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

tools/elfdeps.c

@@ -9,9 +9,13 @@
 #include <popt.h>
 #include <gelf.h>
 
+#include <link.h>
+#include <dlfcn.h>
+
 #include <rpm/rpmstring.h>
 #include <rpm/argv.h>
 
+int libtool_version_fallback = 0;
 int soname_only = 0;
 int fake_soname = 1;
 int filter_soname = 1;
@@ -33,6 +37,53 @@ typedef struct elfInfo_s {
     ARGV_t provides;
 } elfInfo;
 
+/*
+ * If filename contains ".so" followed by a version number, return
+ * a copy of the version number.
+ */
+static char *getLibtoolVer(const char *filename)
+{
+    const char *so;
+    int found_digit, found_dot = 0;
+    // Start from the end of the string.  Verify that it ends with
+    // numbers and dots, preceded by ".so.".
+    so = filename + strlen(filename);
+    while (so > filename+2) {
+	if (*so == '.') {
+	    found_dot++;
+	    so--;
+	    continue;
+	} else if (strchr("0123456789", *so)) {
+	    found_digit++;
+	    so--;
+	    continue;
+	} else if (strncmp(so-2, ".so.", 4) == 0) {
+	    so+=2;
+	    if (found_digit && found_dot > 1) {
+		return strdup(so);
+	    }
+	    break;
+	} else {
+	    return NULL;
+	}
+    }
+    return NULL;
+}
+
+static char *getLibtoolVerFromShLink(const char *filename)
+{
+    void *dl_handle;
+    struct link_map *linkmap;
+    char *version = NULL;
+    dl_handle = dlmopen(LM_ID_NEWLM, filename, RTLD_LAZY);
+    if (dl_handle == NULL) return NULL;
+    if (dlinfo(dl_handle, RTLD_DI_LINKMAP, &linkmap) != -1) {
+	version = getLibtoolVer(linkmap->l_name);
+    }
+    dlclose(dl_handle);
+    return version;
+}
+
 /*
  * Rough soname sanity filtering: all sane soname's dependencies need to
  * contain ".so", and normal linkable libraries start with "lib",
@@ -96,14 +147,21 @@ static const char *mkmarker(GElf_Ehdr *ehdr)
 }
 
 static void addDep(ARGV_t *deps,
-		   const char *soname, const char *ver, const char *marker)
+		   const char *soname, const char *ver, const char *marker,
+		   const char *compare_op, const char *fallback_ver)
 {
     char *dep = NULL;
 
     if (skipSoname(soname))
 	return;
 
-    if (ver || marker) {
+    if (compare_op && fallback_ver) {
+	// when versioned symbols aren't available, the libtool version
+	// might be used to generate a minimum dependency version.
+	rasprintf(&dep,
+		  "%s()%s %s %s", soname, marker ? marker : "",
+		  compare_op, fallback_ver);
+    } else if (ver || marker) {
 	rasprintf(&dep,
 		  "%s(%s)%s", soname, ver ? ver : "", marker ? marker : "");
     }
@@ -143,10 +201,10 @@ static void processVerDef(Elf_Scn *scn, GElf_Shdr *shdr, elfInfo *ei)
 		    auxoffset += aux->vda_next;
 		    continue;
 		} else if (soname && !soname_only) {
-		    addDep(&ei->provides, soname, s, ei->marker);
+		    addDep(&ei->provides, soname, s, ei->marker, NULL, NULL);
 		}
 	    }
-		    
+
 	}
     }
     rfree(soname);
@@ -182,7 +240,7 @@ static void processVerNeed(Elf_Scn *scn, GElf_Shdr *shdr, elfInfo *ei)
 		    break;
 
 		if (genRequires(ei) && soname && !soname_only) {
-		    addDep(&ei->requires, soname, s, ei->marker);
+		    addDep(&ei->requires, soname, s, ei->marker, NULL, NULL);
 		}
 		auxoffset += aux->vna_next;
 	    }
@@ -222,8 +280,14 @@ static void processDynamic(Elf_Scn *scn, GElf_Shdr *shdr, elfInfo *ei)
 	    case DT_NEEDED:
 		if (genRequires(ei)) {
 		    s = elf_strptr(ei->elf, shdr->sh_link, dyn->d_un.d_val);
-		    if (s)
-			addDep(&ei->requires, s, NULL, ei->marker);
+		    if (s) {
+			char *libtool_ver = NULL;
+			if (libtool_version_fallback) {
+			    libtool_ver = getLibtoolVerFromShLink(s);
+			}
+			addDep(&ei->requires, s, NULL, ei->marker, ">=", libtool_ver);
+			free(libtool_ver);
+		    }
 		}
 		break;
 	    }
@@ -322,8 +386,14 @@ static int processFile(const char *fn, int dtype)
 	    const char *bn = strrchr(fn, '/');
 	    ei->soname = rstrdup(bn ? bn + 1 : fn);
 	}
-	if (ei->soname)
-	    addDep(&ei->provides, ei->soname, NULL, ei->marker);
+	if (ei->soname) {
+	    char *libtool_ver = NULL;
+	    if (libtool_version_fallback) {
+		libtool_ver = getLibtoolVer(fn);
+	    }
+	    addDep(&ei->provides, ei->soname, NULL, ei->marker, "=", libtool_ver);
+	    free(libtool_ver);
+	}
     }
 
     /* If requested and present, add dep for interpreter (ie dynamic linker) */
@@ -359,11 +429,12 @@ int main(int argc, char *argv[])
     struct poptOption opts[] = {
 	{ "provides", 'P', POPT_ARG_VAL, &provides, -1, NULL, NULL },
 	{ "requires", 'R', POPT_ARG_VAL, &requires, -1, NULL, NULL },
+	{ "libtool-version-fallback", 0, POPT_ARG_VAL, &libtool_version_fallback, -1, NULL, NULL },
 	{ "soname-only", 0, POPT_ARG_VAL, &soname_only, -1, NULL, NULL },
 	{ "no-fake-soname", 0, POPT_ARG_VAL, &fake_soname, 0, NULL, NULL },
 	{ "no-filter-soname", 0, POPT_ARG_VAL, &filter_soname, 0, NULL, NULL },
 	{ "require-interp", 0, POPT_ARG_VAL, &require_interp, -1, NULL, NULL },
-	POPT_AUTOHELP 
+	POPT_AUTOHELP
 	POPT_TABLEEND
     };