Bug fixes, error checking; V1 complete

.gitignore

@@ -0,0 +1 @@
+minihex

README.md

@@ -1,3 +1,13 @@
 # minihex
 
-A minimalist, single-file hexadecimal editor written in C with no dependencies (except the standard library). The program tries to be as simple as possible. Many bugs exist.
+A minimalist, single-file hexadecimal editor written in less than 100 lines of C with no dependencies (except the standard library). The program tries to be as simple as possible.
+Other features might be added in the future.
+
+## Usage
+
+```
+make
+./minihex <file>
+```
+
+To get help with the commands, do not provide any filename.

hex.c

@@ -1,7 +1,6 @@
 #include <stdio.h>
 #include <ctype.h>
 
-// TODO: Stop appending garbage at file end
 // TODO: Skip repeating lines
 
 #define BYTES 1024
@@ -13,7 +12,6 @@ void print_hex(unsigned char* buf, int byteno, int pos)
   {
     if (i % BYTES_PER_LINE == 0)
     {
-      //printf("%03d:  ", lineno);
       if (i != 0)
       {
         printf("  ");
@@ -26,7 +24,7 @@ void print_hex(unsigned char* buf, int byteno, int pos)
       puts("");
       // Here, we could print positions in hex but I prefer using integers. printf("%04X  ", i); 
       if (pos == 0) printf("\x1b[1;34m%06d:\x1b[0m   ", i);
-      else printf("\x1b[34m%06d:\x1b[0m   ", pos);
+      else printf("\x1b[1;34m%06d:\x1b[0m   ", pos);
     }
     printf("%.2X ", buf[i]);
   }
@@ -58,7 +56,12 @@ int main(int argc, char** argv)
     return -1;
   }
 
-  FILE* f = fopen(argv[1], "r");
+  FILE* f = fopen(argv[1], "rb+");
+  if (!f)
+  {
+    printf("Error opening file %s\n", argv[1]);
+    return -1;
+  }
   unsigned char buf[BYTES];
   int byteno = fread(buf, 1, BYTES, f);
   print_hex(buf, byteno, 0);
@@ -69,31 +72,25 @@ int main(int argc, char** argv)
     int loc;
      
     scanf(" %c", &cmd);
-    if (cmd == 'p' || cmd == 'P' || cmd == 'e' || cmd == 'E') scanf("%d", &loc);
+    if (cmd == 'p' || cmd == 'e') scanf("%d", &loc);
 
     switch(cmd)
     {
       case 'p': 
-      case 'P':
         print_hex(buf + loc, BYTES_PER_LINE, loc);
         break;
       case 'e':
-      case 'E':
-        scanf("%hhx", buf + loc);
+        int value;
+        scanf("%x", &value);
+        if (loc < byteno) buf[loc] = (unsigned char)value;
         break;
       case 's':
-      case 'S':
-        fclose(f);
-        f = fopen(argv[1], "w");
-        if (!f) {
-          perror("Error opening file for writing");
-          return -1;
-        }
-        fwrite(buf, 1, BYTES, f);
+        fseek(f, 0, SEEK_SET);
+        fwrite(buf, 1, byteno, f);
         fclose(f);
+        return 0;
         break;
       case 'q':
-      case 'Q':
         return 0;
     }
   }

test.txt

@@ -1,3 +1,3 @@
-?eÿlo, from a text file.
+ÿÿÿÿo, from a text file.
 This is a public service announcement
-brought to you in part by Slim Shady lol
+brought to you inCpart by Slim Shady lol