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Move our p{read,write}v replacements into their own files.

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macOS's ranlib issued a warning about an empty pread.o file with the
previous arrangement, on systems new enough to require no replacement
functions.  Let's go back to using configure's AC_REPLACE_FUNCS system
to build and include each .o in the library only if it's needed, which
requires moving the *v() functions to their own files.

Also move the _with_retry() wrapper to a more permanent home.

Reported-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/1283127.1610554395%40sss.pgh.pa.us
This commit is contained in:
Thomas Munro
2021-01-14 11:10:24 +13:00
parent 5a6f9bce8d
commit 0d56acfbaa
10 changed files with 248 additions and 154 deletions
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43
src/port/pread.c
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@@ -1,7 +1,7 @@
/*-------------------------------------------------------------------------
*
* pread.c
* Implementation of pread[v](2) for platforms that lack one.
* Implementation of pread(2) for platforms that lack one.
*
* Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
*
@@ -9,8 +9,7 @@
* src/port/pread.c
*
* Note that this implementation changes the current file position, unlike
* the POSIX function, so we use the name pg_pread(). Likewise for the
* iovec version.
* the POSIX function, so we use the name pg_pread().
*
*-------------------------------------------------------------------------
*/
@@ -24,9 +23,6 @@
#include <unistd.h>
#endif
#include "port/pg_iovec.h"
#ifndef HAVE_PREAD
ssize_t
pg_pread(int fd, void *buf, size_t size, off_t offset)
{
@@ -60,38 +56,3 @@ pg_pread(int fd, void *buf, size_t size, off_t offset)
return read(fd, buf, size);
#endif
}
#endif
#ifndef HAVE_PREADV
ssize_t
pg_preadv(int fd, const struct iovec *iov, int iovcnt, off_t offset)
{
#ifdef HAVE_READV
if (iovcnt == 1)
return pg_pread(fd, iov[0].iov_base, iov[0].iov_len, offset);
if (lseek(fd, offset, SEEK_SET) < 0)
return -1;
return readv(fd, iov, iovcnt);
#else
ssize_t sum = 0;
ssize_t part;
for (int i = 0; i < iovcnt; ++i)
{
part = pg_pread(fd, iov[i].iov_base, iov[i].iov_len, offset);
if (part < 0)
{
if (i == 0)
return -1;
else
return sum;
}
sum += part;
offset += part;
if (part < iov[i].iov_len)
return sum;
}
return sum;
#endif
}
#endif