ld.so: load libs with same name experiments

3 files changed, 58 insertions, 0 deletions

diff --git a/src/development/ldso/samename/Makefile b/src/development/ldso/samename/Makefile
new file mode 100644
index 0000000..f35a1e3
--- /dev/null
+++ b/src/development/ldso/samename/Makefile
@@ -0,0 +1,13 @@
+all:
+	mkdir -p foo bar
+	gcc -g -o foo/lib.so lib.c -shared -fPIC -DNAME=\"foo\"
+	gcc -g -o bar/lib.so lib.c -shared -fPIC -DNAME=\"bar\"
+	gcc -g -o main main.c -ldl
+	./main foo/lib.so bar/lib.so
+	LD_LIBRARY_PATH=foo:bar ./main lib.so lib.so
+	LD_LIBRARY_PATH=bar:foo ./main lib.so lib.so
+	LD_LIBRARY_PATH=foo ./main lib.so foo/lib.so
+	LD_LIBRARY_PATH=foo ./main lib.so bar/lib.so
+
+clean:
+	$(RM) -r foo bar main
diff --git a/src/development/ldso/samename/lib.c b/src/development/ldso/samename/lib.c
new file mode 100644
index 0000000..d467d7f
--- /dev/null
+++ b/src/development/ldso/samename/lib.c
@@ -0,0 +1,9 @@
+#include <stdio.h>
+
+#ifndef NAME
+#define NAME __FILE_NAME__
+#endif
+
+void moose() {
+  puts(NAME " says moose");
+}
diff --git a/src/development/ldso/samename/main.c b/src/development/ldso/samename/main.c
new file mode 100644
index 0000000..6d6a8ea
--- /dev/null
+++ b/src/development/ldso/samename/main.c
@@ -0,0 +1,36 @@
+#include <assert.h>
+#include <dlfcn.h>
+#include <stdio.h>
+#include <string.h>
+
+void print_libso() {
+  FILE* m = fopen("/proc/self/maps", "r");
+  assert(m);
+
+  char line[256];
+  while (fgets(line, sizeof(line), m)) {
+    if (strstr(line, "lib.so")) {
+      printf("%s", line);
+    }
+  }
+  fclose(m);
+}
+
+int main(int argc, char* argv[]) {
+  for (int i = 1; i < argc; ++i) {
+    void* h = dlopen(argv[i], RTLD_LAZY | RTLD_GLOBAL);
+    if (!h) {
+      puts(dlerror());
+      return 1;
+    }
+
+    void (*next)() = dlsym(h, "moose");
+    assert(next);
+    next();
+
+    // leak lib, we want to priint the mmap.
+  }
+
+  print_libso();
+  return 0;
+}