load libraries into separate namespaces

Otherwise the bundled library and the system library will use the same
namespace and the path of the bundled library might be returned when you
expected the system one.

src/Makefile

@@ -42,10 +42,11 @@ $(EXEC_TEST): exec.c env.o
 $(ENV_TEST): env.c
 	$(CC) -o $@ $(CFLAGS) -DENV_TEST $^
 
-run_tests: $(EXEC_TEST) $(ENV_TEST) $(CHECKRT_TEST)
+run_tests: $(BIN) $(EXEC_TEST) $(ENV_TEST) $(CHECKRT_TEST)
 	./$(ENV_TEST)
 	./$(EXEC_TEST)
 	./$(CHECKRT_TEST)
+	./patch_libs.sh && ./$(BIN) -v
 
 .PHONY: $(BIN) all clean
 

src/checkrt.c

@@ -57,14 +57,19 @@
 #define PRINT_VERBOSE(FMT, ...)  if (verbose) { fprintf(stderr, FMT, __VA_ARGS__); }
 
 
-static char *get_libname(const char *lib, char verbose)
+static char *get_libpath(const char *lib, char verbose)
 {
   struct link_map *map = NULL;
   char *path;
 
-  void *handle = dlopen(lib, RTLD_LAZY);
+  /* It's very important to use dlmopen() together with the argument LM_ID_NEWLM,
+   * otherwise the bundled library and the system library will use the same
+   * namespace and the path of the bundled library might be returned when you
+   * expected the system one.
+   */
+  void *handle = dlmopen(LM_ID_NEWLM, lib, RTLD_LAZY);
   if (!handle) {
-    PRINT_VERBOSE("error: failed to dlopen() file: %s\n", lib);
+    PRINT_VERBOSE("error: failed to dlmopen() file: %s\n", lib);
     return NULL;
   }
 
@@ -87,7 +92,7 @@ static int symbol_version(const char *lib, const char *symbol, char verbose)
   const char *error = "";
 
   /* let dlopen() do all the compatibility checks */
-  char *orig = get_libname(lib, verbose);
+  char *orig = get_libpath(lib, verbose);
   if (!orig) return -1;
 
   fd = open(orig, O_RDONLY);
@@ -97,7 +102,14 @@ static int symbol_version(const char *lib, const char *symbol, char verbose)
     return -1;
   }
 
-  PRINT_VERBOSE("%s\n", orig);
+  if (verbose) {
+    if (strcmp(lib, orig) == 0) {
+      fprintf(stderr, "%s\n", orig);
+    } else {
+      fprintf(stderr, "%s -> %s\n", lib, orig);
+    }
+  }
+
   free(orig);
 
   /* make sure file size is larger than the required ELF header size */
@@ -236,7 +248,7 @@ static int copy_lib(const char *lib, const char *destDir, char verbose)
   int fdIn = -1, fdOut = -1;
 
   /* get full source and target paths */
-  char *srcFull = get_libname(lib, verbose);
+  char *srcFull = get_libpath(lib, verbose);
   if (!srcFull) goto copy_lib_error;
 
   char *base = basename(srcFull);
@@ -300,13 +312,17 @@ int main(int argc, char **argv)
 {
 #if CHECKRT_TEST == 1
 
-  printf("Test:\n");
+  printf("Test:\n\n");
   copy_lib(LIBGCC_S_SO, "./" LIBGCC_DIR, 1);
   copy_lib(LIBSTDCXX_SO, "./" STDCXX_DIR, 1);
-  symbol_version(LIBGCC_S_SO, "GCC_", 1);
-  symbol_version(LIBSTDCXX_SO, "GLIBCXX_", 1);
+  putchar('\n');
   symbol_version("./" LIBGCC_DIR "/" LIBGCC_S_SO, "GCC_", 1);
+  putchar('\n');
   symbol_version("./" STDCXX_DIR "/" LIBSTDCXX_SO, "GLIBCXX_", 1);
+  putchar('\n');
+  symbol_version(LIBGCC_S_SO, "GCC_", 1);
+  putchar('\n');
+  symbol_version(LIBSTDCXX_SO, "GLIBCXX_", 1);
 
 #else
 
@@ -351,7 +367,6 @@ int main(int argc, char **argv)
   }
   *(p+1) = 0;
 
-  int ver;
   size_t len = strlen(currdir);
   char *libpath = malloc(len + MAX(sizeof(STDCXX_DIR), sizeof(LIBGCC_DIR)) +
     MAX(sizeof(LIBSTDCXX_SO), sizeof(LIBGCC_S_SO)) + 2);
@@ -366,8 +381,9 @@ int main(int argc, char **argv)
     copy_lib(LIBSTDCXX_SO, libpath, v);
   } else {
     /* get symbol versions */
+
     strcpy(p, LIBGCC_DIR "/" LIBGCC_S_SO);
-    ver = symbol_version(libpath, "GCC_", v);
+    int ver = symbol_version(libpath, "GCC_", v);
     if (ver != -1 && ver > symbol_version(LIBGCC_S_SO, "GCC_", v)) {
       printf("%s" LIBGCC_DIR ":", currdir);
     }

src/patch_libs.sh

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+mv gcc/libgcc_s.so.1 gcc/libgcc_s.so.1.bak
+sed -e 's|GCC_[0-9]\.[0-9]|GCC_9.9|g' \
+  -e 's|GCC_[0-9]\.[0-9]\.[0-9]|GCC_9.9.9|g' \
+  -e 's|GCC_[0-9][0-9]\.[0-9]\.[0-9]|GCC_99.9.9|g' \
+  gcc/libgcc_s.so.1.bak > gcc/libgcc_s.so.1
+
+mv cxx/libstdc++.so.6 cxx/libstdc++.so.6.bak
+sed -e 's|GLIBCXX_[0-9]\.[0-9]|GLIBCXX_9.9|g' \
+  -e 's|GLIBCXX_[0-9]\.[0-9]\.[0-9]|GLIBCXX_9.9.9|g' \
+  -e 's|GLIBCXX_[0-9]\.[0-9]\.[0-9][0-9]|GLIBCXX_9.9.99|g' \
+  cxx/libstdc++.so.6.bak > cxx/libstdc++.so.6
+
+