From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Tue, 14 May 2002 13:21:54 +0000 (+0000)
Subject: Document reentr.pl a bit better.  Still rather
X-Git-Tag: perl-5.8.0~889
X-Git-Url: https://perl5.git.perl.org/perl5.git/commitdiff_plain/aa418cf14f5423600e2de800942ca69bd80882ac

Document reentr.pl a bit better.  Still rather
convoluted code, but it ain't broken, so...

p4raw-id: //depot/perl@16590
---

diff --git a/reentr.h b/reentr.h
index d72647b..4c80588 100644
--- a/reentr.h
+++ b/reentr.h
@@ -743,7 +743,7 @@ typedef struct {
 	size_t	_ttyname_size;
 #endif /* HAS_TTYNAME_R */
 
-    int dummy; /* just in case */
+    int dummy; /* cannot have empty structs */
 } REENTR;
 
 /* The wrappers. */
diff --git a/reentr.pl b/reentr.pl
index e8f2544..19b9852 100644
--- a/reentr.pl
+++ b/reentr.pl
@@ -128,29 +128,32 @@ print <<EOF;
 
 EOF
 
-my %seenh;
-my %seena;
-my @seenf;
-my %seenp;
-my %seent;
-my %seens;
-my %seend;
-my %seenu;
-
-while (<DATA>) {
+my %seenh; # the different prototypes signatures for this function
+my %seena; # the different prototypes signatures for this function in order
+my @seenf; # all the seen functions
+my %seenp; # the different prototype signatures for all functions
+my %seent; # the return type of this function
+my %seens; # the type of this function's "S"
+my %seend; # the type of this function's "D"
+my %seenu; # the length of the argument list of this function
+
+while (<DATA>) { # Read in the protypes.
     next if /^\s+$/;
     chomp;
-    my ($f, $h, $t, @p) = split(/\s*\|\s*/, $_, -1);
+    my ($func, $hdr, $type, @p) = split(/\s*\|\s*/, $_, -1);
     my $u;
-    ($f, $u) = split(' ', $f);
-    $seenu{$f} = defined $u ? length $u : 0;
-    my $F = uc $f;
-    push @seenf, $f;
+    # Split off the real function name and the argument list.
+    ($func, $u) = split(' ', $func);
+    $seenu{$func} = defined $u ? length $u : 0;
+    my $FUNC = uc $func; # for output.
+    push @seenf, $func;
     my %m = %map;
-    if ($t) {
-	$m{S} = "$t*";
-	$m{R} = "$t**";
+    if ($type) {
+	$m{S} = "$type*";
+	$m{R} = "$type**";
     }
+
+    # Set any special mapping variables (like X=x_t)
     if (@p) {
 	while ($p[-1] =~ /=/) {
 	    my ($k, $v) = ($p[-1] =~ /^([A-Za-z])\s*=\s*(.*)/);
@@ -158,27 +161,32 @@ while (<DATA>) {
 	    pop @p;
 	}
     }
-    if ($opts{U} && open(U, ">d_${f}_r.U"))  {
+
+    # If given the -U option open up the metaconfig unit for this function.
+    if ($opts{U} && open(U, ">d_${func}_r.U"))  {
 	select U;
     }
-    my $prereqs  = '';
-    my $prereqh  = '';
-    my $prereqsh = '';
-    if ($h ne 'stdio') { # There's no i_stdio.
-	$prereqs  = "i_$h";
-	$prereqh  = "$h.h";
-	$prereqsh = "\$$prereqs $prereqh";
-    }
+
     if ($opts{U}) {
+	# The metaconfig units needs prerequisite dependencies.
+	my $prereqs  = '';
+	my $prereqh  = '';
+	my $prereqsh = '';
+	if ($hdr ne 'stdio') { # There's no i_stdio.
+	    $prereqs  = "i_$hdr";
+	    $prereqh  = "$hdr.h";
+	    $prereqsh = "\$$prereqs $prereqh";
+	}
 	my @prereq = qw(Inlibc Protochk Hasproto i_systypes usethreads);
 	push @prereq, $prereqs;
         my $hdrs = "\$i_systypes sys/types.h define stdio.h $prereqsh";
-        if ($h eq 'time') {
+        if ($hdr eq 'time') {
 	    $hdrs .= " \$i_systime sys/time.h";
 	    push @prereq, 'i_systime';
 	}
+	# Output the metaconfig unit header.
 	print <<EOF;
-?RCS: \$Id: d_${f}_r.U,v $
+?RCS: \$Id: d_${func}_r.U,v $
 ?RCS:
 ?RCS: Copyright (c) 2002 Jarkko Hietaniemi
 ?RCS:
@@ -187,44 +195,44 @@ while (<DATA>) {
 ?RCS:
 ?RCS: Generated by the reentr.pl from the Perl 5.8 distribution.
 ?RCS:
-?MAKE:d_${f}_r ${f}_r_proto: @prereq
+?MAKE:d_${func}_r ${func}_r_proto: @prereq
 ?MAKE:	-pick add \$@ %<
-?S:d_${f}_r:
-?S:	This variable conditionally defines the HAS_${F}_R symbol,
-?S:	which indicates to the C program that the ${f}_r()
+?S:d_${func}_r:
+?S:	This variable conditionally defines the HAS_${FUNC}_R symbol,
+?S:	which indicates to the C program that the ${func}_r()
 ?S:	routine is available.
 ?S:.
-?S:${f}_r_proto:
-?S:	This variable encodes the prototype of ${f}_r.
+?S:${func}_r_proto:
+?S:	This variable encodes the prototype of ${func}_r.
 ?S:.
-?C:HAS_${F}_R:
-?C:	This symbol, if defined, indicates that the ${f}_r routine
-?C:	is available to ${f} re-entrantly.
+?C:HAS_${FUNC}_R:
+?C:	This symbol, if defined, indicates that the ${func}_r routine
+?C:	is available to ${func} re-entrantly.
 ?C:.
-?C:${F}_R_PROTO:
-?C:	This symbol encodes the prototype of ${f}_r.
+?C:${FUNC}_R_PROTO:
+?C:	This symbol encodes the prototype of ${func}_r.
 ?C:.
-?H:#\$d_${f}_r HAS_${F}_R	   /**/
-?H:#define ${F}_R_PROTO \$${f}_r_proto	   /**/
+?H:#\$d_${func}_r HAS_${FUNC}_R	   /**/
+?H:#define ${FUNC}_R_PROTO \$${func}_r_proto	   /**/
 ?H:.
-?T:try hdrs d_${f}_r_proto
-?LINT:set d_${f}_r
-?LINT:set ${f}_r_proto
-: see if ${f}_r exists
-set ${f}_r d_${f}_r
+?T:try hdrs d_${func}_r_proto
+?LINT:set d_${func}_r
+?LINT:set ${func}_r_proto
+: see if ${func}_r exists
+set ${func}_r d_${func}_r
 eval \$inlibc
-case "\$d_${f}_r" in
+case "\$d_${func}_r" in
 "\$define")
 EOF
 	print <<EOF;
 	hdrs="$hdrs"
-	case "\$d_${f}_r_proto:\$usethreads" in
-	":define")	d_${f}_r_proto=define
-		set d_${f}_r_proto ${f}_r \$hdrs
+	case "\$d_${func}_r_proto:\$usethreads" in
+	":define")	d_${func}_r_proto=define
+		set d_${func}_r_proto ${func}_r \$hdrs
 		eval \$hasproto ;;
 	*)	;;
 	esac
-	case "\$d_${f}_r_proto" in
+	case "\$d_${func}_r_proto" in
 	define)
 EOF
     }
@@ -233,41 +241,41 @@ EOF
 	my $v = join(", ", map { $m{$_} } split '', $a);
 	if ($opts{U}) {
 	    print <<EOF ;
-	case "\$${f}_r_proto" in
-	''|0) try='$m{$r} ${f}_r($v);'
-	./protochk "extern \$try" \$hdrs && ${f}_r_proto=$p ;;
+	case "\$${func}_r_proto" in
+	''|0) try='$m{$r} ${func}_r($v);'
+	./protochk "extern \$try" \$hdrs && ${func}_r_proto=$p ;;
 	esac
 EOF
         }
-        $seenh{$f}->{$p}++;
-        push @{$seena{$f}}, $p;
+        $seenh{$func}->{$p}++;
+        push @{$seena{$func}}, $p;
         $seenp{$p}++;
-        $seent{$f} = $t;
-        $seens{$f} = $m{S};
-        $seend{$f} = $m{D};
+        $seent{$func} = $type;
+        $seens{$func} = $m{S};
+        $seend{$func} = $m{D};
     }
     if ($opts{U}) {
 	print <<EOF;
-	case "\$${f}_r_proto" in
-	''|0)	d_${f}_r=undef
- 	        ${f}_r_proto=0
-		echo "Disabling ${f}_r, cannot determine prototype." >&4 ;;
-	* )	case "\$${f}_r_proto" in
+	case "\$${func}_r_proto" in
+	''|0)	d_${func}_r=undef
+ 	        ${func}_r_proto=0
+		echo "Disabling ${func}_r, cannot determine prototype." >&4 ;;
+	* )	case "\$${func}_r_proto" in
 		REENTRANT_PROTO*) ;;
-		*) ${f}_r_proto="REENTRANT_PROTO_\$${f}_r_proto" ;;
+		*) ${func}_r_proto="REENTRANT_PROTO_\$${func}_r_proto" ;;
 		esac
 		echo "Prototype: \$try" ;;
 	esac
 	;;
 	*)	case "\$usethreads" in
-		define) echo "${f}_r has no prototype, not using it." >&4 ;;
+		define) echo "${func}_r has no prototype, not using it." >&4 ;;
 		esac
-		d_${f}_r=undef
-		${f}_r_proto=0
+		d_${func}_r=undef
+		${func}_r_proto=0
 		;;
 	esac
 	;;
-*)	${f}_r_proto=0
+*)	${func}_r_proto=0
 	;;
 esac
 
@@ -278,9 +286,12 @@ EOF
 
 close DATA;
 
+# Prepare to continue writing the reentr.h.
+
 select H;
 
 {
+    # Write out all the known prototype signatures.
     my $i = 1;
     for my $p (sort keys %seenp) {
 	print "#define REENTRANT_PROTO_${p}	${i}\n";
@@ -288,18 +299,18 @@ select H;
     }
 }
 
+my @struct; # REENTR struct members
+my @size;   # struct member buffer size initialization code
+my @init;   # struct member buffer initialization (malloc) code
+my @free;   # struct member buffer release (free) code
+my @wrap;   # the wrapper (foo(a) -> foo_r(a,...)) cpp code
+my @define; # defines for optional features
+
 sub ifprotomatch {
-    my $F = shift;
-    join " || ", map { "${F}_R_PROTO == REENTRANT_PROTO_$_" } @_;
+    my $FUNC = shift;
+    join " || ", map { "${FUNC}_R_PROTO == REENTRANT_PROTO_$_" } @_;
 }
 
-my @struct;
-my @size;
-my @init;
-my @free;
-my @wrap;
-my @define;
-
 sub pushssif {
     push @struct, @_;
     push @size, @_;
@@ -308,12 +319,12 @@ sub pushssif {
 }
 
 sub pushinitfree {
-    my $f = shift;
+    my $func = shift;
     push @init, <<EOF;
-	New(31338, PL_reentrant_buffer->_${f}_buffer, PL_reentrant_buffer->_${f}_size, char);
+	New(31338, PL_reentrant_buffer->_${func}_buffer, PL_reentrant_buffer->_${func}_size, char);
 EOF
     push @free, <<EOF;
-	Safefree(PL_reentrant_buffer->_${f}_buffer);
+	Safefree(PL_reentrant_buffer->_${func}_buffer);
 EOF
 }
 
@@ -325,23 +336,23 @@ sub define {
 /* The @F using \L$n? */
 
 EOF
-    my $G;
-    for my $f (@F) {
-	my $F = uc $f;
-	my $h = "${F}_R_HAS_$n";
-	push @H, $h;
-	my @h = grep { /$p/ } @{$seena{$f}};
-	unless (defined $G) {
-	    $G = $F;
-	    $G =~ s/^GET//;
+    my $GENFUNC;
+    for my $func (@F) {
+	my $FUNC = uc $func;
+	my $HAS = "${FUNC}_R_HAS_$n";
+	push @H, $HAS;
+	my @h = grep { /$p/ } @{$seena{$func}};
+	unless (defined $GENFUNC) {
+	    $GENFUNC = $FUNC;
+	    $GENFUNC =~ s/^GET//;
 	}
 	if (@h) {
-	    push @define, "#if defined(HAS_${F}_R) && (" . join(" || ", map { "${F}_R_PROTO == REENTRANT_PROTO_$_" } @h) . ")\n";
+	    push @define, "#if defined(HAS_${FUNC}_R) && (" . join(" || ", map { "${FUNC}_R_PROTO == REENTRANT_PROTO_$_" } @h) . ")\n";
 
 	    push @define, <<EOF;
-#   define $h
+#   define $HAS
 #else
-#   undef  $h
+#   undef  $HAS
 #endif
 EOF
         }
@@ -353,9 +364,9 @@ EOF
 EOF
     push @define, "#if (" . join(" || ", map { "defined($_)" } @H) . ")\n";
     push @define, <<EOF;
-#   define USE_${G}_$n
+#   define USE_${GENFUNC}_$n
 #else
-#   undef  USE_${G}_$n
+#   undef  USE_${GENFUNC}_$n
 #endif
 
 EOF
@@ -402,171 +413,181 @@ define('ERRNO', 'E',
 define('ERRNO', 'E',
        qw(getnetent getnetbyaddr getnetbyname));
 
-for my $f (@seenf) {
-    my $F = uc $f;
-    my $ifdef = "#ifdef HAS_${F}_R\n";
-    my $endif = "#endif /* HAS_${F}_R */\n";
-    if (exists $seena{$f}) {
-	my @p = @{$seena{$f}};
-	if ($f =~ /^(asctime|ctime|getlogin|setlocale|strerror|ttyname)$/) {
+# The following loop accumulates the "ssif" (struct, size, init, free)
+# sections that declare the struct members (in reentr.h), and the buffer
+# size initialization, buffer initialization (malloc), and buffer
+# release (free) code (in reentr.c).
+#
+# The loop also contains a lot of intrinsic logic about groups of
+# functions (since functions of certain kind operate the same way).
+
+for my $func (@seenf) {
+    my $FUNC = uc $func;
+    my $ifdef = "#ifdef HAS_${FUNC}_R\n";
+    my $endif = "#endif /* HAS_${FUNC}_R */\n";
+    if (exists $seena{$func}) {
+	my @p = @{$seena{$func}};
+	if ($func =~ /^(asctime|ctime|getlogin|setlocale|strerror|ttyname)$/) {
 	    pushssif $ifdef;
 	    push @struct, <<EOF;
-	char*	_${f}_buffer;
-	size_t	_${f}_size;
+	char*	_${func}_buffer;
+	size_t	_${func}_size;
 EOF
 	    push @size, <<EOF;
-	PL_reentrant_buffer->_${f}_size = REENTRANTSMALLSIZE;
+	PL_reentrant_buffer->_${func}_size = REENTRANTSMALLSIZE;
 EOF
-	    pushinitfree $f;
+	    pushinitfree $func;
 	    pushssif $endif;
 	}
-        elsif ($f =~ /^(crypt)$/) {
+        elsif ($func =~ /^(crypt)$/) {
 	    pushssif $ifdef;
 	    push @struct, <<EOF;
 #if CRYPT_R_PROTO == REENTRANT_PROTO_B_CCD
-	$seend{$f} _${f}_data;
+	$seend{$func} _${func}_data;
 #else
-	$seent{$f} _${f}_struct;
+	$seent{$func} _${func}_struct;
 #endif
 EOF
     	    push @init, <<EOF;
 #ifdef __GLIBC__
-	PL_reentrant_buffer->_${f}_struct.initialized = 0;
+	PL_reentrant_buffer->_${func}_struct.initialized = 0;
 #endif
 EOF
 	    pushssif $endif;
 	}
-        elsif ($f =~ /^(drand48|gmtime|localtime|random)$/) {
+        elsif ($func =~ /^(drand48|gmtime|localtime|random)$/) {
 	    pushssif $ifdef;
 	    push @struct, <<EOF;
-	$seent{$f} _${f}_struct;
+	$seent{$func} _${func}_struct;
 EOF
 	    if ($1 eq 'drand48') {
 	        push @struct, <<EOF;
-	double	_${f}_double;
+	double	_${func}_double;
 EOF
 	    }
 	    pushssif $endif;
 	}
-        elsif ($f =~ /^(getgrnam|getpwnam|getspnam)$/) {
+        elsif ($func =~ /^(getgrnam|getpwnam|getspnam)$/) {
 	    pushssif $ifdef;
-	    my $g = $f;
-	    $g =~ s/nam/ent/g;
-	    $g =~ s/^get//;
-	    my $G = uc $g;
+	    # 'genfunc' can be read either as 'generic' or 'genre',
+	    # it represents a group of functions.
+	    my $genfunc = $func;
+	    $genfunc =~ s/nam/ent/g;
+	    $genfunc =~ s/^get//;
+	    my $GENFUNC = uc $genfunc;
 	    push @struct, <<EOF;
-	$seent{$f}	_${g}_struct;
-	char*	_${g}_buffer;
-	size_t	_${g}_size;
+	$seent{$func}	_${genfunc}_struct;
+	char*	_${genfunc}_buffer;
+	size_t	_${genfunc}_size;
 EOF
             push @struct, <<EOF;
-#   ifdef USE_${G}_PTR
-	$seent{$f}*	_${g}_ptr;
+#   ifdef USE_${GENFUNC}_PTR
+	$seent{$func}*	_${genfunc}_ptr;
 #   endif
 EOF
-    	    if ($g eq 'getspent') {
+    	    if ($genfunc eq 'getspent') {
 		push @size, <<EOF;
-	PL_reentrant_buffer->_${g}_size = 1024;
+	PL_reentrant_buffer->_${genfunc}_size = 1024;
 EOF
 	    } else {
 	        push @struct, <<EOF;
-#   ifdef USE_${G}_FPTR
-	FILE*	_${g}_fptr;
+#   ifdef USE_${GENFUNC}_FPTR
+	FILE*	_${genfunc}_fptr;
 #   endif
 EOF
 		    push @init, <<EOF;
-#   ifdef USE_${G}_FPTR
-	PL_reentrant_buffer->_${g}_fptr = NULL;
+#   ifdef USE_${GENFUNC}_FPTR
+	PL_reentrant_buffer->_${genfunc}_fptr = NULL;
 #   endif
 EOF
-		my $sc = $g eq 'getgrent' ?
+		my $sc = $genfunc eq 'getgrent' ?
 		    '_SC_GETGR_R_SIZE_MAX' : '_SC_GETPW_R_SIZE_MAX';
-		my $sz = $g eq 'getgrent' ?
+		my $sz = $genfunc eq 'getgrent' ?
                     '_grent_size' : '_pwent_size';
 		push @size, <<EOF;
 #   if defined(HAS_SYSCONF) && defined($sc) && !defined(__GLIBC__)
-	PL_reentrant_buffer->_${g}_size = sysconf($sc);
+	PL_reentrant_buffer->_${genfunc}_size = sysconf($sc);
 	if (PL_reentrant_buffer->$sz == -1)
 		PL_reentrant_buffer->$sz = REENTRANTUSUALSIZE;
 #   else
 #       if defined(__osf__) && defined(__alpha) && defined(SIABUFSIZ)
-	PL_reentrant_buffer->_${g}_size = SIABUFSIZ;
+	PL_reentrant_buffer->_${genfunc}_size = SIABUFSIZ;
 #       else
 #           ifdef __sgi
-	PL_reentrant_buffer->_${g}_size = BUFSIZ;
+	PL_reentrant_buffer->_${genfunc}_size = BUFSIZ;
 #           else
-	PL_reentrant_buffer->_${g}_size = REENTRANTUSUALSIZE;
+	PL_reentrant_buffer->_${genfunc}_size = REENTRANTUSUALSIZE;
 #           endif
 #       endif
 #   endif 
 EOF
             }
-	    pushinitfree $g;
+	    pushinitfree $genfunc;
 	    pushssif $endif;
 	}
-        elsif ($f =~ /^(gethostbyname|getnetbyname|getservbyname|getprotobyname)$/) {
+        elsif ($func =~ /^(gethostbyname|getnetbyname|getservbyname|getprotobyname)$/) {
 	    pushssif $ifdef;
-	    my $g = $f;
-	    $g =~ s/byname/ent/;
-	    $g =~ s/^get//;
-	    my $G = uc $g;
-	    my $D = ifprotomatch($F, grep {/D/} @p);
-	    my $d = $seend{$f};
+	    my $genfunc = $func;
+	    $genfunc =~ s/byname/ent/;
+	    $genfunc =~ s/^get//;
+	    my $GENFUNC = uc $genfunc;
+	    my $D = ifprotomatch($FUNC, grep {/D/} @p);
+	    my $d = $seend{$func};
 	    $d =~ s/\*$//; # snip: we need need the base type.
 	    push @struct, <<EOF;
-	$seent{$f}	_${g}_struct;
+	$seent{$func}	_${genfunc}_struct;
 #   if $D
-	$d	_${g}_data;
+	$d	_${genfunc}_data;
 #   else
-	char*	_${g}_buffer;
-	size_t	_${g}_size;
+	char*	_${genfunc}_buffer;
+	size_t	_${genfunc}_size;
 #   endif
-#   ifdef USE_${G}_PTR
-	$seent{$f}*	_${g}_ptr;
+#   ifdef USE_${GENFUNC}_PTR
+	$seent{$func}*	_${genfunc}_ptr;
 #   endif
 EOF
     	    push @struct, <<EOF;
-#   ifdef USE_${G}_ERRNO
-	int	_${g}_errno;
+#   ifdef USE_${GENFUNC}_ERRNO
+	int	_${genfunc}_errno;
 #   endif 
 EOF
 	    push @size, <<EOF;
 #if   !($D)
-	PL_reentrant_buffer->_${g}_size = REENTRANTUSUALSIZE;
+	PL_reentrant_buffer->_${genfunc}_size = REENTRANTUSUALSIZE;
 #endif
 EOF
 	    push @init, <<EOF;
 #if   !($D)
-	New(31338, PL_reentrant_buffer->_${g}_buffer, PL_reentrant_buffer->_${g}_size, char);
+	New(31338, PL_reentrant_buffer->_${genfunc}_buffer, PL_reentrant_buffer->_${genfunc}_size, char);
 #endif
 EOF
 	    push @free, <<EOF;
 #if   !($D)
-	Safefree(PL_reentrant_buffer->_${g}_buffer);
+	Safefree(PL_reentrant_buffer->_${genfunc}_buffer);
 #endif
 EOF
 	    pushssif $endif;
 	}
-        elsif ($f =~ /^(readdir|readdir64)$/) {
+        elsif ($func =~ /^(readdir|readdir64)$/) {
 	    pushssif $ifdef;
-	    my $R = ifprotomatch($F, grep {/R/} @p);
+	    my $R = ifprotomatch($FUNC, grep {/R/} @p);
 	    push @struct, <<EOF;
-	$seent{$f}*	_${f}_struct;
-	size_t	_${f}_size;
+	$seent{$func}*	_${func}_struct;
+	size_t	_${func}_size;
 #   if $R
-	$seent{$f}*	_${f}_ptr;
+	$seent{$func}*	_${func}_ptr;
 #   endif
 EOF
 	    push @size, <<EOF;
 	/* This is the size Solaris recommends.
 	 * (though we go static, should use pathconf() instead) */
-	PL_reentrant_buffer->_${f}_size = sizeof($seent{$f}) + MAXPATHLEN + 1;
+	PL_reentrant_buffer->_${func}_size = sizeof($seent{$func}) + MAXPATHLEN + 1;
 EOF
     	    push @init, <<EOF;
-	PL_reentrant_buffer->_${f}_struct = ($seent{$f}*)safemalloc(PL_reentrant_buffer->_${f}_size);
+	PL_reentrant_buffer->_${func}_struct = ($seent{$func}*)safemalloc(PL_reentrant_buffer->_${func}_size);
 EOF
 	    push @free, <<EOF;
-	Safefree(PL_reentrant_buffer->_${f}_struct);
+	Safefree(PL_reentrant_buffer->_${func}_struct);
 EOF
 	    pushssif $endif;
 	}
@@ -574,79 +595,82 @@ EOF
 	push @wrap, $ifdef;
 
 	push @wrap, <<EOF;
-#   undef $f
+#   undef $func
 EOF
+
+        # Write out what we have learned.
+	
         my @v = 'a'..'z';
-        my $v = join(", ", @v[0..$seenu{$f}-1]);
+        my $v = join(", ", @v[0..$seenu{$func}-1]);
 	for my $p (@p) {
 	    my ($r, $a) = split '_', $p;
 	    my $test = $r eq 'I' ? ' == 0' : '';
 	    my $true  = 1;
-	    my $g = $f;
-	    if ($g =~ /^(?:get|set|end)(pw|gr|host|net|proto|serv|sp)/) {
-		$g = "$1ent";
-	    } elsif ($g eq 'srand48') {
-		$g = "drand48";
+	    my $genfunc = $func;
+	    if ($genfunc =~ /^(?:get|set|end)(pw|gr|host|net|proto|serv|sp)/) {
+		$genfunc = "${1}ent";
+	    } elsif ($genfunc eq 'srand48') {
+		$genfunc = "drand48";
 	    }
 	    my $b = $a;
 	    my $w = '';
-	    substr($b, 0, $seenu{$f}) = '';
+	    substr($b, 0, $seenu{$func}) = '';
 	    if ($b =~ /R/) {
-		$true = "PL_reentrant_buffer->_${g}_ptr";
-	    } elsif ($b =~ /T/ && $f eq 'drand48') {
-		$true = "PL_reentrant_buffer->_${g}_double";
+		$true = "PL_reentrant_buffer->_${genfunc}_ptr";
+	    } elsif ($b =~ /T/ && $func eq 'drand48') {
+		$true = "PL_reentrant_buffer->_${genfunc}_double";
 	    } elsif ($b =~ /S/) {
-		if ($f =~ /^readdir/) {
-		    $true = "PL_reentrant_buffer->_${g}_struct";
+		if ($func =~ /^readdir/) {
+		    $true = "PL_reentrant_buffer->_${genfunc}_struct";
 		} else {
-		    $true = "&PL_reentrant_buffer->_${g}_struct";
+		    $true = "&PL_reentrant_buffer->_${genfunc}_struct";
 		}
 	    } elsif ($b =~ /B/) {
-		$true = "PL_reentrant_buffer->_${g}_buffer";
+		$true = "PL_reentrant_buffer->_${genfunc}_buffer";
 	    }
 	    if (length $b) {
 		$w = join ", ",
 		         map {
 			     $_ eq 'R' ?
-				 "&PL_reentrant_buffer->_${g}_ptr" :
+				 "&PL_reentrant_buffer->_${genfunc}_ptr" :
 			     $_ eq 'E' ?
-				 "&PL_reentrant_buffer->_${g}_errno" :
+				 "&PL_reentrant_buffer->_${genfunc}_errno" :
 			     $_ eq 'B' ?
-				 "PL_reentrant_buffer->_${g}_buffer" :
+				 "PL_reentrant_buffer->_${genfunc}_buffer" :
 			     $_ =~ /^[WI]$/ ?
-				 "PL_reentrant_buffer->_${g}_size" :
+				 "PL_reentrant_buffer->_${genfunc}_size" :
 			     $_ eq 'H' ?
-				 "&PL_reentrant_buffer->_${g}_fptr" :
+				 "&PL_reentrant_buffer->_${genfunc}_fptr" :
 			     $_ eq 'D' ?
-				 "&PL_reentrant_buffer->_${g}_data" :
+				 "&PL_reentrant_buffer->_${genfunc}_data" :
 			     $_ eq 'S' ?
-				 ($f =~ /^readdir/ ?
-				  "PL_reentrant_buffer->_${g}_struct" :
-				  "&PL_reentrant_buffer->_${g}_struct" ) :
-			     $_ eq 'T' && $f eq 'drand48' ?
-				 "&PL_reentrant_buffer->_${g}_double" :
+				 ($func =~ /^readdir/ ?
+				  "PL_reentrant_buffer->_${genfunc}_struct" :
+				  "&PL_reentrant_buffer->_${genfunc}_struct" ) :
+			     $_ eq 'T' && $func eq 'drand48' ?
+				 "&PL_reentrant_buffer->_${genfunc}_double" :
 				 $_
 			 } split '', $b;
 		$w = ", $w" if length $v;
 	    }
-	    my $call = "${f}_r($v$w)";
+	    my $call = "${func}_r($v$w)";
 	    $call = "((errno = $call))" if $r eq 'I';
 	    push @wrap, <<EOF;
-#   if !defined($f) && ${F}_R_PROTO == REENTRANT_PROTO_$p
+#   if !defined($func) && ${FUNC}_R_PROTO == REENTRANT_PROTO_$p
 EOF
 	    if ($r eq 'V' || $r eq 'B') {
 	        push @wrap, <<EOF;
-#       define $f($v) $call
+#       define $func($v) $call
 EOF
 	    } else {
-		if ($f =~ /^get/) {
+		if ($func =~ /^get/) {
 		    my $rv = $v ? ", $v" : "";
 		    push @wrap, <<EOF;
-#       define $f($v) ($call$test ? $true : (errno == ERANGE ? Perl_reentrant_retry("$f"$rv) : 0))
+#       define $func($v) ($call$test ? $true : (errno == ERANGE ? Perl_reentrant_retry("$func"$rv) : 0))
 EOF
 		} else {
 		    push @wrap, <<EOF;
-#       define $f($v) ($call$test ? $true : 0)
+#       define $func($v) ($call$test ? $true : 0)
 EOF
 		}
 	    }
@@ -668,7 +692,7 @@ print <<EOF;
 @define
 typedef struct {
 @struct
-    int dummy; /* just in case */
+    int dummy; /* cannot have empty structs */
 } REENTR;
 
 /* The wrappers. */
@@ -682,6 +706,8 @@ EOF
 
 close(H);
 
+# Prepare to write the reentr.c.
+
 die "reentr.c: $!" unless open(C, ">reentr.c");
 select C;
 print <<EOF;