add some amount of redundancy to save files

4 files changed, 96 insertions, 29 deletions

diff --git a/src/globals.h b/src/globals.h
index 60cd40c..c336aa4 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -80,39 +80,38 @@ struct command_t {
 };
 
 /*** prototypes ***/
-void cleanup(void);
-int compare_stocks(const void*, const void*);
-void all_lower(char*);
-void all_upper(char*);
+
+void do_menu(struct player_t*, const struct command_t*, uint len, const char *prompt);
 bool get_stock_info(char *sym, struct money_t*, char **name);
-uint64_t to_sys64(uint64_t);
-uint64_t to_be64(uint64_t);
-uint32_t to_sys32(uint32_t);
-uint32_t to_be32(uint32_t);
-uint16_t to_sys16(uint16_t);
-uint16_t to_be16(uint16_t);
+char *csv_read(char**);
+char *read_string(void);
+char *read_ticker(void);
+int compare_stocks(const void*, const void*);
 struct stock_t *find_stock(struct player_t*, char*);
+uint parse_args(struct player_t*, int argc, char *argv[]);
+uint16_t to_be16(uint16_t);
+uint16_t to_sys16(uint16_t);
+uint32_t to_be32(uint32_t);
+uint32_t to_sys32(uint32_t);
+uint64_t to_be64(uint64_t);
+uint64_t to_sys64(uint64_t);
+ullong read_int(void);
 void add_hist(struct stock_t*, enum history_action, ullong count);
+void all_lower(char*);
+void all_upper(char*);
+void cleanup(void);
+void load_portfolio(struct player_t*, const char*);
 void print_history(struct stock_t*);
-char *read_ticker(void);
-char *read_string(void);
-ullong read_int(void);
 void print_usage(int argc, char *argv[]);
 void print_version(void);
 
-uint parse_args(struct player_t*, int argc, char *argv[]);
-char *csv_read(char**);
-void load_portfolio(struct player_t*, const char*);
-
 void buy_handler(struct player_t*);
-void sell_handler(struct player_t*);
 void info_handler(struct player_t*);
-void update_handler(struct player_t*);
-void save_handler(struct player_t*);
 void load_handler(struct player_t*);
-void quit_handler(struct player_t*);
 void print_handler(struct player_t*);
-
-void do_menu(struct player_t*, const struct command_t*, uint len, const char *prompt);
+void quit_handler(struct player_t*);
+void save_handler(struct player_t*);
+void sell_handler(struct player_t*);
+void update_handler(struct player_t*);
 
 #endif
diff --git a/src/load.c b/src/load.c
index fcb2147..526592e 100644
--- a/src/load.c
+++ b/src/load.c
@@ -4,12 +4,21 @@
 
 #define FAIL() exit(EXIT_FAILURE);
 
+static uint32_t cksum;
+
+#define ADD_CKSUM(x) (cksum += (x*x) + 1)
+
 uint64_t read_be64(FILE *f)
 {
     uint64_t n;
     if(fread(&n, sizeof(n), 1, f) != 1)
         FAIL();
-    return to_sys64(n);
+
+    n = to_sys64(n);
+
+    ADD_CKSUM(n);
+
+    return n;
 }
 
 uint32_t read_be32(FILE *f)
@@ -17,7 +26,23 @@ uint32_t read_be32(FILE *f)
     uint32_t n;
     if(fread(&n, sizeof(n), 1, f) != 1)
         FAIL();
-    return to_sys32(n);
+
+    n = to_sys32(n);
+
+    ADD_CKSUM(n);
+
+    return n;
+}
+
+uint32_t read_be32_nocheck(FILE *f)
+{
+    uint32_t n;
+    if(fread(&n, sizeof(n), 1, f) != 1)
+        FAIL();
+
+    n = to_sys32(n);
+
+    return n;
 }
 
 uint16_t read_be16(FILE *f)
@@ -25,7 +50,12 @@ uint16_t read_be16(FILE *f)
     uint16_t n;
     if(fread(&n, sizeof(n), 1, f) != 1)
         FAIL();
-    return to_sys16(n);
+
+    n = to_sys16(n);
+
+    ADD_CKSUM(n);
+
+    return n;
 }
 
 uint8_t read_int8(FILE *f)
@@ -33,6 +63,9 @@ uint8_t read_int8(FILE *f)
     uint8_t n;
     if(fread(&n, sizeof(n), 1, f) != 1)
         FAIL();
+
+    ADD_CKSUM(n);
+
     return n;
 }
 
@@ -46,6 +79,8 @@ void load_portfolio(struct player_t *player, const char *filename)
     player->portfolio_len = 0;
     player->portfolio = NULL;
 
+    cksum = 0;
+
     FILE *f = fopen(filename, "rb");
 
     char magic[6];
@@ -112,6 +147,15 @@ void load_portfolio(struct player_t *player, const char *filename)
                 hist = hist->next;
             }
         }
+
+        uint32_t ck = read_be32_nocheck(f);
+
+        if(ck != cksum)
+        {
+            printf("FATAL: bad checksum, file is corrupt.\n%d %d", ck, cksum);
+            exit(EXIT_FAILURE);
+        }
+
         int junk = fgetc(f);
         ungetc(junk, f);
 
diff --git a/src/main.c b/src/main.c
index c604dc0..41dcc48 100644
--- a/src/main.c
+++ b/src/main.c
@@ -33,8 +33,8 @@ int main(int argc, char *argv[])
             { "[P]rint portfolio", "print", print_handler },
             { "[U]pdate stock prices", "update", update_handler },
             { "Stock [i]nfo", "info", info_handler },
-            { "[W]rite portfolio", "write", save_handler },
-            { "[L]oad portfolio", "load", load_handler },
+            { "[L]oad portfolio from disk", "load", load_handler },
+            { "[W]rite portfolio to disk", "write", save_handler },
             { "[Q]uit", "quit", quit_handler },
         };
 
diff --git a/src/save.c b/src/save.c
index 27c5e8e..48dd069 100644
--- a/src/save.c
+++ b/src/save.c
@@ -1,9 +1,15 @@
 #include "globals.h"
 
-/* NOTE: integers are represented internally by long long ints, but in the save they are always 64 bits */
+/* NOTE: integers are represented internally as long long ints, but in the save they are always 64 bits */
+
+static uint64_t cksum;
+
+#define ADD_CKSUM(x) (cksum += (x*x) + 1)
 
 static bool write_be64(FILE *f, uint64_t n)
 {
+    ADD_CKSUM(n);
+
     n = to_be64(n);
     if(fwrite(&n, sizeof(n), 1, f) != 1)
         return false;
@@ -12,6 +18,16 @@ static bool write_be64(FILE *f, uint64_t n)
 
 static bool write_be32(FILE *f, uint32_t n)
 {
+    ADD_CKSUM(n);
+
+    n = to_be32(n);
+    if(fwrite(&n, sizeof(n), 1, f) != 1)
+        return false;
+    return true;
+}
+
+static bool write_be32_noupdate(FILE *f, uint32_t n)
+{
     n = to_be32(n);
     if(fwrite(&n, sizeof(n), 1, f) != 1)
         return false;
@@ -20,6 +36,8 @@ static bool write_be32(FILE *f, uint32_t n)
 
 static bool write_be16(FILE *f, uint16_t n)
 {
+    ADD_CKSUM(n);
+
     n = to_be16(n);
     if(fwrite(&n, sizeof(n), 1, f) != 1)
         return false;
@@ -28,6 +46,8 @@ static bool write_be16(FILE *f, uint16_t n)
 
 static bool write_int8(FILE *f, uint8_t n)
 {
+    ADD_CKSUM(n);
+
     if(fwrite(&n, sizeof(n), 1, f) != 1)
         return false;
     return true;
@@ -44,6 +64,8 @@ void save_handler(struct player_t *player)
 
     free(filename);
 
+    cksum = 0;
+
     const char *magic = "PORTv2";
     fwrite(magic, strlen(magic), 1, f);
 
@@ -78,6 +100,8 @@ void save_handler(struct player_t *player)
 
             hist = hist->next;
         }
+
+        write_be32_noupdate(f, cksum);
     }
 
     fclose(f);