ref: 8a559beeb8af82f28deb6c731d74d3a3f65921f9
parent: 4d13d57491ab39034af7af05d4e42ea5a14793f2
author: Anthony J. Bentley <anthony@anjbe.name>
date: Wed Apr 4 20:00:22 EDT 2018
Rewrite rgbfix to perform most actions in memory. Limit file operations to a small number that can be reasonably checked, and do the majority of the actual work on a buffered header in memory where operations won't fail.
--- a/src/fix/main.c
+++ b/src/fix/main.c
@@ -207,9 +207,17 @@
err(1, "Error opening file %s", argv[argc - 1]);
/*
- * Write changes to ROM
+ * Read ROM header
+ *
+ * Offsets in the buffer are 0x100 less than the equivalent in ROM.
*/
+ uint8_t header[0x50];
+ if (fseek(rom, 0x100, SEEK_SET) != 0)
+ err(1, "Could not locate ROM header");
+ if (fread(header, sizeof(uint8_t), sizeof header, rom) != sizeof header)
+ err(1, "Could not read ROM header");
+
if (fixlogo || trashlogo) {/*
* Offset 0x104–0x133: Nintendo Logo
@@ -236,8 +244,7 @@
for (int i = 0; i < sizeof(ninlogo); i++)
ninlogo[i] = ~ninlogo[i];
- fseek(rom, 0x104, SEEK_SET);
- fwrite(ninlogo, 1, 48, rom);
+ memcpy(header + 0x04, ninlogo, sizeof ninlogo);
}
if (settitle) {@@ -258,11 +265,10 @@
* characters may conflict with the title.
*/
- fseek(rom, 0x134, SEEK_SET);
- fwrite(title, 1, strlen(title) + 1, rom);
+ int n = snprintf((char *)header + 0x34, 16, "%s", title);
- while (ftell(rom) < 0x143)
- fputc(0, rom);
+ for (int i = 16; i > n; i--)
+ header[0x34 + i] = '\0';
}
if (setid) {@@ -272,8 +278,7 @@
* characters).
*/
- fseek(rom, 0x13F, SEEK_SET);
- fwrite(id, 1, 4, rom);
+ memcpy(header + 0x3F, id, 4);
}
if (colorcompatible) {@@ -291,20 +296,12 @@
* may conflict.
*/
- uint8_t byte;
-
- fseek(rom, 0x143, SEEK_SET);
- byte = fgetc(rom);
-
- byte |= 1 << 7;
+ header[0x43] |= 1 << 7;
if (coloronly)
- byte |= 1 << 6;
+ header[0x43] |= 1 << 6;
- if (byte & 0x3F)
+ if (header[0x43] & 0x3F)
warnx("Color flag conflicts with game title");-
- fseek(rom, 0x143, SEEK_SET);
- fputc(byte, rom);
}
if (setnewlicensee) {@@ -320,8 +317,8 @@
* as a Super Game Boy flag.
*/
- fseek(rom, 0x144, SEEK_SET);
- fwrite(newlicensee, 1, 2, rom);
+ header[0x44] = newlicensee[0];
+ header[0x45] = newlicensee[1];
}
if (super) {@@ -340,8 +337,7 @@
if (!setlicensee)
warnx("You should probably set both '-s' and '-l 0x33'");- fseek(rom, 0x146, SEEK_SET);
- fputc(3, rom);
+ header[0x46] = 3;
}
if (setcartridge) {@@ -351,8 +347,7 @@
* external RAM, timer, rumble, or battery.
*/
- fseek(rom, 0x147, SEEK_SET);
- fputc(cartridge, rom);
+ header[0x47] = cartridge;
}
if (resize) {@@ -366,8 +361,10 @@
int headbyte;
uint8_t *buf;
- fseek(rom, 0, SEEK_END);
- romsize = ftell(rom);
+ if (fseek(rom, 0, SEEK_END) != 0)
+ err(1, "Could not pad ROM file");
+ if ((romsize = ftell(rom)) == -1)
+ err(1, "Could not pad ROM file");
newsize = 0x8000;
headbyte = 0;
@@ -379,12 +376,13 @@
if (newsize > 0x800000) /* ROM is bigger than 8MiB */
warnx("ROM size is bigger than 8MiB");- buf = malloc(newsize - romsize);
+ if ((buf = malloc(newsize - romsize)) == NULL)
+ err(1, "Could not pad ROM file");
memset(buf, padvalue, newsize - romsize);
- fwrite(buf, 1, newsize - romsize, rom);
+ if (fwrite(buf, 1, newsize - romsize, rom) != newsize - romsize)
+ err(1, "Could not pad ROM file");
- fseek(rom, 0x148, SEEK_SET);
- fputc(headbyte, rom);
+ header[0x48] = headbyte;
free(buf);
}
@@ -394,8 +392,7 @@
* Offset 0x149: RAM Size
*/
- fseek(rom, 0x149, SEEK_SET);
- fputc(ramsize, rom);
+ header[0x49] = ramsize;
}
if (nonjapan) {@@ -403,8 +400,7 @@
* Offset 0x14A: Non-Japanese Region Flag
*/
- fseek(rom, 0x14A, SEEK_SET);
- fputc(1, rom);
+ header[0x4A] = 1;
}
if (setlicensee) {@@ -420,8 +416,7 @@
* See also: the New Licensee ID at 0x144–0x145.
*/
- fseek(rom, 0x14B, SEEK_SET);
- fputc(licensee, rom);
+ header[0x4B] = licensee;
}
if (setversion) {@@ -430,8 +425,7 @@
* Which version of the ROM this is.
*/
- fseek(rom, 0x14C, SEEK_SET);
- fputc(version, rom);
+ header[0x4C] = version;
}
if (fixheadsum || trashheadsum) {@@ -441,17 +435,26 @@
uint8_t headcksum = 0;
- fseek(rom, 0x134, SEEK_SET);
- for (int i = 0; i < (0x14D - 0x134); ++i)
- headcksum = headcksum - fgetc(rom) - 1;
+ for (int i = 0x34; i < 0x4D; ++i)
+ headcksum = headcksum - header[i] - 1;
if (trashheadsum)
headcksum = ~headcksum;
- fseek(rom, 0x14D, SEEK_SET);
- fputc(headcksum, rom);
+ header[0x4D] = headcksum;
}
+ /*
+ * Before calculating the global checksum, we must write the modified
+ * header to the ROM.
+ */
+
+ if (fseek(rom, 0x100, SEEK_SET) != 0)
+ err(1, "Could not locate header for writing");
+
+ if (fwrite(header, sizeof(uint8_t), sizeof header, rom) != sizeof header)
+ err(1, "Could not write modified ROM header");
+
if (fixglobalsum || trashglobalsum) {/*
* Offset 0x14E–0x14F: Global Checksum
@@ -459,15 +462,19 @@
uint16_t globalcksum = 0;
- rewind(rom);
- for (int i = 0; i < 0x14E; ++i)
- globalcksum += fgetc(rom);
+ if (fseek(rom, 0, SEEK_SET) != 0)
+ err(1, "Could not start calculating global checksum");
+ int i = 0;
int byte;
+ while ((byte = fgetc(rom)) != EOF) {+ i++;
+ if (i != 0x150)
+ globalcksum += byte;
+ }
- fseek(rom, 0x150, SEEK_SET);
- while ((byte = fgetc(rom)) != EOF)
- globalcksum += byte;
+ if (ferror(rom))
+ err(1, "Could not calculate global checksum");
if (trashglobalsum)
globalcksum = ~globalcksum;
@@ -475,9 +482,12 @@
fseek(rom, 0x14E, SEEK_SET);
fputc(globalcksum >> 8, rom);
fputc(globalcksum & 0xFF, rom);
+ if (ferror(rom))
+ err(1, "Could not write global checksum");
}
- fclose(rom);
+ if (fclose(rom) != 0)
+ err(1, "Could not complete ROM write");
return 0;
}