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| author | Thomas Munro <tmunro@postgresql.org> | 2018-11-07 09:50:01 +1300 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2018-11-07 09:50:01 +1300 |
| commit | 3fd2a7932ef0708dda57369bb20c0499d905cc82 (patch) | |
| tree | e88ac8da2265607cfdc4fc3fbae46b2a96f3010a /src/include/port.h | |
| parent | b43df566b372650a9b9e2a0dd9e695c1f16da14f (diff) | |
| download | postgresql-3fd2a7932ef0708dda57369bb20c0499d905cc82.tar.gz postgresql-3fd2a7932ef0708dda57369bb20c0499d905cc82.zip | |
Provide pg_pread() and pg_pwrite() for random I/O.
Forward to POSIX pread() and pwrite(), or emulate them if unavailable.
The emulation is not perfect as the file position is changed, so
we'll put pg_ prefixes on the names to minimize the risk of confusion
in future patches that might inadvertently try to mix pread() and read()
on the same file descriptor.
Author: Thomas Munro
Reviewed-by: Tom Lane, Jesper Pedersen
Discussion: https://postgr.es/m/CAEepm=02rapCpPR3ZGF2vW=SBHSdFYO_bz_f-wwWJonmA3APgw@mail.gmail.com
Diffstat (limited to 'src/include/port.h')
| -rw-r--r-- | src/include/port.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/src/include/port.h b/src/include/port.h index 3a53bcf2e4b..81583d557cd 100644 --- a/src/include/port.h +++ b/src/include/port.h @@ -392,6 +392,23 @@ extern double rint(double x); extern int inet_aton(const char *cp, struct in_addr *addr); #endif +/* + * Windows and older Unix don't have pread(2) and pwrite(2). We have + * replacement functions, but they have slightly different semantics so we'll + * use a name with a pg_ prefix to avoid confusion. + */ +#ifdef HAVE_PREAD +#define pg_pread pread +#else +extern ssize_t pg_pread(int fd, void *buf, size_t nbyte, off_t offset); +#endif + +#ifdef HAVE_PWRITE +#define pg_pwrite pwrite +#else +extern ssize_t pg_pwrite(int fd, const void *buf, size_t nbyte, off_t offset); +#endif + #if !HAVE_DECL_STRLCAT extern size_t strlcat(char *dst, const char *src, size_t siz); #endif |