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[PATCH] standardize save/restore of errno & vaxc$errno

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From:
Chip Salzenberg
Date:
November 26, 2008 23:01
Subject:
[PATCH] standardize save/restore of errno & vaxc$errno
Message ID:
20081127070141.GD17663@tytlal.topaz.cx
The fix for bug #1154 will require saving and restoring errno, and I've
found that this basic and nonportable operation had not been standardized.
So here's a patch to do that.

Win32 note: my_pclose() was saving the result of GetLastError(), but was
not using it; in particular it was not calling SetLastError(), which one
might have expected it to do.  Would a Win32 expert care to weigh in?

VMS note: I have no VMS system, and this patch could break something if
vaxc$errno doesn't work as documented online and/or I haven't grokked it
properly.  Some smoke testing would be appropriate.

Share & Enjoy!

diff --git a/perl.h b/perl.h
index d08a4a6..30b64f1 100644
--- a/perl.h
+++ b/perl.h
@@ -1277,6 +1277,11 @@ EXTERN_C char *crypt(const char *, const char *);
 	    set_errno(errcode);		\
 	    set_vaxc_errno(vmserrcode);	\
 	} STMT_END
+#   define dSAVEDERRNO    int saved_errno; unsigned saved_vms_errno
+#   define dSAVE_ERRNO    int saved_errno = errno; unsigned saved_vms_errno = vaxc$errno
+#   define SAVE_ERRNO     ( saved_errno = errno, saved_vms_errno = vaxc$errno )
+#   define RESTORE_ERRNO  SETERRNO(saved_errno, saved_vms_errno)
+
 #   define LIB_INVARG 		LIB$_INVARG
 #   define RMS_DIR    		RMS$_DIR
 #   define RMS_FAC    		RMS$_FAC
@@ -1291,6 +1296,11 @@ EXTERN_C char *crypt(const char *, const char *);
 #   define SS_NORMAL  		SS$_NORMAL
 #else
 #   define SETERRNO(errcode,vmserrcode) (errno = (errcode))
+#   define dSAVEDERRNO    int saved_errno
+#   define dSAVE_ERRNO    int saved_errno = errno
+#   define SAVE_ERRNO     (saved_errno = errno)
+#   define RESTORE_ERRNO  (errno = saved_errno)
+
 #   define LIB_INVARG 		0
 #   define RMS_DIR    		0
 #   define RMS_FAC    		0
diff --git a/doio.c b/doio.c
index 2738323..c945216 100644
--- a/doio.c
+++ b/doio.c
@@ -663,9 +663,9 @@ Perl_do_openn(pTHX_ GV *gv, register const char *oname, I32 len, int as_raw,
     }
 #if defined(HAS_FCNTL) && defined(F_SETFD)
     if (fd >= 0) {
-	const int save_errno = errno;
+	dSAVE_ERRNO;
 	fcntl(fd,F_SETFD,fd > PL_maxsysfd); /* can change errno */
-	errno = save_errno;
+	RESTORE_ERRNO;
     }
 #endif
     IoIFP(io) = fp;
@@ -1014,14 +1014,14 @@ Perl_do_eof(pTHX_ GV *gv)
 
 	{
 	     /* getc and ungetc can stomp on errno */
-	    const int saverrno = errno;
+	    dSAVE_ERRNO;
 	    const int ch = PerlIO_getc(IoIFP(io));
 	    if (ch != EOF) {
 		(void)PerlIO_ungetc(IoIFP(io),ch);
-		errno = saverrno;
+		RESTORE_ERRNO;
 		return FALSE;
 	    }
-	    errno = saverrno;
+	    RESTORE_ERRNO;
 	}
 
         if (PerlIO_has_cntptr(IoIFP(io)) && PerlIO_canset_cnt(IoIFP(io))) {
diff --git a/mg.c b/mg.c
index 6f4cc58..7acff51 100644
--- a/mg.c
+++ b/mg.c
@@ -817,10 +817,10 @@ Perl_magic_get(pTHX_ SV *sv, MAGIC *mg)
 	     }
 #else
 	     {
-		 const int saveerrno = errno;
+		 dSAVE_ERRNO;
 		 sv_setnv(sv, (NV)errno);
 		 sv_setpv(sv, errno ? Strerror(errno) : "");
-		 errno = saveerrno;
+		 RESTORE_ERRNO;
 	     }
 #endif
 	     SvRTRIM(sv);
@@ -1036,7 +1036,7 @@ Perl_magic_get(pTHX_ SV *sv, MAGIC *mg)
 	sv_setpv(sv, errno ? Strerror(errno) : "");
 #else
 	{
-	const int saveerrno = errno;
+	dSAVE_ERRNO;
 	sv_setnv(sv, (NV)errno);
 #ifdef OS2
 	if (errno == errno_isOS2 || errno == errno_isOS2_set)
@@ -1044,7 +1044,7 @@ Perl_magic_get(pTHX_ SV *sv, MAGIC *mg)
 	else
 #endif
 	sv_setpv(sv, errno ? Strerror(errno) : "");
-	errno = saveerrno;
+	RESTORE_ERRNO;
 	}
 #endif
 	SvRTRIM(sv);
diff --git a/perlio.c b/perlio.c
index a3ea344..95c3b24 100644
--- a/perlio.c
+++ b/perlio.c
@@ -3131,8 +3131,8 @@ PerlIOStdio_close(pTHX_ PerlIO *f)
         const int fd = fileno(stdio);
 	int invalidate = 0;
 	IV result = 0;
-	int saveerr = 0;
 	int dupfd = -1;
+	dSAVEDERRNO;
 #ifdef USE_ITHREADS
 	dVAR;
 #endif
@@ -3166,7 +3166,7 @@ PerlIOStdio_close(pTHX_ PerlIO *f)
 	       fileno slot of the FILE *
 	    */
 	    result = PerlIO_flush(f);
-	    saveerr = errno;
+	    SAVE_ERRNO;
 	    invalidate = PerlIOStdio_invalidate_fileno(aTHX_ stdio);
 	    if (!invalidate) {
 #ifdef USE_ITHREADS
@@ -3205,7 +3205,7 @@ PerlIOStdio_close(pTHX_ PerlIO *f)
 	   errno may NOT be expected EBADF
 	 */
 	if (invalidate && result != 0) {
-	    errno = saveerr;
+	    RESTORE_ERRNO;
 	    result = 0;
 	}
 #ifdef SOCKS5_VERSION_NAME
@@ -3367,9 +3367,9 @@ PerlIOStdio_flush(pTHX_ PerlIO *f)
 	/*
 	 * Not writeable - sync by attempting a seek
 	 */
-	const int err = errno;
+	dSAVE_ERRNO;
 	if (PerlSIO_fseek(stdio, (Off_t) 0, SEEK_CUR) != 0)
-	    errno = err;
+	    RESTORE_ERRNO;
 #endif
     }
     return 0;
diff --git a/pp_sys.c b/pp_sys.c
index 11cd863..211633b 100644
--- a/pp_sys.c
+++ b/pp_sys.c
@@ -5167,13 +5167,13 @@ PP(pp_gpwent)
 	 * has a different API than the Solaris/IRIX one. */
 #   if defined(HAS_GETSPNAM) && !defined(_AIX)
 	{
-	    const int saverrno = errno;
+	    dSAVE_ERRNO;
 	    const struct spwd * const spwent = getspnam(pwent->pw_name);
 			  /* Save and restore errno so that
 			   * underprivileged attempts seem
 			   * to have never made the unsccessful
 			   * attempt to retrieve the shadow password. */
-	    errno = saverrno;
+	    RESTORE_ERRNO;
 	    if (spwent && spwent->sp_pwdp)
 		sv_setpv(sv, spwent->sp_pwdp);
 	}
@@ -5551,15 +5551,15 @@ static int
 lockf_emulate_flock(int fd, int operation)
 {
     int i;
-    const int save_errno = errno;
     Off_t pos;
+    dSAVE_ERRNO;
 
     /* flock locks entire file so for lockf we need to do the same	*/
     pos = PerlLIO_lseek(fd, (Off_t)0, SEEK_CUR);    /* get pos to restore later */
     if (pos > 0)	/* is seekable and needs to be repositioned	*/
 	if (PerlLIO_lseek(fd, (Off_t)0, SEEK_SET) < 0)
 	    pos = -1;	/* seek failed, so don't seek back afterwards	*/
-    errno = save_errno;
+    RESTORE_ERRNO;
 
     switch (operation) {
 
diff --git a/sv.c b/sv.c
index efa347b..a86994a 100644
--- a/sv.c
+++ b/sv.c
@@ -2958,7 +2958,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *const sv, STRLEN *const lp, const I32 flags
 	*s = '\0';
     }
     else if (SvNOKp(sv)) {
-	const int olderrno = errno;
+	dSAVE_ERRNO;
 	if (SvTYPE(sv) < SVt_PVNV)
 	    sv_upgrade(sv, SVt_PVNV);
 	/* The +20 is pure guesswork.  Configure test needed. --jhi */
@@ -2972,7 +2972,7 @@ Perl_sv_2pv_flags(pTHX_ register SV *const sv, STRLEN *const lp, const I32 flags
 	{
 	    Gconvert(SvNVX(sv), NV_DIG, 0, s);
 	}
-	errno = olderrno;
+	RESTORE_ERRNO;
 #ifdef FIXNEGATIVEZERO
         if (*s == '-' && s[1] == '0' && !s[2]) {
 	    s[0] = '0';
diff --git a/util.c b/util.c
index aebc8ef..b94aa0e 100644
--- a/util.c
+++ b/util.c
@@ -1271,14 +1271,14 @@ Perl_write_to_stderr(pTHX_ const char* message, int msglen)
     else {
 #ifdef USE_SFIO
 	/* SFIO can really mess with your errno */
-	const int e = errno;
+	dSAVED_ERRNO;
 #endif
 	PerlIO * const serr = Perl_error_log;
 
 	PERL_WRITE_MSG_TO_CONSOLE(serr, message, msglen);
 	(void)PerlIO_flush(serr);
 #ifdef USE_SFIO
-	errno = e;
+	RESTORE_ERRNO;
 #endif
     }
 }
@@ -2879,10 +2879,7 @@ Perl_my_pclose(pTHX_ PerlIO *ptr)
     Pid_t pid;
     Pid_t pid2;
     bool close_failed;
-    int saved_errno = 0;
-#ifdef WIN32
-    int saved_win32_errno;
-#endif
+    dSAVEDERRNO;
 
     LOCK_FDPID_MUTEX;
     svp = av_fetch(PL_fdpid,PerlIO_fileno(ptr),TRUE);
@@ -2895,12 +2892,8 @@ Perl_my_pclose(pTHX_ PerlIO *ptr)
 	return my_syspclose(ptr);
     }
 #endif
-    if ((close_failed = (PerlIO_close(ptr) == EOF))) {
-	saved_errno = errno;
-#ifdef WIN32
-	saved_win32_errno = GetLastError();
-#endif
-    }
+    if ((close_failed = (PerlIO_close(ptr) == EOF)))
+	SAVE_ERRNO;
 #ifdef UTS
     if(PerlProc_kill(pid, 0) < 0) { return(pid); }   /* HOM 12/23/91 */
 #endif
@@ -2918,7 +2911,7 @@ Perl_my_pclose(pTHX_ PerlIO *ptr)
     rsignal_restore(SIGQUIT, &qstat);
 #endif
     if (close_failed) {
-	SETERRNO(saved_errno, 0);
+	RESTORE_ERRNO;
 	return -1;
     }
     return(pid2 < 0 ? pid2 : status == 0 ? 0 : (errno = 0, status));
@@ -5069,12 +5062,12 @@ S_socketpair_udp (int fd[2]) {
     errno = ECONNABORTED;
   tidy_up_and_fail:
     {
-	const int save_errno = errno;
+	dSAVE_ERRNO;
 	if (sockets[0] != -1)
 	    PerlLIO_close(sockets[0]);
 	if (sockets[1] != -1)
 	    PerlLIO_close(sockets[1]);
-	errno = save_errno;
+	RESTORE_ERRNO;
 	return -1;
     }
 }
@@ -5173,14 +5166,14 @@ Perl_my_socketpair (int family, int type, int protocol, int fd[2]) {
 #endif
   tidy_up_and_fail:
     {
-	const int save_errno = errno;
+	dSAVE_ERRNO;
 	if (listener != -1)
 	    PerlLIO_close(listener);
 	if (connector != -1)
 	    PerlLIO_close(connector);
 	if (acceptor != -1)
 	    PerlLIO_close(acceptor);
-	errno = save_errno;
+	RESTORE_ERRNO;
 	return -1;
     }
 }
diff --git a/vms/vms.c b/vms/vms.c
index e674a8a..b5b8a7d 100644
--- a/vms/vms.c
+++ b/vms/vms.c
@@ -11912,10 +11912,10 @@ Perl_flex_stat_int(pTHX_ const char *fspec, Stat_t *statbufp, int lstat_flag)
     char temp_fspec[VMS_MAXRSS];
     char *save_spec;
     int retval = -1;
-    int saved_errno, saved_vaxc_errno;
+    dSAVEDERRNO;
 
     if (!fspec) return retval;
-    saved_errno = errno; saved_vaxc_errno = vaxc$errno;
+    SAVE_ERRNO;
     strcpy(temp_fspec, fspec);
 
     if (decc_bug_devnull != 0) {
@@ -12042,7 +12042,7 @@ Perl_flex_stat_int(pTHX_ const char *fspec, Stat_t *statbufp, int lstat_flag)
 #     endif
     }
     /* If we were successful, leave errno where we found it */
-    if (retval == 0) { errno = saved_errno; vaxc$errno = saved_vaxc_errno; }
+    if (retval == 0) RESTORE_ERRNO;
     return retval;
 
 }  /* end of flex_stat_int() */



-- 
Chip Salzenberg   twitter:chipsalz
"UTOPIA PLANITIA IS IN ORBIT is the new HAN SHOT FIRST" - Crisper Than Thou

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