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michaelpqmichaelpq
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Make EXEC_BACKEND more convenient on Linux and FreeBSD.
Try to disable ASLR when building in EXEC_BACKEND mode, to avoid random memory mapping failures while testing. For developer use only, no effect on regular builds. This has been originally applied as of f3e7806 for v15~, but recently-added buildfarm member gokiburi tests this configuration on older branches as well, causing it to fail randomly as ASLR would be enabled. Suggested-by: Andres Freund <andres@anarazel.de> Tested-by: Bossart, Nathan <bossartn@amazon.com> Discussion: https://postgr.es/m/20210806032944.m4tz7j2w47mant26%40alap3.anarazel.de Backpatch-through: 12
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7 files changed

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‎configure

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@@ -13328,7 +13328,7 @@ $as_echo "#define HAVE_STDBOOL_H 1" >>confdefs.h
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fi
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for ac_header in atomic.h copyfile.h crypt.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
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for ac_header in atomic.h copyfile.h crypt.h fp_class.h getopt.h ieeefp.h ifaddrs.h langinfo.h mbarrier.h poll.h sys/epoll.h sys/ipc.h sys/personality.h sys/prctl.h sys/procctl.h sys/pstat.h sys/resource.h sys/select.h sys/sem.h sys/shm.h sys/sockio.h sys/tas.h sys/un.h termios.h ucred.h utime.h wchar.h wctype.h
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do :
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as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
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ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default"

‎configure.in

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@@ -1407,6 +1407,7 @@ AC_CHECK_HEADERS(m4_normalize([
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poll.h
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sys/epoll.h
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sys/ipc.h
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sys/personality.h
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sys/prctl.h
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sys/procctl.h
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sys/pstat.h

‎src/bin/pg_ctl/pg_ctl.c

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@@ -459,6 +459,10 @@ start_postmaster(void)
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fflush(stdout);
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fflush(stderr);
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#ifdef EXEC_BACKEND
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pg_disable_aslr();
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#endif
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pm_pid = fork();
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if (pm_pid < 0)
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{

‎src/common/exec.c

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@@ -25,6 +25,14 @@
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#include <sys/wait.h>
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#include <unistd.h>
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#ifdef EXEC_BACKEND
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#if defined(HAVE_SYS_PERSONALITY_H)
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#include <sys/personality.h>
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#elif defined(HAVE_SYS_PROCCTL_H)
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#include <sys/procctl.h>
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#endif
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#endif
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/* Inhibit mingw CRT's auto-globbing of command line arguments */
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#if defined(WIN32) && !defined(_MSC_VER)
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extern int _CRT_glob = 0; /* 0 turns off globbing; 1 turns it on */
@@ -623,6 +631,31 @@ set_pglocale_pgservice(const char *argv0, const char *app)
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}
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}
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#ifdef EXEC_BACKEND
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/*
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* For the benefit of PostgreSQL developers testing EXEC_BACKEND on Unix
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* systems (code paths normally exercised only on Windows), provide a way to
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* disable address space layout randomization, if we know how on this platform.
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* Otherwise, backends may fail to attach to shared memory at the fixed address
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* chosen by the postmaster. (See also the macOS-specific hack in
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* sysv_shmem.c.)
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*/
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int
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pg_disable_aslr(void)
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{
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#if defined(HAVE_SYS_PERSONALITY_H)
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return personality(ADDR_NO_RANDOMIZE);
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#elif defined(HAVE_SYS_PROCCTL_H) && defined(PROC_ASLR_FORCE_DISABLE)
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int data = PROC_ASLR_FORCE_DISABLE;
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return procctl(P_PID, 0, PROC_ASLR_CTL, &data);
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#else
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errno = ENOSYS;
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return -1;
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#endif
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}
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#endif
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#ifdef WIN32
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/*

‎src/include/pg_config.h.in

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@@ -612,6 +612,9 @@
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/* Define to 1 if you have the <sys/ipc.h> header file. */
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#undef HAVE_SYS_IPC_H
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/* Define to 1 if you have the <sys/personality.h> header file. */
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#undef HAVE_SYS_PERSONALITY_H
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/* Define to 1 if you have the <sys/prctl.h> header file. */
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#undef HAVE_SYS_PRCTL_H
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‎src/include/port.h

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Original file line numberDiff line numberDiff line change
@@ -114,6 +114,11 @@ extern int find_other_exec(const char *argv0, const char *target,
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/* Doesn't belong here, but this is used with find_other_exec(), so... */
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#define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
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#ifdef EXEC_BACKEND
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/* Disable ASLR before exec, for developer builds only (in exec.c) */
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extern int pg_disable_aslr(void);
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#endif
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#if defined(WIN32) || defined(__CYGWIN__)
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#define EXE ".exe"

‎src/test/regress/pg_regress.c

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@@ -1175,6 +1175,10 @@ spawn_process(const char *cmdline)
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if (logfile)
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fflush(logfile);
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#ifdef EXEC_BACKEND
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pg_disable_aslr();
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#endif
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pid = fork();
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if (pid == -1)
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{

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