core: Add file counting + state management

Signed-off-by: Ian Moffett <ian@mirocom.org>

src/main.c

@@ -1,9 +1,32 @@
+#define _DEFAULT_SOURCE
 #include <stdio.h>
+#include <stdint.h>
+#include <errno.h>
 #include <unistd.h>
+#include <dirent.h>
 #include <fcntl.h>
+#include <string.h>
 
 #define CAV_VERSION "0.0.1"
 
+static const char *input_name = NULL;
+static const char *output_name = "out.cav";
+
+/*
+ * Represents the consume and vomit state machine
+ *
+ * @dir_fd: Input directory file descriptor
+ * @dir: Opened directory
+ * @pass_count: Number of passes made in file
+ * @file_count: Number of files encountered including subdirectories
+ */
+struct cav_state {
+    int dir_fd;
+    DIR *dir;
+    uint8_t pass_count;
+    size_t file_count;
+};
+
 static void
 help(void)
 {
@@ -12,6 +35,8 @@ help(void)
         "--------------------------\n"
         "[-h]   Display this help menu\n"
         "[-v]   Display the version\n"
+        "[-i]   Input directory\n"
+        "[-o]   Output filename\n"
     );
 }
 
@@ -27,12 +52,119 @@ version(void)
     );
 }
 
+/*
+ * Initialize the cav state machine
+ *
+ * @state: State to initialize
+ *
+ * Returns zero on success
+ */
+static int
+state_init(struct cav_state *state)
+{
+    if (state == NULL) {
+        errno = -EINVAL;
+        return -1;
+    }
+
+    state->dir_fd = open(input_name, O_RDONLY);
+    if (state->dir_fd < 0) {
+        return -1;
+    }
+
+    state->dir = fdopendir(state->dir_fd);
+    if (state->dir == NULL) {
+        close(state->dir_fd);
+        return -1;
+    }
+
+    state->pass_count = 0;
+    return 0;
+}
+
+/*
+ * Destroy the consume and vomit state
+ *
+ * @state: State to destroy
+ */
+static void
+state_destroy(struct cav_state *state)
+{
+    if (state == NULL) {
+        return;
+    }
+
+    closedir(state->dir);
+    close(state->dir_fd);
+}
+
+/*
+ * Begin recursively scanning a directory to obtain information
+ * needed to structure the offsets at the beginning of the file.
+ */
+static void
+consume_scan(const char *dir_path, struct cav_state *state, DIR *subdir)
+{
+    struct dirent *dirent;
+    char buf[256];
+    DIR *dir;
+
+    if (dir_path == NULL || state == NULL) {
+        return;
+    }
+
+    dir = (subdir == NULL) ? state->dir : subdir;
+    while ((dirent = readdir(dir)) != NULL) {
+        if (dirent->d_name[0] == '.') {
+            continue;
+        }
+
+        switch (dirent->d_type) {
+        case DT_DIR:
+            snprintf(buf, sizeof(buf), "%s/%s", dir_path, dirent->d_name);
+            if ((subdir = opendir(buf)) == NULL) {
+                printf("failed to open subdir %s\n", buf);
+                perror("opendir");
+                continue;
+            }
+
+            consume_scan(buf, state, subdir);
+            break;
+        default:
+            ++state->file_count;
+            break;
+        }
+    }
+}
+
+/*
+ * Consume a single pass in our yummy yummy consumption
+ * process only to be thrown up again along with stomach
+ * acids of your extraterrestrial friends.
+ */
+static void
+consume_pass(struct cav_state *state)
+{
+    if (state == NULL) {
+        return;
+    }
+
+    switch (state->pass_count++) {
+    case 0:
+        /* Scan pass */
+        consume_scan(input_name, state, NULL);
+        printf("[pass 0] scanned %zu files\n", state->file_count);
+        break;
+    }
+}
+
 int
 main(int argc, char **argv)
 {
+    struct cav_state state;
     int opt;
 
-    while ((opt = getopt(argc, argv, "hv")) != -1) {
+    while ((opt = getopt(argc, argv, "hvi:o:")) != -1) {
         switch (opt) {
         case 'h':
             help();
@@ -40,8 +172,37 @@ main(int argc, char **argv)
         case 'v':
             version();
             return -1;
+        case 'i':
+            input_name = strdup(optarg);
+            break;
+        case 'o':
+            output_name = strdup(optarg);
+            break;
         }
     }
 
+    if (input_name == NULL) {
+        printf("fatal: expected input path\n");
+        return -1;
+    }
+
+    /* Initialize the state machine */
+    if (state_init(&state) < 0) {
+        perror("state_init");
+        return -1;
+    }
+
+    /*
+     * There are three passes required in the consumption operation
+     *
+     * pass 0): Obtain number of files for offset table creation
+     * pass 1): Construct an offset table using what we know
+     * pass 2): Construct the archive segments
+     */
+    for (int i = 0; i < 2; ++i) {
+        consume_pass(&state);
+    }
+
+    state_destroy(&state);
     return 0;
 }