pg_checksums: Handle read and write returns correctly

The read() return was not checking for errors, the write() return was
not checking for short writes.

Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://www.postgresql.org/message-id/flat/5de61b6b-8be9-7771-0048-860328efe027%402ndquadrant.com

diff --git a/src/bin/pg_checksums/pg_checksums.c b/src/bin/pg_checksums/pg_checksums.c
index 8c00ec9a3b1a27177cf1db8de96e4354d0452585..971ae73f5444ac07372c6f6ef604edd345651a2d 100644 (file)
--- a/src/bin/pg_checksums/pg_checksums.c
+++ b/src/bin/pg_checksums/pg_checksums.c
@@ -198,8 +198,12 @@ scan_file(const char *fn, BlockNumber segmentno)
            break;
        if (r != BLCKSZ)
        {
-           pg_log_error("could not read block %u in file \"%s\": read %d of %d",
-                        blockno, fn, r, BLCKSZ);
+           if (r < 0)
+               pg_log_error("could not read block %u in file \"%s\": %m",
+                            blockno, fn);
+           else
+               pg_log_error("could not read block %u in file \"%s\": read %d of %d",
+                            blockno, fn, r, BLCKSZ);
            exit(1);
        }
        blocks++;
@@ -222,6 +226,8 @@ scan_file(const char *fn, BlockNumber segmentno)
        }
        else if (mode == PG_MODE_ENABLE)
        {
+           int     w;
+
            /* Set checksum in page header */
            header->pd_checksum = csum;
 
@@ -233,10 +239,15 @@ scan_file(const char *fn, BlockNumber segmentno)
            }
 
            /* Write block with checksum */
-           if (write(f, buf.data, BLCKSZ) != BLCKSZ)
+           w = write(f, buf.data, BLCKSZ);
+           if (w != BLCKSZ)
            {
-               pg_log_error("could not write block %u in file \"%s\": %m",
-                            blockno, fn);
+               if (w < 0)
+                   pg_log_error("could not write block %u in file \"%s\": %m",
+                                blockno, fn);
+               else
+                   pg_log_error("could not write block %u in file \"%s\": wrote %d of %d",
+                                blockno, fn, w, BLCKSZ);
                exit(1);
            }
        }