Fix incorrect data type choices in some read and write calls.

Recently-introduced code in reconstruct.c was using "unsigned"
to store the result of read(), pg_pread(), or write().  This is
completely bogus: it breaks subsequent tests for the result being
negative, as we're being reminded of by a chorus of buildfarm
warnings.  Switch to "int" as was doubtless intended.  (There are
several other uses of "unsigned" in this file that also look poorly
chosen to me, but for now I'm just trying to clean up the buildfarm.)

A larger problem is that "int" is not necessarily wide enough to hold
the result: per POSIX, all these functions return ssize_t.  In places
where the requested read or write length clearly fits in int, that's
academic.  It may be academic anyway as long as we constrain
individual data files to 1GB, since even a readv or writev-like
operation would then not be responsible for transferring more than
1GB.  Nonetheless it seems like trouble waiting to happen, so I made
a pass over readv and writev calls and fixed the result variables
where that seemed appropriate.  We might want to think about changing
some of the fd.c functions to return ssize_t too, for future-proofing;
but I didn't tackle that here.

Discussion: https://postgr.es/m/1672202.1703441340@sss.pgh.pa.us

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 1e9019156a5104b4471245cec455c5ee650c8d77..1264849883b49d7b72a6c4e8cc585f64044a8000 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -2280,7 +2280,7 @@ XLogWrite(XLogwrtRqst WriteRqst, TimeLineID tli, bool flexible)
            char       *from;
            Size        nbytes;
            Size        nleft;
-           int         written;
+           ssize_t     written;
            instr_time  start;
 
            /* OK to write the page(s) */

diff --git a/src/backend/backup/basebackup.c b/src/backend/backup/basebackup.c
index 5ee9628422e05b35fc24087cf5bb9abb6d460377..84246739ae6344464e0f4a0a500e2c251de08095 100644 (file)
--- a/src/backend/backup/basebackup.c
+++ b/src/backend/backup/basebackup.c
@@ -117,8 +117,8 @@ static void perform_base_backup(basebackup_options *opt, bbsink *sink,
                                IncrementalBackupInfo *ib);
 static void parse_basebackup_options(List *options, basebackup_options *opt);
 static int compareWalFileNames(const ListCell *a, const ListCell *b);
-static int basebackup_read_file(int fd, char *buf, size_t nbytes, off_t offset,
-                                const char *filename, bool partial_read_ok);
+static ssize_t basebackup_read_file(int fd, char *buf, size_t nbytes, off_t offset,
+                                   const char *filename, bool partial_read_ok);
 
 /* Was the backup currently in-progress initiated in recovery mode? */
 static bool backup_started_in_recovery = false;
@@ -525,7 +525,7 @@ perform_base_backup(basebackup_options *opt, bbsink *sink,
        {
            char       *walFileName = (char *) lfirst(lc);
            int         fd;
-           size_t      cnt;
+           ssize_t     cnt;
            pgoff_t     len = 0;
 
            snprintf(pathbuf, MAXPGPATH, XLOGDIR "/%s", walFileName);
@@ -2079,11 +2079,11 @@ convert_link_to_directory(const char *pathbuf, struct stat *statbuf)
  *
  * Returns the number of bytes read.
  */
-static int
+static ssize_t
 basebackup_read_file(int fd, char *buf, size_t nbytes, off_t offset,
                     const char *filename, bool partial_read_ok)
 {
-   int         rc;
+   ssize_t     rc;
 
    pgstat_report_wait_start(WAIT_EVENT_BASEBACKUP_READ);
    rc = pg_pread(fd, buf, nbytes, offset);
@@ -2096,7 +2096,7 @@ basebackup_read_file(int fd, char *buf, size_t nbytes, off_t offset,
    if (!partial_read_ok && rc > 0 && rc != nbytes)
        ereport(ERROR,
                (errcode_for_file_access(),
-                errmsg("could not read file \"%s\": read %d of %zu",
+                errmsg("could not read file \"%s\": read %zd of %zu",
                        filename, rc, nbytes)));
 
    return rc;

diff --git a/src/bin/pg_combinebackup/reconstruct.c b/src/bin/pg_combinebackup/reconstruct.c
index 6decdd89340398e0829bac9f552777d8188efd38..874e6cd150b7de9cdcecf02ba8476e4174de2bf7 100644 (file)
--- a/src/bin/pg_combinebackup/reconstruct.c
+++ b/src/bin/pg_combinebackup/reconstruct.c
@@ -504,7 +504,7 @@ make_rfile(char *filename, bool missing_ok)
 static void
 read_bytes(rfile *rf, void *buffer, unsigned length)
 {
-   unsigned    rb = read(rf->fd, buffer, length);
+   int         rb = read(rf->fd, buffer, length);
 
    if (rb != length)
    {
@@ -512,7 +512,7 @@ read_bytes(rfile *rf, void *buffer, unsigned length)
            pg_fatal("could not read file \"%s\": %m", rf->filename);
        else
            pg_fatal("could not read file \"%s\": read only %d of %d bytes",
-                    rf->filename, (int) rb, length);
+                    rf->filename, rb, length);
    }
 }
 
@@ -614,7 +614,7 @@ write_reconstructed_file(char *input_filename,
    {
        uint8       buffer[BLCKSZ];
        rfile      *s = sourcemap[i];
-       unsigned    wb;
+       int         wb;
 
        /* Update accounting information. */
        if (s == NULL)
@@ -641,7 +641,7 @@ write_reconstructed_file(char *input_filename,
        }
        else
        {
-           unsigned    rb;
+           int         rb;
 
            /* Read the block from the correct source, except if dry-run. */
            rb = pg_pread(s->fd, buffer, BLCKSZ, offsetmap[i]);
@@ -650,9 +650,9 @@ write_reconstructed_file(char *input_filename,
                if (rb < 0)
                    pg_fatal("could not read file \"%s\": %m", s->filename);
                else
-                   pg_fatal("could not read file \"%s\": read only %d of %d bytes at offset %u",
-                            s->filename, (int) rb, BLCKSZ,
-                            (unsigned) offsetmap[i]);
+                   pg_fatal("could not read file \"%s\": read only %d of %d bytes at offset %llu",
+                            s->filename, rb, BLCKSZ,
+                            (unsigned long long) offsetmap[i]);
            }
        }
 
@@ -663,7 +663,7 @@ write_reconstructed_file(char *input_filename,
                pg_fatal("could not write file \"%s\": %m", output_filename);
            else
                pg_fatal("could not write file \"%s\": wrote only %d of %d bytes",
-                        output_filename, (int) wb, BLCKSZ);
+                        output_filename, wb, BLCKSZ);
        }
 
        /* Update the checksum computation. */