From: Thomas Munro Date: Tue, 6 Nov 2018 20:50:01 +0000 (+1300) Subject: Provide pg_pread() and pg_pwrite() for random I/O. X-Git-Tag: REL_12_BETA1~1292 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=3fd2a7932ef0708dda57369bb20c0499d905cc82;p=postgresql 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 --- diff --git a/configure b/configure index 748abaffc2..a600fdfac3 100755 --- a/configure +++ b/configure @@ -15539,6 +15539,32 @@ esac fi +ac_fn_c_check_func "$LINENO" "pread" "ac_cv_func_pread" +if test "x$ac_cv_func_pread" = xyes; then : + $as_echo "#define HAVE_PREAD 1" >>confdefs.h + +else + case " $LIBOBJS " in + *" pread.$ac_objext "* ) ;; + *) LIBOBJS="$LIBOBJS pread.$ac_objext" + ;; +esac + +fi + +ac_fn_c_check_func "$LINENO" "pwrite" "ac_cv_func_pwrite" +if test "x$ac_cv_func_pwrite" = xyes; then : + $as_echo "#define HAVE_PWRITE 1" >>confdefs.h + +else + case " $LIBOBJS " in + *" pwrite.$ac_objext "* ) ;; + *) LIBOBJS="$LIBOBJS pwrite.$ac_objext" + ;; +esac + +fi + ac_fn_c_check_func "$LINENO" "random" "ac_cv_func_random" if test "x$ac_cv_func_random" = xyes; then : $as_echo "#define HAVE_RANDOM 1" >>confdefs.h diff --git a/configure.in b/configure.in index 09b23e9821..75dbe8e734 100644 --- a/configure.in +++ b/configure.in @@ -1698,6 +1698,8 @@ AC_REPLACE_FUNCS(m4_normalize([ getrusage inet_aton mkdtemp + pread + pwrite random rint srandom diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index 9798bd24b4..5a996e7557 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -438,6 +438,9 @@ /* Define to 1 if you have the `ppoll' function. */ #undef HAVE_PPOLL +/* Define to 1 if you have the `pread' function. */ +#undef HAVE_PREAD + /* Define to 1 if you have the `pstat' function. */ #undef HAVE_PSTAT @@ -453,6 +456,9 @@ /* Have PTHREAD_PRIO_INHERIT. */ #undef HAVE_PTHREAD_PRIO_INHERIT +/* Define to 1 if you have the `pwrite' function. */ +#undef HAVE_PWRITE + /* Define to 1 if you have the `random' function. */ #undef HAVE_RANDOM diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32 index f7a051d112..894d658a20 100644 --- a/src/include/pg_config.h.win32 +++ b/src/include/pg_config.h.win32 @@ -322,12 +322,18 @@ /* Define to 1 if you have the `ppoll' function. */ /* #undef HAVE_PPOLL */ +/* Define to 1 if you have the `pread' function. */ +/* #undef HAVE_PREAD */ + /* Define to 1 if you have the `pstat' function. */ /* #undef HAVE_PSTAT */ /* Define to 1 if the PS_STRINGS thing exists. */ /* #undef HAVE_PS_STRINGS */ +/* Define to 1 if you have the `pwrite' function. */ +/* #undef HAVE_PWRITE */ + /* Define to 1 if you have the `random' function. */ /* #undef HAVE_RANDOM */ diff --git a/src/include/port.h b/src/include/port.h index 3a53bcf2e4..81583d557c 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 diff --git a/src/port/pread.c b/src/port/pread.c new file mode 100644 index 0000000000..a22d949cca --- /dev/null +++ b/src/port/pread.c @@ -0,0 +1,55 @@ +/*------------------------------------------------------------------------- + * + * pread.c + * Implementation of pread(2) for platforms that lack one. + * + * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group + * + * IDENTIFICATION + * src/port/pread.c + * + * Note that this implementation changes the current file position, unlike + * the POSIX function, so we use the name pg_pread(). + * + *------------------------------------------------------------------------- + */ + + +#include "postgres.h" + +#ifdef WIN32 +#include +#else +#include +#endif + +ssize_t +pg_pread(int fd, void *buf, size_t size, off_t offset) +{ +#ifdef WIN32 + OVERLAPPED overlapped = {0}; + HANDLE handle; + DWORD result; + + handle = (HANDLE) _get_osfhandle(fd); + if (handle == INVALID_HANDLE_VALUE) + { + errno = EBADF; + return -1; + } + + overlapped.Offset = offset; + if (!ReadFile(handle, buf, size, &result, &overlapped)) + { + _dosmaperr(GetLastError()); + return -1; + } + + return result; +#else + if (lseek(fd, offset, SEEK_SET) < 0) + return -1; + + return read(fd, buf, size); +#endif +} diff --git a/src/port/pwrite.c b/src/port/pwrite.c new file mode 100644 index 0000000000..f3e228cf4f --- /dev/null +++ b/src/port/pwrite.c @@ -0,0 +1,55 @@ +/*------------------------------------------------------------------------- + * + * pwrite.c + * Implementation of pwrite(2) for platforms that lack one. + * + * Portions Copyright (c) 1996-2018, PostgreSQL Global Development Group + * + * IDENTIFICATION + * src/port/pwrite.c + * + * Note that this implementation changes the current file position, unlike + * the POSIX function, so we use the name pg_write(). + * + *------------------------------------------------------------------------- + */ + + +#include "postgres.h" + +#ifdef WIN32 +#include +#else +#include +#endif + +ssize_t +pg_pwrite(int fd, const void *buf, size_t size, off_t offset) +{ +#ifdef WIN32 + OVERLAPPED overlapped = {0}; + HANDLE handle; + DWORD result; + + handle = (HANDLE) _get_osfhandle(fd); + if (handle == INVALID_HANDLE_VALUE) + { + errno = EBADF; + return -1; + } + + overlapped.Offset = offset; + if (!WriteFile(handle, buf, size, &result, &overlapped)) + { + _dosmaperr(GetLastError()); + return -1; + } + + return result; +#else + if (lseek(fd, offset, SEEK_SET) < 0) + return -1; + + return write(fd, buf, size); +#endif +} diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm index 708579d9df..b562044fa7 100644 --- a/src/tools/msvc/Mkvcbuild.pm +++ b/src/tools/msvc/Mkvcbuild.pm @@ -97,6 +97,7 @@ sub mkvcbuild srandom.c getaddrinfo.c gettimeofday.c inet_net_ntop.c kill.c open.c erand48.c snprintf.c strlcat.c strlcpy.c dirmod.c noblock.c path.c dirent.c dlopen.c getopt.c getopt_long.c + pread.c pwrite.c pg_strong_random.c pgcheckdir.c pgmkdirp.c pgsleep.c pgstrcasecmp.c pqsignal.c mkdtemp.c qsort.c qsort_arg.c quotes.c system.c sprompt.c strerror.c tar.c thread.c