Introduce a new function, pv_escape(), to display contents of PVs

that might contain non printable chars.

Subject: Re: [PATCH]: fix: [perl #39583] Pattern Match fails for specific length string
Message-ID: <9b18b3110607051140n10c211a1jf17d3b7914d6f68b@mail.gmail.com>

p4raw-id: //depot/perl@28490

10 files changed, 215 insertions, 54 deletions

diff --git a/dump.c b/dump.c
index 0116e992c4..98405c6fad 100644
--- a/dump.c
+++ b/dump.c
@@ -119,40 +119,121 @@ Perl_dump_eval(pTHX)
     op_dump(PL_eval_root);
 }
 
-char *
-Perl_pv_display(pTHX_ SV *dsv, const char *pv, STRLEN cur, STRLEN len, STRLEN pvlim)
-{
-    const bool nul_terminated = len > cur && pv[cur] == '\0';
-    bool truncated = 0;
 
-    sv_setpvn(dsv, "\"", 1);
-    for (; cur--; pv++) {
-	if (pvlim && SvCUR(dsv) >= pvlim) {
-            truncated = 1;
-	    break;
-        }
-	switch (*pv) {
-	case '\t': sv_catpvs(dsv, "\\t");  break;
-	case '\n': sv_catpvs(dsv, "\\n");  break;
-	case '\r': sv_catpvs(dsv, "\\r");  break;
-	case '\f': sv_catpvs(dsv, "\\f");  break;
-	case '"':  sv_catpvs(dsv, "\\\""); break;
-	case '\\': sv_catpvs(dsv, "\\\\"); break;
-	default:
-	    if (isPRINT(*pv))
-		sv_catpvn(dsv, pv, 1);
-	    else if (cur && isDIGIT(*(pv+1)))
-		Perl_sv_catpvf(aTHX_ dsv, "\\%03o", (U8)*pv);
-	    else
-		Perl_sv_catpvf(aTHX_ dsv, "\\%o", (U8)*pv);
-        }
+/*
+=for apidoc Apd|char*|pv_escape|NN SV *dsv|NN const char *pv|const STRLEN count|const STRLEN max|const U32 flags
+
+Escapes at most the first "count" chars of pv and puts the results into
+buf such that the size of the escaped string will not exceed "max" chars
+and will not contain any incomplete escape sequences.
+
+If flags contains PERL_PV_ESCAPE_QUOTE then the string will have quotes
+placed around it; moreover, if the number of chars converted was less than
+"count" then a trailing elipses (...) will be added after the closing
+quote.
+
+If PERL_PV_ESCAPE_QUOTE is not set, but PERL_PV_ESCAPE_PADR is, then the
+returned string will be right padded with spaces such that it is max chars
+long.
+
+Normally the SV will be cleared before the escaped string is prepared,
+but when PERL_PV_ESCAPE_CAT is set this will not occur.
+
+Returns a pointer to the string contained by SV.
+
+=cut
+*/
+
+char *
+Perl_pv_escape( pTHX_ SV *dsv, const char *pv, const STRLEN count, const STRLEN max, const U32 flags ) {
+    char dq = (flags & PERL_PV_ESCAPE_QUOTE) ? '"' : '\\';
+    char octbuf[8] = "\\0123456";
+    STRLEN wrote = 0;
+    STRLEN chsize = 0;
+    const char *end = pv + count;
+
+    if (flags & PERL_PV_ESCAPE_CAT) {
+	if ( dq == '"' )
+	    sv_catpvn(dsv, "\"", 1);
+    } else {
+	if ( dq == '"' )
+	    sv_setpvn(dsv, "\"", 1);
+	else
+	    sv_setpvn(dsv, "", 0);
+    }
+    for ( ; (pv < end && (!max || (wrote < max))) ; pv++ ) {
+	if ( (*pv == dq) || (*pv == '\\') || isCNTRL(*pv) ) {
+	    chsize = 2;
+	    switch (*pv) {
+		case '\\' : octbuf[1] = '\\'; break;
+		case '\v' : octbuf[1] = 'v';  break;
+		case '\t' : octbuf[1] = 't';  break;
+		case '\r' : octbuf[1] = 'r';  break;
+		case '\n' : octbuf[1] = 'n';  break;
+		case '\f' : octbuf[1] = 'f';  break;
+		case '"'  : if ( dq == *pv ) {
+				octbuf[1] = '"';
+				break;
+			    }
+		default:
+			    /* note the (U8*) casts here are important.
+			     * if they are omitted we can produce the octal
+			     * for a negative number which could produce a
+			     * buffer overrun in octbuf, with it on we are
+			     * guaranteed that the longest the string could be
+			     * is 5, (we reserve 8 just because its the first
+			     * power of 2 larger than 5.)*/
+			    if ( (pv < end) && isDIGIT(*(pv+1)) )
+				chsize = sprintf( octbuf, "\\%03o", (U8)*pv);
+			    else
+				chsize = sprintf( octbuf, "\\%o", (U8)*pv);
+	    }
+	    if ( max && (wrote + chsize > max) ) {
+		break;
+	    } else {
+		sv_catpvn(dsv, octbuf, chsize);
+		wrote += chsize;
+	    }
+	} else {
+	    sv_catpvn(dsv, pv, 1);
+	    wrote++;
+	}
     }
-    sv_catpvs(dsv, "\"");
-    if (truncated)
-	sv_catpvs(dsv, "...");
-    if (nul_terminated)
-	sv_catpvs(dsv, "\\0");
+    if ( dq == '"' ) {
+	sv_catpvn( dsv, "\"", 1 );
+	if ( pv < end )
+	    sv_catpvn( dsv, "...", 3 );
+    } else if ( max && (flags & PERL_PV_ESCAPE_PADR) ) {
+	for ( ; wrote < max ; wrote++ )
+	    sv_catpvn( dsv, " ", 1 );
+    }
+    return SvPVX(dsv);
+}
+
+/*
+=for apidoc pv_display
 
+  char *pv_display(SV *dsv, const char *pv, STRLEN cur, STRLEN len,
+                   STRLEN pvlim, U32 flags)
+
+Similar to
+
+  pv_escape(dsv,pv,cur,pvlim,PERL_PV_ESCAPE_QUOTE);
+
+except that an additional "\0" will be appended to the string when
+len > cur and pv[cur] is "\0".
+
+Note that the final string may be up to 7 chars longer than pvlim.
+
+=cut
+*/
+
+char *
+Perl_pv_display(pTHX_ SV *dsv, const char *pv, STRLEN cur, STRLEN len, STRLEN pvlim)
+{
+    pv_escape( dsv, pv, cur, pvlim, PERL_PV_ESCAPE_QUOTE);
+    if (len > cur && pv[cur] == '\0')
+            sv_catpvn( dsv, "\\0", 2 );
     return SvPVX(dsv);
 }
 
diff --git a/embed.fnc b/embed.fnc
index c965b1ae0a..81127e0375 100644
--- a/embed.fnc
+++ b/embed.fnc
@@ -980,8 +980,10 @@ Apd	|void	|sv_setpvn_mg	|NN SV *sv|NN const char *ptr|STRLEN len
 Apd	|void	|sv_setsv_mg	|NN SV *dstr|NULLOK SV *sstr
 Apdbm	|void	|sv_usepvn_mg	|NN SV *sv|NULLOK char *ptr|STRLEN len
 ApR	|MGVTBL*|get_vtbl	|int vtbl_id
-Ap	|char*	|pv_display	|NN SV *dsv|NN const char *pv|STRLEN cur|STRLEN len \
+Apd	|char*	|pv_display	|NN SV *dsv|NN const char *pv|STRLEN cur|STRLEN len \
 				|STRLEN pvlim
+Apd	|char*	|pv_escape	|NN SV *dsv|NN const char *pv|const STRLEN count \
+				|const STRLEN max|const U32 flags
 Afp	|void	|dump_indent	|I32 level|NN PerlIO *file|NN const char* pat|...
 Ap	|void	|dump_vindent	|I32 level|NN PerlIO *file|NN const char* pat \
 				|NULLOK va_list *args
diff --git a/embed.h b/embed.h
index bc5027e81f..8e26433190 100644
--- a/embed.h
+++ b/embed.h
@@ -1000,6 +1000,7 @@
 #define sv_setsv_mg		Perl_sv_setsv_mg
 #define get_vtbl		Perl_get_vtbl
 #define pv_display		Perl_pv_display
+#define pv_escape		Perl_pv_escape
 #define dump_indent		Perl_dump_indent
 #define dump_vindent		Perl_dump_vindent
 #define do_gv_dump		Perl_do_gv_dump
@@ -3182,6 +3183,7 @@
 #define sv_setsv_mg(a,b)	Perl_sv_setsv_mg(aTHX_ a,b)
 #define get_vtbl(a)		Perl_get_vtbl(aTHX_ a)
 #define pv_display(a,b,c,d,e)	Perl_pv_display(aTHX_ a,b,c,d,e)
+#define pv_escape(a,b,c,d,e)	Perl_pv_escape(aTHX_ a,b,c,d,e)
 #define dump_vindent(a,b,c,d)	Perl_dump_vindent(aTHX_ a,b,c,d)
 #define do_gv_dump(a,b,c,d)	Perl_do_gv_dump(aTHX_ a,b,c,d)
 #define do_gvgv_dump(a,b,c,d)	Perl_do_gvgv_dump(aTHX_ a,b,c,d)
diff --git a/global.sym b/global.sym
index bf8b843ca9..c737e97170 100644
--- a/global.sym
+++ b/global.sym
@@ -605,6 +605,7 @@ Perl_sv_setsv_mg
 Perl_sv_usepvn_mg
 Perl_get_vtbl
 Perl_pv_display
+Perl_pv_escape
 Perl_dump_indent
 Perl_dump_vindent
 Perl_do_gv_dump
diff --git a/perl.h b/perl.h
index 3a762fa907..8fd8e21ebc 100644
--- a/perl.h
+++ b/perl.h
@@ -5628,5 +5628,12 @@ extern void moncontrol(int);
 
    so that Configure picks them up. */
 
+/* these are used by Perl_pv_escape() and are here so that they
+ * are available throughout the core */
+
+#define PERL_PV_ESCAPE_QUOTE  1
+#define PERL_PV_ESCAPE_PADR   2
+#define PERL_PV_ESCAPE_CAT    4
+
 #endif /* Include guard */
 
diff --git a/pod/perlapi.pod b/pod/perlapi.pod
index ca1491df63..d832d0a3e5 100644
--- a/pod/perlapi.pod
+++ b/pod/perlapi.pod
@@ -753,6 +753,62 @@ Found in file perl.c
 
 =back
 
+=head1 Functions in file dump.c
+
+
+=over 8
+
+=item pv_display
+X<pv_display>
+
+  char *pv_display(SV *dsv, const char *pv, STRLEN cur, STRLEN len,
+                   STRLEN pvlim, U32 flags)
+
+Similar to
+
+  pv_escape(dsv,pv,cur,pvlim,PERL_PV_ESCAPE_QUOTE);
+
+except that an additional "\0" will be appended to the string when
+len > cur and pv[cur] is "\0".
+
+Note that the final string may be up to 7 chars longer than pvlim.
+
+	char*	pv_display(SV *dsv, const char *pv, STRLEN cur, STRLEN len, STRLEN pvlim)
+
+=for hackers
+Found in file dump.c
+
+=item pv_escape
+X<pv_escape>
+
+Escapes at most the first "count" chars of pv and puts the results into
+buf such that the size of the escaped string will not exceed "max" chars
+and will not contain any incomplete escape sequences.
+
+If flags contains PERL_PV_ESCAPE_QUOTE then the string will have quotes
+placed around it; moreover, if the number of chars converted was less than
+"count" then a trailing elipses (...) will be added after the closing
+quote.
+
+If PERL_PV_ESCAPE_QUOTE is not set, but PERL_PV_ESCAPE_PADR is, then the
+returned string will be right padded with spaces such that it is max chars
+long.
+
+Normally the SV will be cleared before the escaped string is prepared,
+but when PERL_PV_ESCAPE_CAT is set this will not occur.
+
+Returns a pointer to the string contained by SV.
+
+NOTE: the perl_ form of this function is deprecated.
+
+	char*	pv_escape(SV *dsv, const char *pv, const STRLEN count, const STRLEN max, const U32 flags)
+
+=for hackers
+Found in file dump.c
+
+
+=back
+
 =head1 Functions in file mathoms.c
 
 
diff --git a/proto.h b/proto.h
index 4272b1d396..c595c31b36 100644
--- a/proto.h
+++ b/proto.h
@@ -2674,6 +2674,10 @@ PERL_CALLCONV char*	Perl_pv_display(pTHX_ SV *dsv, const char *pv, STRLEN cur, S
 			__attribute__nonnull__(pTHX_1)
 			__attribute__nonnull__(pTHX_2);
 
+PERL_CALLCONV char*	Perl_pv_escape(pTHX_ SV *dsv, const char *pv, const STRLEN count, const STRLEN max, const U32 flags)
+			__attribute__nonnull__(pTHX_1)
+			__attribute__nonnull__(pTHX_2);
+
 PERL_CALLCONV void	Perl_dump_indent(pTHX_ I32 level, PerlIO *file, const char* pat, ...)
 			__attribute__format__(__printf__,pTHX_3,pTHX_4)
 			__attribute__nonnull__(pTHX_2)
diff --git a/reentr.c b/reentr.c
index 6321eb67e8..4dcaf8052b 100644
--- a/reentr.c
+++ b/reentr.c
@@ -44,7 +44,7 @@ Perl_reentrant_size(pTHX) {
 #ifdef HAS_GETGRNAM_R
 #   if defined(HAS_SYSCONF) && defined(_SC_GETGR_R_SIZE_MAX) && !defined(__GLIBC__)
 	PL_reentrant_buffer->_grent_size = sysconf(_SC_GETGR_R_SIZE_MAX);
-	if (PL_reentrant_buffer->_grent_size == -1U)
+	if (PL_reentrant_buffer->_grent_size == -1)
 		PL_reentrant_buffer->_grent_size = REENTRANTUSUALSIZE;
 #   else
 #       if defined(__osf__) && defined(__alpha) && defined(SIABUFSIZ)
diff --git a/regexec.c b/regexec.c
index 9bb8317e7b..53b9ff71c7 100644
--- a/regexec.c
+++ b/regexec.c
@@ -2616,8 +2616,9 @@ S_push_slab(pTHX)
 
 #define REG_NODE_NUM(x) ((x) ? (int)((x)-prog) : -1)
 
-#ifdef DEBUGGING 
-STATIC void 
+#ifdef DEBUGGING
+
+STATIC void
 S_dump_exec_pos(pTHX_ const char *locinput, const regnode *scan, const bool do_utf8)
 {
     const int docolor = *PL_colors[0];
@@ -2646,24 +2647,30 @@ S_dump_exec_pos(pTHX_ const char *locinput, const regnode *scan, const bool do_u
     if (pref0_len > pref_len)
 	pref0_len = pref_len;
     {
-      const char * const s0 =
-	do_utf8 && OP(scan) != CANY ?
-	pv_uni_display(PERL_DEBUG_PAD(0), (U8*)(locinput - pref_len),
-		       pref0_len, 60, UNI_DISPLAY_REGEX) :
-	locinput - pref_len;
-      const int len0 = do_utf8 ? (int)strlen(s0) : pref0_len;
-      const char * const s1 = do_utf8 && OP(scan) != CANY ?
-	pv_uni_display(PERL_DEBUG_PAD(1),
-		       (U8*)(locinput - pref_len + pref0_len),
-		       pref_len - pref0_len, 60, UNI_DISPLAY_REGEX) :
-	locinput - pref_len + pref0_len;
-      const int len1 = do_utf8 ? (int)strlen(s1) : pref_len - pref0_len;
-      const char * const s2 = do_utf8 && OP(scan) != CANY ?
-	pv_uni_display(PERL_DEBUG_PAD(2), (U8*)locinput,
-		       PL_regeol - locinput, 60, UNI_DISPLAY_REGEX) :
-	locinput;
-      const int len2 = do_utf8 ? (int)strlen(s2) : l;
-      PerlIO_printf(Perl_debug_log,
+	const int is_uni = (do_utf8 && OP(scan) != CANY) ? 1 : 0;
+	const char * const s0 = is_uni ?
+	    pv_uni_display(PERL_DEBUG_PAD(0), (U8*)(locinput - pref_len),
+		    pref0_len, 60, UNI_DISPLAY_REGEX) :
+	    pv_escape(PERL_DEBUG_PAD(0), (locinput - pref_len),
+		    pref0_len, 60, 0);
+
+	const int len0 = strlen(s0);
+	const char * const s1 = is_uni ?
+	    pv_uni_display(PERL_DEBUG_PAD(1),
+		    (U8*)(locinput - pref_len + pref0_len),
+		    pref_len - pref0_len, 60, UNI_DISPLAY_REGEX) :
+	    pv_escape(PERL_DEBUG_PAD(1),
+		    (locinput - pref_len + pref0_len),
+		    pref_len - pref0_len, 60, 0);
+
+	const int len1 = (int)strlen(s1);
+	const char * const s2 = is_uni ?
+	    pv_uni_display(PERL_DEBUG_PAD(2), (U8*)locinput,
+		    PL_regeol - locinput, 60, UNI_DISPLAY_REGEX) :
+	    pv_escape(PERL_DEBUG_PAD(2), locinput,
+		    PL_regeol - locinput, 60, 0);
+	const int len2 = (int)strlen(s2);
+	PerlIO_printf(Perl_debug_log,
 		    "%4"IVdf" <%s%.*s%s%s%.*s%s%s%s%.*s%s>%*s|",
 		    (IV)(locinput - PL_bostr),
 		    PL_colors[4],
@@ -2680,6 +2687,7 @@ S_dump_exec_pos(pTHX_ const char *locinput, const regnode *scan, const bool do_u
 		    "");
     }
 }
+
 #endif
 
 STATIC I32			/* 0 failure, 1 success */
diff --git a/t/lib/warnings/9uninit b/t/lib/warnings/9uninit
index fadcd1bd2a..82fc3873ba 100644
--- a/t/lib/warnings/9uninit
+++ b/t/lib/warnings/9uninit
@@ -1017,7 +1017,7 @@ my ($v);
 my %h = ("\0011\002\r\n\t\f\"\\abcdefghijklmnopqrstuvwxyz", undef);
 $v = join '', %h;
 EXPECT
-Use of uninitialized value $h{"\0011\2\r\n\t\f\"\\abcdefghijkl"...} in join or string at - line 6.
+Use of uninitialized value $h{"\0011\2\r\n\t\f\"\\abcdefghijklm"...} in join or string at - line 6.
 ########
 use warnings 'uninitialized';
 my ($m1, $v);