extractor: Implement cum extractor

Signed-off-by: Chloe M. <chloe@mensia.org>

extractor/cum_xct.c

@@ -6,12 +6,14 @@
  * Author:       Chloe M.
  */
 
+#include <sys/stat.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
 #include <fcntl.h>
 #include <stddef.h>
+#include <libgen.h>
 
 #define REF_MAGIC "CUMHOLE"
 #define REF_MAGIC_LEN 8
@@ -36,6 +38,32 @@ struct hole_ref {
 /* Globals */
 static char *input_path = NULL;
 
+static void
+mkdir_recurse(const char *path)
+{
+    char buf[256];
+    char *p = NULL;
+    size_t len;
+
+    snprintf(buf, sizeof(buf), "%s", path);
+    len = strlen(buf);
+
+    /* Strip trailing slash */
+    if (buf[len - 1] == '/')
+        buf[len - 1] = '\0';
+
+    /* Make directory of each component */
+    for (p = buf; *p != '\0'; ++p) {
+        if (*p == '/') {
+            *p = '\0';
+            mkdir(buf, S_IRWXU);
+            *p = '/';
+        }
+    }
+
+    mkdir(buf, S_IRWXU);
+}
+
 static void
 help(void)
 {
@@ -44,9 +72,35 @@ help(void)
     printf("[-i]    Input CUMHOLE bundle\n");
 }
 
+static int
+push_file(const char *path, void *data, size_t size)
+{
+    int fd;
+
+    if (path == NULL || data == NULL) {
+        return -1;
+    }
+
+    fd = open(path, O_RDWR | O_CREAT, 0777);
+    if (fd < 0) {
+        printf("fatal: failed to open '%s'\n", path);
+        perror("open");
+        return -1;
+    }
+
+    write(fd, data, size);
+    close(fd);
+    return 0;
+}
+
 static void
 do_parse(struct hole_ref *ref)
 {
+    const char *directory_name;
+    struct hole_ref *ref_base = ref;
+    char *path;
+    void *data;
+
     if (ref == NULL) {
         return;
     }
@@ -56,7 +110,19 @@ do_parse(struct hole_ref *ref)
             break;
         }
 
-        printf("found '%s' with size %ld\n", ref->path, ref->size);
+        path = strdup(ref->path);
+        directory_name = dirname(path);
+        mkdir_recurse(directory_name);
+
+        printf("creating %s\n", ref->path);
+        data = (void *)((char *)ref_base + ref->data_off);
+
+        if (push_file(ref->path, data, ref->size) < 0) {
+            free(path);
+            return;
+        }
+
+        free(path);
         ++ref;
     }
 }