added and tested input file size checks

kpack_c.c

@@ -1,9 +1,11 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <stdbool.h>
 #include <unistd.h>
 #include <getopt.h>
-#include <string.h>
-#include <stdbool.h>
+#include <sys/stat.h>
 
 /*
 TODO
@@ -47,8 +49,8 @@ int main(int argc, char *argv[])
     }
     // Check for required infile
     if (optind >= argc) {
-        fprintf(stderr, "Error: Input file is required.\n");
-        fprintf(stderr, str_usage, argv[0]);
+        printf("Error: Input file is required.\n");
+        printf(str_usage, argv[0]);
         return 1;
     }
     infile = argv[optind];
@@ -61,8 +63,8 @@ int main(int argc, char *argv[])
 
     // printf("argc = %d, optind = %d\n", argc - 1, optind);
     if (argc - 1 > optind) {
-        fprintf(stderr, "Error: too many arguments\n");
-        fprintf(stderr, str_usage, argv[0]);
+        printf("Error: too many arguments\n");
+        printf(str_usage, argv[0]);
         return 1;
     }
 
@@ -72,8 +74,32 @@ int main(int argc, char *argv[])
     printf("unpack: %s\n", unpack ? "true" : "false");
     printf("infile: %s\n", infile);
     printf("outfile: %s\n", outfile ? outfile : "Not specified");
+    printf("\n");
 
-    // TODO logic here
+    if (!nologo) {
+        printf("KPackC - Kolibri Packer in C\nUses LZMA v4.32 compression library\n\n");
+    }
+
+    struct stat64 statbuf;
+    int res_stat = stat64(infile, &statbuf);
+    if (res_stat == -1) {
+        printf("Error: cannot load input file\n");
+        return 1;
+    }
+    // printf("statbuf.st_size = %lld\n", statbuf.st_size);
+
+    if (statbuf.st_size == 0 || statbuf.st_size >= 4294967296LL) {
+        printf("Error: input file must be non zero and less than 4G\n");
+        return 1;
+    }
+    unsigned infile_size = (unsigned int)statbuf.st_size;
+    printf("infile_size = %u\n", infile_size);
+
+    FILE *infile_handle = fopen(infile, "rb");
+    if (!infile_handle) {
+        printf("Error: cannot load input file\n");
+        return 1;
+    }
 
     return 0;
 }