1 files changed, 112 insertions, 0 deletions
diff --git a/depends/libcap/libcap/execable.h b/depends/libcap/libcap/execable.h
new file mode 100644
index 0000000..7a2d247
--- /dev/null
+++ b/depends/libcap/libcap/execable.h
@@ -0,0 +1,112 @@
+/*
+ * Copyright (c) 2021 Andrew G. Morgan <morgan@kernel.org>
+ *
+ * Some header magic to help make a shared object run-able as a stand
+ * alone executable binary.
+ *
+ * This is a slightly more sophisticated implementation than the
+ * answer I posted here:
+ *
+ *    https://stackoverflow.com/a/68339111/14760867
+ *
+ * Compile your shared library with:
+ *
+ *   -DSHARED_LOADER="\"ld-linux...\"" (loader for your target system)
+ *   ...
+ *   --entry=__so_start
+ */
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef __EXECABLE_H
+#error "only include execable.h once"
+#endif
+#define __EXECABLE_H
+
+const char __execable_dl_loader[] __attribute((section(".interp"))) =
+    SHARED_LOADER ;
+
+static void __execable_parse_args(int *argc_p, char ***argv_p)
+{
+    int argc = 0;
+    char **argv = NULL;
+    FILE *f = fopen("/proc/self/cmdline", "rb");
+    if (f != NULL) {
+	char *mem = NULL, *p;
+	size_t size = 32, offset;
+	for (offset=0; ; size *= 2) {
+	    char *new_mem = realloc(mem, size+1);
+	    if (new_mem == NULL) {
+		perror("unable to parse arguments");
+		if (mem != NULL) {
+		    free(mem);
+		}
+		exit(1);
+	    }
+	    mem = new_mem;
+	    offset += fread(mem+offset, 1, size-offset, f);
+	    if (offset < size) {
+		size = offset;
+		mem[size] = '\0';
+		break;
+	    }
+	}
+	fclose(f);
+	for (argc=1, p=mem+size-2; p >= mem; p--) {
+	    argc += (*p == '\0');
+	}
+	argv = calloc(argc+1, sizeof(char *));
+	if (argv == NULL) {
+	    perror("failed to allocate memory for argv");
+	    free(mem);
+	    exit(1);
+	}
+	for (p=mem, argc=0, offset=0; offset < size; argc++) {
+	    argv[argc] = mem+offset;
+	    offset += strlen(mem+offset)+1;
+	}
+    }
+    *argc_p = argc;
+    *argv_p = argv;
+}
+
+/*
+ * Linux x86 ABI requires the stack be 16 byte aligned. Keep things
+ * simple and just force it.
+ */
+#if defined(__i386__) || defined(__x86_64__)
+#define __SO_FORCE_ARG_ALIGNMENT  __attribute__((force_align_arg_pointer))
+#else
+#define __SO_FORCE_ARG_ALIGNMENT
+#endif /* def some x86 */
+
+/*
+ * Permit the compiler to override this one.
+ */
+#ifndef EXECABLE_INITIALIZE
+#define EXECABLE_INITIALIZE do { } while(0)
+#endif /* ndef EXECABLE_INITIALIZE */
+
+/*
+ * Note, to avoid any runtime confusion, SO_MAIN is a void static
+ * function.
+ */
+#define SO_MAIN							\
+static void __execable_main(int, char**);			\
+__attribute__((visibility ("hidden")))                          \
+void __so_start(void);					        \
+__SO_FORCE_ARG_ALIGNMENT					\
+void __so_start(void)						\
+{								\
+    int argc;							\
+    char **argv;						\
+    __execable_parse_args(&argc, &argv);			\
+    EXECABLE_INITIALIZE;                                        \
+    __execable_main(argc, argv);				\
+    if (argc != 0) {						\
+	free(argv[0]);						\
+	free(argv);						\
+    }								\
+    exit(0);							\
+}								\
+static void __execable_main