Convert elog.c's useful_strerror() into a globally-used strerror wrapper.

elog.c has long had a private strerror wrapper that handles assorted
possible failures or deficiencies of the platform's strerror.  On Windows,
it also knows how to translate Winsock error codes, which the native
strerror does not.  Move all this code into src/port/strerror.c and
define strerror() as a macro that invokes it, so that both our frontend
and backend code will have all of this behavior.

I believe this constitutes an actual bug fix on Windows, since AFAICS
our frontend code did not report Winsock error codes properly before this.
However, the main point is to lay the groundwork for implementing %m
in src/port/snprintf.c: the behavior we want %m to have is this one,
not the native strerror's.

Note that this throws away the prior use of src/port/strerror.c,
which was to implement strerror() on platforms lacking it.  That's
been dead code for nigh twenty years now, since strerror() was
already required by C89.

We should likewise cause strerror_r to use this behavior, but
I'll tackle that separately.

Patch by me, reviewed by Michael Paquier

Discussion: https://postgr.es/m/2975.1526862605@sss.pgh.pa.us

Author: tglsfdc

configure

@@ -15644,19 +15644,6 @@ esac
 
 fi
 
-ac_fn_c_check_func "$LINENO" "strerror" "ac_cv_func_strerror"
-if test "x$ac_cv_func_strerror" = xyes; then :
-  $as_echo "#define HAVE_STRERROR 1" >>confdefs.h
-
-else
-  case " $LIBOBJS " in
-  *" strerror.$ac_objext "* ) ;;
-  *) LIBOBJS="$LIBOBJS strerror.$ac_objext"
- ;;
-esac
-
-fi
-
 ac_fn_c_check_func "$LINENO" "strlcat" "ac_cv_func_strlcat"
 if test "x$ac_cv_func_strlcat" = xyes; then :
   $as_echo "#define HAVE_STRLCAT 1" >>confdefs.h

configure.in

@@ -1687,7 +1687,7 @@ else
   AC_CHECK_FUNCS([fpclass fp_class fp_class_d class], [break])
 fi
 
-AC_REPLACE_FUNCS([crypt dlopen fls getopt getrusage inet_aton mkdtemp random rint srandom strerror strlcat strlcpy strnlen])
+AC_REPLACE_FUNCS([crypt dlopen fls getopt getrusage inet_aton mkdtemp random rint srandom strlcat strlcpy strnlen])
 
 case $host_os in
 

src/backend/port/win32/socket.c

@@ -690,39 +690,3 @@ pgwin32_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, c
 		memcpy(writefds, &outwritefds, sizeof(fd_set));
 	return nummatches;
 }
-
-
-/*
- * Return win32 error string, since strerror can't
- * handle winsock codes
- */
-static char wserrbuf[256];
-const char *
-pgwin32_socket_strerror(int err)
-{
-	static HANDLE handleDLL = INVALID_HANDLE_VALUE;
-
-	if (handleDLL == INVALID_HANDLE_VALUE)
-	{
-		handleDLL = LoadLibraryEx("netmsg.dll", NULL, DONT_RESOLVE_DLL_REFERENCES | LOAD_LIBRARY_AS_DATAFILE);
-		if (handleDLL == NULL)
-			ereport(FATAL,
-					(errmsg_internal("could not load netmsg.dll: error code %lu", GetLastError())));
-	}
-
-	ZeroMemory(&wserrbuf, sizeof(wserrbuf));
-	if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS |
-					  FORMAT_MESSAGE_FROM_SYSTEM |
-					  FORMAT_MESSAGE_FROM_HMODULE,
-					  handleDLL,
-					  err,
-					  MAKELANGID(LANG_ENGLISH, SUBLANG_DEFAULT),
-					  wserrbuf,
-					  sizeof(wserrbuf) - 1,
-					  NULL) == 0)
-	{
-		/* Failed to get id */
-		sprintf(wserrbuf, "unrecognized winsock error %d", err);
-	}
-	return wserrbuf;
-}

src/backend/utils/error/elog.c

@@ -178,8 +178,6 @@ static void send_message_to_server_log(ErrorData *edata);
 static void write_pipe_chunks(char *data, int len, int dest);
 static void send_message_to_frontend(ErrorData *edata);
 static char *expand_fmt_string(const char *fmt, ErrorData *edata);
-static const char *useful_strerror(int errnum);
-static const char *get_errno_symbol(int errnum);
 static const char *error_severity(int elevel);
 static void append_with_tabs(StringInfo buf, const char *str);
 static bool is_log_level_output(int elevel, int log_min_level);
@@ -3360,7 +3358,7 @@ expand_fmt_string(const char *fmt, ErrorData *edata)
 				 */
 				const char *cp2;
 
-				cp2 = useful_strerror(edata->saved_errno);
+				cp2 = strerror(edata->saved_errno);
 				for (; *cp2; cp2++)
 				{
 					if (*cp2 == '%')
@@ -3383,219 +3381,6 @@ expand_fmt_string(const char *fmt, ErrorData *edata)
 }
 
 
-/*
- * A slightly cleaned-up version of strerror()
- */
-static const char *
-useful_strerror(int errnum)
-{
-	/* this buffer is only used if strerror() and get_errno_symbol() fail */
-	static char errorstr_buf[48];
-	const char *str;
-
-#ifdef WIN32
-	/* Winsock error code range, per WinError.h */
-	if (errnum >= 10000 && errnum <= 11999)
-		return pgwin32_socket_strerror(errnum);
-#endif
-	str = strerror(errnum);
-
-	/*
-	 * Some strerror()s return an empty string for out-of-range errno.  This
-	 * is ANSI C spec compliant, but not exactly useful.  Also, we may get
-	 * back strings of question marks if libc cannot transcode the message to
-	 * the codeset specified by LC_CTYPE.  If we get nothing useful, first try
-	 * get_errno_symbol(), and if that fails, print the numeric errno.
-	 */
-	if (str == NULL || *str == '\0' || *str == '?')
-		str = get_errno_symbol(errnum);
-
-	if (str == NULL)
-	{
-		snprintf(errorstr_buf, sizeof(errorstr_buf),
-		/*------
-		  translator: This string will be truncated at 47
-		  characters expanded. */
-				 _("operating system error %d"), errnum);
-		str = errorstr_buf;
-	}
-
-	return str;
-}
-
-/*
- * Returns a symbol (e.g. "ENOENT") for an errno code.
- * Returns NULL if the code is unrecognized.
- */
-static const char *
-get_errno_symbol(int errnum)
-{
-	switch (errnum)
-	{
-		case E2BIG:
-			return "E2BIG";
-		case EACCES:
-			return "EACCES";
-#ifdef EADDRINUSE
-		case EADDRINUSE:
-			return "EADDRINUSE";
-#endif
-#ifdef EADDRNOTAVAIL
-		case EADDRNOTAVAIL:
-			return "EADDRNOTAVAIL";
-#endif
-		case EAFNOSUPPORT:
-			return "EAFNOSUPPORT";
-#ifdef EAGAIN
-		case EAGAIN:
-			return "EAGAIN";
-#endif
-#ifdef EALREADY
-		case EALREADY:
-			return "EALREADY";
-#endif
-		case EBADF:
-			return "EBADF";
-#ifdef EBADMSG
-		case EBADMSG:
-			return "EBADMSG";
-#endif
-		case EBUSY:
-			return "EBUSY";
-		case ECHILD:
-			return "ECHILD";
-#ifdef ECONNABORTED
-		case ECONNABORTED:
-			return "ECONNABORTED";
-#endif
-		case ECONNREFUSED:
-			return "ECONNREFUSED";
-#ifdef ECONNRESET
-		case ECONNRESET:
-			return "ECONNRESET";
-#endif
-		case EDEADLK:
-			return "EDEADLK";
-		case EDOM:
-			return "EDOM";
-		case EEXIST:
-			return "EEXIST";
-		case EFAULT:
-			return "EFAULT";
-		case EFBIG:
-			return "EFBIG";
-#ifdef EHOSTUNREACH
-		case EHOSTUNREACH:
-			return "EHOSTUNREACH";
-#endif
-		case EIDRM:
-			return "EIDRM";
-		case EINPROGRESS:
-			return "EINPROGRESS";
-		case EINTR:
-			return "EINTR";
-		case EINVAL:
-			return "EINVAL";
-		case EIO:
-			return "EIO";
-#ifdef EISCONN
-		case EISCONN:
-			return "EISCONN";
-#endif
-		case EISDIR:
-			return "EISDIR";
-#ifdef ELOOP
-		case ELOOP:
-			return "ELOOP";
-#endif
-		case EMFILE:
-			return "EMFILE";
-		case EMLINK:
-			return "EMLINK";
-		case EMSGSIZE:
-			return "EMSGSIZE";
-		case ENAMETOOLONG:
-			return "ENAMETOOLONG";
-		case ENFILE:
-			return "ENFILE";
-		case ENOBUFS:
-			return "ENOBUFS";
-		case ENODEV:
-			return "ENODEV";
-		case ENOENT:
-			return "ENOENT";
-		case ENOEXEC:
-			return "ENOEXEC";
-		case ENOMEM:
-			return "ENOMEM";
-		case ENOSPC:
-			return "ENOSPC";
-		case ENOSYS:
-			return "ENOSYS";
-#ifdef ENOTCONN
-		case ENOTCONN:
-			return "ENOTCONN";
-#endif
-		case ENOTDIR:
-			return "ENOTDIR";
-#if defined(ENOTEMPTY) && (ENOTEMPTY != EEXIST) /* same code on AIX */
-		case ENOTEMPTY:
-			return "ENOTEMPTY";
-#endif
-#ifdef ENOTSOCK
-		case ENOTSOCK:
-			return "ENOTSOCK";
-#endif
-#ifdef ENOTSUP
-		case ENOTSUP:
-			return "ENOTSUP";
-#endif
-		case ENOTTY:
-			return "ENOTTY";
-		case ENXIO:
-			return "ENXIO";
-#if defined(EOPNOTSUPP) && (!defined(ENOTSUP) || (EOPNOTSUPP != ENOTSUP))
-		case EOPNOTSUPP:
-			return "EOPNOTSUPP";
-#endif
-#ifdef EOVERFLOW
-		case EOVERFLOW:
-			return "EOVERFLOW";
-#endif
-		case EPERM:
-			return "EPERM";
-		case EPIPE:
-			return "EPIPE";
-		case EPROTONOSUPPORT:
-			return "EPROTONOSUPPORT";
-		case ERANGE:
-			return "ERANGE";
-#ifdef EROFS
-		case EROFS:
-			return "EROFS";
-#endif
-		case ESRCH:
-			return "ESRCH";
-#ifdef ETIMEDOUT
-		case ETIMEDOUT:
-			return "ETIMEDOUT";
-#endif
-#ifdef ETXTBSY
-		case ETXTBSY:
-			return "ETXTBSY";
-#endif
-#if defined(EWOULDBLOCK) && (!defined(EAGAIN) || (EWOULDBLOCK != EAGAIN))
-		case EWOULDBLOCK:
-			return "EWOULDBLOCK";
-#endif
-		case EXDEV:
-			return "EXDEV";
-	}
-
-	return NULL;
-}
-
-
 /*
  * error_severity --- get string representing elevel
  *

src/include/pg_config.h.in

@@ -534,9 +534,6 @@
 /* Define to 1 if you have the <stdlib.h> header file. */
 #undef HAVE_STDLIB_H
 
-/* Define to 1 if you have the `strerror' function. */
-#undef HAVE_STRERROR
-
 /* Define to 1 if you have the `strerror_r' function. */
 #undef HAVE_STRERROR_R
 

src/include/pg_config.h.win32

@@ -405,11 +405,6 @@
 /* Define to 1 if you have the <stdlib.h> header file. */
 #define HAVE_STDLIB_H 1
 
-/* Define to 1 if you have the `strerror' function. */
-#ifndef HAVE_STRERROR
-#define HAVE_STRERROR 1
-#endif
-
 /* Define to 1 if you have the `strerror_r' function. */
 /* #undef HAVE_STRERROR_R */
 

src/include/port.h

@@ -189,6 +189,10 @@ extern int	pg_printf(const char *fmt,...) pg_attribute_printf(1, 2);
 #endif
 #endif							/* USE_REPL_SNPRINTF */
 
+/* Replace strerror() with our own, somewhat more robust wrapper */
+extern char *pg_strerror(int errnum);
+#define strerror pg_strerror
+
 /* Portable prompt handling */
 extern void simple_prompt(const char *prompt, char *destination, size_t destlen,
 			  bool echo);
@@ -355,7 +359,7 @@ extern int	isinf(double x);
 #undef isinf
 #define isinf __builtin_isinf
 #endif							/* __has_builtin(isinf) */
-#endif							/* __clang__ && !__cplusplus*/
+#endif							/* __clang__ && !__cplusplus */
 #endif							/* !HAVE_ISINF */
 
 #ifndef HAVE_MKDTEMP
@@ -403,7 +407,7 @@ extern void srandom(unsigned int seed);
 #ifndef HAVE_DLOPEN
 extern void *dlopen(const char *file, int mode);
 extern void *dlsym(void *handle, const char *symbol);
-extern int dlclose(void *handle);
+extern int	dlclose(void *handle);
 extern char *dlerror(void);
 #endif
 

src/include/port/win32_port.h

@@ -322,8 +322,8 @@ extern int	pgwin32_safestat(const char *path, struct stat *buf);
  * Supplement to <errno.h>.
  *
  * We redefine network-related Berkeley error symbols as the corresponding WSA
- * constants.  This allows elog.c to recognize them as being in the Winsock
- * error code range and pass them off to pgwin32_socket_strerror(), since
+ * constants. This allows strerror.c to recognize them as being in the Winsock
+ * error code range and pass them off to win32_socket_strerror(), since
  * Windows' version of plain strerror() won't cope.  Note that this will break
  * if these names are used for anything else besides Windows Sockets errors.
  * See TranslateSocketError() when changing this list.
@@ -456,8 +456,6 @@ int			pgwin32_connect(SOCKET s, const struct sockaddr *name, int namelen);
 int			pgwin32_select(int nfds, fd_set *readfs, fd_set *writefds, fd_set *exceptfds, const struct timeval *timeout);
 int			pgwin32_recv(SOCKET s, char *buf, int len, int flags);
 int			pgwin32_send(SOCKET s, const void *buf, int len, int flags);
-
-const char *pgwin32_socket_strerror(int err);
 int			pgwin32_waitforsinglesocket(SOCKET s, int what, int timeout);
 
 extern int	pgwin32_noblock;

src/interfaces/ecpg/compatlib/.gitignore

@@ -2,4 +2,5 @@
 /blibecpg_compatdll.def
 /exports.list
 /snprintf.c
+/strerror.c
 /strnlen.c