1 files changed, 119 insertions, 0 deletions
diff --git a/libdl/dltest.c b/libdl/dltest.c
new file mode 100755
index 0000000..e84d5a3
--- /dev/null
+++ b/libdl/dltest.c
@@ -0,0 +1,119 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <string.h>
+#include <dlfcn.h>
+
+extern char *optarg;
+extern int optind, opterr, optopt;
+
+static struct option long_options[] = {
+    {"library", required_argument, 0, 'l'},
+    {"symbol",  required_argument, 0, 's'},
+    {"help",    no_argument,       0, 'h'},
+    {0, 0, 0, 0},
+};
+
+/* This array must parallel long_options[] */
+static const char *descriptions[] = {
+    "specify a library path to look up symbol",
+    "specify symbol to look up",
+    "print this help screen",
+};
+
+void print_help(const char *name) {
+    fprintf(stdout, 
+            "invokation:\n"
+            "\t%s [-l <libname>] -s <symbol name>\n"
+            "\t%s -h\n\n", name, name);
+    fprintf(stdout, "options:\n");
+    struct option *opt = long_options;
+    const char **desc = descriptions;
+    while (opt->name) {
+        fprintf(stdout, "\t-%c/--%s%s: %s\n",
+                opt->val,
+                opt->name,
+                (opt->has_arg ? " (argument)" : ""),
+                *desc);
+        opt++;
+        desc++;
+    }
+}
+
+int get_options(int argc, char **argv, char **lib, char **sym) 
+{
+    int c;
+
+    *lib = 0;
+    *sym = 0;
+
+    while (1) {
+        /* getopt_long stores the option index here. */
+        int option_index = 0;
+
+        c = getopt_long (argc, argv, 
+                         "l:s:h",
+                         long_options, 
+                         &option_index);
+        /* Detect the end of the options. */
+        if (c == -1) break;
+
+        switch (c) {
+		case 'l':
+            *lib = strdup(optarg);
+			break;
+        case 's': 
+            *sym = strdup(optarg);
+            break;
+        case 'h': print_help(argv[0]); exit(EXIT_FAILURE); break;
+        case '?':
+            /* getopt_long already printed an error message. */
+            break;
+        default:
+            fprintf(stderr, "Unknown option");
+            exit(EXIT_FAILURE);
+        }
+    }
+
+    return optind;
+}
+
+int main(int argc, char **argv)
+{
+    char *libname, *symname, *prog = *argv;
+
+    get_options(argc, argv, &libname, &symname);
+
+    if (symname == NULL) {
+        fprintf(stderr, "You must specify a symbol!\n");
+        print_help(prog);
+        exit(EXIT_FAILURE);
+    }
+
+    {
+        const char *dlerr;
+        void *handle, *symbol;
+
+        printf("opening library [%s]\n", libname);
+        dlerr = dlerror();
+        handle = libname ? dlopen(libname, RTLD_NOW) : RTLD_DEFAULT;
+        dlerr = dlerror();
+        if (dlerr != NULL) fprintf(stderr, "dlopen() error: %s\n", dlerr);
+
+        printf("opening symbol [%s]\n", symname);
+        symbol = dlsym(handle, symname);
+        dlerr = dlerror();
+        if (dlerr != NULL) fprintf(stderr, "dlsym() error: %s\n", dlerr);
+
+        printf("closing library [%s]\n", libname);
+        dlclose(handle);
+        dlerr = dlerror();
+        if (dlerr != NULL) fprintf(stderr, "dlclose() error: %s\n", dlerr);
+        else printf("successfully opened symbol\n");
+    }
+
+    if (libname != NULL) free(libname);
+    if (symname != NULL) free(symname);
+    return 0;
+}