initial commit

6 files changed, 58 insertions, 0 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..8d7262a
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,12 @@
+
+all: sayhello sayhello-spanish.so sayhello-swedish.so sayhello-stderr.so
+
+sayhello: sayhello.c
+	$(CC) -o $@ $(CFLAGS) $<
+
+sayhello-%.so: sayhello-%.c
+	$(CC) -o $@ $(CFLAGS) -shared $<
+
+
+clean:
+	rm -f sayhello sayhello-*.so
diff --git a/README b/README
new file mode 100644
index 0000000..054dbb4
--- /dev/null
+++ b/README
@@ -0,0 +1 @@
+Simple dlopen example
diff --git a/sayhello-spanish.c b/sayhello-spanish.c
new file mode 100644
index 0000000..0c6fa0e
--- /dev/null
+++ b/sayhello-spanish.c
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+void sayhello(void) {
+	printf("hola\n");
+}
diff --git a/sayhello-stderr.c b/sayhello-stderr.c
new file mode 100644
index 0000000..b993cf4
--- /dev/null
+++ b/sayhello-stderr.c
@@ -0,0 +1,6 @@
+#include <unistd.h>
+
+void sayhello(void) {
+	const char *buf="hello\n";
+	write(2, buf, 6);
+}
diff --git a/sayhello-swedish.c b/sayhello-swedish.c
new file mode 100644
index 0000000..36dc318
--- /dev/null
+++ b/sayhello-swedish.c
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+void sayhello(void) {
+	printf("hej\n");
+}
diff --git a/sayhello.c b/sayhello.c
new file mode 100644
index 0000000..1f132df
--- /dev/null
+++ b/sayhello.c
@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include <err.h>
+#include <dlfcn.h>
+
+int main(int argc, const char *argv[]) {
+	int i;
+	if (argc < 2)
+		errx(1, "usage: sayhello PLUGIN...");
+
+	for (i=1; i<argc; i++) {
+		const char *plugin = argv[i];
+		void (*sayhello)(void);
+		void *handle = dlopen(plugin, RTLD_NOW | RTLD_LOCAL);
+
+		if (handle == NULL) {
+			warn("%s", plugin);
+			continue;
+		}
+		dlerror(); /* clear existing error */
+
+		/* get the "sayhello" function from plugin */
+		sayhello = (void (*)(void)) dlsym(handle, "sayhello");
+		sayhello();
+
+		dlclose(handle);
+	}
+
+	return 0;
+}