 :     if (mwriter->fd == -1 &&
     247          18 :         (mwriter->fd = open(mwriter->pathname,
     248             :                             O_WRONLY | O_CREAT | O_EXCL | PG_BINARY,
     249             :                             pg_file_create_mode)) < 0)
     250           0 :         pg_fatal("could not open file \"%s\": %m", mwriter->pathname);
     251             : 
     252          52 :     if (mwriter->buf.len > 0)
     253             :     {
     254             :         ssize_t     wb;
     255             : 
     256          52 :         wb = write(mwriter->fd, mwriter->buf.data, mwriter->buf.len);
     257          52 :         if (wb != mwriter->buf.len)
     258             :         {
     259           0 :             if (wb < 0)
     260           0 :                 pg_fatal("could not write \"%s\": %m", mwriter->pathname);
     261             :             else
     262           0 :                 pg_fatal("could not write file \"%s\": wrote only %d of %d bytes",
     263             :                          mwriter->pathname, (int) wb, mwriter->buf.len);
     264             :         }
     265             : 
     266          86 :         if (mwriter->still_checksumming &&
     267          34 :             pg_checksum_update(&mwriter->manifest_ctx,
     268          34 :                                (uint8 *) mwriter->buf.data,
     269          34 :                                mwriter->buf.len) < 0)
     270           0 :             pg_fatal("could not update checksum of file \"%s\"",
     271             :                      mwriter->pathname);
     272          52 :         resetStringInfo(&mwriter->buf);
     273             :     }
     274          52 : }
     275             : 
     276             : /*
     277             :  * Encode bytes using two hexadecimal digits for each one.
     278             :  */
     279             : static size_t
     280       16728 : hex_encode(const uint8 *src, size_t len, char *dst)
     281             : {
     282       16728 :     const uint8 *end = src + len;
     283             : 
     284      130512 :     while (src < end)
     285             :     {
     286      113784 :         unsigned    n1 = (*src >> 4) & 0xF;
     287      113784 :         unsigned    n2 = *src & 0xF;
     288             : 
     289      113784 :         *dst++ = n1 < 10 ? '0' + n1 : 'a' + n1 - 10;
     290      113784 :         *dst++ = n2 < 10 ? '0' + n2 : 'a' + n2 - 10;
     291      113784 :         ++src;
     292             :     }
     293             : 
     294       16728 :     return len * 2;
     295             : }

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