Correct some code in pg_restore when reading the header of a tar archive:

(1) The code doesn't initialize `sum', so the initial "does the checksum
    match?" test is wrong.

(2) The loop that is intended to check for a "null block" just checks
    the first byte of the tar block 512 times, rather than each of the
    512 bytes one time (!), which I'm guessing was the intent.

It was only through sheer luck that this worked in the first place.

Per Coverity static analysis performed by EnterpriseDB.

diff --git a/src/bin/pg_dump/pg_backup_tar.c b/src/bin/pg_dump/pg_backup_tar.c
index 0b8860cf1b36af3b76403ae41fcdf18830f35e85..2743fd17748f1f3f786ea32f65474671a567126a 100644 (file)
--- a/src/bin/pg_dump/pg_backup_tar.c
+++ b/src/bin/pg_dump/pg_backup_tar.c
@@ -1120,7 +1120,7 @@ _tarPositionTo(ArchiveHandle *AH, const char *filename)
                ahlog(AH, 4, "skipping tar member %s\n", th->targetFile);
 
                id = atoi(th->targetFile);
-               if ((TocIDRequired(AH, id, AH->ropt) & 2) != 0)
+               if ((TocIDRequired(AH, id, AH->ropt) & REQ_DATA) != 0)
                        die_horribly(AH, modulename, "dumping data out of order is not supported in this archive format: "
                        "%s is required, but comes before %s in the archive file.\n",
                                                 th->targetFile, filename);
@@ -1155,7 +1155,6 @@ _tarGetHeader(ArchiveHandle *AH, TAR_MEMBER *th)
        size_t          len;
        unsigned long ullen;
        off_t           hPos;
-       int                     i;
        bool            gotBlock = false;
 
        while (!gotBlock)
@@ -1178,7 +1177,7 @@ _tarGetHeader(ArchiveHandle *AH, TAR_MEMBER *th)
                hPos = ctx->tarFHpos;
 
                /* Read a 512 byte block, return EOF, exit if short */
-               len = _tarReadRaw(AH, &h[0], 512, NULL, ctx->tarFH);
+               len = _tarReadRaw(AH, h, 512, NULL, ctx->tarFH);
                if (len == 0)                   /* EOF */
                        return 0;
 
@@ -1188,20 +1187,22 @@ _tarGetHeader(ArchiveHandle *AH, TAR_MEMBER *th)
                                                 (unsigned long) len);
 
                /* Calc checksum */
-               chk = _tarChecksum(&h[0]);
+               chk = _tarChecksum(h);
+               sscanf(&h[148], "%8o", &sum);
 
                /*
-                * If the checksum failed, see if it is a null block. If so, then
-                * just try with next block...
+                * If the checksum failed, see if it is a null block. If so,
+                * silently continue to the next block.
                 */
-
                if (chk == sum)
                        gotBlock = true;
                else
                {
+                       int                     i;
+
                        for (i = 0; i < 512; i++)
                        {
-                               if (h[0] != 0)
+                               if (h[i] != 0)
                                {
                                        gotBlock = true;
                                        break;
@@ -1213,7 +1214,6 @@ _tarGetHeader(ArchiveHandle *AH, TAR_MEMBER *th)
        sscanf(&h[0], "%99s", tag);
        sscanf(&h[124], "%12lo", &ullen);
        len = (size_t) ullen;
-       sscanf(&h[148], "%8o", &sum);
 
        {
                char            buf[100];