fs/fs: Add hex option to 'cat' in fs cli

This adds '-x' and '-X' arguments to 'cat' command in filesystem cli.
Both switches enable hex dump for file contents as either plain hex dump
or hex dump with offset markings.

compat> cat -x blob
F9 FB 10 10 20 C6 34 F6 46 56 36 F6 57 07 02 C4 B2 25 40 F9 FB 01 74 ...
20 11 91 F6 AF 21 B1 3B 02 57 7F 00 00 00 00 31 01 61 05 78 1D B0 CE ...
74 AB 92 B4 75 B7 65 02 17 7D FF FF FF FF

compat> cat -X blob
0000: F9 FB 10 10 20 C6 34 F6 46 56 36 F6 57 07 02 4C
0010: B2 25 40 F9 FB 01 74 00 57 E5 5D E8 91 00 81 21
0020: 20 11 91 F6 AF 21 B1 3B 02 57 7F 00 00 00 00 13
0030: 01 61 05 78 1D B0 CE DA C1 D6 6A 66 AB 03 78 06
0040: 74 AB 92 B4 75 B7 65 02 17 7D FF FF FF FF

Author: andrzej-kaczmarek

fs/fs/src/fs_cli.c

@@ -164,29 +164,56 @@ static int
 fs_cat_cmd(int argc, char **argv)
 {
     int rc;
+    const char *fname;
     struct fs_file *file;
     char buf[32];
+    bool plain_hex;
+    bool verbose_hex;
+    uint16_t offset = 0;
     uint32_t len;
+    int i;
 
-    if (argc != 2) {
-        console_printf("cat <filename>\n");
+    if (argc < 2) {
+        console_printf("cat [-x|X] <filename>\n");
         return -1;
     }
 
-    rc = fs_open(argv[1], FS_ACCESS_READ, &file);
+    plain_hex = !strcmp(argv[1], "-x");
+    verbose_hex = !strcmp(argv[1], "-X");
+
+    fname = plain_hex || verbose_hex ? argv[2] : argv[1];
+
+    rc = fs_open(fname, FS_ACCESS_READ, &file);
     if (rc != FS_EOK) {
-        console_printf("Error opening %s - %d\n", argv[1], rc);
+        console_printf("Error opening %s - %d\n", fname, rc);
         return -1;
     }
 
-    do {
-        rc = fs_read(file, sizeof(buf), buf, &len);
+    while (1) {
+        rc = fs_read(file, verbose_hex ? 16 : sizeof(buf), buf, &len);
         if (rc != FS_EOK) {
-            console_printf("\nError reading %s - %d\n", argv[1], rc);
+            console_printf("\nError reading %s - %d\n", fname, rc);
+            break;
+        }
+
+        if (len == 0) {
             break;
         }
-        console_write(buf, len);
-    } while (len > 0);
+
+        if (verbose_hex) {
+            console_printf("%04X: ", offset);
+        }
+        if (plain_hex || verbose_hex) {
+            for (i = 0; i < len; i++) {
+                console_printf("%02X ", buf[i]);
+            }
+            console_printf("\n");
+        } else {
+            console_write(buf, len);
+        }
+
+        offset += len;
+    }
 
     fs_close(file);