memzap

commit 6c668ce4b667ea2dd1ffa6095f432a5238d6d4b5
parent 06ca031645eab753df49d17d83d38f276c88fae4
Author: sin <sin@2f30.org>
Date:   Mon,  4 Mar 2013 14:27:56 +0000

memzap: Add some comments throughout the code

Diffstat:
M
memzap.c
 | 
18
++++++++++++++++++

1 file changed, 18 insertions(+), 0 deletions(-)
diff --git a/memzap.c b/memzap.c
@@ -121,6 +121,7 @@ main(int argc, char *argv[])
 	if (!WIFSTOPPED(stat))
 		goto out_mmap;
 
+	/* Create .mdiff file and initialize the header */
 	snprintf(mdiff_path, sizeof(mdiff_path),
 		 "%s.mdiff", *argv);
 	fd = create_mdiff(mdiff_path);
@@ -130,20 +131,28 @@ main(int argc, char *argv[])
 	hdr.endianness = 0;
 	hdr.version = 1;
 	mdiff_start_diff(fd);
+
+	/* Trace the child process and diff the memory regions
+	 * per instruction */
 	do {
+		/* Read in the Nth generation of the traced region */
 		readmem(pid, buf, addr, len);
 		if (!once) {
 			dump_base_image(*argv, buf, len);
 			once = true;
 		}
 
+		/* Build a memory region that tracks this buffer */
 		mr_old = build_mem_region(buf, len);
 		if (!mr_old)
 			errx(1, "Failed to build memory region\n");
+		/* Build an rbtree that tracks this memory region */
 		mt_old = build_mem_tree(mr_old);
 		if (!mt_old)
 			errx(1, "Failed to build memory tree\n");
 
+		/* Single step the child in order to get the next
+		 * generation */
 		single_step(pid);
 		wait(&stat);
 		if (!WIFSTOPPED(stat)) {
@@ -152,23 +161,32 @@ main(int argc, char *argv[])
 			break;
 		}
 
+		/* Read in the (N + 1)th generation of the traced
+		 * region */
 		readmem(pid, buf_new, addr, len);
 
+		/* Build a memory region that tracks this buffer */
 		mr_new = build_mem_region(buf_new, len);
 		if (!mr_new)
 			errx(1, "Failed to build memory region\n");
+
+		/* Diff the original copy with the updated copy */
 		rdiff = diff_mem_region(mt_old, mr_new);
 		if (rdiff->nmrdiffs) {
+			/* If we've found differences, then apply them on
+			 * the Nth generation */
 			apply_diff(mr_old, rdiff);
 			hdr.nregions += mdiff_append_rdiff(fd, rdiff);
 		}
 
+		/* Free these and go up for another run */
 		free_mem_region(mr_old);
 		free_mem_tree(mt_old);
 		free_mem_region(mr_new);
 		free_mem_region_diff(rdiff);
 	} while(1);
 
+	/* Insert header at the start of the .mdiff file */
 	mdiff_insert_hdr(fd, &hdr);
 	close_mdiff(fd);
 out_mmap: