Enhance requires with version information from the build root.

The --libtool-version-fallback option will cause elfdeps to
try to use the version information in the shared object's filename
for shared objects that don't provide versioned symbols. This
additional information allows rpm to track minor-version
dependencies.

Author: gordonmessmer

CMakeLists.txt

@@ -190,7 +190,7 @@ include(CheckVariableExists)
 set(OPTFUNCS
 	stpcpy stpncpy putenv mempcpy fdatasync lutimes mergesort
 	getauxval setprogname __progname syncfs sched_getaffinity unshare
-	secure_getenv __secure_getenv mremap strchrnul
+	secure_getenv __secure_getenv mremap strchrnul dlmopen dlinfo
 )
 set(REQFUNCS
 	mkstemp getcwd basename dirname realpath setenv unsetenv regcomp

build/files.cc

@@ -19,6 +19,7 @@
 #ifdef WITH_CAP
 #include <sys/capability.h>
 #endif
+#include <sys/xattr.h>
 
 #ifdef HAVE_LIBDW
 #include <libelf.h>
@@ -55,6 +56,8 @@
 #define DEBUG_ID_DIR		"/usr/lib/debug/.build-id"
 #define DEBUG_DWZ_DIR 		"/usr/lib/debug/.dwz"
 
+#define XATTR_NAME_SOVERS "user.rpm_elf_so_version"
+
 /**
  */
 enum specfFlags_e {
@@ -1708,6 +1711,63 @@ static void argvAddAttr(ARGV_t *filesp, rpmfileAttrs attrs, const char *path)
     free(line);
 }
 
+static int generateElfSoVers(FileList fl)
+{
+    int rc = 0;
+    int i;
+    FileListRec flp;
+
+    /* How are we supposed to create the build-id links?  */
+    char *elf_so_version_macro = rpmExpand("%{?_elf_so_version}", NULL);
+    if (*elf_so_version_macro == '\0') {
+	rc = 1;
+	rpmlog(RPMLOG_WARNING,
+	       _("_elf_so_version macro not set, skipping elf-version generation\n"));
+    }
+
+    if (rc != 0) {
+	free(elf_so_version_macro);
+	return rc;
+    }
+
+    /* Save _elf_so_version for ELF shared objects in this package.  */
+    for (i = 0, flp = fl->files.data(); i < fl->files.size(); i++, flp++) {
+	struct stat sbuf;
+	if (lstat(flp->diskPath, &sbuf) == 0 && S_ISREG (sbuf.st_mode)) {
+	    /* We determine whether this is a main or
+	       debug ELF based on path.  */
+	    int isDbg = strncmp (flp->cpioPath,
+				 DEBUG_LIB_PREFIX, strlen (DEBUG_LIB_PREFIX)) == 0;
+
+	    /* Only save elf_so_version executable files in the main package. */
+	    if (isDbg
+		|| (sbuf.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0)
+	      continue;
+
+	    int fd = open (flp->diskPath, O_RDONLY);
+	    if (fd >= 0) {
+		/* Only real ELF files, that are ET_DYN should have _elf_so_version. */
+		GElf_Ehdr ehdr;
+#ifdef HAVE_DWELF_ELF_BEGIN
+		Elf *elf = dwelf_elf_begin (fd);
+#else
+		Elf *elf = elf_begin (fd, ELF_C_READ, NULL);
+#endif
+		if (elf != NULL && elf_kind (elf) == ELF_K_ELF
+		    && gelf_getehdr (elf, &ehdr) != NULL
+		    && (ehdr.e_type == ET_DYN)) {
+		    fsetxattr(fd, XATTR_NAME_SOVERS,
+			      elf_so_version_macro, strlen(elf_so_version_macro), 0);
+		}
+		elf_end (elf);
+		close (fd);
+	    }
+	}
+    }
+    free(elf_so_version_macro);
+    return rc;
+}
+
 #ifdef HAVE_LIBDW
 /* How build id links are generated.  See macros.in for description.  */
 #define BUILD_IDS_NONE     0
@@ -2582,13 +2642,25 @@ static rpmRC processPackageFiles(rpmSpec spec, rpmBuildPkgFlags pkgFlags,
     if (fl.processingFailed)
 	goto exit;
 
-#ifdef HAVE_LIBDW
 {
     /* Check build-ids and add build-ids links for files to package list. */
     const char *arch = headerGetString(pkg->header, RPMTAG_ARCH);
     if (rpmExpandNumeric("%{?__debug_package}") && !rstreq(arch, "noarch")) {
 	/* Go through the current package list and generate a files list. */
 	ARGV_t idFiles = NULL;
+	/* Go through the current package list and tag shared object files. */
+	if (generateElfSoVers (&fl) != 0) {
+	    rpmlog(RPMLOG_ERR, _("Generating elf-so-version failed\n"));
+	    fl.processingFailed = 1;
+	    goto exit;
+	}
+
+	if (fl.processingFailed)
+	    goto exit;
+
+#ifdef HAVE_LIBDW
+	/* Check build-ids and add build-ids links for files to package list. */
+	/* Go through the current package list and generate a files list. */
 	if (generateBuildIDs (&fl, &idFiles) != 0) {
 	    rpmlog(RPMLOG_ERR, _("Generating build-id links failed\n"));
 	    fl.processingFailed = 1;
@@ -2605,8 +2677,8 @@ static rpmRC processPackageFiles(rpmSpec spec, rpmBuildPkgFlags pkgFlags,
 	if (fl.processingFailed)
 	    goto exit;
     }
-}
 #endif
+}
 
     /* Verify that file attributes scope over hardlinks correctly. */
     if (checkHardLinks(fl.files))

config.h.in

@@ -13,6 +13,8 @@
 #cmakedefine HAVE_DIRENT_H @HAVE_DIRENT_H@
 #cmakedefine HAVE_DIRNAME @HAVE_DIRNAME@
 #cmakedefine HAVE_DLFCN_H @HAVE_DLFCN_H@
+#cmakedefine HAVE_DLINFO @HAVE_DLINFO@
+#cmakedefine HAVE_DLMOPEN @HAVE_DLMOPEN@
 #cmakedefine HAVE_DSA_SET0_KEY @HAVE_DSA_SET0_KEY@
 #cmakedefine HAVE_DSA_SET0_PQG @HAVE_DSA_SET0_PQG@
 #cmakedefine HAVE_DSA_SIG_SET0 @HAVE_DSA_SIG_SET0@

docs/manual/more_dependencies.md

@@ -39,12 +39,16 @@ This has two "side-effects":
 It's a fairly common mistake to replace legacy PreReq dependencies with Requires(pre), but this is not the same, due to the latter point above!
 
 ## Automatic Dependencies
-To reduce the amount of work required by the package builder, RPM scans the file list of a package when it is being built. Any files in the file list which require shared libraries to work (as determined by ldd) cause that package to require the shared library.
+To reduce the amount of work required by the package builder, RPM scans the file list of a package when it is being built. Any files in the file list which require shared libraries to work (as determined by elfdeps for ELF objects) cause that package to require the shared library.
 
-For example, if your package contains /bin/vi, RPM will add dependencies for both libtermcap.so.2 and libc.so.5. These are treated as virtual packages, so no version numbers are used.
+For example, if your package contains /bin/vi, RPM will add dependencies for both libtermcap.so.2 and libc.so.5. These are treated as virtual packages.
 
 A similar process allows RPM to add Provides information automatically. Any shared library in the file list is examined for its soname (the part of the name which must match for two shared libraries to be considered equivalent) and that soname is automatically provided by the package. For example, the libc-5.3.12 package has provides information added for libm.so.5 and libc.so.5. We expect this automatic dependency generation to eliminate the need for most packages to use explicit Requires: lines.
 
+As of rpm version (TBD), the internal dependency generator provides optional support for generating versioned ELF object dependencies on objects that do not provide versioned symbols.  Distributions that wish to make use of this support should enable the \_elf\_provide\_fallback\_versions and \_elf\_require\_fallback\_versions macros.  When these macros are enabled, the dependency generator will attempt to resolve shared object dependencies to a full path.  If the shared object does not provide versioned symbols, and the soname is a symlink to a full name that differs from the soname, and the full name ends in ".so." followed by a sequence of numbers optionally separated by the '.' character, then that trailing sequence will be treated as a version and included in the automatically generated dependencies.  While shared objects with versioned symbols are well supported, and are the preferred approach to ensuring that a dependency actually provides the ABI that another package requires, this fallback approach to versioning dependencies provides reasonably good coverage for the large body of ELF shared objects that do not yet maintain versioned symbols.
+
+The most likely case where the fallback version system will break is a shared object being updated from a purely numeric version suffix to a version suffix with non-numeric characters (e.g. "libfoo.so.3.0.1" is updated to "libfoo.so.3.0.1a").  In that case, the dependency generator would not provide a version for that shared object, and the package maintainer would need to manually add a Provides: tag to the package in order to continue satisfying existing package dependencies.
+
 ## Custom Automatic Dependency
 Customizing automatic dependency generation is covered in [dependency generator documentation]().
 

fileattrs/elf.attr

@@ -1,5 +1,5 @@
-%__elf_provides		%{_rpmconfigdir}/elfdeps --provides --multifile
-%__elf_requires		%{_rpmconfigdir}/elfdeps --requires --multifile
+%__elf_provides		%{_rpmconfigdir}/elfdeps %{?_elf_provide_fallback_versions} --provides --multifile
+%__elf_requires		%{_rpmconfigdir}/elfdeps %{?_elf_require_fallback_versions} --requires --multifile
 %__elf_magic		^(setuid,? )?(setgid,? )?(sticky )?ELF (32|64)-bit.*$
 %__elf_exclude_path	^/lib/modules/.*\\.ko?(\\.[[:alnum:]]*)$
 %__elf_protocol		multifile

macros.in

@@ -551,6 +551,18 @@ Supplements:   (%{name} = %{version}-%{release} and langpacks-%{1})\
 # Use internal dependency generator rather than external helpers?
 %_use_internal_dependency_generator	1
 
+#
+# Generate minimum versions for ELF libraries that don't provide
+# versioned symbol?
+#%_elf_provide_fallback_versions   --full-name-version-fallback
+#%_elf_require_fallback_versions   --full-name-version-fallback
+
+#
+# ELF libraries will usually inherit a version from their package,
+# but this can be overridden by defining _elf_so_version,
+# especially for interchangeable implementations.
+%_elf_so_version %{version}
+
 # Directories whose contents should be considered as documentation.
 %__docdir_path %{_datadir}/doc:%{_datadir}/man:%{_datadir}/info:%{_datadir}/gtk-doc/html:%{_datadir}/gnome/help:%{?_docdir}:%{?_mandir}:%{?_infodir}:%{?_javadocdir}:/usr/doc:/usr/man:/usr/info:/usr/X11R6/man
 

tests/atlocal.in

@@ -50,6 +50,11 @@ if [ "@WITH_IMAEVM@" == "ON" ]; then
 else
     IMA_DISABLED=true;
 fi
+if [ "@HAVE_DLINFO@" == 1 ] && [ "@HAVE_DLMOPEN@" == 1 ]; then
+    HAVE_GNU_DLFCN=true;
+else
+    HAVE_GNU_DLFCN=false;
+fi
 if mknod foodev c 123 123 2>/dev/null; then
    MKNOD_DISABLED=false
    rm -f foodev

tests/data/misc/.elf-version/libhello.so

@@ -0,0 +1 @@
+1.0.0

tests/data/misc/libhello.so

@@ -0,0 +1 @@
+libhello.so.1.0.0