Modify the add_seeds_stringlist() macro to fix a preprocessor error

When OpenSSL is configured using `--with-rand-seed=devrandom`, the preprocessor
reports the following error

    crypto/info.c:104:66: error:
            macro "add_seeds_stringlist" passed 3 arguments, but takes just 2
            add_seeds_stringlist("random-device", { DEVRANDOM, NULL });

The reason why the preprocessor complains about three arguments being passed
is that according to [1], balanced braces in macro arguments don't prevent the
comma from acting as an argument separator:

    3.3 Macro Arguments
    ...
    Parentheses within each argument must balance;
    a comma within such parentheses does not end the argument.
    However, there is no requirement for square brackets or braces to balance,
    and they do not prevent a comma from separating arguments.

Also introduced an iteration pointer `p`, because `dev` is not an lvalue:

    crypto/info.c:78:41: error:
            lvalue required as increment operand
            for (; *dev != NULL; dev++) {

[1] https://gcc.gnu.org/onlinedocs/cpp/Macro-Arguments.html

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/10762)

diff --git a/crypto/info.c b/crypto/info.c
index 8e674fc30a6b850c51cefa3a9c3b68648bb024d1..abba5437e23fd57d6fcf1eaee436ecb6efae8510 100644 (file)
--- a/crypto/info.c
+++ b/crypto/info.c
@@ -72,14 +72,15 @@ DEFINE_RUN_ONCE_STATIC(init_info_strings)
         do {                                                            \
             add_seeds_string(label "(");                                \
             {                                                           \
-                const char *dev[] = strlist;                            \
+                const char *dev[] =  { strlist, NULL };                 \
+                const char **p;                                         \
                 int first = 1;                                          \
                                                                         \
-                for (; *dev != NULL; dev++) {                           \
+                for (p = dev; *p != NULL; p++) {                        \
                     if (!first)                                         \
                         OPENSSL_strlcat(seeds, " ", sizeof(seeds));     \
                     first = 0;                                          \
-                    OPENSSL_strlcat(seeds, *dev, sizeof(seeds));        \
+                    OPENSSL_strlcat(seeds, *p, sizeof(seeds));          \
                 }                                                       \
             }                                                           \
             OPENSSL_strlcat(seeds, ")", sizeof(seeds));                 \
@@ -101,10 +102,10 @@ DEFINE_RUN_ONCE_STATIC(init_info_strings)
         add_seeds_string("getrandom-syscall");
 #endif
 #ifdef OPENSSL_RAND_SEED_DEVRANDOM
-        add_seeds_stringlist("random-device", { DEVRANDOM, NULL });
+        add_seeds_stringlist("random-device", DEVRANDOM);
 #endif
 #ifdef OPENSSL_RAND_SEED_EGD
-        add_seeds_stringlist("EGD", { DEVRANDOM_EGD, NULL });
+        add_seeds_stringlist("EGD", DEVRANDOM_EGD);
 #endif
 #ifdef OPENSSL_RAND_SEED_OS
         add_seeds_string("os-specific");