feat: .tar application loading

src/fs/tar.c

@@ -0,0 +1,128 @@
+// Copyright (c) 2023-2026 Chris (boreddevnl)
+// This software is released under the GNU General Public License v3.0. See LICENSE file for details.
+// This header needs to maintain in any file it is present in, as per the GPL license terms.
+#include "tar.h"
+#include "fat32.h"
+
+// The standard TAR header block is 512 bytes.
+struct tar_header {
+    char filename[100];
+    char mode[8];
+    char uid[8];
+    char gid[8];
+    char size[12];
+    char mtime[12];
+    char chksum[8];
+    char typeflag;
+    char linkname[100];
+    char magic[6];
+    char version[2];
+    char uname[32];
+    char gname[32];
+    char devmajor[8];
+    char devminor[8];
+    char prefix[155];
+    char pad[12];
+} __attribute__((packed));
+
+// Helper: parse tar octal field representation
+static uint64_t tar_parse_octal(const char *str, int size) {
+    uint64_t result = 0;
+    while (size-- > 0) {
+        if (*str >= '0' && *str <= '7') {
+            result = (result << 3) + (*str - '0');
+        }
+        str++;
+    }
+    return result;
+}
+
+// Helper: Make directories sequentially for nested paths
+static void tar_mkdir_recursive(const char *path) {
+    char temp[256];
+    int i = 0;
+    if (path[0] == '/') {
+        temp[0] = '/';
+        i = 1;
+    }
+    while (path[i] && i < 255) {
+        temp[i] = path[i];
+        if (path[i] == '/') {
+            temp[i] = '\0';
+            fat32_mkdir(temp);
+            temp[i] = '/';
+        }
+        i++;
+    }
+    if (i > 0 && temp[i - 1] != '/') {
+        temp[i] = '\0';
+        fat32_mkdir(temp);
+    }
+}
+
+void tar_parse(void *archive, uint64_t archive_size) {
+    uint8_t *ptr = (uint8_t *)archive;
+    uint8_t *end = ptr + archive_size;
+
+    while (ptr + 512 <= end) {
+        struct tar_header *header = (struct tar_header *)ptr;
+
+        // End of archive is marked by empty blocks
+        if (header->filename[0] == '\0') {
+            break;
+        }
+
+        uint64_t file_size = tar_parse_octal(header->size, 11);
+        
+        char full_path[256];
+        // Ensure path starts with a '/' for VFS consistency
+        if (header->filename[0] != '/') {
+            full_path[0] = '/';
+            int j = 0;
+            while (header->filename[j] && j < 254) {
+                full_path[j + 1] = header->filename[j];
+                j++;
+            }
+            full_path[j + 1] = '\0';
+        } else {
+            int j = 0;
+            while (header->filename[j] && j < 255) {
+                full_path[j] = header->filename[j];
+                j++;
+            }
+            full_path[j] = '\0';
+        }
+
+        if (header->typeflag == '5') {
+            // It's a directory
+            tar_mkdir_recursive(full_path);
+        } else if (header->typeflag == '0' || header->typeflag == '\0') {
+            // It's a normal file
+            // First ensure the parent directory exists
+            char parent_path[256];
+            int last_slash = -1;
+            for (int j = 0; full_path[j]; j++) {
+                parent_path[j] = full_path[j];
+                if (full_path[j] == '/') {
+                    last_slash = j;
+                }
+            }
+            if (last_slash > 0) {
+                parent_path[last_slash] = '\0';
+                tar_mkdir_recursive(parent_path);
+            }
+            
+            // Extract the file data block directly into the VFS
+            FAT32_FileHandle *fh = fat32_open(full_path, "w");
+            if (fh && fh->valid) {
+                fat32_write(fh, ptr + 512, file_size);
+                fat32_close(fh);
+            }
+        }
+        
+        // Advance pointer to the next file header
+        // Header block (512) + File data (padded to 512-byte multiples)
+        uint64_t data_blocks = (file_size + 511) / 512;
+        ptr += 512 + (data_blocks * 512);
+    }
+}