1 files changed, 87 insertions, 0 deletions
diff --git a/src/mem/io-ptrace.c b/src/mem/io-ptrace.c
new file mode 100644
index 0000000..cf9a861
--- /dev/null
+++ b/src/mem/io-ptrace.c
@@ -0,0 +1,87 @@
+#include "io.h"
+#include <stdio.h>
+#include <err.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+
+static size_t
+mem_io_ptrace_do(const struct mem_io *io, void *ptr, const size_t offset, const size_t size, size_t (*iofun)(void*, size_t, size_t, FILE*))
+{
+   if (fseek(io->backing, offset, SEEK_SET) != 0) {
+      warn("fseek(/proc/%u/mem, %zu)", io->pid, offset);
+      return 0;
+   }
+
+   return iofun(ptr, 1, size, io->backing);
+}
+
+static size_t
+mem_io_ptrace_write(const struct mem_io *io, const void *ptr, const size_t offset, const size_t size)
+{
+   clearerr(io->backing);
+   const size_t ret = mem_io_ptrace_do(io, (void*)ptr, offset, size, (size_t(*)())fwrite);
+
+   if (ferror(io->backing))
+      warn("fwrite(/proc/%u/mem)", io->pid);
+
+   return ret;
+}
+
+static size_t
+mem_io_ptrace_read(const struct mem_io *io, void *ptr, const size_t offset, const size_t size)
+{
+   clearerr(io->backing);
+   const size_t ret = mem_io_ptrace_do(io, ptr, offset, size, fread);
+
+   if (ferror(io->backing))
+      warn("fread(/proc/%u/mem)", io->pid);
+
+   return ret;
+}
+
+static void
+mem_io_ptrace_cleanup(struct mem_io *io)
+{
+   if (io->backing)
+      fclose(io->backing);
+
+   if (io->pid)
+      ptrace(PTRACE_DETACH, io->pid, 1, 0);
+}
+
+bool
+mem_io_ptrace_init(struct mem_io *io, const pid_t pid)
+{
+   *io = (struct mem_io){
+      .pid = pid,
+      .read = mem_io_ptrace_read,
+      .write = mem_io_ptrace_write,
+      .cleanup = mem_io_ptrace_cleanup
+   };
+
+   if (ptrace(PTRACE_ATTACH, pid, NULL, NULL) == -1L) {
+      warn("ptrace(PTRACE_ATTACH, %u, NULL, NULL)", pid);
+      goto fail;
+   }
+
+   {
+      int status;
+      if (waitpid(pid, &status, 0) == -1 || !WIFSTOPPED(status)) {
+         warn("waitpid(%u) == %d", pid, status);
+         goto fail;
+      }
+   }
+
+   char path[128];
+   snprintf(path, sizeof(path), "/proc/%u/mem", pid);
+   if (!(io->backing = fopen(path, "w+b"))) {
+      warn("fopen(%s)", path);
+      goto fail;
+   }
+
+   return true;
+
+fail:
+   io->cleanup(io);
+   return false;
+}