pcre2test: dynamically allocate buffer for JITTARGET (#835)

Always ask `pcre2_config()` for the expected size of buffers and abort if
it is too small.

In the documentation, remove the description of a static buffer size for
JITTARGET.

Author: carenas

doc/pcre2api.3

@@ -1,4 +1,4 @@
-.TH PCRE2API 3 "19 October 2025" "PCRE2 10.48-DEV"
+.TH PCRE2API 3 "29 October 2025" "PCRE2 10.48-DEV"
 .SH NAME
 PCRE2 - Perl-compatible regular expressions (revised API)
 .sp
@@ -1296,14 +1296,15 @@ documentation for more details.
 .sp
   PCRE2_CONFIG_JITTARGET
 .sp
-The \fIwhere\fP argument should point to a buffer that is at least 64 code
-units long. (The exact length required can be found by calling
-\fBpcre2_config()\fP with \fBwhere\fP set to NULL.) The buffer is filled with a
-string that contains the name of the architecture for which the JIT compiler is
-configured, for example "x86 32bit (little endian + unaligned)". If JIT support
-is not available, PCRE2_ERROR_BADOPTION is returned, otherwise the number of
-code units used is returned. This is the length of the string, plus one unit
-for the terminating zero.
+The \fIwhere\fP argument should point to a buffer that is suitably aligned and
+wide enough to hold the full string. The exact length required is returned when
+calling \fBpcre2_config()\fP with \fBwhere\fP set to NULL first. The buffer is
+filled with a string that contains the name of the architecture for which the JIT
+compiler is configured at build time, for example, a 64-bit ARM CPU that supports
+the Armv8.1 extension writes "ARM-64 (LSE) 64bit (little endian + unaligned)".
+If JIT support is not available, PCRE2_ERROR_BADOPTION is returned, otherwise
+the number of code units used is returned. This is the length of the string,
+plus one code unit for the NUL character.
 .sp
   PCRE2_CONFIG_LINKSIZE
 .sp
@@ -4606,6 +4607,6 @@ Cambridge, England.
 .rs
 .sp
 .nf
-Last updated: 19 October 2025
+Last updated: 29 October 2025
 Copyright (c) 1997-2024 University of Cambridge.
 .fi

src/pcre2test.c

@@ -2942,9 +2942,9 @@ static int pcre2_config(uint32_t what, void *where)
 DISPATCH(return, pcre2_config_, (what, where));
 }
 
-static void config_str(uint32_t what, char *where)
+static char *config_str(uint32_t what, char *where, int size)
 {
-DISPATCH(, config_str_, (what, where));
+DISPATCH(return, config_str_, (what, where, size));
 }
 
 static BOOL decode_modifiers(uint8_t *p, int ctx, patctl *pctl, datctl *dctl)
@@ -3014,7 +3014,7 @@ static void
 print_version(FILE *f, BOOL include_mode)
 {
 char buf[VERSION_SIZE];
-config_str(PCRE2_CONFIG_VERSION, buf);
+config_str(PCRE2_CONFIG_VERSION, buf, sizeof(buf));
 fprintf(f, "PCRE2 version %s", buf);
 if (include_mode)
   {
@@ -3033,7 +3033,7 @@ static void
 print_unicode_version(FILE *f)
 {
 char buf[VERSION_SIZE];
-config_str(PCRE2_CONFIG_UNICODE_VERSION, buf);
+config_str(PCRE2_CONFIG_UNICODE_VERSION, buf, sizeof(buf));
 fprintf(f, "Unicode version %s", buf);
 }
 
@@ -3046,9 +3046,9 @@ fprintf(f, "Unicode version %s", buf);
 static void
 print_jit_target(FILE *f)
 {
-char buf[VERSION_SIZE];
-config_str(PCRE2_CONFIG_JITTARGET, buf);
+char *buf = config_str(PCRE2_CONFIG_JITTARGET, NULL, 0);
 fputs(buf, f);
+free(buf);
 }
 
 

src/pcre2test_inc.h

@@ -558,24 +558,41 @@ return 0;
 
 Arguments:
   what       the item to read
-  where      the 8-bit buffer to receive the string
+  where      the 8-bit buffer to receive the string (NULLABLE)
+  size       sizeof(where) or 0 to ask for the buffer to be allocated
+
+Returns:     the string where the data was written
 */
 
-static void
-config_str(uint32_t what, char *where)
+static char *
+config_str(uint32_t what, char *where, int size)
 {
-int r1, r2;
-PCRE2_UCHAR buf[VERSION_SIZE];
+int r2;
+PCRE2_UCHAR *buf;
+int needed_len;
 
-r1 = pcre2_config(what, NULL);
-r2 = pcre2_config(what, buf);
-if (r1 < 0 || r1 != r2 || r1 >= VERSION_SIZE)
+needed_len = pcre2_config(what, NULL);
+if (needed_len <= 0)
   {
   cfprintf(clr_test_error, stderr, "pcre2test: Error in pcre2_config(%d)\n", what);
   exit(1);
   }
+else if (size != 0 && needed_len > size)
+  {
+  cfprintf(clr_test_error, stderr,
+    "pcre2test: Static buffer provided to pcre2_config(%d) too small\n", what);
+  exit(1);
+  }
+
+buf = malloc(needed_len * sizeof(PCRE2_UCHAR));
+r2 = pcre2_config(what, buf);
+PCRE2_ASSERT(r2 == needed_len);
+
+if (where == NULL) where = malloc(needed_len);
+while (r2-- > 0) where[r2] = (char)buf[r2];
+free(buf);
 
-while (r1-- > 0) where[r1] = (char)buf[r1];
+return where;
 }