Don't require a user of librpmio to link to librpm_sequoia

When rpm is configured to use Sequoia for the OpenPGP implementation
('configure --crypto=sequoia'), librpmio is linked against
librpm_sequoia.

librpm_sequoia can't directly implement the OpenPGP API, because
librpmio won't reexport librpm_sequoia's symbols, and we don't want
a program linking against librpmio to explicitly link against
(i.e., need a DT_NEEDED entry for) librpm_sequoia.

We can circumvent this problem by having librpm_sequoia provide
identical functions under different names, and then having librpmio
provide forwarders.  That's what this commit does: a Sequoia-specific
file forwards pgpFoo to _pgpFoo.  It's a bit ugly, but it is better
than a brittle, non-portable hack.

Fixes #2051.

4 files changed, 78 insertions, 3 deletions

diff --git a/rpm.pc.in b/rpm.pc.in
index 5449f01a0..1f76f0685 100644
--- a/rpm.pc.in
+++ b/rpm.pc.in
@@ -12,5 +12,5 @@ Requires: popt
 Requires.private: @ZSTD_REQUIRES@
 # Conflicts:
 Cflags: -I${includedir}
-Libs: -L${libdir} -lrpm -lrpmio @WITH_RPM_SEQUOIA_LIB@
+Libs: -L${libdir} -lrpm -lrpmio
 Libs.private: -lpopt -lrt -lpthread @WITH_LZMA_LIB@ @WITH_BZ2_LIB@ @WITH_ZLIB_LIB@ @LUA_LIBS@
diff --git a/rpmio/Makefile.am b/rpmio/Makefile.am
index 106e69d00..e302f3209 100644
--- a/rpmio/Makefile.am
+++ b/rpmio/Makefile.am
@@ -32,6 +32,10 @@ librpmio_la_SOURCES += digest_openssl.c rpmpgp_internal.c rpmpgp_internal.h
 else
 if WITH_LIBGCRYPT
 librpmio_la_SOURCES += digest_libgcrypt.c rpmpgp_internal.c rpmpgp_internal.h
+else
+if WITH_RPM_SEQUOIA
+librpmio_la_SOURCES += rpmpgp_sequoia.c
+endif
 endif
 endif
 
diff --git a/rpmio/rpmpgp_sequoia.c b/rpmio/rpmpgp_sequoia.c
new file mode 100644
index 000000000..4c086d7a5
--- /dev/null
+++ b/rpmio/rpmpgp_sequoia.c
@@ -0,0 +1,72 @@
+// When rpm is configured to use Sequoia for the OpenPGP implementation
+// ('configure --crypto=sequoia'), librpmio is linked against
+// librpm_sequoia.
+//
+// librpm_sequoia can't directly implement the OpenPGP API, because
+// librpmio won't reexport librpm_sequoia's symbols, and we don't want
+// a program linking against librpmio to explicitly link against
+// (i.e., need a DT_NEEDED entry for) librpm_sequoia.
+//
+// We can circumvent this problem by having librpm_sequoia provide
+// identical functions under different names, and then having librpmio
+// provide forwarders.  That's what this file does: it forwards pgpFoo
+// to _pgpFoo.  It's a bit ugly, but it is better than a brittle,
+// non-portable hack.
+
+#include "rpmpgpval.h"
+
+// Wrap a function.
+//
+// Define f to call _f, which has an identical function signature.
+#define W(rt, f, params, args) \
+  extern rt _##f params;       \
+  rt f params {                \
+    return _##f args;          \
+  }
+
+W(int, pgpSignatureType, (pgpDigParams _digp), (_digp))
+W(pgpDigParams, pgpDigParamsFree, (pgpDigParams digp), (digp))
+W(int, pgpDigParamsCmp, (pgpDigParams p1, pgpDigParams p2), (p1, p2))
+W(unsigned int, pgpDigParamsAlgo,
+  (pgpDigParams digp, unsigned int algotype), (digp, algotype))
+W(const uint8_t *, pgpDigParamsSignID, (pgpDigParams digp), (digp))
+W(const char *, pgpDigParamsUserID, (pgpDigParams digp), (digp))
+W(int, pgpDigParamsVersion, (pgpDigParams digp), (digp))
+W(uint32_t, pgpDigParamsCreationTime, (pgpDigParams digp), (digp))
+W(rpmRC, pgpVerifySignature,
+  (pgpDigParams key, pgpDigParams sig, DIGEST_CTX hashctx),
+  (key, sig, hashctx))
+W(int, pgpPubkeyKeyID,
+  (const uint8_t * pkt, size_t pktlen, pgpKeyID_t keyid),
+  (pkt, pktlen, keyid))
+W(char *, pgpArmorWrap,
+  (int atype, const unsigned char * s, size_t ns),
+  (atype, s, ns))
+W(int, pgpPubKeyCertLen,
+  (const uint8_t *pkts, size_t pktslen, size_t *certlen),
+  (pkts, pktslen, certlen))
+W(int, pgpPrtParams,
+  (const uint8_t *pkts, size_t pktlen, unsigned int pkttype, pgpDigParams *ret),
+  (pkts, pktlen, pkttype, ret))
+W(int, pgpPrtParamsSubkeys,
+  (const uint8_t *pkts, size_t pktlen,
+   pgpDigParams mainkey, pgpDigParams **subkeys,
+   int *subkeysCount),
+  (pkts, pktlen, mainkey, subkeys, subkeysCount))
+W(pgpArmor, pgpParsePkts,
+  (const char *armor, uint8_t ** pkt, size_t * pktlen),
+  (armor, pkt, pktlen))
+W(rpmRC, pgpPubKeyLint,
+  (const uint8_t *pkts, size_t pktslen, char **explanation),
+  (pkts, pktslen, explanation))
+W(int, rpmInitCrypto, (void), ())
+W(int, rpmFreeCrypto, (void), ())
+W(DIGEST_CTX, rpmDigestInit, (int hashalgo, rpmDigestFlags flags),
+  (hashalgo, flags))
+W(DIGEST_CTX, rpmDigestDup, (DIGEST_CTX octx), (octx))
+W(size_t, rpmDigestLength, (int hashalgo), (hashalgo))
+W(int, rpmDigestUpdate, (DIGEST_CTX ctx, const void * data, size_t len),
+  (ctx, data, len))
+W(int, rpmDigestFinal,
+  (DIGEST_CTX ctx, void ** datap, size_t *lenp, int asAscii),
+  (ctx, datap, lenp, asAscii))
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 789280399..44f4595ea 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -12,8 +12,7 @@ EXTRA_DIST += local.at $(TESTSUITE)
 
 AM_CPPFLAGS = -I$(top_srcdir)/include
 
-rpmpgpcheck_LDADD = ../rpmio/librpmio.la \
-	@WITH_RPM_SEQUOIA_LIB@
+rpmpgpcheck_LDADD = ../rpmio/librpmio.la
 
 ## testsuite components
 TESTSUITE_AT = rpmtests.at