Implement general purpose CLI tool

Makefile

@@ -0,0 +1,6 @@
+.PHONY: examples
+
+examples: examples/example_cli.c
+
+examples/example_cli.c:
+	clang -Wall -g -Isrc -o examples/empack_cli src/empack.c examples/empack_cli.c

examples/empack_cli.c

@@ -6,6 +6,8 @@
 
 #include "empack.h"
 
+
+
 #define USAGE                                                          \
 "empack_cli [OPTIONS] <file | msgpack hex>\r\n"                        \
 "    file: File to read binary Msgpack data from, \"-\" for stdin\r\n" \
@@ -14,25 +16,121 @@
 "OPTIONS\r\n"                                                          \
 "    -h/--help: Print this message\r\n"
 
+
+
+static int
+char_to_nibble(char c, uint8_t *nibble)
+{
+    if ((c >= '0') && (c <= '9')) {
+        (*nibble) = c - '0';
+    } else if ((c >= 'a') && (c <= 'f')) {
+        (*nibble) = c - 'a' + 0x0a;
+    } else if ((c >= 'A') && (c <= 'F')) {
+        (*nibble) = c - 'A' + 0x0a;
+    } else {
+        return (-1);
+    }
+
+    return (0);
+}
+
 static void
 print_func(const char *buf, uint32_t buflen, void *arg)
 {
     printf("%.*s", buflen, buf);
 }
 
+
+
 int
 main(int argc, char **argv)
 {
-    const uint8_t input[] = { 0x82, 0xa7, 0x63, 0x6f, 0x6d, 0x70, 0x61, 0x63, 0x74, 0xc3, 0xa6, 0x73, 0x63, 0x68, 0x65, 0x6d, 0x61, 0x00 };
-    size_t input_len = sizeof(input);
     empack_t empack;
-    uint8_t arena[256];
+    uint8_t arena[0x4000];
-    uint32_t chars_printed;
+    struct stat file_stat;
+    uint8_t *input = NULL;
+    size_t input_len = 0;
+    size_t input_bufsz = 0;
+    uint32_t chars_printed = 0;
+
+    if (argc != 2) {
+        fprintf(stderr, USAGE);
+        return (-1);
+    }
+
+    if ((!strcmp(argv[1], "-h")) || (!strcmp(argv[1], "--help"))) {
+        printf(USAGE);
+        return (0);
+    }
+
+    if (!strcmp(argv[1], "-")) {
+        /* read bytes from stdin */
+        while (1) {
+            size_t read;
+
+            input_bufsz += 1024;
+            input = realloc(input, input_bufsz);
+
+            read = fread(&input[input_len], 1, input_bufsz, stdin);
+            if (read == 0) {
+                break;
+            }
+
+            input_len += read;
+        }
+    } else if (stat(argv[1], &file_stat) == 0) {
+        /* read bytes from a file */
+        FILE *fd = fopen(argv[1], "r");
+        if (fd == NULL) {
+            fprintf(stderr, "Failed to open file \"%s\"\r\n", argv[1]);
+            return (-1);
+        }
+
+        input_bufsz = file_stat.st_size;
+        input = malloc(input_bufsz);
+        input_len = fread(input, 1, input_bufsz, fd);
+        fclose(fd);
+
+        if (input_len != input_bufsz) {
+            fprintf(stderr, "Failed to read file \"%s\"\r\n", argv[1]);
+            return (-1);
+        }
+    } else {
+        /* interpret argument as hex data */
+        size_t arg_sz = strlen(argv[1]);
+        if ((arg_sz % 2) != 0) {
+            fprintf(stderr, "Invalid hex data - odd number of characters\r\n");
+            return (-1);
+        }
+
+        input_bufsz = arg_sz / 2;
+        input = malloc(input_bufsz);
+        if (input == NULL) {
+            fprintf(stderr, "Failed to allocate appropriate resources\r\n");
+            return (-1);
+        }
+
+        for (size_t i = 0; i < arg_sz; i += 2) {
+            uint8_t hi;
+            uint8_t lo;
+
+            if (char_to_nibble(argv[1][i], &hi) ||
+                char_to_nibble(argv[1][i+1], &lo)) {
+                fprintf(stderr, "Invalid hex byte at offset %u\r\n", (uint32_t)(i / 2));
+                free(input);
+                return (-1);
+            }
+
+            input[input_len] = (hi << 4) | lo;
+            input_len++;
+        }
+    }
 
     empack_init(&empack, arena, sizeof(arena));
 
     if (empack_parse(&empack, input, input_len)) {
         fprintf(stderr, "Parsing error\r\n");
+        free(input);
         return (-1);
     }
 
@@ -46,5 +144,6 @@ main(int argc, char **argv)
            empack.arena_sz,
            (empack.arena_used * 100) / empack.arena_sz);
 
+    free(input);
     return (0);
 }