add __memperm() for checking current memory permissions

1 files changed, 36 insertions, 0 deletions

diff --git a/src/__memperm.c b/src/__memperm.c
new file mode 100644
index 00000000..e3bcd64d
--- /dev/null
+++ b/src/__memperm.c
@@ -0,0 +1,36 @@
+#include <inttypes.h>
+#include <stdio.h>
+#include "_memperm.h"
+
+int __memperm(void *ptr)
+{
+	uintptr_t addr = (uintptr_t)ptr;
+	int ret = PROT_NONE;
+
+	FILE *map = fopen("/proc/self/maps", "r");
+	if (map == NULL) {
+		return -1;
+	}
+
+	while (!feof(map)) {
+		uintmax_t low = 0;
+		uintmax_t high = 0;
+		char perms[5];
+		fscanf(map, "%ju-%ju %4s%*s\n", &low, &high, perms);
+		if (low <= addr && high >= addr) {
+			if (perms[0] == 'r') {
+				ret |= PROT_READ;
+			}
+			if (perms[1] == 'w') {
+				ret |= PROT_WRITE;
+			}
+			if (perms[2] == 'x') {
+				ret |= PROT_EXEC;
+			}
+			break;
+		}
+	}
+
+	fclose(map);
+	return ret;
+}