From f1e9a32ee7fad2263636a51536ce0f9f13f09949 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Petr=20P=C3=ADsa=C5=99?= <ppisar@redhat.com>
Date: Wed, 23 Jan 2019 10:16:20 +0100
Subject: [PATCH] Declare POSIX regex function names as macros to PCRE
 functions
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POSIX regex libraries differ in regex_t size. If a program includes
<pcreposix.h>, but is not linked to pcreposix library at run-time
(either in effect of --as-needed or a lazy binding in dlopen)
other implementation touches memory out of the structure and the
program can crash.

That means once a program includes <pcreposix.h>, it must link to the
pcreposix library.

This patch replaces the POSIX regex declaration with macros to the
PCRE uniqely-named function. This ensures that the PCRE's regex_t
structure is always handled by the PCRE functions.

This patch still preserves the POSIX regex definitions in order to
preseve ABI with application compiled before this change. The
definition can be removed in the future.

Signed-off-by: Petr Písař <ppisar@redhat.com>
---
 pcreposix.c | 50 +++++++++++++++++++++++++++++++++++++++++++++-----
 pcreposix.h | 20 ++++++++++++++------
 2 files changed, 59 insertions(+), 11 deletions(-)

diff --git a/pcreposix.c b/pcreposix.c
index a76d6bf..3f2f3ef 100644
--- a/pcreposix.c
+++ b/pcreposix.c
@@ -39,7 +39,10 @@ POSSIBILITY OF SUCH DAMAGE.
 
 
 /* This module is a wrapper that provides a POSIX API to the underlying PCRE
-functions. */
+functions. The operative functions are called pcre_regcomp(), etc., with
+wrappers that use the plain POSIX names. This makes it easier for an
+application to be sure it gets the PCRE versions in the presence of other
+POSIX regex libraries. */
 
 
 #ifdef HAVE_CONFIG_H
@@ -204,12 +207,49 @@ static const char *const pstring[] = {
 
 
 /*************************************************
-*          Translate error code to string        *
+*      Wrappers with traditional POSIX names     *
 *************************************************/
 
+/* Keep defining them to preseve ABI with application linked to pcreposix
+ * library before they were changed into macros. */
+
+#undef regerror
 PCREPOSIX_EXP_DEFN size_t PCRE_CALL_CONVENTION
 regerror(int errcode, const regex_t *preg, char *errbuf, size_t errbuf_size)
 {
+return pcre_regerror(errcode, preg, errbuf, errbuf_size);
+}
+
+#undef regfree
+PCREPOSIX_EXP_DEFN void PCRE_CALL_CONVENTION
+regfree(regex_t *preg)
+{
+pcre_regfree(preg);
+}
+
+#undef regcomp
+PCREPOSIX_EXP_DEFN int PCRE_CALL_CONVENTION
+regcomp(regex_t *preg, const char *pattern, int cflags)
+{
+return pcre_regcomp(preg, pattern, cflags);
+}
+
+#undef regexec
+PCREPOSIX_EXP_DEFN int PCRE_CALL_CONVENTION
+regexec(const regex_t *preg, const char *string, size_t nmatch,
+  regmatch_t pmatch[], int eflags)
+{
+return pcre_regexec(preg, string, nmatch, pmatch, eflags);
+}
+
+
+/*************************************************
+*          Translate error code to string        *
+*************************************************/
+
+PCREPOSIX_EXP_DEFN size_t PCRE_CALL_CONVENTION
+pcre_regerror(int errcode, const regex_t *preg, char *errbuf, size_t errbuf_size)
+{
 const char *message, *addmessage;
 size_t length, addlength;
 
@@ -243,7 +283,7 @@ return length + addlength;
 *************************************************/
 
 PCREPOSIX_EXP_DEFN void PCRE_CALL_CONVENTION
-regfree(regex_t *preg)
+pcre_regfree(regex_t *preg)
 {
 (PUBL(free))(preg->re_pcre);
 }
@@ -266,7 +306,7 @@ Returns:      0 on success
 */
 
 PCREPOSIX_EXP_DEFN int PCRE_CALL_CONVENTION
-regcomp(regex_t *preg, const char *pattern, int cflags)
+pcre_regcomp(regex_t *preg, const char *pattern, int cflags)
 {
 const char *errorptr;
 int erroffset;
@@ -320,7 +360,7 @@ be set. When this is the case, the nmatch and pmatch arguments are ignored, and
 the only result is yes/no/error. */
 
 PCREPOSIX_EXP_DEFN int PCRE_CALL_CONVENTION
-regexec(const regex_t *preg, const char *string, size_t nmatch,
+pcre_regexec(const regex_t *preg, const char *string, size_t nmatch,
   regmatch_t pmatch[], int eflags)
 {
 int rc, so, eo;
diff --git a/pcreposix.h b/pcreposix.h
index c77c0b0..6f108b8 100644
--- a/pcreposix.h
+++ b/pcreposix.h
@@ -131,13 +131,21 @@ file. */
 #  endif
 #endif
 
-/* The functions */
-
-PCREPOSIX_EXP_DECL int regcomp(regex_t *, const char *, int);
-PCREPOSIX_EXP_DECL int regexec(const regex_t *, const char *, size_t,
+/* The functions. The actual code is in functions with pcre_xxx names for
+uniqueness. POSIX names are provided for API compatibility with POSIX regex
+functions. It's done this way to ensure to they are always get from the
+PCRE library and not by accident from elsewhere. (regex_t differs in size
+elsewhere.) */
+
+PCREPOSIX_EXP_DECL int pcre_regcomp(regex_t *, const char *, int);
+#define regcomp pcre_regcomp
+PCREPOSIX_EXP_DECL int pcre_regexec(const regex_t *, const char *, size_t,
                      regmatch_t *, int);
-PCREPOSIX_EXP_DECL size_t regerror(int, const regex_t *, char *, size_t);
-PCREPOSIX_EXP_DECL void regfree(regex_t *);
+#define regexec pcre_regexec
+PCREPOSIX_EXP_DECL size_t pcre_regerror(int, const regex_t *, char *, size_t);
+#define regerror pcre_regerror
+PCREPOSIX_EXP_DECL void pcre_regfree(regex_t *);
+#define regfree pcre_regfree
 
 #ifdef __cplusplus
 }   /* extern "C" */
-- 
2.17.2